@article {rieb_controls_2024,
	title = {Controls on the Respiration of Ancient Carbon Draining From Permafrost Soils Into Sunlit Arctic Surface Waters},
	journal = {Journal of Geophysical Research: Biogeosciences},
	volume = {129},
	number = {5},
	year = {2024},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2023JG007853},
	month = {05/2024},
	pages = {e2023JG007853},
	abstract = {The thawing of ancient organic carbon stored in arctic permafrost soils, and its oxidation to carbon dioxide (CO2, a greenhouse gas), is predicted to amplify global warming. However, the extent to which organic carbon in thawing permafrost soils will be released as CO2 is uncertain. A critical unknown is the extent to which dissolved organic carbon (DOC) from thawing permafrost soils is respired to CO2 by microbes upon export of freshly thawed DOC to both dark bottom waters and sunlit surface waters. In this study, we quantified the radiocarbon age and 13C composition of CO2 produced by microbial respiration of DOC that was leached from permafrost soils and either kept in the dark or exposed to ultraviolet and visible wavelengths of light. We show that permafrost DOC most labile to microbial respiration was as old or older (ages 4,000{\textendash}11,000 a BP) and more 13C-depleted than the bulk DOC in both dark and light-exposed treatments, likely indicating respiration of old, 13C-depleted lignin and lipid fractions of the permafrost DOC pool. Light exposure either increased, decreased, or had no effect on the magnitude of microbial respiration of old permafrost DOC relative to respiration in the dark, depending on both the extent of DOC oxidation during exposure to light and the wavelength of light. Together, these findings suggest that photochemical changes affecting the lability of permafrost DOC during sunlight exposure are an important control on the magnitude of microbial respiration of permafrost DOC in arctic surface waters.},
	keywords = {Arctic, dissolved organic carbon, permafrost, photochemistry, radiocarbon, respiration},
	issn = {2169-8961},
	doi = {10.1029/2023JG007853},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2023JG007853},
	author = {Rieb, E. C. and Polik, C. A. and Ward, C. P. and Kling, G. W. and Cory, R. M.}
}
@article {broek_improving_2024,
	title = {Improving Ionplus MICADAS performance with recessed graphite},
	journal = {Radiocarbon},
	year = {2024},
	note = {Place: EDINBURGH BLDG, SHAFTESBURY RD, CB2 8RU CAMBRIDGE, ENGLAND Publisher: CAMBRIDGE UNIV PRESS Type: Article; Early Access},
	month = {04/2024},
	abstract = {Cathodes with recessed sample surfaces have several benefits in cesium sputter ion sources, including higher output, more efficient use of sample material, and improved focusing of the extracted ion beam. However, the Ionplus MICADAS uses cathodes with a graphite surface that is essentially flush with the sample holder. To evaluate the performance of recessed graphite with the MICADAS and determine the optimal surface depth, we tested four different depths, including the standard (flush) pressing method, 0.5 mm, 1.0 mm, and 1.5 mm. We found that recessed depths of 1.0 and 1.5 mm resulted in 20\% higher ion beam current compared to the standard method under the same source conditions. The results are consistent with the beam produced from the recessed targets being more narrowly focused with a lower emittance, resulting in better transmission through the accelerator. Small graphite samples (200 mu g C) with recessed surfaces produced higher currents for longer, leading to a 2-3x increase in sample ionization efficiency. Additionally, there was some evidence that isotopic ratio measurements of recessed samples were more stable over time. Overall, samples recessed to 1 mm depth offered numerous advantages over the standard pressing method and we have subsequently started pressing all MICADAS graphite using this approach.},
	keywords = {AMS, MICADAS, radiocarbon},
	issn = {0033-8222},
	doi = {10.1017/RDC.2024.36},
	url = {https://www.cambridge.org/core/journals/radiocarbon/article/abs/improving-ionplus-micadas-performance-with-recessed-graphite/F8B44939DDC06FBFD1ED93D5DB7C8456},
	author = {Broek, Taylor A. B. and Roberts, Mark L.}
}
@article {miles_interactions_2024,
	title = {Interactions between local glaciers and adjacent grounded Ross Sea ice in the Royal Society Range, Antarctica},
	journal = {Quaternary Science Reviews},
	volume = {329},
	year = {2024},
	month = {04/2024},
	pages = {108591},
	abstract = {The Antarctic Ice Sheet (AIS) has the potential to exert a major control on future global sea level. Here, we gain insight into the response of the Antarctic Ice Sheet (AIS) to changing climate through assessment of ice-sheet behavior during and since the Last Glacial Maximum (LGM) along the western coast of McMurdo Sound. We examine whether expansion of grounded ice in this sector of the Ross Embayment during the last glaciation was caused by increased flux from East Antarctic outlets and local glaciers or was produced by marine influences, such as lowered sea level or reduced melting of submarine grounded ice. During the LGM, grounded ice derived from the Ross Sea deposited a well-defined drift sheet along the Royal Society headlands on the western coast of McMurdo Sound. Twenty-six new radiocarbon dates of subfossil algae within this drift sheet suggest that the ice sheet was at its maximum extent by at least \~{}18.4 ka and maintained this position for about five thousand years. Cross-cutting relationships show that local alpine glaciers did not contribute to the grounded ice but rather fluctuated asynchronously. This same relationship held true during the penultimate glaciation, dated to roughly 137{\textendash}191 ka with 10Be exposure ages. An explanation for this out-of-phase relationship is that different mechanisms controlled their respective extents. Because they lack significant surface melting ablation zones, the local alpine glaciers, which largely terminate on land, were driven by changes in accumulation. These glaciers likely expanded during warmer times when accumulation was higher. In contrast, marine factors, such as global sea-level change and/or subglacial melting, controlled ice fluctuations in the Ross Embayment, including McMurdo Sound, leading to advance during the LGM.},
	keywords = {Alpine glaciers, Antarctica, Be exposure age dating, Last glacial maximum, radiocarbon, Ross Sea},
	issn = {0277-3791},
	doi = {10.1016/j.quascirev.2024.108591},
	url = {https://www.sciencedirect.com/science/article/pii/S0277379124000921},
	author = {Miles, Maraina and Hall, Brenda and Denton, George}
}
@article {grimley_updated_2024,
	title = {Updated chronology for Peoria Silt (loess) accumulation in Illinois and western Indiana from radiocarbon dating of terrestrial gastropod shells},
	journal = {Quaternary Research},
	year = {2024},
	month = {05/2024},
	pages = {1{\textendash}19},
	abstract = {Based on calibrated radiocarbon ages of terrestrial gastropod shells (Succineidae, Discus, Stenotrema, Webbhelix), the chronology of Peoria Silt (loess) deposition in the Central Lowlands is updated. These taxa provide reliable ages (within \textasciitilde0.2 ka), based on historical shell dating, shell-organic age comparisons, and stratigraphic consistency. A compilation of 53 new and 36 published Peoria Silt shell ages (calibrated), from 12 localities, date from 30.0 to 17.4 ka. Proximal (fossiliferous) loess from 10 sections had mean loess accumulation rates of 0.6{\textendash}2.2 mm/yr. Study sites along the upper Mississippi, Illinois, to mid-Mississippi, and Ohio-Wabash Valleys suggest Peoria loess accumulated from \textasciitilde27 to 15 ka, \textasciitilde29 to 18 ka, and \textasciitilde30 to 18 ka, respectively. The cessation age for Peoria Silt, based on surface extrapolations, is \textasciitilde1{\textendash}6 ka earlier than some prior Illinois estimates, even assuming slower loess accumulation in the modern solum. Younger loess in northwestern Illinois likely reflects, in part, Superior and Des Moines Lobe glacial-meltwater sediment, and Iowan Erosion Surface inputs to the upper Mississippi Valley, after the Lake Michigan Lobe receded. Furthermore, stronger winds, drier conditions, and reduced vegetation cover in valley deflation areas may have favored higher accumulation rates and later loess deposition in northwestern relative to southeastern areas.},
	keywords = {chronology, Illinois, Indiana, Kentucky, Last Glacial, Loess, Peoria Silt, radiocarbon, Succineidae, Wisconsin Episode},
	issn = {0033-5894, 1096-0287},
	doi = {10.1017/qua.2024.15},
	url = {https://www.cambridge.org/core/journals/quaternary-research/article/updated-chronology-for-peoria-silt-loess-accumulation-in-illinois-and-western-indiana-from-radiocarbon-dating-of-terrestrial-gastropod-shells/67CEEB07C31701FF4C2095346BD07F99},
	author = {Grimley, David A. and Loope, Henry M. and Jacobs, Peter M. and Nash, T. Andrew and Dendy, Sarah N. and Conroy, Jessica L. and Curry, B. Brandon}
}
@article {castrillejo_comparability_2023,
	title = {Comparability of Radiocarbon Measurements in Dissolved Inorganic Carbon of Seawater Produced at ETH-Zurich},
	journal = {Radiocarbon},
	year = {2023},
	note = {Publisher: Cambridge University Press},
	month = {03/2023},
	pages = {1{\textendash}10},
	abstract = {Radiocarbon observations (Δ14C) in dissolved inorganic carbon (DIC) of seawater provide useful information about ocean carbon cycling and ocean circulation. To deliver high-quality observations, the Laboratory of Ion Beam Physics (LIP) at ETH-Zurich developed a new simplified method allowing the rapid analysis of radiocarbon in DIC of small seawater samples, which is continually assessed by following internal quality controls. However, a comparison with externally produced 14C measurements to better establish an equivalency between methods was still missing. Here, we make the first intercomparison with the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility based on 14 duplicate seawater samples collected in 2020. We also compare with prior deep-water observations from the 1970s to 1990s. The results show a very good agreement in both comparisons. The mean Δ14C of 12 duplicate samples measured by LIP and NOSAMS were statistically identical within one sigma uncertainty while two other duplicate samples agreed within two sigma. Based on this small number of duplicate samples, LIP values appear to be slightly lower than the NOSAMS values, but more measurements will be needed for confirmation. We also comment on storage and preservation techniques used in this study, including the freezing of samples collected in foil bags.},
	keywords = {14C, comparison, DIC, dissolved inorganic carbon, radiocarbon, SEAWATER},
	issn = {0033-8222, 1945-5755},
	doi = {10.1017/RDC.2023.16},
	url = {https://www.cambridge.org/core/journals/radiocarbon/article/comparability-of-radiocarbon-measurements-in-dissolved-inorganic-carbon-of-seawater-produced-at-ethzurich/B9F6C6AA45835FA3ED0BF8E0CD9788E3},
	author = {Castrillejo, Maxi and Hansman, Roberta L. and Graven, Heather D. and Lester, Joanna G. and Bollhalder, Silvia and K{\"u}ndig, Kayley and Wacker, Lukas}
}
@article {jiang_comparing_2023,
	title = {Comparing the isotopic and molecular composition of dissolved organic carbon between the oligotrophic South China Sea and the adjacent North Pacific Ocean: Signals of biodegradation, conservative mixing, and terrestrial input},
	journal = {Marine Chemistry},
	volume = {257},
	year = {2023},
	month = {11/2023},
	pages = {104331},
	abstract = {The cycling of oceanic dissolved organic carbon (DOC) is a crucial component of the global carbon cycle, yet the identification of sources and the mechanisms of its molecular transformation remain poorly understood. This study compared the isotopic and molecular composition of DOC between the oligotrophic South China Sea (SCS) and the adjacent North Pacific Ocean (NPO), and traced both its allochthonous and autochthonous sources as well as its dynamic cycling processes. DOC was collected through solid-phase extraction (SPE) from water samples of both the SCS and NPO. Carbon content, isotopic ratios, and high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) measurements revealed that SPE-DOC contained both labile and refractory fractions. According to our mass balance model, the labile fraction of SPE-DOC exhibited a decline from 11.5 to 12.6~μM in surface waters to a negligible concentration below 1000~m. Conversely, the refractory fraction of SPE-RDOC maintained a relatively consistent value, ranging from 12.7 to 19.0~μM across the entire water column. The vertical distribution patterns of the molecular composition and carbon isotopic ratios jointly indicated that the DOC distributions are shaped by distinct biological and physical processes within different biogeochemical realms of the water column. The production and transformation of the relatively labile DOC fractions were the dominant processes in the epipelagic and mesopelagic zones (upper 1000~m). The extent of diapycnal mixing between the SCS and NPO explained the different vertical distributions of refractory DOC molecules in the bathypelagic oceans. The molecular indices of polyphenol compounds, aromaticity, double bond saturation state, terrestrial mass peaks, and δ13C ratios of SPE-DOC indicated contributions from terrestrial sources, likely riverine input, in the SCS. This study sheds light on the molecular evidence of DOC sources, as well as their transformation and conservative mixing processes along the overturning circulation in marginal seas.},
	keywords = {carbon isotopes, dissolved organic carbon, FT-ICR-MS, North pacific ocean, radiocarbon, south china sea},
	issn = {0304-4203},
	doi = {10.1016/j.marchem.2023.104331},
	url = {https://www.sciencedirect.com/science/article/pii/S0304420323001275},
	author = {Jiang, Peng and Chen, Hongmei and Liu, Zhanfei and Li, Xiaolin}
}
@article {stlaurent_new_2023,
	title = {New insights on black carbon in pelagic Atlantic sediments},
	journal = {Marine Chemistry},
	year = {2023},
	month = {09/2023},
	pages = {104312},
	abstract = {Black carbon (BC) is ubiquitous in pelagic sediments and presumed to have an older radiocarbon age due to long ocean residence times and pre-aging in terrestrial soils. Here, we analyzed sediments from five regions in the subtropical Atlantic Ocean to quantify the black carbon fraction of the total organic carbon pool. Black carbon, derived from the chemothermal oxidation method, comprised between 17 {\textpm} 6\% of the sedimentary organic carbon in the Northwest Argentina Basin and 65 {\textpm} 18\% in the Amazon Delta. Black carbon sediment accumulation rates were six times greater in the Sierra Leone Rise (8.4 {\textpm} 4.1 mg cm-2 kyr-1) compared to the remote Northwest Argentina Basin (1.3 {\textpm} 0.4 mg cm-2 kyr-1), possibly due to enhanced regional atmospheric deposition from annual African grassland fires. The radiocarbon age for BC from subtropical Atlantic sediments were more modern compared to the bulk total organic carbon, and BC source was apportioned as biomass burning byproducts from their stable carbon isotopic signatures and characteristic ratios of polycyclic aromatic hydrocarbons. This study demonstrated that subtropical Atlantic Ocean sediments serve as an important sink for young BC.},
	keywords = {Atlantic Ocean, BLACK CARBON, Polycyclic aromatic hydrocarbons, radiocarbon, sediments},
	issn = {0304-4203},
	doi = {10.1016/j.marchem.2023.104312},
	url = {https://www.sciencedirect.com/science/article/pii/S0304420323001081},
	author = {St.Laurent, Kari and Cantwell, Mark and Lohmann, Rainer}
}
@article {schwing_organic_2023,
	title = {Organic carbon and planktic foraminifera radiocarbon derived Holocene sediment accumulation rates in the northern slopes of the Gulf of Mexico},
	journal = {Deep Sea Research Part I: Oceanographic Research Papers},
	volume = {193},
	year = {2023},
	month = {03/2023},
	pages = {103959},
	abstract = {In the context of climate regulation and anthropogenic waste detoxification (e.g. oil spills), estimates of deep ocean sedimentation and carbon sequestration are of the utmost importance. Radiocarbon (14C) is a common radioisotope that can be used to establish millennial scale sediment accumulation rates. The objectives of this study were to: 1) establish ages for co-occurring total organic carbon (TOC) and planktic foraminifera (carbonate) in the northeastern Gulf of Mexico (GoM), 2) use these ages to estimate accumulation rates independently, 3) identify any evidence of redistribution, and 4) examine any offset between TOC and carbonate 14C ages as a tool to potentially identify selective TOC transport. Sediment samples were collected in May 2018 from the RV Point Sur using an Ocean Instruments MC-800 multi corer. Radiocarbon measurements of both planktic foraminifera and TOC subsamples were made at the National Ocean Science Accelerator Mass Spectrometry Facility (NOSAMS). Radiocarbon ages, calibrated using the OxCal 4.4, ranged from recent to 6407 BP. Linear (LAR: 4{\textendash}24~cm/kyr) and mass accumulation rates (MAR: 1.5{\textendash}11.5~g/cm2/kyr) were generally consistent with those reported by other recent studies in the GoM. At two sites, C14 ages decreased from the surface to the second sampling increment which was consistent with sediment redistribution. The TOC-carbonate offsets, which are indicative of lateral advection and organic matter aging, were lower than those found in the majority of other regions, which was consistent with less lateral transport or a more oligotrophic setting. The magnitude in radiocarbon age offsets with depth could potentially be used as a relative aging or transport assessment tool in areas with little resuspension.},
	keywords = {accumulation rates, Foraminifera, Gulf of Mexico, radiocarbon, Radiogeochemistry},
	issn = {0967-0637},
	doi = {10.1016/j.dsr.2022.103959},
	url = {https://www.sciencedirect.com/science/article/pii/S0967063722002722},
	author = {Schwing, Patrick and Chanton, Jeffrey and Bosman, Samantha and Brooks, Gregg and Larson, Rebekka A. and Romero, Isabel and Diercks, Arne}
}
@article {fang_radiocarbon_2023,
	title = {Radiocarbon Constraints on Carbon Release From the Antarctic Ice Sheet Into the Amundsen Sea Embayment},
	journal = {Journal of Geophysical Research: Biogeosciences},
	volume = {128},
	number = {3},
	year = {2023},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022JG007053},
	month = {03/2023},
	pages = {e2022JG007053},
	abstract = {The Amundsen Sea Embayment in West Antarctica is experiencing rapid ice mass loss, resulting in biogeochemical changes via altered nutrient and organic matter supply. However, organic carbon released from melting ice has not yet been accurately quantified. In this paper, we have integrated new dissolved organic carbon (DOC) data obtained close to the melting Dotson Ice Shelf (DIS) with published radiocarbon (Δ14C) data on sinking and suspended particulate organic carbon (POC), sedimentary OC, DOC and dissolved inorganic carbon to quantify the effect of ice melt to the carbon cycle. Elevated DOC concentrations in deep water near the DIS indicate the transport of carbon sources from the ice shelf to the water column at a rate of 4.6 {\textpm} 2.0 {\texttimes} 1010 g C yr-1. Furthermore, Δ14C-DOC measurements suggest there is a possible dark chemoautotrophic production under the influence of meltwater input. The vertical profile of Δ14C in the sedimentary OC from the Sea Ice Zone and the edge of the DIS demonstrates the presence of aged organic carbon sources during warm episodes at \~{}11.5 and 15.9 ka BP. Our study indicates that deep water is not only affected by OC discharge from meltwater but also by biological processes due to altered nutrient inputs. Limited data hampers a precise assessment of the influence of meltwater on the carbon cycle. Further sampling in front of the DIS will be beneficial to enhance our understanding of the role of Antarctic Ice Sheet melting in the downstream ecosystem.},
	keywords = {Antarctica, melting ice, organic carbon fluxes, radiocarbon},
	issn = {2169-8961},
	doi = {10.1029/2022JG007053},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022JG007053},
	author = {Fang, Ling and Kim, Minkyoung}
}
@article {white_refractory_2023,
	title = {Refractory Dissolved Organic Matter has Similar Chemical Characteristics but Different Radiocarbon Signatures With Depth in the Marine Water Column},
	journal = {Global Biogeochemical Cycles},
	volume = {37},
	number = {4},
	year = {2023},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022GB007603},
	month = {04/2023},
	pages = {e2022GB007603},
	abstract = {The >5,000-year radiocarbon age (14C-age) of much of the 630 {\textpm} 30 Pg C oceanic dissolved organic carbon (DOC) reservoir remains an enigma in the marine carbon cycle. The fact that DOC is significantly older than dissolved inorganic carbon at every depth in the ocean forms the basis of our current framing of the marine DOC cycle, where some component persists over multiple cycles of ocean mixing. As a result, 14C-depleted, aged DOC is hypothesized to be present as a uniform reservoir with a constant 14C signature and concentration throughout the water column. However, key requirements of this model, including direct observations of DOC with similar 14C signatures in the surface and deep ocean, have never been met. Despite decades of research, the distribution of Δ14C values in marine DOC remains a mystery. Here, we applied a thermal fractionation method to compare operationally defined refractory DOC (RDOC) from different depths in the North Pacific Ocean. We found that RDOC shares chemical characteristics (as recorded by OC bond strength) throughout the water column but does not share the same 14C signature. Our results support one part of the current paradigm{\textemdash}that RDOC is comprised of structurally related components throughout the ocean that form a {\textquotedblleft}background{\textquotedblright} reservoir. However, in contrast to the current paradigm, our results are consistent with a vertical concentration gradient and a vertical and inter-ocean Δ14C gradient for RDOC. The observed Δ14C gradient is compatible with the potential addition of pre-aged DOC to the upper ocean.},
	keywords = {marine dissolved organic matter, radiocarbon, ramped pyrolysis oxidation},
	issn = {1944-9224},
	doi = {10.1029/2022GB007603},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022GB007603},
	author = {White, Margot E. and Nguyen, Tran B. and Koester, Irina and Lardie Gaylord, Mary C. and Beman, J. Michael and Smith, Kenneth L. and McNichol, Ann P. and Beaupr{\'e}, Steven R. and Aluwihare, Lihini I.}
}
@article {broek_optimization_2022,
	title = {Optimization of the LLNL/CAMS gas-accepting ion source and 1 MV compact AMS for natural abundance radiocarbon analysis of CO2},
	journal = {Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms},
	volume = {530},
	year = {2022},
	month = {11/2022},
	pages = {1{\textendash}7},
	abstract = {The Lawrence Livermore National Laboratory {\textendash} Center for Accelerator Mass Spectrometry (LLNL/CAMS) 1 MV AMS system was converted from a biomedical AMS instrument to a natural abundance 14C spectrometer. The system is equipped with a gas-accepting hybrid ion source capable of measuring both solid (graphite) and gaseous (CO2) samples. Here we describe a series of experiments intended to establish and optimize 14CO2 measurement capabilities at natural abundance levels. A maximum instantaneous ionization efficiency of 8~\% was achieved with 3~\% CO2 in helium at a flow rate of approximately 220~{\textmu}L/min (3.5~{\textmu}g C/min). For modern materials (e.g., OX I) we measured an average of 240~{\textpm}~50 14C counts/{\textmu}g C, equivalent to a total system efficiency of approximately 3~\%. Experimental CO2 samples with F14C values ranging from 0.20 to 1.05 measured as both graphite and directly as CO2 gas produced equivalent values with an average offset of~<~2σ.},
	keywords = {Accelerator mass spectrometry, CO, Gas-accepting ion source, radiocarbon},
	issn = {0168-583X},
	doi = {10.1016/j.nimb.2022.08.012},
	url = {https://www.sciencedirect.com/science/article/pii/S0168583X22002178},
	author = {Broek, Taylor A. B. and Moreland, Kimber C. and Ognibene, Ted J. and McFarlane, Karis J. and Brown, Thomas A.}
}
@article {longworth_radiocarbon_2022,
	title = {Radiocarbon measurement of CO2 from carbonate minerals using a hybrid gas ion source with an open split interface},
	journal = {Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms},
	volume = {531},
	year = {2022},
	month = {11/2022},
	pages = {49{\textendash}55},
	abstract = {We have developed a method for measuring radiocarbon in carbonate minerals as CO2 gas via a NEC MCSNICS hybrid sputter gas ion source (HGIS). The method uses helium as a carrier gas to displace CO2 from sample vials to an open split, where a glass capillary samples the mixture for delivery directly to the HGIS. This method skips the gas transfer and quantification steps used in a closed inlet HGIS system, simplifying sample measurement. Samples larger than 8 mg carbonate can be measured. Results from measurements of consensus standards (TIRI I, IAEA C2, and an internal modern shell standard), and samples from a marine core (F14C = 0.4{\textendash}1.15) show that the method agrees well with traditional AMS measurement of the same samples as graphite, and that the 1σ uncertainty is about 1\%. We discuss advantages and disadvantages of continuous flow sample introduction, and the effect of reduced precision on calibrated age-depth models produced using gas-source data.},
	keywords = {Carbonate, Hybrid gas ion source, radiocarbon},
	issn = {0168-583X},
	doi = {10.1016/j.nimb.2022.08.013},
	url = {https://www.sciencedirect.com/science/article/pii/S0168583X2200218X},
	author = {Longworth, Brett E. and Burton, Joshua R. and Pendleton, Simon L. and Moser, Sydney D. and Roberts, Mark L. and Kurz, Mark D.}
}
@article {kruger_sediment_2022,
	title = {Sediment organic matter compositional changes in a tropical rift lake as a function of water depth and distance from shore},
	journal = {Organic Geochemistry},
	year = {2022},
	month = {11/2022},
	pages = {104527},
	abstract = {Little is known of modern carbon cycling in East African rift lakes. These large tropical systems with anoxic bottom waters can act as test cases for carbon cycling under future climate change scenarios as well as key sediment repositories for paleolimnology studies and fossil fuel generation. This study is the first to combine stable and radiocarbon isotopic information on bulk sediment and biomarkers (n-alcohols) in an African rift lake by investigating surface sediments collected on a nearshore to offshore transect in northern Lake Malawi. This study is also the first to report radiocarbon content in water column particulate organic, dissolved organic and inorganic carbon from an African rift lake. General surface-sediment trends with increasing water depth were an increase in \%TOC, and decreases in grain size, δ13C and C/N. Carbon radioisotope analyses showed that bulk sedimentary organic matter was modern across the transect. Biomarker data indicated a primarily aquatic origin for sedimentary organic matter at offshore sites; terrestrial material dominated the n-alcohol signature closest to the shore. Protokerogen stable isotope signatures were similar, and radiocarbon was somewhat depleted relative to bulk sediment organic matter. As compared to bulk organic matter, lipids were 13C-depleted throughout the sampling transect and 14C-depleted at the most nearshore location. This indicates an aged lipid carbon source and likely significant diagenetic alteration of modern sources prior to deposition in nearshore sediments, perhaps a combination of soil erosion, in-river processing, sediment resuspension and mobilization, and preferential degradation of younger organic matter in the oxic nearshore region.},
	keywords = {-Alcohols, C/N ratio, carbon isotopes, Lake Malawi, Protokerogen, radiocarbon, Sedimentary organic carbon},
	issn = {0146-6380},
	doi = {10.1016/j.orggeochem.2022.104527},
	url = {https://www.sciencedirect.com/science/article/pii/S0146638022001619},
	author = {Kruger, Brittany R. and Werne, Josef P. and Minor, Elizabeth C.}
}
@article {2923,
	title = {Carbon Isotopic and Lithologic Constraints on the Sources and Cycling of Inorganic Carbon in Four Large Rivers in China: Yangtze, Yellow, Pearl, and Heilongjiang},
	journal = {Journal of Geophysical Research: Biogeosciences},
	volume = {126},
	year = {2021},
	month = {Jan-02-2021},
	abstract = {Transport of terrigenous carbon by rivers has been affected extensively by climate change and anthropogenic activities in China over the last few decades. Here, we present results on carbon isotopes (C-13, C-14) of dissolved and particulate inorganic carbon (DIC and PIC) and combined with major lithologic ions measured in the four largest rivers in China, namely, the Yangtze, Yellow, Pearl, and Heilongjiang rivers, to reveal the sources and transport of terrigenous inorganic carbon in the rivers. The DIC concentrations showed large variations in the four rivers and ranged from 253 to 3,122 mu M. The Yangtze, Yellow and Pearl rivers transported high DIC contents that had low Delta C-14 values of millennium-aged DIC and very old PIC; however, the Heilongjiang River presented a lower DIC concentration with much younger C-14 ages than the global average (1,100 mu M). The strong correlations between the DIC isotope values and major lithological ions (Ca2+ and Mg2+) suggest that chemical weathering played important but variable roles in controlling the production and fate of DIC in the rivers. Using dual isotopes and the MixSIAR model, we calculated that the chemical weathering of carbonate rocks contributed 95 +/- 5\% of the riverine DIC to the headwater of the Yangtze River while silicate rock weathering and riverine organic matter respiration contributed 62 +/- 25\% and 5 +/- 5\% of the DIC in the middle and lower reaches of the river, respectively. In contrast, chemical weathering of silicate rocks contributed the dominant fraction of DIC in the Yellow (55 +/- 17\%), Pearl (61 +/- 20\%) and Heilongjiang (83 +/- 29\%) rivers.},
	keywords = {Carbon cycle, Chemical weathering, inorganic carbon in large rivers, radiocarbon, stable carbon isotope},
	issn = {2169-8953},
	doi = {10.1029/2020JG005901},
	url = {https://apps.webofknowledge.com/InboundService.do?product=WOS\&Func=Frame\&DestFail=http\%3A\%2F\%2Fwww.webofknowledge.com\&SrcApp=search\&SrcAuth=Alerting\&SID=7EQ3XpZtZiWye3DFos4\&customersID=Alerting\&mode=FullRecord\&IsProductCode=Yes\&AlertId=4d48b20a-7d27-4fa2-},
	author = {Shan, Sen and Luo, Chunle and Qi, Yuanzhi and Cai, Wei-Jun and Sun, Shuwen and Fan, Di and Wang, Xuchen}
}
@article {2921,
	title = {Climate control on terrestrial biospheric carbon turnover},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {118},
	year = {2021},
	month = {Nov-02-2022},
	pages = {e2011585118},
	abstract = {Terrestrial vegetation and soils hold three times more carbon than the atmosphere. Much debate concerns how anthropogenic activity will perturb these surface reservoirs, potentially exacerbating ongoing changes to the climate system. Uncertainties specifically persist in extrapolating point-source observations to ecosystem-scale budgets and fluxes, which require consideration of vertical and lateral processes on multiple temporal and spatial scales. To explore controls on organic carbon (OC) turnover at the river basin scale, we present radiocarbon (C-14) ages on two groups of molecular tracers of plant-derived carbon-leaf-wax lipids and lignin phenols-from a globally distributed suite of rivers. We find significant negative relationships between the C-14 age of these biomarkers and mean annual temperature and precipitation. Moreover, riverine biospheric-carbon ages scale proportionally with basin-wide soil carbon turnover times and soil C-14 ages, implicating OC cycling within soils as a primary control on exported biomarker ages and revealing a broad distribution of soil OC reactivities. The ubiquitous occurrence of a long-lived soil OC pool suggests soil OC is globally vulnerable to perturbations by future temperature and precipitation increase. Scaling of riverine biospheric-carbon ages with soil OC turnover shows the former can constrain the sensitivity of carbon dynamics to environmental controls on broad spatial scales. Extracting this information from fluvially dominated sedimentary sequences may inform past variations in soil OC turnover in response to anthropogenic and/or climate perturbations. In turn, monitoring riverine OC composition may help detect future climate-change-induced perturbations of soil OC turnover and stocks.},
	keywords = {Carbon cycle, carbon turnover times, fluvial carbon, plant biomarkers, radiocarbon},
	issn = {0027-8424},
	doi = {10.1073/pnas.2011585118},
	url = {https://www.researchgate.net/publication/349357864_Climate_control_on_terrestrial_biospheric_carbon_turnover},
	author = {Eglinton, Timothy I. and Galy, Valier V. and Hemingway, Jordon D. and Feng, Xiaojuan and Bao, Hongyan and Blattmann, Thomas M. and Dickens, Angela F. and Gies, Hannah and Giosan, Liviu and Haghipour, Negar and Hou, Pengfei and Lupker, Maarten and McIntyre, Cameron P. and Montlu{\c c}on, Daniel B. and Peucker-Ehrenbrink, Bernhard and Ponton, Camilo and Schefu{\ss}, Enno and Schwab, Melissa S. and Voss, Britta M. and Wacker, Lukas and Wu, Ying and Zhao, Meixun}
}
@article {2944,
	title = {A FRAMEWORK FOR TRANSDISCIPLINARY RADIOCARBON RESEARCH: USE OF NATURAL-LEVEL AND ELEVATED-LEVEL -14- C IN ANTARCTIC FIELD RESEARCHABSTRACT},
	journal = {Radiocarbon},
	volume = {63},
	year = {2021},
	month = {Jan-10-2021},
	pages = {1555 - 1568},
	abstract = {Radiocarbon (C-14) is an isotopic tracer used to address a wide range of scientific research questions. However, contamination by elevated levels of C-14 is deleterious to natural-level laboratory workspaces and accelerator mass spectrometer facilities designed to precisely measure small amounts of C-14. The risk of contaminating materials and facilities intended for natural-level C-14 with elevated-level C-14-labeled materials has dictated near complete separation of research groups practicing profoundly different measurements. Such separation can hinder transdisciplinary research initiatives, especially in remote and isolated field locations where both natural-level and elevated-level radiocarbon applications may be useful. This paper outlines the successful collaboration between researchers making natural-level C-14 measurements and researchers using C-14-labeled materials during a subglacial drilling project in West Antarctica (SALSA 2018-2019). Our strict operating protocol allowed us to successfully carry out C-14 labeling experiments within close quarters at our remote field camp without contaminating samples of sediment and water intended for natural level C-14 measurements. Here we present our collaborative protocol for maintaining natural level C-14 cleanliness as a framework for future transdisciplinary radiocarbon collaborations.},
	keywords = {AMS, contamination, LEUCINE, radiocarbon},
	issn = {0033-8222},
	doi = {10.1017/RDC.2021.55},
	url = {https://www.cambridge.org/core/product/identifier/S0033822221000552/type/journal_articlehttps://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033822221000552},
	author = {Venturelli, Ryan A and Vick-Majors, Trista J and Collins, Billy and Gagnon, Alan and Kasic, Kathy and Kurz, Mark D and Li, Wei and Priscu, John and Roberts, Mark and Rosenheim, Brad E}
}
@article {2922,
	title = {RADIOCARBON IN DISSOLVED ORGANIC CARBON BY UV OXIDATION: PROCEDURES AND BLANK CHARACTERIZATION AT NOSAMSABSTRACT},
	journal = {Radiocarbon},
	volume = {63},
	year = {2021},
	month = {Jan-02-2021},
	pages = {357 - 374},
	abstract = {This study describes a procedural blank assessment of the ultraviolet photochemical oxidation (UV oxidation) method that is used to measure carbon isotopes of dissolved organic carbon (DOC) at the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS). A retrospective compilation of Fm and δ 13 C results for secondary standards (OX-II, glycine) between 2009 and 2018 indicated that a revised blank correction was required to bring results in line with accepted values. The application of a best-fit mass-balance correction yielded a procedural blank of 22.0 {\textpm} 6.0 μg C with Fm of 0.30 {\textpm} 0.20 and δ 13 C of-32.0 {\textpm} 3.0{\textperthousand} for this period, which was notably higher and more variable than previously reported. Changes to the procedure, specifically elimination of higher organic carbon reagents and improved sample and reactor handling, reduced the blank to 11.0 {\textpm} 2.75 μg C, with Fm of 0.14 {\textpm} 0.10 and δ 13 C of-31.0 {\textpm} 5.5{\textperthousand}. A thorough determination of the entire sample processing blank is required to ensure accurate isotopic compositions of seawater DOC using the UV oxidation method. Additional efforts are needed to further reduce the procedural blank so that smaller DOC samples can be analyzed, and to increase sample throughput.},
	keywords = {blank, dissolved organic carbon, radiocarbon, UV oxidation},
	issn = {0033-8222},
	doi = {10.1017/RDC.2020.102},
	url = {https://www.cambridge.org/core/journals/radiocarbon/article/abs/radiocarbon-in-dissolved-organic-carbon-by-uv-oxidation-procedures-and-blank-characterization-at-nosams/AA39A2C74772934B44D9BF81C2DF723C},
	author = {Xu, Li and Roberts, Mark L and Elder, Kathryn L and Kurz, Mark D and McNichol, Ann P and Reddy, Christopher M and Ward, Collin P and Hanke, Ulrich M}
}
@article {2914,
	title = {Carbon cycling in the deep Mariana Trench in the western north Pacific Ocean: Insights from radiocarbon proxy data},
	journal = {Deep Sea Research Part I: Oceanographic Research Papers},
	volume = {164},
	year = {2020},
	month = {Jan-10-2020},
	pages = {103370},
	abstract = {The Mariana Trench in the western North Pacific (NP) contains the deepest (11,000 m) point in the ocean and thus remains the least explored environment. Carbon cycling in the deep Mariana Trench is largely unknown and remains a curious mystery. Here, we report radiocarbon (Delta C-14) and stable carbon isotope (delta C-13) compositions of dissolved inorganic and organic carbon (DIC and DOC) and sinking particulate organic carbon (POC) for samples collected at 2000 m, 4000 m and 6000 m from the Mariana Trench in the western NP. DOC had much lower Delta C-14 values (-189 parts per thousand to -538 parts per thousand) than DIC (38 parts per thousand to -236 parts per thousand) and POC (11 parts per thousand-38 parts per thousand) at the same depths, indicating the different cycling processes and time scales of different carbon pools. The C-14 ages of DOC were approximately 1700 years and 4400 years older than those of DIC in the surface (2 m) and deep (10,000 m) waters of the Mariana Trench. Both DOC and DIC Delta C-14 values at hadal depths (>6000 m) in the trench are comparable to values at other sites in the deep NP, suggesting that water movement and mixing at hadal depths in the Mariana Trench are active and follow the deep-water circulation patterns of the NP. POC fluxes at the three deep depths showed large variations, but their modern Delta C-14 values indicate that the effective biological pump that drives fresh surface-produced particles to sink rapidly to deep depths in the trench could provide essential food sources for microbial and benthic communities living in an extremely harsh environment of the Mariana Trench.},
	keywords = {carbon cycling, Mariana trench, North pacific ocean, Particle flux, radiocarbon, stable carbon isotope},
	issn = {09670637},
	doi = {10.1016/j.dsr.2020.103370},
	url = {https://apps.webofknowledge.com/InboundService.do?product=WOS\&Func=Frame\&DestFail=http\%3A\%2F\%2Fwww.webofknowledge.com\&SrcApp=search\&SrcAuth=Alerting\&SID=5FcsGoXKXNO2xQfU7KW\&customersID=Alerting\&mode=FullRecord\&IsProductCode=Yes\&AlertId=4d48b20a-7d27-4fa2-},
	author = {Shan, Sen and Qi, Yuanzhi and Tian, Jiwei and Wang, Xuchen and Luo, Chunle and Zhou, Chun and Zhang, Xiao-Hua and Xin, Yu and Wang, Yonghong}
}
@article {2700,
	title = {Carbon Cycling in the World{\textquoteright}s Deepest Blue Hole},
	journal = {Journal of Geophysical Research: Biogeosciences},
	volume = {125},
	year = {2020},
	month = {Jan-02-2020},
	abstract = {Blue holes are unique geomorphological features with steep biogeochemical gradients and distinctive microbial communities. Carbon cycling in blue holes, however, remains poorly understood. Here we describe potential mechanisms of dissolved carbon cycling in the world{\textquoteright}s deepest blue hole, the Yongle Blue Hole (YBH), which was recently discovered in the South China Sea. In the YBH, we found some of the lowest concentrations (e.g., 22 μM) and oldest ages (e.g., 6,810 years before present) of dissolved organic carbon, as well as the highest concentrations (e.g., 3,090 μM) and the oldest ages (e.g., 8,270 years before present) of dissolved inorganic carbon observed in oceanic waters. Sharp gradients of dissolved oxygen, H2S, and CH4 and changes in bacterially mediated sulfur cycling with depth indicated that sulfur- and/or methane-based metabolisms are closely linked to carbon cycling in the YBH. Our results showed that the YBH is a unique and easily accessible natural laboratory for examining carbon cycling in anoxic systems, which has potential for understanding carbon dynamics in both paleo and modern oceans{\textemdash}particularly in the context of global change.},
	keywords = {anoxia, carbon cycling, dissolved carbon, radiocarbon, sulfur cycling, Yongle blue hole},
	issn = {2169-8953},
	doi = {10.1029/2019JG005307},
	url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JG005307},
	author = {Yao, P. and Wang, X. C. and Bianchi, T. S. and Yang, Z. S. and Fu, L. and Zhang, X. H. and Chen, L. and Zhao, B. and Morrison, E. S. and Shields, M. R. and Liu, Y. N. and Bi, N. S. and Qi, Y. Z. and Zhou, S. and Liu, J. W. and Zhang, H. H. and Zhu, C. J. and Yu, Z. G.}
}
@article {2883,
	title = {Clumped Isotopes Link Older Carbon Substrates With Slower Rates of Methanogenesis in Northern Lakes},
	journal = {Geophysical Research Letters},
	volume = {47},
	year = {2020},
	month = {Apr-03-2022},
	abstract = {The release of long-stored carbon from thawed permafrost could fuel increased methanogenesis in northern lakes, but it remains unclear whether old carbon substrates released from permafrost are metabolized as rapidly by methanogenic microbial communities as recently produced organic carbon. Here, we apply methane (CH4) clumped isotope (Δ18) and 14C measurements to test whether rates of methanogenesis are related to carbon substrate age. Results from culture experiments indicate that Δ18 values are negatively correlated with CH4 production rate. Measurements of ebullition samples from thermokarst lakes in Alaska and glacial lakes in Sweden indicate strong negative correlations between CH4 Δ18 and the fraction modern carbon. These correlations imply that CH4 derived from older carbon substrates is produced relatively slowly. Relative rates of methanogenesis, as inferred from Δ18 values, are not positively correlated with CH4 flux estimates, highlighting the likely importance of environmental variables other than CH4 production rates in controlling ebullition fluxes.},
	keywords = {clumped isotopes, ebullition flux, lakes, methane, permafrost, radiocarbon},
	issn = {0094-8276},
	doi = {10.1029/2019GL086756},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019GL086756},
	author = {Douglas, Peter M. J. and Gonzalez Moguel, Regina and Walter Anthony, Katey M. and Wik, Martin and Crill, Patrick M. and Dawson, Katherine S. and Smith, Derek A. and Yanay, Ella and Lloyd, Max K. and Stolper, Daniel A. and Eiler, John M. and Sessions, Alex L.}
}
@article {2915,
	title = {Dissolved black carbon is not likely a significant refractory organic carbon pool in rivers and oceansAbstract},
	journal = {Nature Communications},
	volume = {11},
	year = {2020},
	month = {Jan-12-2020},
	abstract = {Rivers are the major carriers of dissolved black carbon (DBC) from land to ocean; the sources of DBC during its continuous transformation and cycling in the ocean, however, are not well characterized. Here, we present new carbon isotope data for DBC in four large and two small mountainous rivers, the Yangtze and Yellow river estuaries, the East China Sea and the North Pacific Ocean. We found that the carbon isotope signatures of DBC are relatively homogeneous, and the DBC C-14 ages in rivers are predominantly young and increase during continuous transport and cycling in the ocean. The results of charcoal leaching experiments indicate that DBC is released from charcoal and degraded by bacteria. Our study suggests that riverine DBC is labile and respired during transport and mixing into the ocean and that residual DBC is cycled and aged on the same time scales as bulk DOC in the ocean. Black carbon is a recalcitrant byproduct of biomass burning that ultimately accumulates in oceanic sinks. Here the authors assessed the sources and cycling of dissolved black carbon in rivers and oceans, finding that oceanic pools are cycled and aged on the same time scales as dissolved organic carbon.},
	keywords = {Changjiang, cycle, flux, HUANGHE RIVERS, level, particulate, quantification, radiocarbon, sea},
	doi = {10.1038/s41467-020-18808-8},
	url = {http://www.nature.com/articles/s41467-020-18808-8http://www.nature.com/articles/s41467-020-18808-8.pdfhttp://www.nature.com/articles/s41467-020-18808-8.pdfhttp://www.nature.com/articles/s41467-020-18808-8},
	author = {Qi, Yuanzhi and Fu, Wenjing and Tian, Jiwei and Luo, Chunle and Shan, Sen and Sun, Shuwen and Ren, Peng and Zhang, Hongmei and Liu, Jiwen and Zhang, Xiaohua and Wang, Xuchen}
}
@article {2918,
	title = {RADIOCARBON RESERVOIR AGES IN THE HOLOCENE DEAD SEAABSTRACT},
	journal = {Radiocarbon},
	volume = {62},
	year = {2020},
	month = {Jan-10-2020},
	pages = {1453 - 1473},
	abstract = {The sources and fate of radiocarbon (C-14) in the Dead Sea hypersaline solution are evaluated with C-14 measurements in organic debris and primary aragonite collected from exposures of the Holocene Ze{\textquoteright}elim Formation. The reservoir age (RA) is defined as the difference between the radiocarbon age of the aragonite at time of its precipitation (representing lake{\textquoteright}s dissolved inorganic carbon pig) and the age of contemporaneous organic debris (representing atmospheric radiocarbon). Evaluation of the data for the past 6000 yr from Dead Sea sediments reveal that the lake{\textquoteright}s RA decreased from 2890 yr at 6 cal kyr BP to 2300 yr at present. The RA lies at similar to 2400 yr during the past 3000 yr, when the lake was characterized by continuous deposition of primary aragonite, which implies a continuous supply of freshwater-bicarbonate into the lake. This process reflects the overall stability of the hydrological-climate conditions in the lake{\textquoteright}s watershed during the late Holocene where bicarbonate originated from dissolution of the surface cover in the watershed that was transported to the Dead Sea by the freshwater runoff. An excellent correlation (R-2=0.98) exists between aragonite ages and contemporaneous organic debris, allowing the estimation of ages of various primary deposits where organic debris are not available.},
	keywords = {aragonite, Dead Sea, Holocene, radiocarbon, reservoir ages},
	issn = {0033-8222},
	doi = {10.1017/RDC.2020.28},
	url = {https://apps.webofknowledge.com/InboundService.do?product=WOS\&Func=Frame\&DestFail=http\%3A\%2F\%2Fwww.webofknowledge.com\&SrcApp=search\&SrcAuth=Alerting\&SID=8AkJOJLKFU3j5nkGaRI\&customersID=Alerting\&mode=FullRecord\&IsProductCode=Yes\&AlertId=4d48b20a-7d27-4fa2-},
	author = {Weber, Nurit and Lazar, Boaz and Stern, Ofra and Burr, George and Gavrieli, Ittai and Roberts, Mark and Kurz, Mark D and Yechieli, Yoseph and Stein, Mordechai}
}
@article {2676,
	title = {Removal of Refractory Dissolved Organic Carbon in the Amundsen Sea, Antarctica},
	journal = {Scientific Reports},
	volume = {10},
	year = {2020},
	month = {Jan-12-2020},
	abstract = {The removal mechanism of refractory deep-ocean dissolved organic carbon (deep-DOC) is poorly understood. The Amundsen Sea Polynya (ASP) serves as a natural test basin for assessing the fate of deep-DOC when it is supplied with a large amount of fresh-DOC and exposed to strong solar radiation during the polynya opening in austral summer. We measured the radiocarbon content of DOC in the water column on the western Amundsen shelf. The radiocarbon content of DOC in the surface water of the ASP reflected higher primary production than in the region covered by sea ice. The radiocarbon measurements of DOC, taken two years apart in the ASP, were different, suggesting rapid cycling of DOC. The increase in DOC concentration was less than expected from the observed increase in radiocarbon content from those at the greatest depths. Based on a radiocarbon mass balance, we show that deep-DOC is consumed along with fresh-DOC in the ASP. Our observations imply that water circulation through the surface layer, where fresh-DOC is produced, may play an important role in global DOC cycling.},
	keywords = {CIRCUMPOLAR DEEP-WATER, cycle, DOC, glaciers, INFLOW, MATTER, pacific, phytoplankton, poc, radiocarbon},
	doi = {10.1038/s41598-020-57870-6},
	url = {http://www.nature.com/articles/s41598-020-57870-6http://www.nature.com/articles/s41598-020-57870-6.pdfhttp://www.nature.com/articles/s41598-020-57870-6.pdfhttp://www.nature.com/articles/s41598-020-57870-6},
	author = {Fang, Ling and Lee, SangHoon and Lee, Shin-Ah and Hahm, Doshik and Kim, Guebuem and Druffel, Ellen R. M. and Hwang, Jeomshik}
}
@article {hurwitz_yellowstones_2020,
	title = {Yellowstone{\textquoteright}s Old Faithful Geyser Shut Down by a Severe Thirteenth Century Drought},
	journal = {Geophysical Research Letters},
	volume = {47},
	number = {20},
	year = {2020},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020GL089871},
	month = {10/2020},
	pages = {e2020GL089871},
	abstract = {To characterize eruption activity of the iconic Old Faithful Geyser in Yellowstone National Park over past centuries, we obtained 41 new radiocarbon dates of mineralized wood preserved in the mound of silica that precipitated from erupted waters. Trees do not grow on active geyser mounds, implying that trees grew on the Old Faithful Geyser mound during a protracted period of eruption quiescence. Rooted stumps and root crowns located on higher parts of the mound are evidence that at the time of tree growth, the geyser mound closely resembled its current appearance. The range of calibrated radiocarbon dates (1233{\textendash}1362 CE) is coincident with a series of severe multidecadal regional droughts toward the end of the Medieval Climate Anomaly, prior to the onset of the Little Ice Age. Climate models project increasingly severe droughts by mid-21st century, suggesting that geyser eruptions could become less frequent or completely cease.},
	keywords = {drought, Medieval Climate Anomaly, mineralization, Old Faithful Geyser, radiocarbon, Yellowstone},
	issn = {1944-8007},
	doi = {10.1029/2020GL089871},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2020GL089871},
	author = {Hurwitz, Shaul and King, John C. and Pederson, Gregory T. and Martin, Justin T. and Damby, David E. and Manga, Michael and Hungerford, Jefferson D. G. and Peek, Sara}
}
@book {2719,
	title = {Mapping Isotopic and Dissolved Organic Matter Baselines in Waters and Sediments of the~Gulf of Mexico},
	year = {2019},
	pages = {160 - 181},
	publisher = {Springer International Publishing},
	organization = {Springer International Publishing},
	address = {Cham},
	abstract = {The Deepwater Horizon oil spill released petroleum hydrocarbons that were depleted in δ13C and Δ14C at depth into the Gulf of Mexico. Stable-carbon and radiocarbon isotopic values and high-resolution mass spectrometry were used to follow the distributions of this petroleum and to track its transformation into petrocarbon, a term used to describe crude oil or transformed crude oil following biodegradation, weathering, oxygenation, or loss of lighter components. The term petrocarbon includes oil- or methane-derived carbon assimilated or incorporated into microbial biomass or into the food web as well as degraded and undegraded petroleum constituents. Here we report (1) the increase in the relative abundance of oxygen-containing carbon compounds making up the dissolved organic matter (DOM) with increasing depth through the water column, indicating the biodegradation of DOM as it was transported to depth in the water column, (2) the finding of 14C depletion in DOM indicating petrocarbon inputs, and (3) the decrease and subsequent increase of 14C in the isotopic composition of sinking particles indicating the capture of petrocarbon in sediment traps. In addition, we discuss the 14C depletion of this material once it is sedimented to the seafloor and the implications for oil spill budgets of seafloor petrocarbon deposition.},
	keywords = {Dissolved organic matter, FTICR-MS, Gulf baselines, High-resolution mass spectrometry, organic carbon, radiocarbon, Ramped pyrolysis, Sediment organic matter},
	isbn = {978-3-030-12962-0},
	doi = {10.1007/978-3-030-12963-710.1007/978-3-030-12963-7_10},
	url = {https://link.springer.com/chapter/10.1007/978-3-030-12963-7_10},
	author = {Chanton, Jeffrey P. and Jaggi, Aprami and Radovi{\'c}, Jago{\v s} R. and Rosenheim, Brad E. and Walker, Brett D. and Larter, Stephen R. and Rogers, Kelsey and Bosman, Samantha and Oldenburg, Thomas B. P.},
	editor = {Murawski, Steven A. and Ainsworth, Cameron H. and Gilbert, Sherryl and Hollander, David J. and Paris, Claire B. and Schl{\"u}ter, Michael and Wetzel, Dana L.}
}
@article {2661,
	title = {On the Origin of Aged Sedimentary Organic Matter Along a River-Shelf-Deep Ocean Transect},
	journal = {Journal of Geophysical Research: Biogeosciences},
	volume = {124},
	year = {2019},
	month = {Jun-08-2021},
	pages = {2582 - 2594},
	abstract = {To assess the influences of carbon sources and transport processes on the C-14 age of organic matter (OM) in continental margin sediments, we examined a suite of samples collected along a river-shelf-deep ocean transect in the East China Sea (ECS). Ramped pyrolysis-oxidiation was conducted on suspended particulate matter in the Yangtze River and on surface sediments from the ECS shelf and northern Okinawa Trough. C-14 ages were determined on OM decomposition products within different temperature windows. These measurements suggest that extensive amounts of pre-old (i.e., millennial age) organic carbon (OC) are subject to degradation within and beyond the Yangtze River Delta, and this process is accompanied by an exchange of terrestrial and marine OM. These results, combined with fatty acid concentration data, suggest that both the nature and extent of OM preservation/degradation as well as the modes of transport influence the C-14 ages of sedimentary OM. Additionally, we find that the age of (thermally) refractory OC increases during across-shelf transport and that the age offset between the lowest and highest temperature OC decomposition fractions also increases along the shelf-to-trough transect. Amplified interfraction spread or C-14 heterogeneity is the greatest in the Okinawa Trough. Aged sedimentary OM across the transect may be a consequence of several reasons including fossil OC input, selective degradation of younger OC, hydrodynamic sorting processes, and aging during lateral transport. Consequently, each of them should be considered in assessing the C-14 results of sedimentary OM and its implications for the carbon cycle and interpretation of sedimentary records.},
	keywords = {Carbon cycle, hydrodynamic processes, organic carbon, radiocarbon, sediments},
	issn = {2169-8953},
	doi = {10.1029/2019JG005107},
	url = { https://doi.org/10.1029/2019JG005107},
	author = {Bao, Rui and Zhao, Meixun and McNichol, Ann and Wu, Ying and Guo, Xinyu and Haghipour, Negar and Eglinton, Timothy I.}
}
@article {2641,
	title = {Petrocarbon evolution: Ramped pyrolysis/oxidation and isotopic studies of contaminated oil sediments from the Deepwater Horizon oil spill in the Gulf of Mexico},
	journal = {PLOS ONE},
	volume = {14},
	year = {2019},
	month = {Apr-02-2021},
	pages = {e0212433},
	abstract = {Hydrocarbons released during the Deepwater Horizon (DWH) oil spill weathered due to exposure to oxygen, light, and microbes. During weathering, the hydrocarbons{\textquoteright} reactivity and lability was altered, but it remained identifiable as "petrocarbon" due to its retention of the distinctive isotope signatures (C-14 and C-13) of petroleum. Relative to the initial estimates of the quantity of oil-residue deposited in Gulf sediments based on 2010-2011 data, the overall coverage and quantity of the fossil carbon on the seafloor has been attenuated. To analyze recovery of oil contaminated deep-sea sediments in the northern Gulf of Mexico we tracked the carbon isotopic composition (C-13 and C-14, radiocarbon) of bulk sedimentary organic carbon through time at 4 sites. Using ramped pyrolysis/oxidation, we determined the thermochemical stability of sediment organic matter at 5 sites, two of these in time series. There were clear differences between crude oil (which decomposed at a lower temperature during ramped oxidation), natural hydrocarbon seep sediment (decomposing at a higher temperature; Delta C-14 = -189 parts per thousand) and our control site (decomposing at a moderate temperature; Delta C-14 = -189 parts per thousand), in both the stability (ability to withstand ramped temperatures in oxic conditions) and carbon isotope signatures. We observed recovery toward our control site bulk Delta C-14 composition at sites further from the wellhead in similar to 4 years, whereas sites in closer proximity had longer recovery times. The thermographs also indicated temporal changes in the composition of contaminated sediment, with shifts towards higher temperature CO2 evolution over time at a site near the wellhead, and loss of higher temperature CO2 peaks at a more distant site.},
	keywords = {C-14 ANALYSES; MARINE SNOW, degradation, fractionation, organic-matter, POLYCYCLIC AROMATIC-HYDROCARBONS; MICROBIAL COMMUNITY RESPONSE, radiocarbon, STABLE CARBON, surface sediments},
	doi = {10.1371/journal.pone.0212433},
	url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0212433},
	author = {Rogers, Kelsey L. and Bosman, Samantha H. and Lardie-Gaylord, Mary and McNichol, Ann and Rosenheim, Brad E. and Montoya, Joseph P. and Chanton, Jeffrey P.},
	editor = {Cooper, Lee W.}
}
@article {2666,
	title = {Single step Production of graphite from organic Samples for Radiocarbon Measurements},
	journal = {Radiocarbon},
	volume = {61},
	year = {2019},
	month = {Jan-12-2019},
	pages = {1843 - 1854},
	abstract = {We present a new low-cost, high-throughput method for converting many types of organic carbon samples into graphite for radiocarbon (14C) measurements by accelerator mass spectrometry (AMS). The method combines sample combustion and reduction to graphite into a single procedure. In the Single Step method, solid samples are placed directly into Pyrex containing zinc, titanium hydride and iron catalyst. The tube is evacuated, flame sealed, and placed in a muffle furnace for 7 hr. A variety of organic samples have been tested including oxalic acid, sucrose, wood, peat, collagen, humic acid, and contamination swipe samples. The method significantly reduces the time required to produce a graphite sample for 14C measurement, with analytical precision and accuracy approaching that of traditional two-step combustion and hydrogen reduction methods. The details and applicability of the method are presented.},
	keywords = {graphite, radiocarbon, sealed tube graphite, single step graphite},
	issn = {0033-8222},
	doi = {10.1017/RDC.2019.136},
	url = {https://www.cambridge.org/core/product/identifier/S003382221900136X/type/journal_articlehttps://www.cambridge.org/core/services/aop-cambridge-core/content/view/S003382221900136X},
	author = {Elder, K L and Roberts, M L and Walther, T and Xu, L}
}
@article {2774,
	title = {Testing the Utility of Geochemical Proxies to Reconstruct Holocene Coastal Environments and Relative Sea Level: A Case Study from Hungry Bay, Bermuda},
	journal = {Open Quaternary},
	volume = {5},
	year = {2019},
	month = {May-02-2019},
	abstract = {On low-lying, tropical and sub-tropical coastlines freshwater marshes may be replaced by salt-tolerant mangroves in response to relative sea-level rise. Pollen analysis of radiocarbon-dated sediment cores showed that such a change occurred in Hungry Bay, Bermuda during the late Holocene. This well-established paleoenvironmental trajectory provides an opportunity to explore if geochemical proxies (bulk-sediment δ13C and Rock-Eval pyrolysis) can reconstruct known environmental changes and relative sea level. We characterized surface sediment from depositional environments in Bermuda (freshwater wetlands, saline mangroves, and wrack composed of Sargassum natans macroalgae) using geochemical measurements and demonstrate that a multi-proxy approach can objectively distinguish among these environments. However, application of these techniques to the transgressive sediment succession beneath Hungry Bay suggests that freshwater peat and mangrove peat cannot be reliably distinguished in the sedimentary record, possibly because of post-depositional convergence of geochemical characteristics on decadal to multi-century timescales and/or the relatively small number of modern samples analyzed. Sediment that includes substantial contributions from Sargassum is readily identified by geochemistry, but has a limited spatial extent. Radiocarbon dating indicates that beginning at {\textendash}700 CE, episodic marine incursions into Hungry Bay (e.g., during storms) carried Sargassum that accumulated as wrack and thickened through repeated depositional events until ~300 CE. It took a further ~550 years for a peat-forming mangrove community to colonize Hungry Bay, which then accumulated sediment rapidly, but likely out of equilibrium with regional relative sea-level rise.},
	keywords = {mangrove, radiocarbon, Rock-Eval pyrolysis, Sargassum, δ13C},
	doi = {10.5334/oq.49},
	url = {http://www.openquaternary.com/articles/10.5334/oq.49/},
	author = {Kemp, Andrew C. and Vane, Christopher H. and Khan, Nicole S. and Ellison, Joanna C. and Engelhart, Simon E. and Horton, Benjamin P. and Nikitina, Daria and Smith, Struan R. and Rodrigues, Lisa J. and Moyer, Ryan P.}
}
@article {2644,
	title = {Upwelling in the Ocean Basins North of the ACC: 1. On the Upwelling Exposed by the Surface Distribution of C-14},
	journal = {Journal of Geophysical Research: Oceans},
	volume = {124},
	year = {2019},
	month = {Apr-04-2020},
	pages = {2591 - 2608},
	abstract = {he upwelling associated with the ocean{\textquoteright}s overturning circulation is hard to observe directly. Here, a large data set of surface C-14 measurements is compiled in order to show where deep water is brought back up to the surface in the ocean basins north of the Antarctic Circumpolar Current (ACC). Maps constructed from the data set show that low-C-14 deep water from the ACC is drawn up to the surface in or near the upwelling zones off Northwest Africa and Namibia in the Atlantic, off Costa Rica and Peru in the Pacific, and in the northern Arabian Sea in the Indian Ocean. Deep water also seems to be reaching the surface in the subarctic Pacific gyre near the Kamchatka Peninsula. The low-C-14 water drawn up to the surface in the upwelling zones is also shown to spread across the ocean basins. It is easily seen, for example, in the western Atlantic off Florida and in the western Pacific off New Guinea and Palau. The spreading allows one to estimate the volumes of upwelling, which, it turns out, are similar to the volumes of large-scale upwelling derived from inverse box models. This means that very large volumes of cool subsurface water are reaching the surface in and near the upwelling zonesmuch larger volumes than would be expected from the local winds.

Plain Language Summary The deep layers of the ocean are filled with cold dense water that sinks from the surface near Antarctica and in the northern North Atlantic. This process is understood reasonably well. The countervailing processthe way that the dense water is brought back up to the surfaceis not as well understood. Oceanographers now agree that the ocean{\textquoteright}s deep water is drawn back up to the surface (upwelled) mainly around Antarctica as part of the wind-driven overturning in the Antarctic Circumpolar Current (ACC). But cool water is also known to reach the surface in upwelling zones around the ocean{\textquoteright}s margins. Here we map the upwelling north of the ACC with the radioactive isotope carbon-14 and show that the deep water upwelled to the surface around Antarctica seems to be drawn up to the surface a second time in the upwelling zones. The water drawn up to the surface in the upwelling zones then flows back to the North Atlantic and sinks again to complete the cycle.},
	keywords = {Ocean circulation, overturning circulation, radiocarbon, Upwelling},
	issn = {2169-9275},
	doi = {10.1029/2018JC014794},
	url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JC014794},
	author = {Toggweiler, J. R. and Druffel, Ellen R. M. and Key, Robert M. and Galbraith, Eric D.}
}
@book {2720,
	title = {The Utility of Stable and Radioisotopes in Fish Tissues as Biogeochemical Tracers of Marine Oil Spill Food Web Effects},
	year = {2019},
	pages = {219 - 238},
	publisher = {Springer International Publishing},
	organization = {Springer International Publishing},
	address = {Cham},
	abstract = {Direct exposure to petroleum compounds was widely reported for a variety of taxa following the DWH. Evidence of exposure ranged from oiling of skin, shells, or feathers, depending on the taxa, to observation of ingested oil in small translucent, invertebrates, to biomarkers of petroleum compounds within an organism{\textquoteright}s tissues, such as PAHs in the hepatopancreas of invertebrates or the liver of fishes, or metabolic products of PAH catabolism in the bile of various vertebrate taxa. Development of natural biogeochemical tracers to examine indirect effects, especially over long (months to years) time scales, can be much more problematic. In this chapter, we describe the utility of employing stable isotopes and radioisotopes to 1) examine whether food web effects can be inferred from shifts in stable isotope values measured in vertebrate taxa; 2) examine the assimilation and trophic transfer of petrocarbon in marine food webs; and, 3) serve as long-term biogeochemical tracers either of petrocarbon assimilation or trophic shifts that are indicative of food web effects of marine oil spills. Data and analyses are largely drawn from DWH-related studies but with broader implications to marine oil spills in general.},
	keywords = {Petrocarbon, radiocarbon, Reef fish, Stable isotopes},
	isbn = {978-3-030-12962-0},
	doi = {10.1007/978-3-030-12963-710.1007/978-3-030-12963-7_13},
	url = {https://link.springer.com/chapter/10.1007/978-3-030-12963-7_13},
	author = {Patterson III, William F. and Chanton, Jeffery P. and Hollander, David J. and Goddard, Ethan A. and Barnett, Beverly K. and Tarnecki, Joseph H.},
	editor = {Murawski, Steven A. and Ainsworth, Cameron H. and Gilbert, Sherryl and Hollander, David J. and Paris, Claire B. and Schl{\"u}ter, Michael and Wetzel, Dana L.}
}
@article {2613,
	title = {Dimensions of Radiocarbon Variability within Sedimentary Organic MatterABSTRACT},
	journal = {Radiocarbon},
	volume = {60},
	year = {2018},
	month = {Jan-06-2018},
	pages = {775 - 790},
	abstract = {Organic carbon (OC) radiocarbon (14C) signatures in marine surface sediments are highly variable and the
causes of this heterogeneity remain ambiguous. Here, we present results from a detailed 14C-based investigation of an Arabian Sea sediment, including measurements on organic matter (OM) in bulk sediment, specific grain size fractions, and OC decomposition products from ramped-pyrolysis-oxidation (RPO). Our results show that 14C ages of OM increase with increasing grain size, suggesting that grain size is an important factor controlling the 14C heterogeneity in marine sediments. Analysis of RPO decomposition products from different grain size fractions reveals an overall increase in age of corresponding thermal fractions from finer to coarser fractions. We suggest that hydrodynamic properties of sediment grains exert the important control on the 14C age distribution of OM among grain size fractions. We propose a conceptual model to account for this dimensionality in 14C variability that invokes two predominant modes of OM preservation within different grain size fractions of Arabian Sea sediment: finer (<63 μm) fractions are influenced by OM-mineral grain aggregation processes, giving rise to relatively uniform 14C ages, whereas OM preserved in coarser (>63 μm) fractions includes materials encapsulated within microfossils and/or entrained fossil (14C-depleted) OC hosted in detrital mineral grains. Our findings highlight the value of RPO for assessment of 14C age variability in sedimentary OC, and for assessing mechanisms of OM preservation in aquatic sediments.},
	keywords = {arabian sea, grain size, hydrodynamic processes, organicmatter, radiocarbon, ramped pyrolysis-oxidation},
	issn = {0033-8222},
	doi = {10.1017/RDC.2018.22},
	url = {https://www.cambridge.org/core/journals/radiocarbon/article/dimensions-of-radiocarbon-variability-within-sedimentary-organic-matter/A81022494F34D8C3B88D39A43112BB08},
	author = {Bao, Rui and McNichol, Ann P and McIntyre, Cameron P and Xu, Li and Eglinton, Timothy I}
}
@article {2711,
	title = {Interstadial Rise and Younger Dryas Demise of Scotland{\textquoteright}s Last Ice Fields},
	journal = {Paleoceanography and Paleoclimatology},
	volume = {33},
	year = {2018},
	month = {Jan-04-2018},
	pages = {412 - 429},
	abstract = {Establishing the atmospheric expression of abrupt climate change during the last glacial termination is key to understanding driving mechanisms. In this paper, we present a new 14C chronology of glacier behavior during late-glacial time from the Scottish Highlands, located close to the overturning region of the North Atlantic Ocean. Our results indicate that the last pulse of glaciation culminated between ~12.8 and ~12.6 ka, during the earliest part of the Younger Dryas stadial and as much as a millennium earlier than several recent estimates. Comparison of our results with existing minimum-limiting 14C data also suggests that the subsequent deglaciation of Scotland was rapid and occurred during full stadial conditions in the North Atlantic. We attribute this pattern of ice recession to enhanced summertime melting, despite severely cool winters, and propose that relatively warm summers are a fundamental characteristic of North Atlantic stadials.},
	keywords = {late glacial, Loch Lomond Readvance, marine reservoir effect, moraine chronology, radiocarbon, seasonality},
	doi = {10.1002/palo.v33.410.1002/2018PA003341},
	url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2018PA003341},
	author = {Bromley, G. and Putnam, A. and Borns, H. and Lowell, T. and Sandford, T. and Barrell, D.}
}
@article {2630,
	title = {An Investigation of Gas Exchange and Water Circulation in the Amundsen Sea Based On Dissolved Inorganic Radiocarbon},
	journal = {Geophysical Research Letters},
	volume = {453},
	year = {2018},
	month = {Apr-11-2020},
	pages = {12,368 - 12,375},
	abstract = {We used radiocarbon isotope ratios in dissolved inorganic carbon to assess gas exchange and water circulation in the western Amundsen Sea. Radiocarbon isotope ratios indicate that Circumpolar Deep Water enters the basin along the seafloor and that the upper layer is formed through modification of this water mass. In the Amundsen Sea Polynya, radiocarbon isotope ratios of surface water are higher than those of underlying Winter Water, implying rapid absorption of atmospheric CO2. A CO2 absorption rate of 45mmol m(-2) d(-1) calculated for a site in the central polynya is higher than that near the Dotson Ice Shelf (28mmolm(-2) d(-1)). The turnover time of water in the Dotson Trough region of the western Amundsen Sea is estimated to be 10-30years, based on results from a box model and radiocarbon mass balance.

Plain Language Summary The western Amundsen Sea is experiencing raid physical changes including rapid glacial melting and declining sea ice cover. The suggested heat source is the intrusion of warm Circumpolar Deep Water (CDW) along the seafloor of the Amundsen Shelf. Therefore, understanding the behavior of the intruded CDW, especially how long it stays on the shelf, is important. Physical oceanographic studies have examined the flux of CDW onto and out of the Amundsen Shelf. However, the turnover time of water in the Amundsen Sea is still poorly understood. In this paper, we use radiocarbon isotope signature from dissolved inorganic carbon to examine how rapidly atmospheric CO2 is absorbed into the Amundsen Sea Polynya and how long the water should stay in the western Amundsen Shelf to have the observed radiocarbon isotope signature. Based on our results and the current understanding of the water circulation in the western Amundsen Sea, we found that the water sits on the Amundsen Shelf for a few decades before it moves off shelf.},
	keywords = {Amundsen sea, dissolved inorganic carbon, gas exchange, radiocarbon, water circulation},
	issn = {0094-8276},
	doi = {10.1029/2018GL079464},
	url = {http://apps.webofknowledge.com/InboundService.do?product=WOS\&Func=Frame\&DestFail=http\%3A\%2F\%2Fwww.webofknowledge.com\%3FDestParams\%3DUT\%253DWOS\%25253A000453250000030\%2526customersID\%253DAlerting\%2526smartRedirect\%253Dyes\%2526action\%253Dretrieve\%2526mode\%25},
	author = {Kim, Bumsoo and Lee, SangHoon and Kim, Minkyoung and Hahm, Doshik and Rhee, Tae Siek and Hwang, Jeomshik}
}
@article {2723,
	title = {Isotopic composition of sinking particles: Oil effects, recovery andbaselines in the Gulf of Mexico, 2010{\textendash}2015},
	journal = {Elem Sci Anth},
	volume = {6},
	year = {2018},
	month = {Sep-01-2018},
	pages = {43},
	abstract = {The extensive release of oil during the 2010 Deepwater Horizon spill in the northern Gulf of Mexico perturbed the pelagic ecosystem and associated sinking material. To gauge the recovery and post-spill baseline sources, we measured Δ14C, δ13C and δ34S of sinking particles near the spill site and at a reference site and natural seep site. Particulates were collected August 2010{\textendash}April 2016 in sediment traps moored at sites with depths of 1160{\textendash}1660 m. Near the spill site, changes in Δ14C indicated a 3-year recovery period, while δ34S indicated 1{\textendash}2 years, which agreed with estimates of 1{\textendash}2 years based on hydrocarbon composition. Under post-spill baseline conditions, carbon inputs to sinking particulates in the northern Gulf were dominated by surface marine production (80{\textendash}85\%) and riverine inputs (15{\textendash}20\%). Near the spill site, Δ14C values were depleted in October 2010 ({\textendash}140 to {\textendash}80{\textperthousand}), increasing systematically by 0.07 {\textpm} 0.02{\textperthousand} day{\textendash}1 until July 2013 when values reached {\textendash}3.2 {\textpm} 31.0{\textperthousand}. This Δ14C baseline was similar to particulates at the reference site (3.8 {\textpm} 31.1{\textperthousand}). At both sites, δ13C values stayed constant throughout the study period ({\textendash}21.9 {\textpm} 0.5{\textperthousand} and {\textendash}21.9 {\textpm} 0.9{\textperthousand}, respectively). δ34S near the spill site was depleted (7.4 {\textpm} 3.1{\textperthousand}) during October 2010{\textendash}September 2011, but enriched (16.9 {\textpm} 2.0{\textperthousand}) and similar to the reference site (16.2 {\textpm} 3.1{\textperthousand}) during November 2012{\textendash}April 2015. At the seep site, Δ14C values were {\textendash}21.7 {\textpm} 45.7{\textperthousand} except during August 2012{\textendash}January 2013 when a significant Δ14C depletion of {\textendash}109.0 {\textpm} 29.1{\textperthousand} was observed. We interpret this depletion period, also observed in δ13C data, as caused by the incorporation of naturally seeped oil into sinking particles. Determination of post-spill baselines for these isotopic signatures allows for evaluation of anthropogenic inputs in future.},
	keywords = {Deep Water Horizon Oil Spill, Gulf of Mexico, isotopes, radiocarbon, sediment trap, sinking particulates},
	doi = {10.1525/elementa.298},
	url = {https://www.elementascience.org/article/10.1525/elementa.298},
	author = {Chanton, Jeffrey P. and Giering, Sarah L. C. and Bosman, Samantha H. and Rogers, Kelsey L. and Sweet, Julia and Asper, Vernon L. and Diercks, Arne R. and Passow, Uta}
}
@article {2611,
	title = {Linear decline in red snapper (Lutjanus campechanus) otolith Δ14C extends the utility of the bomb radiocarbon chronometer for fish age validation in the Northern Gulf of Mexico},
	journal = {ICES Journal of Marine Science},
	volume = {8870697346588911255202655996472975862129455810210311781289189114143320657330766513996026526319911984699},
	year = {2018},
	month = {Mar-05-2018},
	abstract = {Radiocarbon (D14C) was analyzed in northern Gulf of Mexico (nGOM) red snapper (Lutjanus campechanus) otolith cores (n{\textonequarter}23), otolith
edge samples (n{\textonequarter}12), and whole age-0 otoliths (n{\textonequarter}9), with edge samples and whole age-0 otoliths constituting known-age samples.
There was no significant difference in the linear relationship of D14C versus year of formation between regional corals and known-age otolith
samples, and a linear regression fit to the combined data from 1980 to 2015 extends the utility of the bomb radiocarbon chronometer
for age validation. The entire regional coral and known-age otolith data set (1940 to 2015) was then utilized as a reference series to validate
otolith-derived red snapper age estimates for cored otolith samples. A loess regression was fit to the reference data and then the sum
of squared residuals (SSR) was computed from predicted versus observed birth years for cored adult otolith samples. This process was
then repeated for ages biased 61{\textendash}4 years. Ages with no bias applied had the lowest SSR, thus validating red snapper age estimates and
demonstrating the utility of the combined regional coral and known-age red snapper otolith D14C time series for age validation of nGOM
marine fishes.},
	keywords = {Age validation, otoliths, radiocarbon, red snapper},
	issn = {1054-3139},
	doi = {10.1093/icesjms/fsy043},
	url = {https://academic.oup.com/icesjms/advance-article/doi/10.1093/icesjms/fsy043/4992258http://academic.oup.com/icesjms/advance-article-pdf/doi/10.1093/icesjms/fsy043/24775644/fsy043.pdf},
	author = {Barnett, Beverly K and Thornton, Laura and Allman, Robert and Chanton, Jeffrey P and Patterson, William F}
}
@article {2737,
	title = {Radiocarbon and Stable Isotope Evidence for Changes in Sediment Mixing in the North Pacific over the Past 30 kyrAbstract},
	journal = {Radiocarbon},
	volume = {60},
	year = {2018},
	month = {Jan-02-2018},
	pages = {113 - 135},
	abstract = {Deep-sea sediment mixing by bioturbation is ubiquitous on the seafloor, and it can be an important influence on the fidelity of paleoceanographic records. Bioturbation can be difficult to quantify, especially in the past, but diffusive models based on radioactive tracer profiles have provided a relatively successful approach. However, a singular, constant mixing regime is unlikely to prevail in a region where dynamic oceanographic changes in the bottom water environment are a consequence of paleoclimatic variability. In this study, foraminiferal stable isotopes, radiocarbon (14C) dating, and 230Th fluxes are utilized to understand the sediment mixing history in the easternmost region of the North Pacific. In the uppermost sediment, a 12,000-yr offset between planktonic foraminifera species N. incompta and G. bulloides is observed that coincides with age plateaus at 2000{\textendash}2500 yr for N. incompta and 15,000{\textendash}16,000 yr for G. bulloides despite coincident glacial-interglacial shifts in δ18O of benthic species. These age plateaus, particularly for G. bulloides, are a result of changing foraminiferal abundance related to assemblage shifts and carbonate preservation changes since the last glacial period, providing a window into the extent of mixing in the past. The 14C and stable isotope results can be simulated using an iterative model that couples these changes in foraminiferal abundance with variability in mixing depth over time. The best-fit model output suggests that the deepest, or most intense, mixing of the past 30,000 yr (30 kyr) may have occurred during the Holocene. Even though changes in mixing affect the 14C and δ18O of planktonic species that have dramatically varying abundance, substantial age control is nevertheless provided by δ18O measurements on the more consistently abundant benthic foraminifera Uvigerina, thus allowing the construction of a reliable chronology for these cores.},
	keywords = {bioturbation, north pacific, radiocarbon, Stable isotopes},
	issn = {0033-8222},
	doi = {10.1017/RDC.2017.91},
	url = {https://www.cambridge.org/core/product/identifier/S0033822217000911/type/journal_articlehttps://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033822217000911},
	author = {Costa, Kassandra M and McManus, Jerry F and Anderson, Robert F}
}
@article {2605,
	title = {Radiocarbon Content of Dissolved Organic Carbon in the South Indian Ocean},
	journal = {Geophysical Research Letters},
	volume = {45},
	year = {2018},
	month = {01/2018},
	pages = {872 - 879},
	abstract = {We report four profiles of the radiocarbon content of dissolved organic carbon (DOC) spanning the South Indian Ocean (SIO), ranging from the Polar Front (56{\textdegree}S) to the subtropics (29{\textdegree}S). Surface waters held mean DOC Δ14C values of -426 {\textpm} 6{\textperthousand} (~4,400 14C years) at the Polar Front and DOC Δ14C values of -252 {\textpm} 22{\textperthousand} (~2,000 14C years) in the subtropics. At depth, Circumpolar Deep Waters held DOC Δ14C values of -491 {\textpm} 13{\textperthousand} (~5,400 years), while values in Indian Deep Water were more depleted, holding DOC Δ14C values of -503 {\textpm} 8{\textperthousand} (~5,600 14C years). High-salinity North Atlantic Deep Water intruding into the deep SIO had a distinctly less depleted DOC Δ14C value of -481 {\textpm} 8{\textperthousand} (~5,100 14C years). We use multiple linear regression to assess the dynamics of DOC Δ14C values in the deep Indian Ocean, finding that their distribution is characteristic of water masses in that region. },
	keywords = {dissolved organic carbon, indian ocean, radiocarbon},
	doi = {10.1002/grl.v45.210.1002/2017GL076295},
	url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017GL076295},
	author = {Bercovici, S. K. and McNichol, A. P. and Xu, L. and Hansell, D. A.}
}
@article {2626,
	title = {Spatiotemporal Variation of the Quality, Origin, and Age of Particulate Organic Matter Transported by the Yangtze River (Changjiang)},
	journal = {Journal of Geophysical Research: Biogeosciences},
	volume = {123},
	year = {2018},
	month = {Jan-09-2018},
	pages = {2908 - 2921},
	abstract = {Information on the age dynamics of particulate organic matter (POM) in large river systems is currently sparse and represents an important knowledge gap in our understanding of the global carbon cycle. Here we examine variations in organic geochemical characteristics of suspended sediments from the Changjiang (Yangtze River) system collected between 1997 and 2010. Higher particulate organic carbon content (POC\%) values were observed in the middle reach, especially after 2003, and are attributed to the increase of in situ (aquatic) primary production associated with decreased total suspended matter concentrations. Corresponding C-14 values from depth profiles taken in 2009 and 2010 indicate spatial and temporal variations in POC sources within the basin. Two isotopic mass balance approaches were explored to quantitatively apportion different sources of Changjiang POM. Results indicate that contributions of biomass and pre-aged soil organic matter are dominant, regardless of hydrological conditions, with soil-derived organic carbon comprising 17-56\% of POC based on a Monte Carlo three-end-member mixing model. In contrast, binary mixing model calculations suggest that up to 80\% of POC (2009 samples only) derived from biospheric sources. The emplacement of the Three Gorges Dam and resulting trapping of sediment from the upper reach of the watershed resulted in a modification of POM C-14 ages in the reservoir. With the resulting decline in sediment load and increase in the proportion of modern POC in the lower reach, these changes in POM flux and composition of the Changjiang have significant implications for downstream carbon cycle processes.},
	keywords = {Changjiang, organic carbon, radiocarbon, suspended particulate matter, Three Gorges Dam},
	issn = {2169-8953},
	doi = {10.1029/2017JG004285},
	url = {http://doi.wiley.com/10.1029/2017JG004285http://onlinelibrary.wiley.com/wol1/doi/10.1029/2017JG004285/fullpdfhttps://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029\%2F2017JG004285},
	author = {Wu, Ying and Eglinton, Timothy I. and Zhang, Jing and Montlu{\c c}on, Daniel B.}
}
@book {2568,
	title = {Coastal Research LibraryCoastline Changes of the Baltic Sea from South to EastConstraints of Radiocarbon Dating in Southeastern Baltic Lagoons: Assessing the Vital Effects},
	series = {Coastline Changes of the Baltic Sea from South to East},
	number = {19},
	year = {2017},
	pages = {137 - 171},
	publisher = {Springer International Publishing},
	organization = {Springer International Publishing},
	address = {Cham},
	abstract = {During the past decades, a suite of radiocarbon (14C), infrared optically stimulated luminescence (IR-OSL), and electron spin resonance (ESR) dates were compiled on a variety of materials from the Curonian and Vistula lagoons and spits of the southeastern Baltic Sea. These dated materials generally included lagoon sediments and mollusc shells, along with samples of fossil fish remains, peat, wood, and water bicarbonates. A growing number of 14C dates (conventional and AMS) demonstrates disparities and contradictions with the associated IR-OSL dates and palaeobotanical investigations of contemporary materials. Detailed analyses of 14C, IR-OSL and ESR chronologies and experimental 14C dating of modern live molluscs and water bicarbonates from the Curonian Lagoon and its main tributary {\textendash} Nemunas-Neris River system {\textendash} reveals a substantial influx of {\textquotedblleft}old{\textquotedblright} carbonates into the lagoon. As a result, the uncertainty of reservoir effect added a considerable error to the 14C ages. Moreover, fossil molluscs of the same species extracted from boreholes and outcrops yield significantly younger ages (up to several millennia) than the enclosing sediments. Both of these trends {\textendash} aging and rejuvenation {\textendash} highlight an urgent need for constraining the local reservoir correction (ΔR). Several scenarios are presented to explain the impact of vital effects on radiocarbon chronology of carbonates and to offer strategies to account for them in future studies.},
	keywords = {Curonian lagoon, ESR, IR-OSL, Molluscs, radiocarbon, Reservoir effect, Vistula lagoon},
	isbn = {978-3-319-49892-8},
	issn = {2211-0577},
	doi = {10.1007/978-3-319-49894-210.1007/978-3-319-49894-2_8},
	url = {http://link.springer.com/10.1007/978-3-319-49894-2_8},
	author = {Bitinas, Albertas and {\v z}eika, Jonas and Buynevich, Ilya V. and {\v s}yte, Aldona and Molodkov, Anatoly and e, Alma},
	editor = {Harff, Jan and {\'n}czyk, Kazimierz and von Storch, Hans}
}
@article {Zigah2017,
	title = {Constraining the sources and cycling of dissolved organic carbon in a large oligotrophic lake using radiocarbon analyses},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {208},
	year = {2017},
	pages = {102-118},
	abstract = {Abstract We measured the concentrations and isotopic compositions of solid phase extracted (SPE) dissolved organic carbon (DOC) and high molecular weight (HMW) \{DOC\} and their constituent organic components in order to better constrain the sources and cycling of \{DOC\} in a large oligotrophic lacustrine system (Lake Superior, North America). \{SPE\} \{DOC\} constituted a significant proportion (41-71\%) of the lake \{DOC\} relative to \{HMW\} \{DOC\} (10-13\%). Substantial contribution of 14C-depleted components to both \{SPE\} \{DOC\} (Δ14C = 25 to 43{\textperthousand}) and \{HMW\} \{DOC\} (Δ14C = 22 to 32{\textperthousand}) was evident during spring mixing, and depressed their radiocarbon values relative to the lake dissolved inorganic carbon (DIC; Δ14C \~{} 59{\textperthousand}). There was preferential removal of 14C-depleted (older) and thermally recalcitrant components from \{HMW\} \{DOC\} and \{SPE\} \{DOC\} in the summer. Contemporary photoautotrophic addition to \{HMW\} \{DOC\} was observed during summer stratification in contrast to \{SPE\} DOC, which decreased in concentration during stratification. Serial thermal oxidation radiocarbon analysis revealed a diversity of sources (both contemporary and older) within the \{SPE\} DOC, and also showed distinct components within the \{HMW\} DOC. The thermally labile components of \{HMW\} \{DOC\} were 14C-enriched and are attributed to heteropolysaccharides (HPS), peptides/amide and amino sugars (AMS) relative to the thermally recalcitrant components reflecting the presence of older material, perhaps carboxylic-rich alicyclic molecules (CRAM). The solvent extractable lipid-like fraction of \{HMW\} \{DOC\} was very 14C-depleted (as old as 1270-2320 14C years) relative to the substances isolated by acid hydrolysis of \{HMW\} DOC. Our data constrain relative influences of contemporary \{DOC\} and old DOC, and \{DOC\} cycling in a modern freshwater ecosystem.},
	keywords = {atmospheric co2, Carbohydrate-like substance, Carboxylic-rich alicyclic molecules (CRAM), Contemporary DOC, dissolved inorganic carbon, dissolved organic carbon, Freshwater carbon cycling, Heteropolysaccharides (HPS), High molecular weight DOC, Lake Superior, Lipid-like fraction, Old DOC, Oligotrophic lake, Protein-like substance, radiocarbon, Serial thermal oxidation, Solid phase extracted DOC, Stable isotope, Unhydrolysable material},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2017.03.021},
	url = {http://www.sciencedirect.com/science/article/pii/S0016703717301722},
	author = {Prosper K. Zigah and Elizabeth C. Minor and Ann P. McNichol and Li Xu and Josef P. Werne}
}
@article {2765,
	title = {Hydrologic controls on seasonal and inter-annual variability of Congo River particulate organic matter source and reservoir age},
	journal = {Chemical Geology},
	volume = {466},
	year = {2017},
	month = {Jan-09-2017},
	pages = {454 - 465},
	abstract = {We present dissolved organic carbon (DOC) concentrations, particulate organic matter (POM) composition (δ13C, δ15N, ∆14C, N/C), and particulate glycerol dialkyl glycerol tetraether (GDGT) distributions from a 34-month time-series near the mouth of the Congo River. An end-member mixing model using δ13C and N/C indicates that exported POM is consistently dominated by C3 rainforest soil sources, with increasing contribution from C3 vegetation and decreasing contribution from phytoplankton at high discharge. Large C4 inputs are never observed despite covering ≈ 13\% of the catchment. Low and variable ∆14C values during 2011 [annual mean = (- 148 {\textpm} 82) {\textperthousand}], when discharge from left-bank tributaries located in the southern hemisphere reached record lows, likely reflect a bias toward pre-aged POM derived from the Cuvette Congolaise swamp forest. In contrast, ∆14C values were stable near - 50{\textperthousand} between January and June 2013, when left-bank discharge was highest. We suggest that headwater POM is replaced and/or diluted by C3 vegetation and pre-aged soils during transit through the Cuvette Congolaise, whereas left-bank tributaries export significantly less pre-aged material. GDGT distributions provide further evidence for seasonal and inter-annual variability in soil provenance. The cyclization of branched tetraethers and the GDGT-0 to crenarchaeol ratio are positively correlated with discharge (r >= 0.70; p-value <= 4.3 {\texttimes} 10- 5) due to the incorporation of swamp-forest soils when discharge from right-bank tributaries located in the northern hemisphere is high. Both metrics reach record lows during 2013, supporting our interpretation of increased left-bank contribution at this time. We conclude that hydrologic variability is a major control of POM provenance in the Congo River Basin and that tropical wetlands can be a significant POM source despite their small geographic coverage.},
	keywords = {biomarkers, Congo River, GDGTs, Particulate organic matter, radiocarbon},
	issn = {00092541},
	doi = {10.1016/j.chemgeo.2017.06.034},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0009254117303935},
	author = {Hemingway, Jordon D. and Schefu{\ss}, Enno and Spencer, Robert G.M. and Dinga, Bienvenu Jean and Eglinton, Timothy I. and McIntyre, Cameron and Galy, Valier V.}
}
@article {2862,
	title = {A probabilistic method of assessing carbon accumulation rate at Imnavait Creek Peatland, Arctic Long Term Ecological Research Station, Alaska},
	journal = {Journal of Quaternary Science},
	volume = {32},
	year = {2017},
	month = {Jan-07-2017},
	pages = {579 - 586},
	abstract = {Arctic peatlands are an important part of the global carbon cycle, accumulating atmospheric carbon as organic matter since the Late glacial. Current methods for understanding the changing efficiency of the peatland carbon sink rely on peatlands with an undisturbed stratigraphy. Here we present a method of estimating primary carbon accumulation rate from a site where permafrost processes have either vertically or horizontally translocated nearby carbon-rich sediment out of stratigraphic order. Briefly, our new algorithm estimates the probability of the age of deposition of a random increment of sediment in the core. The method assumes that if sediment age is measured at even depth increments, dates are more likely to occur during intervals of higher accumulation rate and vice versa. Multiplying estimated sedimentation rate by measured carbon density yields carbon accumulation rate. We perform this analysis at the Imnavait Creek Peatland, near the Arctic Long Term Ecological Research network site at Toolik Lake, Alaska. Using classical radiocarbon age modeling, we find unreasonably high rates of carbon accumulation at various Holocene intervals. With our new method, we find accumulation rate changes that are in improved agreement within the context of other sites throughout Alaska and the rest of the Circum-Arctic region.},
	keywords = {carbon accumulation, Imnavait, peatlands, permafrost, radiocarbon, Toolik LTER},
	doi = {10.1002/jqs.2952},
	url = {https://onlinelibrary.wiley.com/doi/10.1002/jqs.2952},
	author = {Nichols, Jonathan E. and Peteet, Dorothy M. and Frolking, Steve and Karavias, John}
}
@article {2509,
	title = {Quantifying bamboo coral growth rate nonlinearity with the radiocarbon bomb spike: A new model for paleoceanographic chronology development},
	journal = {Deep Sea Research Part I: Oceanographic Research Papers},
	year = {2017},
	month = {Jan-04-2017},
	abstract = {Bamboo corals, long-lived cold water gorgonin octocorals, offer unique paleoceanographic archives of the intermediate ocean. These Isididae corals are characterized by alternating gorgonin nodes and high Mg-calcite internodes, which synchronously extend radially. Bamboo coral calcite internodes have been utilized to obtain geochemical proxy data, however, growth rate uncertainty has made it difficult to construct precise chronologies for these corals. Previous studies have relied upon a single tie point from records of the anthropogenic Δ14C bomb spike preserved in the gorgonin nodes of live-collected corals to calculate a mean radial extension rate for the outer ~50 years of skeletal growth. Bamboo coral chronologies are typically constructed by applying this mean extension rate to the entire coral record, assuming constant radial extension with coral age. In this study, we aim to test this underlying assumption by analyzing the organic nodes of six California margin bamboo corals at high enough resolution (<0.5 mm) to identify the Δ14C bomb spike, including two tie points at 1957 and 1970, plus the coral collection date (2007.5) for four samples. Radial extension rates between tie points ranged from 10 to 204 {\textmu}m/year, with a decrease in growth rate evident between the 1957{\textendash}1970 and 1970{\textendash}2007.5 periods for all four corals. A negative correlation between growth rate and coral radius (r =-0.7; p=0.04) was determined for multiple bamboo coral taxa and individuals from the California margin, demonstrating a decline in radial extension rate with specimen age and size. To provide a mechanistic basis for these observations, a simple mathematical model was developed based on the assumption of a constant increase in circular cross sectional area with time to quantify this decline in radial extension rate with coral size between chronological tie points. Applying the area-based model to our Δ14C bomb spike time series from individual corals improves chronology accuracy for all live-collected corals with complete Δ14C bomb spikes. Hence, this study provides paleoceanographers utilizing bamboo corals with a method for reducing age model uncertainty within the anthropogenic bomb spike era (~1957-present). Chronological uncertainty is larger for the earliest portion of coral growth, particularly for skeleton precipitated prior to bomb spike tie points, meaning age estimations for samples living before 1957 remain uncertain. Combining this technique with additional chronological markers could improve age models for an entire bamboo coral. Finally, the relative consistency in growth rate in similarly-aged corals of the same depth and location supports the hypothesis that skeletal growth may be limited by local environmental conditions.},
	keywords = {14C nuclear bomb spike, Bamboo coral, Chronologies, Gorgonin, Growth rate, paleoceanography, radiocarbon},
	issn = {09670637},
	doi = {10.1016/j.dsr.2017.04.006},
	url = {https://doi.org/10.1016/j.dsr.2017.04.006},
	author = {Frenkel, M.M. and LaVigne, M. and Miller, H.R. and Hill, T.M. and McNichol, A. and Gaylord, M. Lardie}
}
@article { ISI:000395186600009,
	title = {Short organic carbon turnover time and narrow C-14 age spectra in early Holocene wetland paleosols},
	journal = {GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS},
	volume = {18},
	number = {{1}},
	year = {2017},
	month = {JAN},
	pages = {142-155},
	type = {Article},
	abstract = {Paleosols contain information about the rates of soil organic carbon turnover when the soil was actively forming. However, this temporal information is often difficult to interpret without tight stratigraphic control on the age of the paleosol. Here we apply ramped pyrolysis/oxidation (Ramped PyrOx) C-14 analyses to evaluate age spectra of transgressive early Holocene paleosols from the Mississippi Delta in southeastern Louisiana, USA. We find C-14 age spectra from soil organic matter (SOM) in both paleosols and overlying basal peats that represent variability in age that is close to, or only slightly greater than, analytical uncertainty of C-14 measurements, despite different sources of carbon with likely disparate ages. Such age spectra have not previously been observed in the sedimentary record. Here they indicate vigorous soil carbon turnover prior to burial, which homogenized C-14 ages within SOM across the entire thermochemical spectrum. The weighted bulk C-14 ages from Ramped PyrOx of paleosols and overlying peats are identical within analytical and process-associated uncertainty, and corroborate C-14 ages from charcoal fragments and plant macrofossils from the overlying peat. The youngest ages from Ramped PyrOx age spectra may also potentially be applied as chronometers for stratigraphic burial ages. Our results suggest rapid turnover (<<300 years) of carbon in these soils relative to input of allochthonous carbon, indicating that the C-14 age of different soil components is decoupled from thermochemical stability and instead reflects vigorous turnover processes. The concurrence of paleosol and peat C-14 ages also suggests that pedogenic processes were linked with the development of coastal marshes, and that the priming effect potentially masked the signal of allochthonous carbon inputs during sea level rise.},
	keywords = {paleosol, radiocarbon, ramped PyrOx, soil organic carbon, turnover time},
	issn = {1525-2027},
	doi = {10.1002/2016GC006526},
	author = {Vetter, Lael and Rosenheim, Brad E. and Fernandez, Alvaro and Tornqvist, Torbjoern E.}
}
@article {2600,
	title = {Turning up the Heat on Organic Matter to Track Carbon},
	journal = {Eos},
	volume = {98},
	year = {2017},
	month = {Jul-09-2018},
	keywords = {Antarctic sediments, Foraminifera, radiocarbon, stable carbon isotopes},
	doi = {10.1029/2017EO080771},
	url = {https://eos.org/meeting-reports/turning-up-the-heat-on-organic-matter-to-track-carbon},
	author = {McNichol, Ann and Rosenheim, Brad and Galy, Valier}
}
@article { ISI:000375679100005,
	title = {Carbon isotopic (C-14 and C-13) characterization of fossil-fuel derived dissolved organic carbon in wet precipitation in Shandong Province, China},
	journal = {JOURNAL OF ATMOSPHERIC CHEMISTRY},
	volume = {73},
	number = {{2}},
	year = {2016},
	month = {JUN},
	pages = {207-221},
	type = {Article},
	abstract = {We present results from a 1-year study of radiocarbon and stable carbon isotope measurement of dissolved organic carbon (DOC) of wet precipitation samples collected in the Shandong province of China. A total of 32 rainfall and 4 snow samples were collected from two coastal cities (Qingdao and Yantai) and one inland site (Taian) during 2014. Concentrations of DOC in the rainwater and snow samples varied widely from 28 to 616 mu M. In general, rainwater originating from marine sources had relatively low DOC concentrations compared with continentally generated precipitation. Values of delta C-13-DOC and Delta C-14-DOC in the snow and rainwater ranged from -19.0 to -29.4 \% and -23 to -494 \%, with corresponding radiocarbon ages of 125 to 5410 years before present. The dominant DOC in the wet precipitation had a relatively old C-14 age (average 2841 years) and a depleted C-13 value (average -24.4 Years), indicating the mixing of contemporary organic carbon with C-14-depleted fossil fuel-derived soluble organic carbon in the atmosphere. Using a dual isotopic two-endmember model, we calculate that 7 \% to 52 \% of DOC in the snow and rainfall originated from fossil fuels. It is estimated that the flux of DOC in continental rainfall of China is 23 x 10(12) g C yr(-1) and of this, 7.1 x 10(12) g C yr(-1) could be fossil-fuel OC. On a global scale, the DOC flux in rainfall is estimated to be 357 Tg C yr(-1), and 110 Tg C yr(-1) could be fossil fuel-derived. Our study demonstrates that wet precipitation is an important removal process for old fossil fuel carbon from the atmosphere. This removal mechanism could play an important role in the carbon cycle, especially for the anthropogenically derived fraction, and it should be taken into consideration in global carbon cycle models.},
	keywords = {Atmospheric pollution, Fossil fuelemission, organic carbon, radiocarbon, Wet precipitation},
	issn = {0167-7764},
	doi = {10.1007/s10874-015-9323-3},
	author = {Wang, Xuchen and Ge, Tiantian and Xu, Caili and Xue, Yuejun and Luo, Chunle}
}
@article { ISI:000389875700006,
	title = {DISSOLVED INORGANIC RADIOCARBON IN THE NORTHWEST PACIFIC CONTINENTAL MARGIN},
	journal = {RADIOCARBON},
	volume = {58},
	number = {{3}},
	year = {2016},
	month = {SEP},
	pages = {517-529},
	type = {Article},
	abstract = {This article presents a modified method for extraction of dissolved inorganic carbon (DIC) from seawater for radiocarbon measurement by accelerator mass spectrometry (AMS). Standard tests indicate that the extraction efficiencies of DIC are >96\%, and the respective precisions of. Delta C-14-DIC and delta C-13-DIC analyses are 6\% and 0.1\% or better. Using the method, we report. Delta C-14-DIC profiles collected from the shelf and slope in the East China Sea (ECS) of the northwest Pacific Ocean. Both the DIC concentration and. Delta C-14-DIC in the shelf and slope regions seem primarily affected by the Kuroshio Current. It is estimated that 54-65\% of the bottom water in the shelf region could be from the intrusion of Kuroshio intermediate water, which carries a high concentration and low. Delta C-14 values of DIC, and which influenced the DIC and its Delta C-14 signature on the shelf. Compared with the. Delta C-14-DIC profiles at other sites in the northwest Pacific reported previously, it appears that the. Delta C-14-DIC distributions are mainly controlled by the major oceanic currents in the region, and large variations in. Delta C-14-DIC occurred mostly in the upper 800m of the water column. The similarity of. Delta C-14-DIC at depth suggests that the deep-water circulation patterns have been relatively stable in the northwest Pacific Ocean in the last 20 yr.},
	keywords = {continental margin, dissolved inorganic carbon, East China Sea, radiocarbon, stable carbon isotope},
	issn = {0033-8222},
	doi = {10.1017/RDC.2016.23},
	author = {Ge, Tiantian and Wang, Xuchen and Zhang, Jing and Luo, Chunle and Xue, Yuejun}
}
@article { ISI:000372829700018,
	title = {A Note on Reporting of Reservoir C-14 Disequilibria and Age Offsets},
	journal = {RADIOCARBON},
	volume = {58},
	number = {{1}},
	year = {2016},
	month = {MAR},
	pages = {205-211},
	type = {Article},
	abstract = {Reservoir age offsets are widely used to correct marine and speleothem radiocarbon age measurements for various calibration purposes. They also serve as a powerful tracer for carbon cycle dynamics. However, a clear terminology regarding reservoir age offsets is lacking, sometimes leading to miscalculations. This note seeks to provide consistent conventions for reporting reservoir C-14 disequilibria useful to a broad range of environmental sciences. This contribution introduces the (FR)-R-14 and R-14 metrics to express the relative C-14 disequilibrium between two contemporaneous reservoirs and the R metric as the associated reservoir age offset.},
	keywords = {freshwater effect, hardwater effect, radiocarbon, Reservoir age, Reservoir effect, ventilation age},
	issn = {0033-8222},
	doi = {10.1017/RDC.2015.22},
	author = {Soulet, Guillaume and Skinner, Luke C. and Beaupr{\'e}, Steven R. and Galy, Valier}
}
@article { ISI:000364572000008,
	title = {An effective method of UV-oxidation of dissolved organic carbon in natural waters for radiocarbon analysis by accelerator mass spectrometry},
	journal = {JOURNAL OF OCEAN UNIVERSITY OF CHINA},
	volume = {14},
	number = {{6}},
	year = {2015},
	month = {DEC},
	pages = {989-993},
	type = {Article},
	abstract = {Radiocarbon (C-14) measurement of dissolved organic carbon (DOC) is a very powerful tool to study the sources, transformation and cycling of carbon in the ocean. The technique, however, remains great challenges for complete and successful oxidation of sufficient DOC with low blanks for high precision carbon isotopic ratio analysis, largely due to the overwhelming proportion of salts and low DOC concentrations in the ocean. In this paper, we report an effective UV-Oxidation method for oxidizing DOC in natural waters for radiocarbon analysis by accelerator mass spectrometry (AMS). The UV-oxidation system and method show 95\%+/- 4\% oxidation efficiency and high reproducibility for DOC in both river and seawater samples. The blanks associated with the method was also low (about 3 A mu g C) that is critical for C-14 analysis. As a great advantage of the method, multiple water samples can be oxidized at the same time so it reduces the sample processing time substantially compared with other UV-oxidation method currently being used in other laboratories. We have used the system and method for C-14 studies of DOC in rivers, estuaries, and oceanic environments and have received promise results.},
	keywords = {AMS, dissolved organic carbon, natural waters, radiocarbon, UV-oxidation},
	issn = {1672-5182},
	doi = {10.1007/s11802-015-2935-z},
	author = {Xue Yuejun and Ge Tiantian and Wang Xuchen}
}
@article {2454,
	title = {Growth rate determinations from radiocarbon in bamboo corals (genus  Keratoisis )},
	journal = {Deep Sea Research Part I: Oceanographic Research Papers},
	volume = {105},
	year = {2015},
	month = {Jan-11-2015},
	pages = {26 - 40},
	abstract = {Radiocarbon (14C) measurements are an important tool for determining growth rates of bamboo corals, a cosmopolitan group of calcitic deep-sea corals. Published growth rate estimates for bamboo corals are highly variable, with potential environmental or ecological drivers of this variability poorly constrained. Here we systematically investigate the application of 14C for growth rate determinations in bamboo corals using 55 14C dates on the calcite and organic fractions of six bamboo corals (identified as Keratoisis sp.) from the western North Atlantic Ocean. Calcite 14C measurements on the distal surface of these corals and five previously published bamboo corals exhibit a strong one-to-one relationship with the 14C of dissolved inorganic carbon (DI14C) in ambient seawater (r2=0.98), confirming the use of Keratoisis sp. calcite 14C as a proxy for seawater 14C activity. Radial growth rates determined from 14C age-depth regressions, 14C plateau tuning and bomb 14C reference chronologies range from 12 to 78 {\textmu}m y-1, in general agreement with previously published radiometric growth rates. We document potential biases to 14C growth rate determinations resulting from water mass variability, bomb radiocarbon, secondary infilling (ontogeny), and growth rate nonlinearity. Radial growth rates for Keratoisis sp. specimens do not correlate with ambient temperature, suggesting that additional biological and/or environmental factors may influence bamboo coral growth rates.},
	keywords = {Bamboo coral, Deep-sea coral, Growth rates, radiocarbon},
	issn = {09670637},
	doi = {10.1016/j.dsr.2015.08.004},
	url = {http://linkinghub.elsevier.com/retrieve/pii/S0967063715001405http://api.elsevier.com/content/article/PII:S0967063715001405?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0967063715001405?httpAccept=text/plain},
	author = {Farmer, Jesse R. and Robinson, Laura F. and {\"o}nisch, {\"a}rbel}
}
@article {2638,
	title = {Hidden cycle of dissolved organic carbon in the deep ocean},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {111},
	year = {2014},
	month = {Jan-11-2016},
	pages = {16706 - 16711},
	abstract = {Marine dissolved organic carbon (DOC) is a large (660 Pg C) reactive carbon reservoir that mediates the oceanic microbial food web and interacts with climate on both short and long timescales. Carbon isotopic content provides information on the DOC source via [Formula: see text]C and age via [Formula: see text]C. Bulk isotope measurements suggest a microbially sourced DOC reservoir with two distinct components of differing radiocarbon age. However, such measurements cannot determine internal dynamics and fluxes. Here we analyze serial oxidation experiments to quantify the isotopic diversity of DOC at an oligotrophic site in the central Pacific Ocean. Our results show diversity in both stable and radio isotopes at all depths, confirming DOC cycling hidden within bulk analyses. We confirm the presence of isotopically enriched, modern DOC cocycling with an isotopically depleted older fraction in the upper ocean. However, our results show that up to 30\% of the deep DOC reservoir is modern and supported by a 1 Pg/y carbon flux, which is 10 times higher than inferred from bulk isotope measurements. Isotopically depleted material turns over at an apparent time scale of 30,000 y, which is far slower than indicated by bulk isotope measurements. These results are consistent with global DOC measurements and explain both the fluctuations in deep DOC concentration and the anomalous radiocarbon values of DOC in the Southern Ocean. Collectively these results provide an unprecedented view of the ways in which DOC moves through the marine carbon cycle.},
	keywords = {Carbon cycle, carbon isotopes, dissolved organic carbon, Oceanography, radiocarbon},
	issn = {0027-8424},
	doi = {10.1073/pnas.1407445111},
	url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1407445111https://syndication.highwire.org/content/doi/10.1073/pnas.1407445111},
	author = {Follett, Christopher L. and Repeta, Daniel J. and Rothman, Daniel H. and Xu, Li and Santinelli, Chiara}
}
@article { ISI:000348452800012,
	title = {Preferential burial of permafrost-derived organic carbon in Siberian-Arctic shelf waters},
	journal = {JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS},
	volume = {119},
	number = {{12}},
	year = {2014},
	month = {DEC},
	pages = {8410-8421},
	type = {Article},
	abstract = {The rapidly changing East Siberian Arctic Shelf (ESAS) receives large amounts of terrestrial organic carbon (OC) from coastal erosion and Russian-Arctic rivers. Climate warming increases thawing of coastal Ice Complex Deposits (ICD) and can change both the amount of released OC, as well as its propensity to be converted to greenhouse gases (fueling further global warming) or to be buried in coastal sediments. This study aimed to unravel the susceptibility to degradation, and transport and dispersal patterns of OC delivered to the ESAS. Bulk and molecular radiocarbon analyses on surface particulate matter (PM), sinking PM and underlying surface sediments illustrate the active release of old OC from coastal permafrost. Molecular tracers for recalcitrant soil OC showed ages of 3.4-13 C-14-ky in surface PM and 5.5-18 C-14-ky in surface sediments. The age difference of these markers between surface PM and surface sediments is larger (i) in regions with low OC accumulation rates, suggesting a weaker exchange between water column and sediments, and (ii) with increasing distance from the Lena River, suggesting preferential settling of fluvially derived old OC nearshore. A dual-carbon end-member mixing model showed that (i) contemporary terrestrial OC is dispersed mainly by horizontal transport while being subject to active degradation, (ii) marine OC is most affected by vertical transport and also actively degraded in the water column, and (iii) OC from ICD settles rapidly and dominates surface sediments. Preferential burial of ICD-OC released into ESAS coastal waters might therefore lower the suggested carbon cycle climate feedback from thawing ICD permafrost.},
	keywords = {biomarkers, carbon, permafrost, radiocarbon},
	issn = {2169-9275},
	doi = {10.1002/2014JC010261},
	author = {Vonk, Jorien E. and Semiletov, Igor P. and Dudarev, Oleg V. and Eglinton, Timothy I. and Andersson, August and Shakhova, Natalia and Charkin, Alexander and Heim, Birgit and Gustafsson, {\"O}rjan}
}
@article { ISI:000342993200010,
	title = {Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change},
	journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
	volume = {119},
	number = {{8}},
	year = {2014},
	month = {AUG},
	pages = {1630-1651},
	type = {Article},
	abstract = {Continued warming of the Arctic may cause permafrost to thaw and speed the decomposition of large stores of soil organic carbon (OC), thereby accentuating global warming. However, it is unclear if recent warming has raised the current rates of permafrost OC release to anomalous levels or to what extent soil carbon release is sensitive to climate forcing. Here we use a time series of radiocarbon age-offsets (C-14) between the bulk lake sediment and plant macrofossils deposited in an arctic lake as an archive for soil and permafrost OC release over the last 14,500 years. The lake traps and archives OC imported from the watershed and allows us to test whether prior warming events stimulated old carbon release and heightened age-offsets. Today, the age-offset (2ka; thousand of calibrated years before A.D. 1950) and the depositional rate of ancient OC from the watershed into the lake are relatively low and similar to those during the Younger Dryas cold interval (occurring 12.9-11.7ka). In contrast, age-offsets were higher (3.0-5.0ka) when summer air temperatures were warmer than present during the Holocene Thermal Maximum (11.7-9.0ka) and BOlling-AllerOd periods (14.5-12.9ka). During these warm times, permafrost thaw contributed to ancient OC depositional rates that were similar to 10 times greater than today. Although permafrost OC was vulnerable to climate warming in the past, we suggest surface soil organic horizons and peat are presently limiting summer thaw and carbon release. As a result, the temperature threshold to trigger widespread permafrost OC release is higher than during previous warming events.},
	keywords = {carbon cycling, lake sediment, paleoclimatology, permafrost, radiocarbon, Younger Dryas},
	issn = {2169-8953},
	doi = {10.1002/2014JG002688},
	author = {Gaglioti, Benjamin V. and Mann, Daniel H. and Jones, Benjamin M. and Pohlman, John W. and Kunz, Michael L. and Wooller, Matthew J.}
}
@article {2460,
	title = {Seasonal variability of organic matter composition in an Alaskan glacier outflow: insights into glacier carbon sources},
	journal = {Environmental Research Letters},
	volume = {9},
	year = {2014},
	month = {Jan-05-2014},
	pages = {055005},
	abstract = {Glacier ecosystems are a significant source of bioavailable, yet ancient dissolved organic carbon
(DOC). Characterizing DOC in Mendenhall Glacier out flow (southeast Alaska) we document a
seasonal persistence to the radiocarbon-depleted signature of DOC, highlighting ancient DOC as
a ubiquitous feature of glacier out flow. We observed no systematic depletion in Δ14C-DOC with
increasing discharge during the melt season that would suggest mobilization of an aged subglacial carbon store. However, DOC concentration, δ13C-DOC,Δ14C-DOC and fluorescence signatures appear to have been in fluenced by runoff from vegetated hillslopes above the glacier during onset and senescence of melt. In the peak glacier melt period, the Δ 14 C-DOC of stream samples at the out flow (-181.7 to-355.3{\textperthousand}) was comparable to the Δ 14 C-DOC for snow samples from the accumulation zone (-207.2 to-390.9{\textperthousand}), suggesting that ancient DOC from the glacier surface is exported in glacier runoff. The pre-aged DOC in glacier snow and runoff is consistent with contributions from fossil fuel combustion sources similar to those documented previously in ice cores and thus provides evidence for anthropogenic perturbation of the carbon cycle. Overall, our results emphasize the need to further characterize DOC inputs to glacier ecosystems, particularly in light of predicted changes in glacier mass and runoff in the coming century.},
	keywords = {alaska, dissolved organic carbon, glacier, organic matter, radiocarbon},
	doi = {10.1088/1748-9326/9/5/055005},
	url = {http://iopscience.iop.org/article/10.1088/1748-9326/9/5/055005/meta},
	author = {Spencer, Robert G M and Vermilyea, Andrew and Fellman, Jason and Raymond, Peter and Stubbins, Aron and Scott, Durelle and Hood, Eran}
}
@article { ISI:000312696400053,
	title = {Radiocarbon evidence that carbon from the Deepwater Horizon spill entered the planktonic food web of the Gulf of Mexico},
	journal = {ENVIRONMENTAL RESEARCH LETTERS},
	volume = {7},
	number = {{4}},
	year = {2012},
	month = {OCT-DEC},
	type = {Article},
	abstract = {The Deepwater Horizon (Macondo) oil spill released large volumes of oil and gas of distinct carbon isotopic composition to the northern Gulf of Mexico, allowing Graham et al (2010 Environ. Res. Lett. 5 045301) to use stable carbon isotopes (delta C-13) to infer the introduction of spilled oil into the planktonic food web. Surface ocean organic production and measured oil are separated by 5-7 parts per thousand in stable carbon isotope (delta C-13) space, while in radiocarbon (Delta C-14) space these two potential sources are separated by more than 1000 parts per thousand. Thus radiocarbon isotopes provide a more sensitive tracer by which to infer possible introduction of Macondo oil into the food web. We measured Delta C-14 and delta C-13 in plankton collected from within 100 km of the spill site as well as in coastal and offshore DIC (dissolved inorganic carbon or Sigma CO2) to constrain surface production values. On average, plankton values were depleted in C-14 relative to surface DIC, and we found a significant linear correlation between Delta C-14 and delta C-13 in plankton. Cumulatively, these results are consistent with the hypothesis that carbon released from the Deepwater Horizon spill contributed to the offshore planktonic food web. Our results support the findings of Graham et al (2010 Environ. Res. Lett. 5 045301), but we infer that methane input may be important.},
	keywords = {carbon isotope, Gulf oil spill, methane, petroleum hydrocarbon, radiocarbon},
	issn = {1748-9326},
	doi = {10.1088/1748-9326/7/4/045303},
	author = {Chanton, J. P. and Cherrier, J. and Wilson, R. M. and Sarkodee-Adoo, J. and Bosman, S. and Mickle, A. and Graham, W. M.}
}
@article {2440,
	title = {Constant Holocene Southern-Ocean 14C reservoir ages and ice-shelf flow rates},
	volume = {296},
	year = {2010},
	month = {2010/7/15/},
	pages = {115 - 123},
	abstract = {Southern Ocean radiocarbon reservoir ages (i.e. non-zero radiocarbon ages in seawater) are the highest in the world{\textquoteright}s surface ocean. Constraining these reservoir ages at present and in the past is important not only because unknown reservoir ages limit the interpretation of Antarctic radiocarbon chronologies, but also because reservoir ages provide information about ocean circulation (as a recorder of past circulation and as an end member for major deep-water masses in today{\textquoteright}s ocean). In this study, we use paired U/Th and 14C ages of an unusual set of solitary coral samples trapped by fringing ice shelves in the Ross Sea to provide the first detailed study of Holocene reservoir ages for the Southern Ocean. Our results indicate a relatively constant marine radiocarbon reservoir age of 1144 {\textpm} 120 years for the past 6000 years. These results are consistent with extrapolation of the relationship between 14C and alkalinity seen elsewhere, supporting the use of this empirical relationship in high latitudes. The results also suggest constant deep-ocean circulation and air{\textendash}sea exchange during the Holocene and provide a good target for tuning ocean models of modern circulation. Combining the new ages for corals with their distance from the modern-day ice-shelf grounding line provides some of the first long-term records of ice-shelf velocities for any region and indicates constant flow of the McMurdo Ice Shelf during the Holocene, at a rate similar to that observed today.},
	keywords = {coral, marine reservoir effect, McMurdo Ice Shelf, radiocarbon, Southern Ocean, U/Th dating},
	isbn = {0012-821X},
	doi = {10.1016/j.epsl.2010.04.054},
	url = {http://www.sciencedirect.com/science/article/pii/S0012821X10003067},
	author = {Hall, Brenda L. and Henderson, Gideon M. and Baroni, Carlo and Kellogg, Thomas B.}
}
@article { ISI:000279905800011,
	title = {Constant Holocene Southern-Ocean C-14 reservoir ages and ice-shelf flow rates},
	journal = {EARTH AND PLANETARY SCIENCE LETTERS},
	volume = {296},
	number = {{1-2}},
	year = {2010},
	month = {JUL 15},
	pages = {115-123},
	type = {Article},
	abstract = {Southern Ocean radiocarbon reservoir ages (i.e. non-zero radiocarbon ages in seawater) are the highest in the world{\textquoteright}s surface ocean. Constraining these reservoir ages at present and in the past is important not only because unknown reservoir ages limit the interpretation of Antarctic radiocarbon chronologies, but also because reservoir ages provide information about ocean circulation (as a recorder of past circulation and as an end member for major deep-water masses in today{\textquoteright}s ocean). In this study, we use paired U/Th and C-14 ages of an unusual set of solitary coral samples trapped by fringing ice shelves in the Ross Sea to provide the first detailed study of Holocene reservoir ages for the Southern Ocean. Our results indicate a relatively constant marine radiocarbon reservoir age of 1144 +/- 120 years for the past 6000 years. These results are consistent with extrapolation of the relationship between C-14 and alkalinity seen elsewhere, supporting the use of this empirical relationship in high latitudes. The results also suggest constant deep-ocean circulation and air-sea exchange during the Holocene and provide a good target for tuning ocean models of modern circulation. Combining the new ages for corals with their distance from the modern-day ice-shelf grounding line provides some of the first long-term records of ice-shelf velocities for any region and indicates constant flow of the McMurdo Ice Shelf during the Holocene, at a rate similar to that observed today. (C) 2010 Elsevier B.V. All rights reserved.},
	keywords = {coral, marine reservoir effect, McMurdo Ice Shelf, radiocarbon, Southern Ocean, U/Th dating},
	issn = {0012-821X},
	doi = {10.1016/j.epsl.2010.04.054},
	author = {Hall, Brenda L. and Henderson, Gideon M. and Baroni, Carlo and Kellogg, Thomas B.}
}
@article {2445,
	title = {Radiocarbon-derived sedimentation rates in the Gulf of Mexico},
	journal = {Deep-Sea Research Part Ii-Topical Studies in Oceanography},
	volume = {55},
	year = {2008},
	note = {United States Mineral Management Service [1435-01-99-CT-30991]},
	month = {Dec},
	pages = {2572-2576},
	abstract = {Sedimentation rates were determined for the northern Gulf of Mexico margin sediments at water depths ranging from 770 to 3560m, using radiocarbon determinations of organic matter. Resulting sedimentation rates ranged from 3 to 15 cm/kyr, decreasing with increasing water depth. These rates agree with long-term sedimentation rates estimated previously using stratigraphic methods, and with estimates of sediment delivery rates by the Mississippi River to the northern Gulf of Mexico, but are generally higher by 1-2 orders of magnitude than those estimated by (210)Pb(xs) methods. Near-surface slope sediments from 2737 to water depth in the Mississippi River fan were much older than the rest. They had minimum (14)C ages of 16-27 kyr and delta(13)C values ranging from -24 parts per thousand to -26.59 parts per thousand, indicating a terrestrial origin of organic matter. The sediments from this site were thus likely deposited by episodic mass wasting of slope sediment through the canyon, delineating the previously suggested main pathway of sediment and clay movement to abyssal Gulf sediments. (C) 2008 Published by Elsevier Ltd.},
	keywords = {accumulation, ATCHAFALAYA RIVER, cores, Gulf of Mexico, ice-sheet, Mass, Meltwater, MISSISSIPPI RIVER DELTA, Nepheloid layer transport, Organic carbon burial rates, radiocarbon, Sedimentation rates, TERRIGENOUS ORGANIC-MATTER, wasting},
	isbn = {0967-0645},
	doi = {10.1016/j.dsr2.2008.07.005},
	author = {Santschi, P. H. and Rowe, G. T.}
}
@article {1937,
	title = {Dissolved and particulate organic matter source-age characterization in the upper and lower Chesapeake Bay: A combined isotope and biochemical approach},
	journal = {Limnology and Oceanography},
	volume = {51},
	year = {2006},
	note = {045nhTimes Cited:24
Cited References Count:37
},
	month = {May},
	pages = {1421-1431},
	abstract = {In order to characterize the sources and ages of organic matter contributing to river and estuarine outflow waters, the present study investigated Delta C-14 and delta C-13 signatures of the major operationally defined biochemical classes of ultrafiltered dissolved organic matter (UDOM) in conjunction with lipid biomarker and elemental compositions of UDOM and suspended particulate organic matter (POM) in the Chesapeake Bay. Freshwater (Susquehanna River) UDOM was dominated by a molecularly uncharacterized (MUC) fraction, followed by total carbohydrate (TCHO), total hydrolysable amino acid (THAA) and total lipid (TLE) components. In contrast, UDOM at the bay mouth (salinity similar to 22-24) was comprised mainly of TCHO, followed by MUC, THAA, and TLE. The Delta C-14 and delta C-13 signatures of both UDOM and its major biochemical classes indicate that Susquehanna DOM is derived in part from old allochthonous terrestrial sources, whereas young marine sources dominate at the bay mouth. In contrast to the other biochemical classes, lipophilic DOM at both sites was very old (similar to 5,000-7,000 years B.P.). In addition, factor analysis of lipid biomarker compounds revealed unique signatures for the UDOM and POM pools that imply disparate source and/or recycling properties as well as potential influences due to physical partitioning. Lipid biomarker compounds showed that although autochthonous riverine/estuarine sources dominated both the UDOM and POM pools, terrigenous lipids were elevated in the Susquehanna during high flow conditions. The presence of lipid biomarkers diagnostic of "fresh" algal material in UDOM further suggested its greater reactivity than POM. The observed biochemical and lipid biomarker compositions and isotopic signatures of UDOM and POM are consistent with previous findings suggesting that these two major organic matter pools have dissimilar reactivities and cycling times, and they derive from comparatively unique source-age materials in rivers and estuaries.},
	keywords = {biomarkers, carbon, delta-c-13, lipid-composition, ocean, radiocarbon, river, san-francisco, sediments, variability},
	isbn = {0024-3590},
	doi = {10.4319/lo.2006.51.3.1421},
	author = {Loh, A. N. and Bauer, J. E. and Canuel, E. A.}
}
@article {2003,
	title = {Input of particulate organic and dissolved inorganic carbon from the Amazon to the Atlantic Ocean},
	journal = {Geochemistry Geophysics Geosystems},
	volume = {6},
	year = {2005},
	note = {909pwTimes Cited:17
Cited References Count:21
},
	month = {Mar 18},
	abstract = {We report concentrations and isotope measurements (radiocarbon and stable carbon) of dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POC) in waters collected from the mouth of the Amazon River and the North Brazil Current. Samples were collected in November 1991, when the Amazon hydrograph was at its annual minimum and the North Brazil Current had retroflected into the equatorial North Atlantic. The DIC D 14 C results revealed postbomb carbon in river and ocean waters, with slightly higher values at the river mouth. The low DIC delta(13)C signature of the river end-member (-11\%) demonstrates that about half of the DIC originated from the remineralization of terrestrially derived organic matter. A linear relationship between DIC and salinity indicates that DIC was mixed nearly conservatively in the transition zone from the river mouth to the open ocean, though there was a small amount (<= 10\%) of organic matter remineralization in the mesohaline region. The POC Delta(14)C values in the river mouth were markedly lower than those values from the western Amazon region (Hedges et al., 1986). We conclude that the dominant source of POC near the river mouth and in the inner Amazon plume during November 1991 was aged, resuspended material of significant terrestrial character derived from shelf sediments, while the outer plume contained mainly marine-derived POC.},
	keywords = {accumulation, amazon, C-14, carbon cycling, CO2, continental-shelf, poc, radiocarbon, river system, Sediment, total co(2), water},
	isbn = {1525-2027},
	doi = {10.1029/2004GC000842},
	author = {Druffel, E. R. M. and Bauer, J. E. and Griffin, S.}
}
@article {2056,
	title = {Deglacial sea surface temperatures of the western tropical Pacific: A new look at old coral},
	journal = {Paleoceanography},
	volume = {19},
	year = {2004},
	note = {885czTimes Cited:30
Cited References Count:37
},
	month = {Dec 30},
	abstract = {Using Secondary Ion Mass Spectrometry ( SIMS) ion microprobe techniques, we generated annual Sr/Ca cycles with subweekly resolution from chunks of Porites coral retrieved from a Tahiti barrier reef drill core (149degreesW, 17degreesS), representing the period 13,650 to 13,100 years B.P. The centers of pristine skeletal septa were selectively targeted with a 10 mum diameter ion beam spot, avoiding adjacent pore spaces occupied by secondary aragonite needles. Applying a Sr/Ca-sea surface temperature (SST) calibration equation derived from modern Tahiti Porites having the same low growth rate as the fossil specimens, we obtained SSTs similar to0.5degrees-1.5degreesC cooler during the Bolling-Allerod relative to the present day, with no significant change in seasonality. On the contrary, we estimate that analysis of bulk samples would yield excessively cool Sr/Ca-based SST estimates due to the occupation by secondary aragonite crystals of up to 50\% of the skeletal pore space in the ancient samples. We find that growth rate effects on coral Sr/Ca further depress the apparent mean annual derived SSTs (by >3degreesC) and amplify the apparent seasonality by selectively enhancing wintertime cooling. Our microscale analysis of pristine skeleton and application of an appropriate growth-dependent calibration yield Sr/Ca-derived SSTs that are in good agreement with those derived from Mg/Ca ratios of calcitic foraminifera which indicate a continuous postglacial warming of the western tropical Pacific, in phase with the warming of the tropical Atlantic.},
	keywords = {bolling-allerod, climate-change, coral sr/ca, diagenesis, ion microprobe, last deglaciation, paleotemperature proxy, radiocarbon, record, sea surface temperature, sr/ca, strontium, symbiotic coral, trace-elements, tropical pacific},
	isbn = {0883-8305},
	doi = {10.1029/2004PA001084},
	author = {Cohen, A. L. and Hart, S. R.}
}
@article {2039,
	title = {Evaluation of ocean carbon cycle models with data-based metrics},
	journal = {Geophysical Research Letters},
	volume = {31},
	year = {2004},
	note = {811adTimes Cited:110
Cited References Count:17
},
	month = {Apr 2},
	abstract = {New radiocarbon and chlorofluorocarbon-11 data from the World Ocean Circulation Experiment are used to assess a suite of 19 ocean carbon cycle models. We use the distributions and inventories of these tracers as quantitative metrics of model skill and find that only about a quarter of the suite is consistent with the new data-based metrics. This should serve as a warning bell to the larger community that not all is well with current generation of ocean carbon cycle models. At the same time, this highlights the danger in simply using the available models to represent the state-of-the-art modeling without considering the credibility of each model.},
	keywords = {anthropogenic co2, pacific-ocean, radiocarbon},
	isbn = {0094-8276},
	doi = {10.1029/2003GL018970},
	url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2\&amp;SrcAuth=Alerting\&amp;SrcApp=Alerting\&amp;DestApp=WOS\&amp;DestLinkType=FullRecord;UT=WOS:000220743900001},
	author = {Matsumoto, K. and Sarmiento, J. L. and Key, R. M. and Aumont, O. and Bullister, J. L. and Caldeira, K. and Campin, J. M. and Doney, S. C. and Drange, H. and Dutay, J. C. and Follows, M. and Gao, Y. and Gnanadesikan, A. and Gruber, N. and Ishida, A. and Joos, F. and Lindsay, K. and Maier-Reimer, E. and Marshall, J. C. and Matear, R. J. and Monfray, P. and Mouchet, A. and Najjar, R. and Plattner, G. K. and Schlitzer, R. and Slater, R. and Swathi, P. S. and Totterdell, I. J. and Weirig, M. F. and Yamanaka, Y. and Yool, A. and Orr, J. C.}
}
@article {2044,
	title = {Radiocarbon and stable isotope constraints on Last Glacial Maximum and Younger Dryas ventilation in the western North Atlantic},
	journal = {Paleoceanography},
	volume = {19},
	year = {2004},
	note = {870dfTimes Cited:72
Cited References Count:60
},
	month = {Nov 3},
	abstract = {[1] Foraminiferal abundance, C-14 ventilation ages, and stable isotope ratios in cores from high deposition rate locations in the western subtropical North Atlantic are used to infer changes in ocean and climate during the Younger Dryas (YD) and Last Glacial Maximum (LGM). The delta(18)O of the surface dwelling planktonic foram Globigerinoides ruber records the present-day decrease in surface temperature (SST) of similar to 4 degreesC from Gulf Stream waters to the northeastern Bermuda Rise. If during the LGM the modern delta(18)O/salinity relationship was maintained, this SST contrast was reduced to 2 degreesC. With LGM to interglacial delta(18)O changes of at least 2.2parts per thousand, SSTs in the western subtropical gyre may have been as much as 5 degreesC colder. Above similar to 2.3 km, glacial delta(13)C was higher than today, consistent with nutrient-depleted ( younger) bottom waters, as identified previously. Below that, delta(13)C decreased continually to - 0.5parts per thousand, about equal to the lowest LGM delta(13)C in the North Pacific Ocean. Seven pairs of benthic and planktonic foraminiferal C-14 dates from cores > 2.5 km deep differ by 1100 +/- 340 years, with a maximum apparent ventilation age of similar to 1500 years at 4250 m and at similar to 4700 m. Apparent ventilation ages are presently unavailable for the LGM < 2.5 km because of problems with reworking on the continental slope when sea level was low. Because LGM \&delta;C-13 is about the same in the deep North Atlantic and the deep North Pacific, and because the oldest apparent ventilation ages in the LGM North Atlantic are the same as the North Pacific today, it is possible that the same water mass, probably of southern origin, flowed deep within each basin during the LGM. Very early in the YD, dated here at 11.25 +/- 0.25 ( n = 10) conventional C-14 kyr BP ( equal to 12.9 calendar kyr BP), apparent ventilation ages < 2.3 km water depth were about the same as North Atlantic Deep Water today. Below similar to 2.3 km, four YD pairs average 1030 +/- 400 years. The oldest apparent ventilation age for the YD is 1600 years at 4250 m. This strong contrast in ventilation, which indicates a front between water masses of very different origin, is similar to glacial profiles of nutrient-like proxies. This suggests that the LGM and YD modes of ocean circulation were the same.},
	keywords = {benthic foraminifera, deep-sea sediments, ice-age, Ocean circulation, ocean ventilation, pacific-ocean, radiocarbon, SARGASSO SEA, southern-ocean, Thermohaline circulation, united-states, water circulation, western north atlantic},
	isbn = {0883-8305},
	doi = {10.1029/2004PA001029},
	url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2\&amp;SrcAuth=Alerting\&amp;SrcApp=Alerting\&amp;DestApp=WOS\&amp;DestLinkType=FullRecord;UT=WOS:000225033500003},
	author = {Keigwin, L. D.}
}
@article {2117,
	title = {Ocean ventilation and sedimentation since the glacial maximum at 3 km in the western North Atlantic},
	journal = {Geochemistry Geophysics Geosystems},
	volume = {3},
	year = {2002},
	note = {565rlTimes Cited:26
Cited References Count:43
},
	month = {Jun 22},
	abstract = {[1] Stable isotope, sedimentological, and radiocarbon data from cores at similar to 3 km water depth on the Blake Ridge, western subtropical North Atlantic, reveal the history of deep water ventilation since the last glacial maximum (LGM). Bulk sediment accumulation rates varied locally by a factor of 2 under the influence of bottom currents in this sediment drift environment, but the sand flux, mostly foraminifera, was nearly identical at a given time. This suggests that the rain rate of foraminifera (mostly planktonic) was constant, that transport of foraminifera was negligible, and that current-controlled differences in clay and silt transport drive bulk accumulation. In two of the cores, flux peaks in the benthic foraminifera Cibicidoides and Uvigerina peregrina occurred during the Younger Dryas (YD) cold event, and at 18.2, 19.6, 21.1, 25.0, and 28.1 ka. Radiocarbon measurements on those benthic foraminifera show the ventilation age of bottom waters was similar to 1000 years during the YD, and for older events it was as great as 2000 years. These results contrast with Holocene ventilation, which was similar to 500 years and 700 years at 1500 years and similar to 7100 years before present, respectively.},
	keywords = {abyssal circulation, benthic foraminifera, c-14 ages, Calibration, climate-change, deep-water, Holocene, Last glacial maximum, ocean ventilation, radiocarbon, radiocarbon age, sea, sediment drifts, Younger Dryas},
	isbn = {1525-2027},
	doi = {10.1029/2001GC000283},
	author = {Keigwin, L. D. and Schlegel, M. A.}
}
@article {2383,
	title = {Lake-Level History of Lake-Michigan for the Past 12,000 Years - the Record from Deep Lacustrine Sediments},
	journal = {Journal of Great Lakes Research},
	volume = {20},
	year = {1994},
	note = {Nl348Times Cited:47
Cited References Count:29
},
	month = {1994},
	pages = {73-92},
	abstract = {Collection and analysis of an extensive set of seismic-reflection profiles and cores from southern Lake Michigan have provided new data that document the history of the lake basin for the past 12,000 years. Analyses of the seismic data, together with radiocarbon dating, magnetic, sedimentologic, isotopic, and paleontologic studies of core samples, have allowed us to reconstruct lake-level changes during this recent part of the lake{\textquoteright}s history.The post-glacial history of lake-level changes in the Lake Michigan basin begins about 11.2 ka with the fall from the high Calumet level, caused by the retreat of the Two Rivers glacier, which had blocked the northern outlet of the lake. This lake-level fall was temporarily reversed by a major influx of water from glacial Lake Agassiz (about 10.6 ka), during which deposition of the distinctive gray Wilmette Bed of the Lake Michigan Formation interrupted deposition of red glaciolacustrine sediment. Lake level then continued to fall, culminating in the opening of the North Bay outlet at about 10.3 ka. During the resulting Chippewa low phase, lake level was about 80 m lower than it is today in the southern basin of Lake Michigan.
The rise of the early Holocene lake level, controlled primarily by isostatic rebound of the North Bay outlet, resulted in a prominent, planar, transgressive unconformity that eroded most of the shoreline features below present lake level. Superimposed on this overall rise in lake level, a second influx of water from Lake Agassiz temporarily raised lake levels an unknown amount about 9.1 ka. At about 7 ka, lake level may have fallen below the level of the outlet because of sharply drier climate. Sometime between 6 and 5 ka, the character of the lake changed dramatically, probably due mostly to climatic causes, becoming highly undersaturated with respect to calcium carbonate and returning primary control of lake level to the isostatically rising North Bay outlet. Post-Nipissing (about 5 ka) lake level has fallen about 6 m due to erosion of the Port Huron outlet, a trend around which occurred relatively small (+/- approximately 2 m), short-term fluctuations controlled mainly by climatic changes. These cyclic fluctuations are reflected in the sedimentological and sediment-magnetic properties of the sediments.
},
	keywords = {lake michigan, ostracodes, radiocarbon, sedimentology, sediments, southern},
	isbn = {0380-1330},
	author = {Colman, S. M. and Forester, R. M. and Reynolds, R. L. and Sweetkind, D. S. and King, J. W. and Gangemi, P. and Jones, G. A. and Keigwin, L. D. and Foster, D. S.}
}
@article {2393,
	title = {Ams-Graphite Target Production Methods at the Woods-Hole Oceanographic Institution during 1986-1991},
	journal = {Radiocarbon},
	volume = {35},
	year = {1993},
	note = {Lg927Times Cited:12
Cited References Count:14
},
	month = {1993},
	pages = {301-310},
	abstract = {In July 1986, an AMS radiocarbon target preparation laboratory was established at the Woods Hole Oceanographic Institution to produce graphite to be analyzed at the NSF-Accelerator Facility for Radioisotope Analysis at the University of Arizona (Tucson). By June 1991, 923 graphite targets had been prepared and 847 analyzed. Our lab procedures during this time included the careful documentation of weights of all starting samples, catalysts and final graphite yields, as well as the volume of CO2 gas evolved during CaCO3 hydrolysis or closed-tube organic carbon combustions. From these data, we evaluate the methods used in general and in our lab.},
	keywords = {accelerator mass-spectrometry, facility, ocean, radiocarbon, samples, sediments},
	isbn = {0033-8222},
	author = {Gagnon, A. R. and Jones, G. A.}
}
