@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 {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 {holt_tropical_2023,
	title = {A Tropical Cocktail of Organic Matter Sources: Variability in Supraglacial and Glacier Outflow Dissolved Organic Matter Composition and Age Across the Ecuadorian Andes},
	journal = {Journal of Geophysical Research: Biogeosciences},
	volume = {128},
	number = {5},
	year = {2023},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022JG007188},
	month = {05/2023},
	pages = {e2022JG007188},
	abstract = {The biogeochemistry of rapidly retreating Andean glaciers is poorly understood, and Ecuadorian glacier dissolved organic matter (DOM) composition is unknown. This study examined molecular composition and carbon isotopes of DOM from supraglacial and outflow streams (n = 5 and 14, respectively) across five ice capped volcanoes in Ecuador. Compositional metrics were paired with streamwater isotope analyses (δ18O) to assess if outflow DOM composition was associated with regional precipitation gradients and thus an atmospheric origin of glacier DOM. Ecuadorian glacier outflows exported ancient, biolabile dissolved organic carbon (DOC), and DOM contained a high relative abundance (RA) of aliphatic and peptide-like compounds (>=27\%RA). Outflows were consistently more depleted in Δ14C-DOC (i.e., older) compared to supraglacial streams (mean -195.2 and -61.3{\textperthousand} respectively), perhaps due to integration of spatially heterogenous and variably aged DOM pools across the supraglacial environment, or incorporation of aged subglacial OM as runoff was routed to the outflow. Across Ecuador, Δ14C-DOC enrichment was associated with decreased aromaticity of DOM, due to increased contributions of organic matter (OM) from microbial processes or atmospheric deposition of recently fixed and subsequently degraded OM (e.g., biomass burning byproducts). There was a regional gradient between glacier outflow DOM composition and streamwater δ18O, suggesting covariation between regional precipitation gradients and the DOM exported from glacier outflows. Ultimately, this highlights that atmospheric deposition may exert a control on glacier outflow DOM composition, suggesting regional air circulation patterns and precipitation sources in part determine the origins and quality of OM exported from glacier environments.},
	keywords = {cryosphere, dissolved organic carbon, Dissolved organic matter, Ecuador, FT-ICR MS, glaciers, δ13C-DOC, Δ14C-DOC},
	issn = {2169-8961},
	doi = {10.1029/2022JG007188},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022JG007188},
	author = {Holt, Amy D. and Kellerman, Anne M. and Battin, Tom. I. and McKenna, Amy M. and Hood, Eran and Andino, Patricio and Crespo-P{\'e}rez, Ver{\'o}nica and Peter, Hannes and Sch{\"o}n, Martina and De Staercke, Vincent and Styllas, Michail and Tolosano, Matteo and Spencer, Robert G. M.}
}
@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 {2871,
	title = {Dissolved organic carbon in basalt-hosted deep subseafloor fluids of the Juan de Fuca Ridge flank},
	journal = {Earth and Planetary Science Letters},
	volume = {513},
	year = {2019},
	month = {Jan-05-2019},
	pages = {156 - 165},
	abstract = {Marine dissolved organic carbon (DOC) is highly depleted in radiocarbon and thus inferred to be largely refractory to removal processes that operate on less than millennial timescales. However, a growing number of reports have shown that a large fraction of marine DOC can be effectively removed during circulation through submarine hydrothermal systems. What is not clear, however, is whether the DOC that remains in hydrothermal fluids is remnant non-reactive DOC from recharged seawater, or DOC that has been largely produced in the subsurface. We collected and characterized warm (\~{}65 {\textdegree}C) hydrothermal fluids from deep (18, 40, 73, 200 m) within the basalt-hosted basement of the Juan de Fuca Ridge flank in the Northeast Pacific Ocean. DOC concentrations in hydrothermal fluids were 9 to 18 μM, much lower than measured in local deep seawater (37.5 μM). DOC C values of -683{\textperthousand} to -856{\textperthousand} were much lower than the C-dissolved inorganic carbon (DIC) values of -880{\textperthousand} to -918{\textperthousand}, while DOC C values of -23.6{\textperthousand} to -27.0{\textperthousand} were much heavier than that of the particulate organic carbon (POC) pool ({\textperthousand}), suggesting that biological production in the subsurface is not a primary source of DOC. Rather, our data suggest that isotopically enriched DOC are selectively removed from recharged seawater, leaving DOC that is very isotopically depleted in the basaltic basement fluids. Despite the removal of 50{\textendash}75\% of DOC in the subsurface, nuclear magnetic resonance (NMR) functional group analyses indicate that aromatic compounds were added to basaltic basement fluids during passage through the deep subseafloor and may partly contribute to the depleted 14C DOC in the ridge-flank basement fluids.},
	keywords = {aromatic organic compound, basaltic basement fluid, carbon isotopes, dissolved organic carbon, Juan de Fuca, selective removal, subseafloor},
	issn = {0012821X},
	doi = {10.1016/j.epsl.2019.02.008},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0012821X19300998},
	author = {Lin, Huei-Ting and Repeta, Daniel J. and Xu, Li and Rapp{\'e}, Michael S.}
}
@article {2869,
	title = {Radiocarbon age of different photoreactive fractions of freshwater dissolved organic matter},
	journal = {Organic Geochemistry},
	volume = {135},
	year = {2019},
	month = {Jan-09-2019},
	pages = {11 - 15},
	abstract = {Dissolved organic carbon (DOC) plays a major role in aquatic carbon cycling. In order to determine if DOC photolability was related to DOC age, we tested the effect of oxidation time using UV irradiation on natural radiocarbon concentrations (Δ14C) of DOC in six US rivers. The most photo-labile DOC was 14C youngest. After a 100 min UV irradiation, most DOC (>93\%) was oxidized in two out of the six rivers studied. On the other hand, the other four rivers still had a considerable amount (>20\%) of DOC resistant to UV oxidation, which showed lower Δ14C values than those of bulk DOC. We also found that the concentration and Δ14C value of bulk DOC are controlled by the photochemically intermediate fraction. The results suggest that 14C age of organic matter is not homogeneous within DOC, the degree of which may depend on the characteristics unique to rivers.},
	keywords = {dissolved organic carbon, Mixing model, Oxidation time, UV irradiation, Δ14C},
	issn = {01466380},
	doi = {10.1016/j.orggeochem.2019.06.006},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S014663801930107X},
	author = {Ishikawa, Naoto F. and Butman, David and Raymond, Peter A.}
}
@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 {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 { ISI:000389875700005,
	title = {RAPID C-14 ANALYSIS OF DISSOLVED ORGANIC CARBON IN NON-SALINE WATERS},
	journal = {RADIOCARBON},
	volume = {58},
	number = {{3}},
	year = {2016},
	month = {SEP},
	pages = {505-515},
	type = {Article},
	abstract = {The radiocarbon content of dissolved organic carbon (DOC) in rivers, lakes, and other non-saline waters can provide valuable information on carbon cycling dynamics in the environment. DOC is typically prepared for C-14 analysis by accelerator mass spectrometry (AMS) either by ultraviolet (UV) oxidation or by freeze-drying and sealed tube combustion. We present here a new method for the rapid analysis of C-14 of DOC using wet chemical oxidation (WCO) and automated headspace sampling of CO2. The approach is an adaption of recently developed methods using aqueous persulfate oxidant to determine the delta C-13 of DOC in non-saline water samples and the C-14 content of volatile organic acids. One advantage of the current method over UV oxidation is higher throughput: 22 samples and 10 processing standards can be prepared in one day and analyzed in a second day, allowing a full suite of C-14 processing standards and blanks to be run in conjunction with samples. A second advantage is that there is less potential for cross-contamination between samples.},
	keywords = {carbon-cycling, dissolved organic carbon, method development, wet chemical oxidation},
	issn = {0033-8222},
	doi = {10.1017/RDC.2016.17},
	author = {Lang, Susan Q. and McIntyre, Cameron P. and Bernasconi, Stefano M. and Fruh-Green, Gretchen L. and Voss, Britta M. and Eglinton, Timothy I. and Wacker, Lukas}
}
@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 {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 {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:000290199000003,
	title = {Multiple-source heterotrophy fueled by aged organic carbon in an urbanized estuary},
	journal = {MARINE CHEMISTRY},
	volume = {124},
	number = {{1-4}},
	year = {2011},
	month = {MAR 20},
	pages = {14-22},
	type = {Article},
	abstract = {The lower Hudson River is a highly urbanized estuary that receives large inputs of treated wastewater. To determine how organic matter from wastewater influences carbon cycling in this type of system, we measured chlorophyll a, pCO(2). dissolved organic carbon (DOC), delta(13)C-DOC, and Delta(14)C-DOC along the salinity gradient and at wastewater treatment plants. Isotopic mixing curves indicate a net removal of DOC that is (13)C enriched and (14)C depleted. The amount of DOC removed was consistent with CO(2) evasion from the estuary. During two transects at average to low flow, the lower Hudson River Estuary was a heterotrophic system with CO(2) evasion balanced by the utilization of aged DOC derived from wastewater and marine phytoplankton that enter the estuary at the seaward end-member. DOC removals were largest during a period of high river flow, when isotopic mixing curves also suggest large contributions from labile terrestrial OC sources. Overall, our results suggest that net heterotrophy in the lower Hudson River Estuary is fueled by aged labile DOC derived from a combination of sources, which are influenced by seasonal phytoplankton blooms, hydrological conditions, and the nature of wastewater inputs. (C) 2010 Elsevier B.V. All rights reserved.},
	keywords = {(13)C, (14)C, Carbon cycle, Carbon dioxide, Chlorophyll, dissolved organic carbon, Heterotrophy, Hudson River Estuary, Isotope mixing curves, Sewage, USA, Wastewater},
	issn = {0304-4203},
	doi = {10.1016/j.marchem.2010.11.003},
	author = {Griffith, David R. and Raymond, Peter A.}
}
