@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 {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 {2693,
	title = {A centuries-long delay between a paleo-ice-shelf collapse and grounding-line retreat in the Whales Deep Basin, eastern Ross Sea, Antarctica},
	journal = {Scientific Reports},
	volume = {8},
	year = {2018},
	month = {Jan-12-2018},
	abstract = {Recent thinning and loss of Antarctic ice shelves has been followed by near synchronous acceleration of ice flow that may eventually lead to sustained deflation and significant contraction in the extent of grounded and floating ice. Here, we present radiocarbon dates from foraminifera that constrain the time elapsed between a previously described paleo-ice-shelf collapse and the subsequent major grounding-line retreat in the Whales Deep Basin (WDB) of eastern Ross Sea. The dates indicate that West Antarctic Ice Sheet (WAIS) grounding-line retreat from the continental shelf edge was underway prior to 14.7 {\textpm} 0.4 cal kyr BP. A paleo-ice-shelf collapse occurred at 12.3 {\textpm} 0.2 cal kyr BP. The grounding position was maintained on the outer-continental shelf until at least 11.5 {\textpm} 0.3 cal kyr BP before experiencing a 200-km retreat. Given the age uncertainties, the major grounding-line retreat lagged ice-shelf collapse by at least two centuries and by as much as fourteen centuries. In the WDB, the centuries-long delay in the retreat of grounded ice was partly due to rapid aggradational stacking of an unusually large volume of grounding-zone-wedge sediment as ice-stream discharge accelerated following ice-shelf collapse. This new deglacial reconstruction shows that ongoing changes to ice shelves may trigger complex dynamics whose consequences are realized only after a significant lag.},
	doi = {10.1038/s41598-018-29911-8},
	url = {https://www.nature.com/articles/s41598-018-29911-8},
	author = {Bart, Philip J. and DeCesare, Matthew and Rosenheim, Brad E. and Majewski, Wojceich and McGlannan, Austin}
}
@article {2751,
	title = {Large-Scale Intrusion of Circumpolar Deep Water on Antarctic Margin Recorded by Stylasterid Corals},
	journal = {Paleoceanography and Paleoclimatology},
	volume = {33},
	year = {2018},
	month = {May-11-2018},
	pages = {1306 - 1321},
	abstract = {We present centennial-scale radiocarbon (14C) records archived by deep sea stylasterid corals from the outer shelf and upper slope of the Antarctic margin. These novel stylasterids (Errina spp.) were collected from the western Ross Sea shelf (500 m) and slope (1,700 m), as well as the eastern Wilkes Land shelf (670 m). We provide two corals from each region and document an abrupt reversal of 14C ages in the upper (younger) part of each coral. We test the statistical robustness of each record and demonstrate the significance of the age reversals, as well as the ability of these corals to record environmental change. We discuss a variety of possible drivers for this 14C reversal and conclude that it is most likely an encroachment of 14C-depeleted Circumpolar Deep Water (CDW). This water mass has regionally intruded onto the Antarctic margin in recent decades, facilitating loss of grounded Antarctic ice; which has implications for global sea level, deep-water formation, and carbon sequestration in the Southern Ocean. Thus, understanding the past variability of CDW on the margin is vital to better constrain climate change trajectories in the near future. We estimate large-scale encroachment of CDW onto the shelf likely commencing after 1830 CE ({\textpm}120 year). We present possible drivers for the intrusion, but highlight the need for additional chronologic constraint. This study not only demonstrates the utility of a novel coral taxon but also presents the paleoceanographic community with a testable hypothesis concerning a recent, widespread CDW intrusion.},
	issn = {2572-4517},
	doi = {10.1029/2018PA003439},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018PA003439},
	author = {King, Theresa M. and Rosenheim, Brad E. and Post, Alexandra L. and Gabris, Theresa and Burt, Taylor and Domack, Eugene W.}
}
@article {2752,
	title = {Mangrove sediment carbon stocks along an elevation gradient: Influence of the late Holocene marine regression (New Caledonia)},
	journal = {Marine Geology},
	volume = {404},
	year = {2018},
	month = {Jan-10-2018},
	pages = {60 - 70},
	abstract = {Among blue carbon ecosystems, mangroves are very efficient in storing carbon in their sediments over decadal to millennial time scales. However, this ability varies with numerous parameters, including climate and sea-level variations. In New Caledonia, mangrove ecosystems develop in semi-arid conditions with a typical zonation: Rhizophora spp. colonize the seaward side of the intertidal area, while Avicennia marina develops at higher elevations, just below the salt-flat. Within this context, we determined both the quantity (organic carbon content and carbon stocks) and the characteristics (carbon over nitrogen ratios (C/N), stable carbon and nitrogen isotopes, radiocarbon age) of the organic matter stored beneath each mangrove stands. Carbon stocks were determined down to different limits with depth: approximate extension of the root systems, one-meter depth, and the hard substrate. Within the extension of the root systems, the sediment carbon stock was lower than 100 MgC ha-1 regardless of the mangrove species. This low value resulted directly from the dry climate that limits mangrove productivity. At depth beneath every zone, a buried layer enriched in mangrove-derived organic matter, with C/N values around 40 and δ13C values around -26{\textperthousand} was observed. This layer likely resulted from a sea-level high stand during the late Holocene that allowed a long period of stability of the mangrove, slowly accumulating organic matter within the sediment. In this buried layer, the carbon stock was higher than in the upper sediment and reached up to 665, 255 and 300 MgC ha-1 in the salt-flat zone, the A. marina stand and the R. spp. stand, respectively. The highest stock, determined beneath the salt-flat, was suggested to be related to a period of sea-level stability that lasted ~3000 years, whereas beneath the other zones, which are at lower elevations, mangrove colonization was more recent and the sea-level was continuously decreasing till recently. Sea-level variations, and, specifically current sea-level rise, may strongly influence mangrove development due to their migration along the tidal elevation gradient to maintain the biotic conditions needed for their development.},
	keywords = {Blue carbon, carbon isotopes, carbon sequestration, Coastal wetlands, Sea-level change, Semi-arid mangrove forest},
	issn = {00253227},
	doi = {10.1016/j.margeo.2018.07.005},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0025322717306072},
	author = {Jacotot, Adrien and Marchand, Cyril and Rosenheim, Brad E. and Domack, Eugene W. and Allenbach, Michel}
}
@article {2698,
	title = {Permafrost Organic Carbon Mobilization From the Watershed to the Colville River Delta: Evidence From 14C Ramped Pyrolysis and Lignin Biomarkers},
	journal = {Geophysical Research Letters},
	volume = {44},
	year = {2017},
	month = {Apr-11-2019},
	pages = {11,491 - 11,500},
	abstract = {The deposition of terrestrial-derived permafrost particulate organic carbon (POC) has been recorded in major Arctic river deltas. However, associated transport pathways of permafrost POC from the watershed to the coast have not been well constrained. Here we utilized a combination of ramped pyrolysis-oxidation radiocarbon analysis (RPO 14C) along with lignin biomarkers, to track the linkages between soils and river and delta sediments. Surface and deep soils showed distinct RPO thermographs which may be related to degradation and organo-mineral interaction. Soil material in the bed load of the river channel was mostly derived from deep old permafrost. Both surface and deep soils were transported and deposited to the coast. Hydrodynamic sorting and barrier island protection played important roles in terrestrial-derived permafrost POC deposition near the coast. On a large scale, ice processes (e.g., ice gauging and strudel scour) and ocean currents controlled the transport and distribution of permafrost POC on the Beaufort Shelf.},
	keywords = {Arctic, carbon cycling, Colville River, Lignin, permafrost, pyrolysis},
	issn = {0094-8276},
	doi = {10.1002/grl.v44.2210.1002/2017GL075543},
	url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL075543},
	author = {Zhang, Xiaowen and Bianchi, Thomas S. and Cui, Xingqian and Rosenheim, Brad E. and Ping, Chien-Lu and Hanna, Andrea J. M. and Kanevskiy, Mikhail and Schreiner, Kathryn M. and Allison, Mead A.}
}
@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 {14,
	title = {Quantification of refractory organic material in Amazon mudbanks of the French Guiana Coast},
	journal = {Marine Geology},
	volume = {363},
	year = {2015},
	pages = {93-101},
	abstract = {Sub-oxic overturning mudbanks originating in the Amazon outlet and traveling northwestward along the coast of South America store 3.5 Tg organic carbon on the Amazon shelf, annually. The predominance of old soil carbon burial associated with the sediment has been supported by relatively old bulk radiocarbon ages (~ 2200{\textendash}3200 14C y) reported, but this amount has yet to be quantified for this dynamic setting. Here, we employ ramped pyrolysis radiocarbon dating to mudbank sediments from three cores to further constrain the amount of refractory sedimentary organic carbon present. Using radiocarbon age as a proxy for reactivity, we find that at least 36\% of this organic carbon is pre-aged refractory terrestrial organic carbon, likely sourced from terrestrial soils and averaging ages of 16,100 {\textpm} 300 14C y. This implies significant preservation of pre-aged terrestrial soil material in this marine environment despite the mobility and oxygen availability in the muds. Concurrently, an average of 77\% of this organic material is aged over 1000 14C y, consistent with previous estimates that the majority of organic carbon buried along the shelf is refractory. Analyses of extracted lignin phenols and terrestrial humic acids also support this preservation of refractory terrestrial material. These data indicate that sediment discharged from the Amazon River may preserve refractory terrestrial carbon in marine sediments at a minimum of 3.1 Tg C/y, which is more efficient than originally thought.},
	issn = {0025-3227},
	doi = {10.1016/j.margeo.2015.02.009},
	url = {http://www.sciencedirect.com/science/article/pii/S0025322715000456},
	author = {Williams, Elizabeth K. and Rosenheim, Brad E. and Allison, Mead and McNichol, Ann P. and Xu, Li}
}
@article {2480,
	title = {Using Natural Abundance Radiocarbon To Trace the Flux of Petrocarbon to the Seafloor Following the Deepwater Horizon Oil Spill},
	journal = {Environmental Science \& Technology},
	volume = {49},
	year = {2015},
	month = {Aug-01-2016},
	pages = {847 - 854},
	abstract = {In 2010, the Deepwater Horizon accident released 4.6{\textendash}6.0 {\texttimes} 1011 grams or 4.1 to 4.6 million barrels of fossil petroleum derived carbon (petrocarbon) as oil into the Gulf of Mexico. Natural abundance radiocarbon measurements on surface sediment organic matter in a 2.4 {\texttimes} 1010 m2 deep-water region surrounding the spill site indicate the deposition of a fossil-carbon containing layer that included 1.6 to 2.6 {\texttimes} 1010 grams of oil-derived carbon. This quantity represents between 0.5 to 9.1\% of the released petrocarbon, with a best estimate of 3.0{\textendash}4.9\%. These values may be lower limit estimates of the fraction of the oil that was deposited on the seafloor because they focus on a limited mostly deep-water area of the Gulf, include a conservative estimate of thickness of the depositional layer, and use an average background or prespill radiocarbon value for sedimentary organic carbon that produces a conservative value. A similar approach using hopane tracer estimated that 4{\textendash}31\% of 2 million barrels of oil that stayed in the deep sea settled on the bottom. Converting that to a percentage of the total oil that entered into the environment (to which we normalized our estimate) converts this range to 1.8 to 14.4\%. Although extrapolated over a larger area, our independent estimate produced similar values.},
	issn = {0013-936X},
	doi = {10.1021/es5046524},
	url = {http://pubs.acs.org/doi/abs/10.1021/es5046524http://pubs.acs.org/doi/pdf/10.1021/es5046524},
	author = {Chanton, Jeffrey and Zhao, Tingting and Rosenheim, Brad E. and Joye, Samantha and Bosman, Samantha and Brunner, Charlotte and Yeager, Kevin M. and Diercks, Arne R. and Hollander, David}
}
@article {68,
	title = {Using Natural Abundance Radiocarbon To Trace the Flux of Petrocarbon to the Seafloor Following the Deepwater Horizon Oil Spill},
	journal = {Environmental science \& technology},
	year = {2014},
	abstract = {In 2010, the Deepwater Horizon accident released 4.6?6.0 ? 1011 grams or 4.1 to 4.6 million barrels of fossil petroleum derived carbon (petrocarbon) as oil into the Gulf of Mexico. Natural abundance radiocarbon measurements on surface sediment organic matter in a 2.4 ? 1010 m2 deep-water region surrounding the spill site indicate the deposition of a fossil-carbon containing layer that included 1.6 to 2.6 ? 1010 grams of oil-derived carbon. This quantity represents between 0.5 to 9.1\% of the released petrocarbon, with a best estimate of 3.0?4.9\%. These values may be lower limit estimates of the fraction of the oil that was deposited on the seafloor because they focus on a limited mostly deep-water area of the Gulf, include a conservative estimate of thickness of the depositional layer, and use an average background or prespill radiocarbon value for sedimentary organic carbon that produces a conservative value. A similar approach using hopane tracer estimated that 4?31\% of 2 million barrels of oil that stayed in the deep sea settled on the bottom. Converting that to a percentage of the total oil that entered into the environment (to which we normalized our estimate) converts this range to 1.8 to 14.4\%. Although extrapolated over a larger area, our independent estimate produced similar values.; In 2010, the Deepwater Horizon accident released 4.6?6.0 ? 1011 grams or 4.1 to 4.6 million barrels of fossil petroleum derived carbon (petrocarbon) as oil into the Gulf of Mexico. Natural abundance radiocarbon measurements on surface sediment organic matter in a 2.4 ? 1010 m2 deep-water region surrounding the spill site indicate the deposition of a fossil-carbon containing layer that included 1.6 to 2.6 ? 1010 grams of oil-derived carbon. This quantity represents between 0.5 to 9.1\% of the released petrocarbon, with a best estimate of 3.0?4.9\%. These values may be lower limit estimates of the fraction of the oil that was deposited on the seafloor because they focus on a limited mostly deep-water area of the Gulf, include a conservative estimate of thickness of the depositional layer, and use an average background or prespill radiocarbon value for sedimentary organic carbon that produces a conservative value. A similar approach using hopane tracer estimated that 4?31\% of 2 million barrels of oil that stayed in the deep sea settled on the bottom. Converting that to a percentage of the total oil that entered into the environment (to which we normalized our estimate) converts this range to 1.8 to 14.4\%. Although extrapolated over a larger area, our independent estimate produced similar values.},
	issn = {0013-936X},
	doi = {10.1021/es5046524},
	url = {http://dx.doi.org/10.1021/es5046524},
	author = {Chanton, Jeffrey and Zhao, Tingting and Rosenheim, Brad E. and Joye, Samantha and Bosman, Samantha and Brunner, Charlotte and Yeager, Kevin M. and Diercks, Arne R. and Hollander, David}
}
@article {132,
	title = {Direct measurement of riverine particulate organic carbon age structure},
	journal = {Geophysical Research Letters},
	volume = {39},
	year = {2012},
	note = {id: 2248; PT: J; TC: 0; UT: WOS:000309605800002},
	pages = {L19703-L19703},
	abstract = {Carbon cycling studies focusing on transport and transformation of terrigenous carbon sources toward marine sedimentary sinks necessitate separation of particulate organic carbon (OC) derived from many different sources and integrated by river systems. Much progress has been made on isolating and characterizing young biologically-formed OC that is still chemically intact, however quantification and characterization of old, refractory rock-bound OC has remained troublesome. Quantification of both endmembers of riverine OC is important to constrain exchanges linking biologic and geologic carbon cycles and regulating atmospheric CO2 and O-2. Here, we constrain petrogenic OC proportions in suspended sediment from the headwaters of the Ganges River in Nepal through direct measurement using ramped pyrolysis radiocarbon analysis. The unique results apportion the biospheric and petrogenic fractions of bulk particulate OC and characterize biospheric OC residence time. Compared to the same treatment of POC from the lower Mississippi-Atchafalaya River system, contrast in age spectra of the Ganges tributary samples illustrates the difference between small mountainous river systems and large integrative ones in terms of the global carbon cycle. Citation: Rosenheim, B. E., and V. Galy (2012), Direct measurement of riverine particulate organic carbon age structure, Geophys. Res. Lett., 39, L19703, doi:10.1029/2012GL052883.},
	issn = {0094-8276},
	doi = {10.1029/2012GL052883},
	author = {Rosenheim, Brad E. and Galy, Valier}
}
