@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 {2612,
	title = {Climate variability and cultural eutrophication at Walden Pond (Massachusetts, USA) during the last 1800 years},
	journal = {PLOS ONE},
	volume = {131786944304936355638925103443261363251824210727417625108525645371825392233490545519069849653235772249},
	year = {2018},
	month = {Apr-04-2018},
	pages = {e0191755},
	abstract = {Recent shifts in the ecological condition of Walden Pond, MA, are of
potentially wide interest due to the lake{\textquoteright}s importance as a cultural,
historical, and recreational resource in addition to its scientific
value as an indicator of local and global environmental change. Algal
microfossils in six sediment cores document changes in hydroclimate and
trophic status of the lake during the last 1800 years and extend two
previous sediment core records of shorter length. Low percentages of
planktonic diatoms in the longest cores (WAL-3, WAL-15) indicate
shallowing and/or greater water clarity associated with a relatively
arid interval during the Medieval Climate Anomaly, ca. A.D. 1150-1300,
Cultural eutrophication of the lake since the A.D. 1920s caused diatoms
in the genera Asterionella and Synedra to increase in relative abundance
at the expense of Cyclotella, Discostella, and the chrysophyte alga
Mallomonas allorgel. Percentages of Asterionella and Synedra have
remained fairly stable since A.D. 2000 when a previous sediment core
study was conducted, but scaled chrysophytes have become more numerous.
These findings suggest that, although mitigation efforts have curtailed
anthropogenic nutrient inputs to Walden Pond, the lake has not returned
to the pre-impact condition described by Henry David Thoreau and may
become increasingly vulnerable to further changes in water quality in a
warmer and possibly wetter future.},
	keywords = {BOREAL LAKES, canada, CRAWFORD LAKE, DEPTH MODELS, ENVIRONMENTAL-CHANGE, ice-age, new-england, NORTH-AMERICA, NORTHEASTERN UNITED-STATES, organic-matter},
	doi = {10.1371/journal.pone.0191755},
	url = {https://www.sciencedaily.com/releases/2018/04/180404143418.htm},
	author = {Stager, J. Curt and Wiltse, Brendan and Hubeny, J. Bradford and Yankowsky, Eric and Nardelli, David and Primack, Richard},
	editor = {Doi, Hideyuki}
}
@article {2020,
	title = {Compound-specific radiocarbon dating of the varved Holocene sedimentary record of Saanich Inlet, Canada},
	journal = {Paleoceanography},
	volume = {19},
	year = {2004},
	note = {819piTimes Cited:18
Cited References Count:69
},
	month = {May 1},
	abstract = {[1] The radiocarbon contents of various biomarkers extracted from the varve-counted sediments of Saanich Inlet, Canada, were determined to assess their applicability for dating purposes. Calibrated ages obtained from the marine planktonic archaeal biomarker crenarchaeol compared favorably with varve-count ages. The same conclusion could be drawn for a more general archaeal biomarker (GDGT-0), although this biomarker proved to be less reliable due to its less-specific origin. The results also lend support to earlier indications that marine crenarchaeota use dissolved inorganic carbon (DIC) as their carbon source. The average reservoir age offset DeltaR of 430 years, determined using the crenarchaeol radiocarbon ages, varied by +/-110 years. This may be caused by natural variations in ocean-atmosphere mixing or upwelling at the NE Pacific coast but variability may also be due to an inconsistency in the marine calibration curve when used at sites with high reservoir ages.},
	keywords = {british-columbia, compound-specific radiocarbon dating, crenarchaeol, ionization mass-spectrometry, marine-sediments, mediterranean sea, membrane-lipids, ne pacific, odp leg 169s, organic-matter, pacific-ocean, rapid isolation, Reservoir age, reservoir ages, saanich inlet},
	isbn = {0883-8305},
	doi = {10.1029/2003PA000927},
	url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2\&amp;SrcAuth=Alerting\&amp;SrcApp=Alerting\&amp;DestApp=WOS\&amp;DestLinkType=FullRecord;UT=WOS:000221326700001},
	author = {Smittenberg, R. H. and Hopmans, E. C. and Schouten, S. and Hayes, J. M. and Eglinton, T. I. and Damste, J. S. S.}
}
@article {2073,
	title = {Radiocarbon dating of individual fatty acids as a tool for refining Antarctic margin sediment chronologies},
	journal = {Radiocarbon},
	volume = {45},
	year = {2003},
	note = {735tqTimes Cited:25
Cited References Count:29
},
	month = {2003},
	pages = {17-24},
	abstract = {We have measured the radiocarbon contents of individual, solvent-extractable, short-chain (C-14, C-16, and C-18) fatty acids isolated from Ross Sea surface sediments. The corresponding C-14 ages are equivalent to that of the post-bomb dissolved inorganic carbon (DIC) reservoir. Moreover, molecular C-14 variations in surficial (upper 15 cm) sediments indicate that these compounds may prove useful for reconstructing chronologies of Antarctic margin sediments containing uncertain (and potentially variable) quantities of relict organic carbon. A preliminary molecular C-14 chronology suggests that the accumulation rate of relict organic matter has not changed during the last 500 C-14 yr. The focus of this study is to determine the validity of compound-specific C-14 analysis as a technique for reconstructing chronologies of Antarctic margin sediments.},
	keywords = {carbon, ice-sheet, marine-sediments, north-atlantic, organic-matter, ross-sea, southern-ocean},
	isbn = {0033-8222},
	author = {Ohkouchi, N. and Eglinton, T. I. and Hayes, J. M.}
}
@article {2120,
	title = {In situ calcium carbonate dissolution in the Pacific Ocean},
	journal = {Global Biogeochemical Cycles},
	volume = {16},
	year = {2002},
	note = {649rqTimes Cited:86
Cited References Count:60
},
	month = {Dec 31},
	abstract = {Over the past several years researchers have been working to synthesize the WOCE/JGOFS global CO(2) survey data to better understand carbon cycling processes in the oceans. The Pacific Ocean data set has over 35,000 sample locations with at least two carbon parameters, oxygen, nutrients, CFC tracers, and hydrographic parameters. In this paper we estimate the in situ CaCO(3) dissolution rates in the Pacific Ocean water column. Calcium carbonate dissolution rates ranging from 0.01-1.1 mumol kg(-1) yr(-1) are observed in intermediate and deepwater beginning near the aragonite saturation horizon. In the North Pacific Intermediate Water between 400 and 800 m, CaCO(3) dissolution rates are more than 7 times faster than observed in middle and deep water depths (average=0.051 m mol kg(-1) yr(-1)). The total amount of CaCO(3) that is dissolved within the Pacific is determined by integrating excess alkalinity throughout the water column. The total inventory of CaCO(3) added by particle dissolution in the Pacific Ocean, north of 40degreesS, is 157 Pg C. This amounts to an average dissolution rate of approximately 0.31 Pg C yr(-1). This estimate is approximately 74\% of the export production of CaCO(3) estimated for the Pacific Ocean. These estimates should be considered to be upper limits for in situ carbonate dissolution in the Pacific Ocean, since a portion of the alkalinity increase results from inputs from sediments.},
	keywords = {anthropogenic co(2), anthropogenic co2, aragonite saturation, atmospheric carbon, caco(3) dissolution, calcite saturation, carbonate lysocline, chemical lysocline, coccolithophore emiliania-huxleyi, indian-ocean, north pacific, organic-matter, Pacific Ocean, panama basin, particulate matter},
	isbn = {0886-6236},
	doi = {10.1029/2002GB001866},
	author = {Feely, R. A. and Sabine, C. L. and Lee, K. and Millero, F. J. and Lamb, M. F. and Greeley, D. and Bullister, J. L. and Key, R. M. and Peng, T. H. and Kozyr, A. and Ono, T. and Wong, C. S.}
}
@article {2116,
	title = {Possible biological or physical explanations for decadal scale trends in North Pacific nutrient concentrations and oxygen utilization},
	journal = {Deep-Sea Research Part Ii-Topical Studies in Oceanography},
	volume = {49},
	year = {2002},
	note = {507ceTimes Cited:24
Cited References Count:71
},
	month = {2002},
	pages = {345-362},
	abstract = {We analyze North Pacific GEOSECS (1970s) and WOCE (1990s) observations to examine potential decadal trends of the marine biological carbon pump. Nitrate concentrations ([NO3]) and apparent oxygen utilization (AOU) decreased significantly in intermediate waters (by -0.6 and -2.9 mu mol kg(-1) respectively, at sigma (theta) = 27.4 kg m(-3), corresponding to approximate to 1050 m). In shallow waters (above roughly 750 m) [NO3-] and AOU increased, though the changes were not statistically significant. A sensitivity study with an ocean general circulation model indicates that reasonable perturbations of the biological carbon pump due to changes in export production or remineralization. efficiency are insufficient to account for the intermediate water tracer trends. However, changes in water ventilation rates could explain the intermediate water tracer trends and would be consistent with trends of water age derived from radiocarbon. Trends in AOU and [NO3-] provide relatively poor constraints on decadal scale trends in the marine biological carbon pump for two reasons. First, most of the expected changes due to decadal scale perturbations of the marine biota occur in shallow waters, where the available data are typically too sparse to account for the strong spatial and temporal variability. Second, alternative explanations for the observed tracer trends (e.g., changes in the water ventilation rates) cannot be firmly rejected. Our data analysis does not disprove the null-hypothesis of an unchanged biological carbon pump in the North Pacific. (C) 2001 Published by Elsevier Science Ltd.},
	keywords = {anthropogenic co2 invasion, atmospheric co2, carbon-cycle, el-nino, hydrographic data, organic-matter, redfield ratios, sargasso-sea, subtropical gyre, vertical fluxes},
	isbn = {0967-0645},
	url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2\&amp;SrcAuth=Alerting\&amp;SrcApp=Alerting\&amp;DestApp=WOS\&amp;DestLinkType=FullRecord;UT=WOS:000173008600015},
	author = {Keller, K. and Slater, R. D. and Bender, M. and Key, R. M.}
}
