@article {2994,
	title = {14C Blank Corrections for 25{\textendash}100 μg Samples at the National Ocean Sciences AMS Laboratory},
	journal = {Radiocarbon},
	volume = {61},
	year = {2019},
	month = {10/2019},
	pages = {1403 - 1411},
	abstract = {Replicate radiocarbon (14C) measurements of organic and inorganic control samples, with known Fraction Modern values in the range Fm = 0{\textendash}1.5 and mass range 6 μg{\textendash}2 mg carbon, are used to determine both the mass and radiocarbon content of the blank carbon introduced during sample processing and measurement in our laboratory. These data are used to model, separately for organic and inorganic samples, the blank contribution and subsequently {\textquotedblleft}blank correct{\textquotedblright} measured unknowns in the mass range 25{\textendash}100 μg. Data, formulas, and an assessment of the precision and accuracy of the blank correction are presented.},
	keywords = {AMS, AMS dating, blank corrections},
	isbn = {0033-8222, 1945-5755},
	doi = {10.1017/RDC.2019.74},
	url = {https://www.cambridge.org/core/journals/radiocarbon/article/14c-blank-corrections-for-25100-g-samples-at-the-national-ocean-sciences-ams-laboratory/494B9CF72445198570213B4A2CC303D0},
	author = {Roberts, M. L. and Elder, K. L. and Jenkins, W. J. and Gagnon, A. R. and Xu, L. and Hlavenka, J. D. and Longworth, B. E.}
}
@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 {153,
	title = {Carbon dynamics in the western Arctic Ocean: insights from full-depth carbon isotope profiles of DIC, DOC, and POC},
	journal = {Biogeosciences},
	volume = {9},
	year = {2012},
	note = {id: 2254; PT: J; TC: 4; UT: WOS:000302179500026},
	pages = {1217-1224},
	abstract = {Arctic warming is projected to continue throughout the coming century. Yet, our currently limited understanding of the Arctic Ocean carbon cycle hinders our ability to predict how changing conditions will affect local Arctic ecosystems, regional carbon budgets, and global climate. We present here the first set of concurrent, full-depth, dual-isotope profiles for dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and suspended particulate organic carbon (POCsusp) at two sites in the Canada Basin of the Arctic Ocean. The carbon isotope composition of sinking and suspended POC in the Arctic contrasts strongly with open ocean Atlantic and Pacific sites, pointing to a combination of inputs to Arctic POCsusp at depth, including surface-derived organic carbon (OC), sorbed/advected OC, and OC derived from in situ DIC fixation. The latter process appears to be particularly important at intermediate depths, where mass balance calculations suggest that OC derived from in situ DIC fixation contributes up to 22\% of POCsusp. As in other oceans, surface-derived OC is still a dominant source to Arctic POCsusp. Yet, we suggest that significantly smaller vertical POC fluxes in the Canada Basin make it possible to see evidence of DIC fixation in the POCsusp pool even at the bulk isotope level.},
	issn = {1726-4170},
	doi = {10.5194/bg-9-1217-2012},
	author = {Griffith, D. R. and McNichol, A. P. and Xu, L. and McLaughlin, F. A. and Macdonald, R. W. and Brown, K. A. and Eglinton, T. I.}
}
@article {400,
	title = {Determination of biodiesel blending percentages using natural abundance radiocarbon analysis: Testing the accuracy of retail biodiesel blends},
	journal = {Environmental Science \& Technology},
	volume = {42},
	year = {2008},
	note = {id: 1864; 281JN Times Cited:3 Cited References Count:39; YY},
	pages = {2476-2482},
	abstract = {Blends of biodiesel and petrodiesel are being used increasingly worldwide. Due to several factors, inaccurate blending of these two mixtures can occur. To test the accuracy of biodiesel blending, we developed and validated a radiocarbon-based method and then analyzed a variety of retail biodiesel blends. Error propagation analysis demonstrated that this method calculates absolute blend content with +/- 1\% accuracy, even when real-world variability in the component biodiesel and petrodiesel sources is taken into account. We independently confirmed this accuracy using known endmembers and prepared mixtures. This is the only published method that directly quantifies the carbon of recent biological origin in biodiesel blends. Consequently, it robustly handles realistic chemical variability in biological source materials and provides unequivocal apportionment of renewable versus nonrenewable carbon in a sample fuel blend. Analysis of retail biodiesel blends acquired in 2006 in the United States revealed that inaccurate blending happens frequently. Only one out of ten retail samples passed the specifications that the United States Department of Defense requires for blends that are 20\% biodiesel (v/v; referred to as B20).},
	issn = {0013-936X},
	doi = {10.1021/Es071814j},
	author = {Reddy, C. M. and DeMello, J. A. and Carmichael, C. A. and Peacock, E. E. and Xu, L. and Arey, J. S.}
}
@article {403,
	title = {Evaluation of gas chromatographic isotope fractionation and process contamination by carbon in compound-specific radiocarbon analysis},
	journal = {Analytical Chemistry},
	volume = {79},
	year = {2007},
	note = {id: 615; 140ID Times Cited:11 Cited References Count:32},
	pages = {2042-2049},
	abstract = {The relevance of both modern and fossil carbon contamination as well as isotope fractionation during preparative gas chromatography for compound-specific radiocarbon analysis (CSRA) was evaluated. Two independent laboratories investigated the influence of modern carbon contamination in the sample cleanup procedure and preparative capillary gas chromatography (pcGC) of a radiocarbon-dead 3,3{\textquoteright},4,4{\textquoteright},5,5{\textquoteright}-hexachlorobiphenyl (PCB 169) reference. The isolated samples were analyzed for their C-14/C-12 ratio by accelerator mass spectrometry. Sample Delta C-14 values of -996 +/- 20 and -985 +/- 20\% agreed with a Delta C-14 of -995 +/- 20\% for the unprocessed PCB 169, suggesting that no significant contamination by nonfossil carbon was introduced during the sample preparation process at either laboratory. A reference compound containing a modern C-14/C-12 ratio (vanillin) was employed to evaluate process contamination from fossil C. No negative bias due to fossil C was observed (sample Delta C-14 value of 165 +/- 20\% agreed with Delta C-14 of 155 +/- 12\% for the unprocessed vanillin). The extent of isotopic fractionation that can be induced during pcGC was evaluated by partially collecting the vanillin model compound of modern C-14/C-12 abundance. A significant change in the delta C-13 and delta C-14 values was observed when only parts of the eluting peak were collected (delta C-13 values ranged from -15.75 to -49.91\% and delta C-14 values from -82.4 to +4.71\%). Delta C-14 values, which are normalized to a delta C-13 of -25\%, did not deviate significantly (-58.9 to -5.8\%, considering the uncertainty of similar to +/- 20\%). This means that normalization of radiocarbon results to a delta C-13 of -25\%, normally performed to remove effects of environmental isotope fractionation on C-14-based age determinations, also cor-rects sufficiently for putative isotopic fractionation that may occur during pcGC isolation of individual compounds for CSRA.},
	issn = {0003-2700},
	doi = {10.1021/Ac061821a},
	author = {Zencak, Z. and Reddy, C. M. and Teuten, E. L. and Xu, L. and McNichol, A. P. and Gustafsson, O.}
}
@article {1896,
	title = {Radiocarbon dating of a very large African baobab},
	journal = {Tree Physiology},
	volume = {27},
	year = {2007},
	note = {230afTimes Cited:35
Cited References Count:43
},
	month = {Nov},
	pages = {1569-1574},
	abstract = {In late 2004, Grootboom, probably the largest known African baobab (Adansonia digitata L.), collapsed unexpectedly in northeastern Namibia. Ten wood samples collected from different areas of the trunk were processed and investigated by accelerator mass spectrometry radiocarbon dating. The radiocarbon dates of three samples were greater than 1000 years BP (radiocarbon years before present, i.e., before AD 1950). The corresponding calibrated calendar age of the oldest sample was 1275 +/- 50 years, making Grootboom the oldest known angiosperm tree with reliable dating results. Variations in radiocarbon dates among the wood samples indicated that, morphologically, Grootboom was a quintuple tree, whereas genetically, it was a single individual. Ages of extreme lateral samples revealed that, over the past 500-600 years, Grootbooom had almost ceased growing, providing information about climate changes in central southern Africa. The sudden demise of Grootboom coincided with the spread of the poorly studied baobab disease, which has become epidemic in Namibia.},
	keywords = {Adansonia digitata, Age, Age determination, amazonia, c-14 content, cal kyr bp, Calibration, dendrochronology, dendroclimatology, holocene logs, location-dependent differences, southern-hemisphere, tasmanian conifers, Trees, tropical trees},
	isbn = {0829-318x},
	author = {Patrut, A. and von Reden, K. F. and Pohlman, J. W. and Wittmann, R. and Mitchell, C. S. and Lowy, D. A. and Alberts, A. H. and Gerlach, D. and Xu, L.}
}
@article {707,
	title = {Tracking the weathering of an oil spill with comprehensive two-dimensional gas chromatography},
	journal = {Environmental Forensics},
	volume = {7},
	year = {2006},
	note = {032ldTimes Cited:62Cited References Count:21},
	month = {Mar},
	pages = {33-44},
	abstract = {Comprehensive two-dimensional gas chromatography (GC x GC) was used to investigate the Bouchard 120 oil spill. The latter occurred on April 25, 2003, when the barge Bouchard 120 spilled similar to 375,000 liters of No. 6 fuel oil into Buzzards Bay, Massachusetts. In order to gain a better understanding of the natural processes affecting the fate of the spilled product, we collected and analyzed oil-covered rocks from Nyes Neck beach in North Falmouth, Massachusetts. Here we discuss the data from samples collected on May 9, 2003, and six months later, on November 23, 2003. Along with standard two-dimensional gas chromatographic analysis, we employed unique data-visualization techniques such as difference, ratio, and addition chromatograms to highlight how evaporation, water washing, and biodegradation weathered the spilled oil. These approaches provide a new perspective to studying oil spills and aid attempts to remediate them.},
	issn = {1527-5922},
	doi = {10.1080/15275920500506758},
	author = {Nelson, R. K. and Kile, B. M. and Plata, D. L. and Sylva, S. P. and Xu, L. and Reddy, C. M. and Gaines, R. B. and Frysinger, G. S. and Reichenbach, S. E.}
}
@article {922,
	title = {Abundance, composition, and vertical transport of PAHs in marsh sediments},
	journal = {Environ Sci Technol},
	volume = {39},
	year = {2005},
	note = {White, Helen KXu, LiLima, Ana Lucia CEglinton, Timothy IReddy, Christopher MengResearch Support, Non-U.S. Gov{\textquoteright}tResearch Support, U.S. Gov{\textquoteright}t, Non-P.H.S.2005/11/22 09:00Environ Sci Technol. 2005 Nov 1;39(21):8273-80.},
	month = {Nov 01},
	pages = {8273-80},
	abstract = {Petroleum-derived hydrocarbons continue to persist in Wild Harbor, West Falmouth, MA, following a spill of No. 2 fuel oil in 1969 from the barge Florida. Recent analysis of marsh sediments revealed that residues of degraded oil are present with concentrations of total petroleum hydrocarbons as high as approximately 9 mg g(-1). Polycyclic aromatic hydrocarbons (PAHs) constitute only a minor fraction of these residues with maximum concentrations of 134 mirog g(-1), but their fate is of interest because of their potential toxicity to organisms. As compared to typical unweathered No. 2 fuel oil, the current distribution of PAHs in the sediments reflects substantial weathering by abiotic and biotic processes, specifically a preferential loss of naphthalenes relative to phenanthrenes, as well as isomer-specific biodegradation of alkylated PAHs. Based on comparison to results from an earlier study, it appears that little or no change has occurred to the distribution of PAHs since 1989, indicating that weathering at this site has stalled or is now proceeding at a significantly slower rate. To assess whether sediment-water partitioning and molecular diffusion in the interstitial medium are now the dominant processes controlling the vertical distribution of PAHs, downcore profiles were compared to a numerical model. While in some cases the model accurately reproduced the measured data, there were instances where the distribution of PAHs was slightly under or overestimated. Reasons for these discrepancies are discussed and are likely due to bioturbation, colloid-facilitated transport, or both. Assessment of the influence of these processes on the spilled oil expands our understanding of the overall fate of these compounds and their potential long-term effects on the environment.},
	issn = {0013-936X},
	doi = {10.1021/es050475w},
	author = {White, H. K. and Xu, L. and Lima, A. L. and Eglinton, T. I. and Reddy, C. M.}
}
@article {1984,
	title = {Contribution of biomass burning to polycyclic aromatic hydrocarbons in European background aerosols},
	journal = {Environmental Science and Technology},
	volume = {39},
	year = {2005},
	note = {id: 510},
	month = {2005},
	pages = {2976-2982},
	author = {Mandalakis, M. and Gustafsson, O. and Alsberg, T. and Reddy, C. and Xu, L. and Klanova, J. and Holoubek, I. and Stephanou, E.}
}
@article {1977,
	title = {Radiocarbon dating of alkenones from marine sediments: I. Isolation protocol},
	journal = {Radiocarbon},
	volume = {47},
	year = {2005},
	note = {993nkTimes Cited:13
Cited References Count:22
},
	month = {2005},
	pages = {401-412},
	abstract = {The chemical and isotopic compositions of long-chain (C-36-C-39) unsaturated ketones (alkenones), a unique class of algal lipids, encode surface ocean properties useful for paleoceanographic reconstruction. Recently, we have sought to extend the utility of alkenones as oceanic tracers through measurement of their radiocarbon contents. Here. we describe a method for isolation of alkenones from sediments as a compound class based on a sequence of wet chemical techniques. The steps involved, which include silica gel column chromatography, urea adduction, and silver nitrate-silica gel column chromatography, exploit various structural attributes of the alkenones. Amounts of purified alkenones estimated by GC/FID measurements were highly correlated with CO2 yields after sample combustion, indicating purities of greater than 90\% for samples containing >= 100 mu g C. The degree of alkenone unsaturation (U-37(K{\textquoteright})) also varied minimally through the procedure. We also describe a high-performance liquid chromatography (HPLC) method to isolate individual alkenones for molecular-level structural and isotopic determination.},
	keywords = {AMS, carbon, indicators, proxy, records, tool},
	isbn = {0033-8222},
	author = {Ohkouchi, N. and Xu, L. and Reddy, C. M. and Montlucon, D. and Eglinton, T. I.}
}
@article {696,
	title = {Two abundant bioaccumulated halogenated compounds are natural products},
	journal = {Science},
	volume = {307},
	year = {2005},
	note = {Teuten, Emma LXu, LiReddy, Christopher MengResearch Support, Non-U.S. Gov{\textquoteright}tResearch Support, U.S. Gov{\textquoteright}t, Non-P.H.S.2005/02/12 09:00Science. 2005 Feb 11;307(5711):917-20.},
	month = {Feb 11},
	pages = {917-20},
	abstract = {Methoxylated polybrominated diphenyl ethers (MeO-PBDEs) have been found bioaccumulated in the tissues of a variety of aquatic animals and at concentrations comparable to those of anthropogenic halogenated organic compounds, including polychlorinated biphenyls (PCBs). The origin of the MeO-PBDEs has been uncertain; circumstantial evidence supports a natural and/or an industrial source. By analyzing the natural abundance radiocarbon content of two MeO-PBDEs isolated from a True{\textquoteright}s beaked whale (Mesoplodon mirus), we show that these compounds were naturally produced.},
	issn = {0036-8075 (Linking)},
	doi = {10.1126/science.1106882},
	author = {Teuten, E. L. and Xu, L. and Reddy, C. M.}
}
@article {404,
	title = {Using comprehensive two-dimensional gas chromatography retention indices to estimate environmental partitioning properties for a complete set of diesel fuel hydrocarbons},
	journal = {Analytical Chemistry},
	volume = {77},
	year = {2005},
	note = {id: 1700; 985UM Times Cited:30 Cited References Count:56},
	pages = {7172-7182},
	abstract = {Comprehensive two-dimensional gas chromatography (GC x GC) provides nearly complete composition data for some complex mixtures such as petroleum hydrocarbons. However, the potential wealth of physical property information contained in the corresponding two-dimensional chromatograms is largely untapped. We developed a simple but robust method to estimate GC x GC retention indices for diesel-range hydrocarbons. By exploiting n-alkanes as reference solutes in both dimensions, calculated retention indices were insensitive to uncertainty in the enthalpy of gas-stationary-phase transfer for a suite of representative diesel components. We used the resulting two-dimensional retention indices to estimate the liquid vapor pressures, aqueous solubilities, air-water partition coefficients, octanol-water partition coefficients, and vaporization enthalpies of a nearly complete set of diesel fuel hydrocarbons. Partitioning properties were typically estimated within a factor of 2; this is not as accurate as some previous estimation or measurement methods. However, these relationships may allow powerful and incisive analysis of phase-transfer processes affecting petroleum hydrocarbon mixtures in the environment. For example, GC x GC retention data might be used to quantitatively deconvolve the effects of water washing and evaporation on environmentally released diesel fuels.},
	issn = {0003-2700},
	doi = {10.1021/Ac051051n},
	author = {Arey, J. S. and Nelson, R. K. and Xu, L. and Reddy, C. M.}
}
@article {698,
	title = {Abrupt tropical vegetation response to rapid climate changes},
	journal = {Science},
	volume = {304},
	year = {2004},
	note = {Hughen, Konrad AEglinton, Timothy IXu, LiMakou, MatthewengResearch Support, Non-U.S. Gov{\textquoteright}t2004/05/25 05:00Science. 2004 Jun 25;304(5679):1955-9. Epub 2004 May 20.},
	month = {Jun 25},
	pages = {1955-9},
	abstract = {Identifying leads and lags between high- and low-latitude abrupt climate shifts is needed to understand where and how such events were triggered. Vascular plant biomarkers preserved in Cariaco basin sediments reveal rapid vegetation changes in northern South America during the last deglaciation, 15,000 to 10,000 years ago. Comparing the biomarker records to climate proxies from the same sediment core provides a precise measure of the relative timing of changes in different regions. Abrupt deglacial climate shifts in tropical and high-latitude North Atlantic regions were synchronous, whereas changes in tropical vegetation consistently lagged climate shifts by several decades.},
	issn = {0036-8075 (Linking)},
	doi = {10.1126/science.1092995},
	author = {Hughen, K. A. and Eglinton, T. I. and Xu, L. and Makou, M.}
}
@article {2010,
	title = {Plans for Expanded 14C Analyses at the NOSAMS Facility--a status and progress report. 9th International Conference on Accelerator Mass Spectrometry, Nagoya, Japan, 9/2002},
	journal = {Nuclear Instruments and Methods in Physics Research},
	volume = {B 223-224},
	year = {2004},
	note = {id: 1810},
	month = {2004},
	pages = {50-54},
	author = {von Reden, K. and Donoghue, J. and Elder, K. and Gagnon, A. and Gerlach, D. and Griffin, V. S. and Healy, R. and Long, P. and McNichol, A. P. and Percy, D. and Roberts, M. L. and Schneider, R. J. and Xu, L. and Hayes, J.}
}
@article {2040,
	title = {Radiocarbon apportionment of fossil versus biofuel combustion sources of polycyclic aromatic hydrocarbons in the Stockholm metropolitan area},
	journal = {Environ Sci Technol},
	volume = {38},
	year = {2004},
	note = {Mandalakis, ManolisGustafsson, Orjan
Reddy, Christopher M
Xu, Li
eng
Comparative Study
Research Support, Non-U.S. Gov{\textquoteright}t
Research Support, U.S. Gov{\textquoteright}t, Non-P.H.S.
2004/11/17 09:00
Environ Sci Technol. 2004 Oct 15;38(20):5344-9.
},
	month = {Oct 15},
	pages = {5344-9},
	abstract = {Source-diagnostic markers and the isotopic composition of polycyclic aromatic hydrocarbons (PAHs) were examined in surface sediments from the greater Stockholm waterways to deduce the contribution from biomass sources to the environmental PAH load. The summed concentration of 20 PAHs ranged from 0.8 to 45.1 microg/g (dry weight) and exhibited a steep decline with increasing distance from the city center evidencing that sources within the metropolitan area of Stockholm dominate its PAH burden. Several diagnostic PAH ratios indicated an overwhelming predominance of pyrogenic sources over the petrogenic ones, while retene and 1,7-dimethylphenanthrene were unable to correctly evaluate the contribution from biomass combustion. The stable carbon isotope composition (delta13C) of individual PAHs ranged from -24.8 to -27.0\% but also was proved inefficient to discriminate between different types of fuels due to the overlapping signals in various sources. The delta14C values of PAHs ranged between -550.4 and -934.1\%, indicating a clear predominance of fossil fuel sources. By using an isotopic mass balance approach, we estimated that on average 17+/-9\% of PAHs derived from biomass combustion. This radiocarbon apportionment, in conjunction with detailed energy statistics for the Stockholm region, revealed that the ambient PAH burden is roughly similar, per unit energy produced, from fossil fuels and biofuels. Societies{\textquoteright} shifting energy policies toward a larger reliance on biofuels may thus not lead to further deterioration of air quality and respiratory ailments for the urban population.},
	keywords = {*Bioelectric Energy Sources, *Fossil Fuels, Biomass, Carbon Radioisotopes, Cities, Environmental Monitoring, Fresh Water, Geologic Sediments/*analysis, Polycyclic Aromatic Hydrocarbons/*analysis/isolation \& purification, Sweden, Water Pollutants, Chemical/*analysis/isolation \& purification},
	isbn = {0013-936X (Print)0013-936X (Linking)},
	doi = {10.1021/es049088x},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/15543735},
	author = {Mandalakis, M. and Gustafsson, O. and Reddy, C. M. and Xu, L.}
}
@article {2027,
	title = {Radiocarbon evidence for a naturally-produced, bioaccumulation halogenated organic compound},
	journal = {Environmental Science and Technology},
	volume = {38},
	year = {2004},
	note = {id: 1806},
	month = {2004},
	pages = {1992-1997},
	author = {Reddy, C. M. and Xu, L. and O{\textquoteright}Neil, G. W. and Nelson, R. K. and Eglinton, T. I. and Faulkner, D. J. and Norstrom, R. and Ross, P. S. and Tittlemier, S. A.}
}
@article {2068,
	title = {Heterogeneity in the radiocarbon content of Polycyclic aromatic hydrocarbons in household soot},
	journal = {Environmental Forensics},
	volume = {4},
	year = {2003},
	note = {id: 507},
	month = {2003},
	pages = {191-197},
	author = {Reddy, C. M. and Xu, L. and O{\textquoteright}Connor, R.}
}
@article {708,
	title = {Using radiocarbon to apportion sources of polycyclic aromatic hydrocarbons in household soot},
	journal = {Environmental Forensics},
	volume = {4},
	year = {2003},
	note = {731ytTimes Cited:16Cited References Count:42},
	month = {Sep},
	pages = {191-197},
	abstract = {To determine whether polycyclic aromatic hydrocarbons (FAHs) in household soot were derived from the combustion of scrap wood or creosote that was impregnated in the wood (or some combination of both), the molecular composition and radiocarbon (C-14) content of the total carbon and several PAHs in the soot was investigated. The 5730-year half-life of C-14 makes it an ideal marker for identifying creosote-derived PAHs (C-14-free) versus those derived from the combustion of wood (contemporary C-14). The C-14 abundance of phenanthrene, fluoranthene, pyrene, and retene was determined by accelerator mass spectrometry after solvent extraction and purification by preparative capillary gas chromatography. The molecular analysis (presence of retene and 1,7-dimethylphenanthrene) and bulk C-14 content (contemporary) of the soot indicated that wood combustion was a strong source of carbon to the soot. The C-14 of retene in two soot samples was also contemporary, indicating that it was derived from the combustion of the scrap wood. These results are consistent with previous work that has suggested that retene is an excellent marker of wood combustion. However, the C-14 content of phenanthrene, fluoranthene, and pyrene in one soot sample was much lower and revealed that these compounds had a mixed creosote and wood source. Using an isotopic mass balance approach, we estimate that 40 to 70\% of phenanthrene, fluoranthene, and pyrene were derived from the combustion of the scrap wood. The results of this study show that molecular marker and bulk C-14 analysis can be potentially misleading in apportioning sources of every PAH, and that molecular-level C-14 analysis of PAHs can be a powerful tool for environmental forensics.},
	issn = {1527-5922},
	doi = {10.1080/15275920390230778},
	author = {Reddy, C. M. and Xu, L. and O{\textquoteright}Connor, R.}
}
@conference {1744,
	title = {Plans for expanded 14C analyses at the NOSAMS facility - a status and progress report},
	booktitle = {International Conference on Accelerator Mass Spectrometry},
	year = {2002},
	note = {id: 1685},
	month = {2002},
	address = {Nagoya, Japan},
	author = {von Reden, K. F. and Donoghue, J. and Elder, K. and Gagnon, A. and Gerlach, D. and Griffin, V. and Healy, R. and Long, P. and McNichol, A. and Percy, D. and Roberts, M. L. and Schneider, R. J. and Xu, L. and Hayes, J. M.}
}
@article {637,
	title = {Radiocarbon as a tool to apportion the sources of polycyclic aromatic hydrocarbons and black carbon in environmental samples},
	journal = {Environmental Science \& Technology},
	volume = {36},
	year = {2002},
	note = {541gfTimes Cited:133Cited References Count:59},
	month = {Apr 15},
	pages = {1774-1782},
	abstract = {To determine the relative inputs of polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) in environmental samples from the combustion of fossil fuels and biomass we have developed two independent analytical methods for determining the C-14 abundance of PAHs and BC. The 5730 yr half-life of C-14 makes it an ideal tracer for identifying combustion products derived from fossil fuels (C-14-free) versus those stemming from modern biomass (contemporary C-14). The C-14 abundance of PAHs in several environmental Standard Reference Materials was measured by accelerator mass spectrometry after extraction and then purification by high-performance liquid chromatography and preparative capillary gas chromatography. This method yields pure compounds that allow for a high degree of confidence in the C-14 results. The PAHs data were then used to compare and evaluate results from an operationally defined thermal oxidation method used to isolate a BC fraction. The C-14 compositions of PAHs and BC were very similar and suggest that the thermal oxidation method employed for isolating BC is robust and free from interferences by non-BC components. In addition, these data indicate that both the PAHs and the BC species derive mostly from fossil fuels and/or their combustion products.},
	issn = {0013-936x},
	doi = {10.1021/es011343f},
	author = {Reddy, C. M. and Pearson, A. and Xu, L. and McNichol, A. P. and Benner, B. A. and Wise, S. A. and Klouda, G. A. and Currie, L. A. and Eglinton, T. I.}
}
@article {2103,
	title = {Radiocarbon content of synthetic and natural semi-volatile halogenated organic compounds},
	journal = {Environ Pollut},
	volume = {120},
	year = {2002},
	note = {Reddy, Christopher MXu, Li
Eglinton, Timothy I
Boon, Jan P
Faulkner, D John
eng
Research Support, Non-U.S. Gov{\textquoteright}t
Research Support, U.S. Gov{\textquoteright}t, Non-P.H.S.
England
2002/10/25 04:00
Environ Pollut. 2002;120(2):163-8.
},
	month = {2002},
	pages = {163-8},
	abstract = {Some halogenated organic compounds, such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polybrominated diphenyl ethers (PBDEs), have been suggested to have natural sources but separating these compounds from their commercially synthesized counterparts is difficult. Molecular-level 14C analysis may be beneficial since most synthetic compounds are manufactured from petrochemicals (14C-free) and natural compounds should have "modern" or "contemporary" 14C levels. As a baseline study, we measured, for the first time, the 14C abundance in commercial PCB and PBDE mixtures, a number of organochlorine pesticides, as well as one natural product 2-(3{\textquoteright},5{\textquoteright}-dibromo-2{\textquoteright}-methoxyphenoxy)-3,5-dibromoanisole. The latter compound was isolated from a marine sponge and is similar in structure to a PBDE. All of the synthetic compounds were 14C-free except for the pesticide toxaphene. which had a modern 14C abundance, as did the brominated natural compound. The result for toxaphene was not surprising since it was commercially synthesized by the chlorination of camphene derived from pine trees. These results suggest that measuring the 14C content of halogenated organic compounds may be quite useful in establishing whether organic compounds encountered in the environment have natural or synthetic origins (or both) provided that any synthetic counterparts derive from petrochemical feedstock.},
	keywords = {Animals, Carbon Radioisotopes/*analysis, Environmental Pollutants/*analysis, Hydrocarbons, Halogenated/chemical synthesis/*chemistry, Insecticides/chemistry, Polychlorinated Biphenyls/chemistry, Porifera/*chemistry, Toxaphene/chemistry},
	isbn = {0269-7491 (Print)0269-7491 (Linking)
},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/12395826},
	author = {Reddy, C. M. and Xu, L. and Eglinton, T. I. and Boon, J. P. and Faulkner, D. J.}
}
@article {2104,
	title = {The West Falmouth oil spill after thirty years: the persistence of petroleum hydrocarbons in marsh sediments},
	journal = {Environ Sci Technol},
	volume = {36},
	year = {2002},
	note = {Reddy, Christopher MEglinton, Timothy I
Hounshell, Aubrey
White, Helen K
Xu, Li
Gaines, Richard B
Frysinger, Glenn S
eng
Research Support, Non-U.S. Gov{\textquoteright}t
Research Support, U.S. Gov{\textquoteright}t, Non-P.H.S.
2002/12/19 04:00
Environ Sci Technol. 2002 Nov 15;36(22):4754-60.
},
	month = {Nov 15},
	pages = {4754-60},
	abstract = {The long-term fate of petroleum hydrocarbons in marsh sediments (West Falmouth, MA) contaminated in 1969 by the spill of the barge Florida was investigated. A 36-cm-long sediment core was collected in August 2000, and sediment extracts were analyzed by gas chromatography (GC) and comprehensive two-dimensional gas chromatography (GC x GC). The latter technique is capable of separating 1 order of magnitude more compounds than the former and was used to observe whether any compositional changes in the unresolved complex mixture (UCM) occurred. No evidence of petroleum residues was detected in the top 6 cm (0-6 cm) and the lower 8 cm (28-36 cm) of the core. However, the central sections 16-28 cm) were dominated by a UCM in the boiling range of n-C13-n-C25 alkanes, consistent with a No. 2 fuel oil source. The 12-14- and 14-16-cm sections had the highest concentrations of UCM approximately 8 mg g(-1)). These values are similar to concentrations observed shortly after the spill. Initial GC x GC analysis revealed that only the n-alkanes were completely degraded, and contrary to previous studies, pristane and phytane as well as numerous other branched alkanes are still present in the sediments. These results suggestthatatthis site hydrocarbon contamination will persist indefinitely in the sedimentary record.},
	keywords = {*Accidents, Chromatography, Gas, Environmental Monitoring, Geologic Sediments/*chemistry, Hydrocarbons/*analysis, Massachusetts, Petroleum/*analysis, Ships, Time Factors, Water Pollutants, Chemical/*analysis},
	isbn = {0013-936X (Print)0013-936X (Linking)},
	doi = {10.1021/es020656n},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/12487296},
	author = {Reddy, C. M. and Eglinton, T. I. and Hounshell, A. and White, H. K. and Xu, L. and Gaines, R. B. and Frysinger, G. S.}
}
@article {409,
	title = {Identification of a novel alkenone in Black Sea sediments},
	journal = {Organic Geochemistry},
	volume = {32},
	year = {2001},
	note = {id: 1946; PT: J; UT: WOS:000168692100002},
	pages = {633-645},
	abstract = {We report the identification of a novel long-chain ketone in Holocene Black Sea sediments. Based on chemical properties, and chromatographic and mass spectrometric characteristics, this compound has been identified as a diunsaturated C-36 ethyl ketone. Further analyses indicated the position and configuration of the double bonds, and the novel alkenone was determined to be hexatriaconta-(16E,21E)-dien-3-one. While this compound is present in only trace quantities in Unit I sediments, it is the most abundant alkenone in portions of Unit II. Its presence thus apparently pre-dates the invasion of Emiliania huxleyi in the Black Sea. The down-core profiles and isotopic compositions suggest that the precursor for the C-36:2 alkenone may be distinct from that of the C37-39 alkenones, however the biological origin of this novel compound is presently unknown. (C) 2001 Elsevier Science Ltd. All rights reserved.},
	issn = {0146-6380},
	doi = {10.1016/S0146-6380(01)00019-5},
	author = {Xu, L. and Reddy, C. M. and Farrington, J. W. and Frysinger, G. S. and Gaines, R. B. and Johnson, C. G. and Nelson, R. K. and Eglinton, T. I.}
}
@article {911,
	title = {Identification of a novel alkenone in Black Sea sediments},
	journal = {Organic Geochemistry},
	volume = {32},
	year = {2000},
	note = {id: 1719},
	pages = {633-645},
	abstract = {We report the identification of a novel long-chain ketone in Holocene Black Sea sediments. Based on chemical properties, and chromatographic and mass spectrometric characteristics, this compound has been identified as a di-unsaturated C36 ethyl ketone. Further analyses indicated the position and configuration of the double bonds, and the novel alkenone was determined to be hexatriaconta-(16E,21E)-dien-3-one. While this compound is present in only trace quantities in Unit I sediments, it is the most abundant alkenone in portions of Unit II. Its presence thus apparently pre-dates the invasion of Emiliania huxleyi in the Black Sea. The down-core profiles and isotopic compositions suggest that the precursor for the C36:2 alkenone may be distinct from that of the C37-39 alkenones, however the biological origin of this novel compound is presently unknown.},
	keywords = {Alkenone, Black Sea, Haptophytes, Holocene, Sediment, Structure characterization},
	doi = {10.1016/S0146-6380(01)00019-5},
	author = {Xu, L. and Reddy, C. M. and Farrington, J. W. and Frysinger, G. S. and Gaines, R. B. and Johnson, C. G. and Nelson, R. K. and Eglinton, T. I.}
}
@article {636,
	title = {Stable chlorine isotopic compositions of aroclors and aroclor-contaminated sediments},
	journal = {Environmental Science \& Technology},
	volume = {34},
	year = {2000},
	note = {330rcTimes Cited:39Cited References Count:16},
	month = {Jul 1},
	pages = {2866-2870},
	abstract = {An exploratory investigation was conducted to evaluate if stable chlorine isotopic ratios of polychlorinated biphenyls (PCBs) could be useful in studying the processes that determine their transport and fate in the environment First, we determined the variability of delta(37)Cl in the source materials for PCBs. Second, we determined if the delta(37)Cl values of contaminated environmental samples fell outside the range in source variability. The isotopic variability among the source materials (Aroclors) was rather small; delta(37)- Cl values ranged from -3.37 to -2.11\% (mean and standard deviation, -2.78 +/- 0.39\%, n = 12). There was no correlation between the delta(37)Cl values and percentages of chlorine in the mixtures. We also found very similar values in several Clophen mixtures and one Phenoclor. The delta(37)Cl values in the total PCBs isolated from Aroclor-contaminated sediments from the Hudson River, New Bedford Harbor, and Turtle River Estuary ranged from -4.54 to -2.25\% (n = 19). While most of the delta(37)Cl values were within 2 standard deviations of the mean Aroclor value (our assumed estimate for overall source variability), two of the PCB contaminated sediment samples from New Bedford Harbor did appear to be isotopically distinct. The PCBs in these sediments had lower amounts of less chlorinated congeners (when compared to the source material) and were likely isotopically affected by alteration processes that preferentially removed these congeners. Compound specific measurements of two congeners in Aroclor 1268 suggest that there are no large congener-specific differences in the stable chlorine isotope ratios in Aroclors. This study shows that the delta(37)Cl Values of PCBs may be a potentially useful diagnostic tool in studying the transport and fate of PCBs and indicates that additional research is warranted.},
	issn = {0013-936x},
	doi = {10.1021/es9908220},
	author = {Reddy, C. M. and Heraty, L. J. and Holt, B. D. and Sturchio, N. C. and Eglinton, T. I. and Drenzek, N. J. and Xu, L. and Lake, J. L. and Maruya, K. A.}
}
