@article {45,
	title = {Deciphering microbial carbon substrates in PAH contaminated sediments using phospholipid fatty acids, and compound specific δ13C and Δ14C},
	journal = {Organic Geochemistry},
	volume = {69},
	year = {2014},
	pages = {76-87},
	abstract = {Stable and radiogenic carbon isotopes (δ13C and Δ14C) of organic compounds and phospholipid fatty acids (PLFAs), as well as polycyclic aromatic hydrocarbon (PAH) ratios were used to determine sources and fates of organic contaminants in highly contaminated, and less contaminated sediments of Hamilton Harbour. The highly contaminated sediments had an order of magnitude more total petroleum hydrocarbons (TPHs) compared to the less contaminated sediments. The TPHs extracted from both sites were depleted in 14C (average Δ14C of -775{\textperthousand} and -973{\textperthousand}, for Sites 1 and 2, respectively) consistent with inputs of fossil derived contaminants. Fossil carbon also contributed to the unextractable residue (Δ14C = -503 {\textpm} 55{\textperthousand}) in the sediment at the highly contaminated site relative to the less contaminated site (Δ14C = -132 {\textpm} 2{\textperthousand}) indicating inputs of fossil carbon not derived from petroleum or PAHs. Diagnostic PAH ratios (e.g. PAH:NaP between 0.01 and 1), and less negative δ13C (-25.6 {\textpm} 0.2{\textperthousand}) of the unextractable residue indicated that a coal derived source was the most likely source of these inputs. Despite the presence of this fossil carbon, there was little evidence of utilization of ancient carbon by the microbial community. The Δ14C of PLFAs from the highly contaminated site were slightly more 14C depleted (Δ14C = -138 {\textpm} 20{\textperthousand}) relative to the PLFAs from the less contaminated site (Δ14C = -77 {\textpm} 42{\textperthousand}), demonstrating some microbial metabolism of older carbon; however, the majority of the carbon metabolized was modern at both sites, indicating that there was minimal natural attenuation via bioremediation of fossil fuel organic contaminants.},
	issn = {0146-6380},
	doi = {10.1016/j.orggeochem.2014.01.017},
	url = {http://www.sciencedirect.com/science/article/pii/S0146638014000308},
	author = {Morrill, Penny L. and Szponar, Natalie and Johnston, Mathew and Marvin, Chris and Slater, Gregory F.}
}
@article {398,
	title = {Determination of Microbial Carbon Sources and Cycling during Remediation of Petroleum Hydrocarbon Impacted Soil Using Natural Abundance (14)C Analysis of PLFA},
	journal = {Environmental science \& technology},
	volume = {44},
	year = {2010},
	note = {id: 2054; PT: J; UT: WOS:000275993700017},
	pages = {2322-2327},
	abstract = {In a petroleum impacted land-farm soil in Sarnia, Ontario, compound-specific natural abundance radiocarbon analysis identified biodegradation by the soil microbial community as a major pathway for hydrocarbon removal in a novel remediation system. During remediation of contaminated soils by a plant growth promoting rhizobacteria enhanced phytoremediation system (PEPS), the measured Delta(14)C of phospholipid fatty acid (PLEA) biomarkers ranged from -793 parts per thousand to -897 parts per thousand, directly demonstrating microbial uptake and utilization of petroleum hydrocarbons (Delta(14)C(PHC) = -1000 parts per thousand). Isotopic mass balance indicated that more than 80\% of microbial PLEA carbon was derived from petroleum hydrocarbons (PHC) and a maximum of 20\% was obtained from metabolism of more modern carbon sources. These PLFA from the contaminated soils were the most (14)C-depleted biomarkers ever measured for an in situ environmental system, and this study demonstrated that the microbial community in this soil was subsisting primarily on petroleum hydrocarbons. In contrast, the microbial community in a nearby uncontaminated control soil maintained a more modern. Delta(14)C signature than total organic carbon (Delta(14)C(PLFA) = +36 parts per thousand to -147 parts per thousand, Delta(14)C(TOC) = -148 parts per thousand), indicating preferential consumption of the most modern plant-derived fraction of soil organic carbon. Measurements of delta(13)C and Delta(14)C of soil CO(2) additionally demonstrated that mineralization of PHC contributed to soil CO(2) at the contaminated site. The CO(2) in the uncontaminated control soil exhibited substantially more modern Delta(14)C values, and lower soil CO(2) concentrations than the contaminated soils, suggesting increased rates of soil respiration in the contaminated soils. In combination, these results demonstrated that biodegradation in the soil microbial community was a primary pathway of petroleum hydrocarbon removal in the PEPS system. This study highlights the power of natural abundance radiocarbon for determining microbial carbon sources and identifying biodegradation pathways in complex remediation systems.},
	issn = {0013-936X},
	doi = {10.1021/es9029717},
	author = {Cowie, Benjamin R. and Greenberg, Bruce M. and Slater, Gregory F.}
}
@article {489,
	title = {Microbial carbon cycling in oligotrophic regional aquifers near the Tono Uranium Mine, Japan as inferred from delta(13)C and Delta(14)C values of in situ phospholipid fatty acids and carbon sources},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {74},
	year = {2010},
	note = {id: 2057; PT: J; UT: WOS:000278510300008},
	pages = {3785-3805},
	abstract = {Microorganisms are ubiquitous in deep subsurface environments, but their role in the global carbon cycle is not well-understood. The natural abundance delta(13)C and Delta(14)C values of microbial membrane phospholipid fatty acids (PLFAs) were measured and used to assess the carbon sources of bacteria in sedimentary and granitic groundwaters sampled from three boreholes in the vicinity of the Tono Uranium Mine, Gifu, Japan. Sample storage experiments were performed and drill waters analyzed to characterize potential sources of microbial contamination. The most abundant PLFA structures in all waters sampled were 16:0,16:1 omega 7c, cy17:0, and 18:1 omega 7c. A PLFA biomarker for type 11 methanotrophs, 18:1 omega 8c, comprised 3\% and 18\% of total PLFAs in anoxic sedimentary and granitic waters, respectively, sampled from the KNA-6 borehole. The presence of this biomarker was unexpected given that type II methanotrophs are considered obligate aerobes. However, a bacterium that grows aerobically with CH(4) as the sole energy source and which also produces 56\% of its total PLFAs as 18:1 omega 8c was isolated from both waters, providing additional evidence for the presence of type II methanotrophs. The Delta(14)C values determined for type II methanotroph PLFAs in the sedimentary (-86 parts per thousand) and granite (-867 parts per thousand) waters were very similar to the Delta(14)C values of dissolved inorganic carbon (DIC) in each water (similar to-850 parts per thousand). This suggests that type II methanotrophs ultimately derive all their carbon from inorganic sources, whether directly from DIC and/or from CH4 produced by the reduction of DIC. In contrast, delta(13)C values of type II PLFAs in the sedimentary (-93 parts per thousand) and granite (-60 parts per thousand) waters indicate that these organisms use different carbon assimilation schemes in each environment despite very similar delta(13)C(CH4) values (-similar to 95 parts per thousand) for each water. The delta(13)C(PLFA) values (-28 parts per thousand to -45 parts per thousand) of non-methanotrophic bacteria in the KNA-6 LTL water do not clearly distinguish between heterotrophic and autotrophic metabolisms, but Delta(14)C(PLFA) values indicate that >65\% of total bacteria filtered from the KNA-6 LTL water are heterotrophs. Ancient Delta(14)C values (similar to-1000 parts per thousand) of some PLFAs suggest that many heterotrophs utilize ancient organic matter, perhaps from lignite seams within the sedimentary rocks. The more negative range of delta(13)C(PLFA) values determined for the KNA-6 granitic water (-42 parts per thousand to -66 parts per thousand) are likely the result of a microbial ecosystem dominated by chemolithoautotrophy, perhaps fuelled by abiogenic H(2). Results of sample storage experiments showed substantial shifts in microbial community composition and delta(13)C(PLFA) values (as much as 5 parts per thousand) during 2-4 days of dark, refrigerated, aseptic storage. However, water samples collected and immediately filtered back in the lab from freshly drilled MSB-2 borehole appeared to maintain the same relative relationships between delta(13)C(PLFA) values for sedimentary and granitic host rocks as observed for samples directly filtered under artesian flow from the KNA-6 borehole of the Tono Uranium Mine. (C) 2010 Elsevier Ltd. All rights reserved.},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2010.03.016},
	author = {Mills, Christopher T. and Amano, Yuki and Slater, Gregory F. and Dias, Robert F. and Iwatsuki, Teruki and Mandernack, Kevin W.}
}
@article {1919,
	title = {Intrinsic bacterial biodegradation of petroleum contamination demonstrated in situ using natural abundance, molecular-level 14C analysis},
	journal = {Organic Geochemistry},
	volume = {37},
	year = {2006},
	note = {id: 594},
	month = {2006},
	pages = {981-989},
	author = {Slater, Gregory F. and Nelson, Robert K. and Kile, Brian M. and Reddy, Christopher M.}
}
