@article {2879,
	title = {Biosignatures Associated with Freshwater Microbialites},
	journal = {Life},
	volume = {10},
	year = {2020},
	month = {Jan-05-2020},
	pages = {66},
	abstract = {Freshwater microbialites (i.e., lithifying microbial mats) are quite rare in northern latitudes of the North American continent, with two lakes (Pavilion and Kelly Lakes) of southeastern BC containing a morphological variety of such structures. We investigated Kelly Lake microbialites using carbon isotope systematics, phospholipid fatty acids (PLFAs) and quantitative PCR to obtain biosignatures associated with microbial metabolism. δ13CDIC values (mean δ13CDIC -4.9 {\textpm} 1.1‱, n = 8) were not in isotopic equilibrium with the atmosphere; however, they do indicate 13C-depleted inorganic carbon into Kelly Lake. The values of carbonates on microbialite surfaces (δ13C) fell within the range predicted for equilibrium precipitation from ambient lake water δ13CDIC (-2.2 to -5.3‱). Deep microbialites (26 m) had an enriched δ13Ccarb value of -0.3 {\textpm} 0.5‱, which is a signature of photoautotrophy. The deeper microbialites (>20 m) had higher biomass estimates (via PLFAs), and a greater relative abundance of cyanobacteria (measured by 16S copies via qPCR). The majority of PLFAs constituted monounsaturated and saturated PLFAs, which is consistent with gram-negative bacteria, including cyanobacteria. The central PLFA δ13C values were highly depleted (-9.3 to -15.7‱) relative to δ13C values of bulk organic matter, suggesting a predominance of photoautotrophy. A heterotrophic signature was also detected via the depleted iso- and anteiso-15:0 lipids (-3.2 to -5.2‱). Based on our carbonate isotopic biosignatures, PLFA, and qPCR measurements, photoautotrophy is enriched in the microbialites of Kelly Lake. This photoautotrophy enrichment is consistent with the microbialites of neighboring Pavilion Lake. This indication of photoautotrophy within Kelly Lake at its deepest depths raises new insights into the limits of measurable carbonate isotopic biosignatures under light and nutrient limitations. },
	keywords = {Biosignatures, Kelly Lake, microbialites, Pavilion Lake},
	doi = {10.3390/life10050066},
	url = {https://pubmed.ncbi.nlm.nih.gov/32429118/},
	author = {White, Richard Allen and Soles, Sarah A. and Brady, Allyson L. and Southam, Gordon and Lim, Darlene S.S. and Slater, Greg F.}
}
@article {91,
	title = {Assessing microbial carbon sources and potential PAH degradation using natural abundance 14C analysis},
	journal = {Environmental Pollution},
	volume = {175},
	year = {2013},
	note = {id: 2268},
	pages = {125-130},
	abstract = {Natural abundance 14C analysis was applied to PLFAs collected from an industrial site in southern Ontario in order to assess microbial carbon sources and potential PAH biodegradation in soils. Δ14C of microbial phospholipid fatty acids (PLFA) at the site ranged from +54{\textperthousand} to -697{\textperthousand}. Comparison of these values to surrounding carbon sources found that microbial carbon sources were derived primarily from vegetation and/or natural organic matter present in the soils rather than PAHs. This study highlights that microbes are able to utilize almost all available pools of organic matter including older pools which are thought to contain recalcitrant compounds. Furthermore, it shows that even with the presence of an active microbial community, there may be little biodegradation of PAHs. This study illustrates challenges in assessing microbial activity in the environment and the advantage of using natural abundance 14C analysis as a tool to elucidate microbial carbon sources.},
	issn = {0269-7491},
	doi = {10.1016/j.envpol.2012.12.020},
	url = {http://www.sciencedirect.com/science/article/pii/S0269749112005453},
	author = {Mahmoudi, Nagissa and Fulthorpe, Roberta R. and Burns, Leanne and Mancini, Silvia and Slater, Greg F.}
}
@article {228,
	title = {Sources of n-alkanes in an urbanized estuary: Insights from molecular distributions and compound-specific stable and radiocarbon isotopes},
	journal = {Marine Chemistry},
	volume = {126},
	year = {2011},
	note = {id: 2169},
	pages = {239-249},
	abstract = {Diagnostic molecular ratios and compound-specific 13C and 14C analyses were used to identify n-alkane sources in surface sediments collected along a transect from an urbanized estuary draining a peat-rich catchment (Tyne, UK). The most abundant homologues were generally C29 or C31, and the carbon preference index (CPI; 1.8 to 6.4) and average chain length (ACL; 28.5 to 29.5) of C25{\textendash}C33 n-alkanes became progressively lower in samples closer to the mouth of estuary. δ13C signatures of C19{\textendash}C31 n-alkanes ranged from - 37.1 to - 29.3{\textperthousand} and in general became more depleted with increasing carbon number. Δ14C values for C21 (- 945 to - 738{\textperthousand}) were significantly more depleted compared to C29 (- 591 to - 65{\textperthousand}) and C31 (- 382 to - 96{\textperthousand}), pointing to a much higher component of fossil (i.e., 14C-free) carbon in the shorter homologue. The radiocarbon contents for these three n-alkanes decreased toward the North Sea, which in conjunction with an up to 4{\textperthousand} seaward 13C-enrichment in C29 and C31 and seaward decreases in CPI and ACL pointed to petrogenic hydrocarbon contamination in lower estuarine sediments. Independent 13C and 14C mass balances used to calculate the relative proportions of modern (i.e., plant wax) and fossil (i.e., petrogenic) n-alkanes yielded similar results and demonstrated that mixing with marine-derived organic matter (OM) or microbial degradation during estuarine transport led to a seaward decline in modern, longer-chain homologues, resulting in an increasingly larger fossil carbon contribution toward the mouth of estuary. The ability to clearly distinguish anthropogenic from natural inputs suggests that compound-specific radiocarbon analysis can successfully delineate the age of terrigenous OM delivered to the coastal zone even near historically polluted systems such as the Tyne.},
	issn = {0304-4203},
	doi = {10.1016/j.marchem.2011.06.002},
	author = {Ahad, Jason M. E. and Ganeshram, Raja S. and Bryant, Charlotte L. and Cisneros-Dozal, Luz M. and Ascough, Philippa L. and Fallick, Anthony E. and Slater, Greg F.}
}
@article { ISI:000279304700045,
	title = {Assessing Microbial Uptake of Petroleum Hydrocarbons in Groundwater Systems Using Natural Abundance Radiocarbon},
	journal = {ENVIRONMENTAL SCIENCE \& TECHNOLOGY},
	volume = {44},
	number = {{13}},
	year = {2010},
	month = {JUL 1},
	pages = {5092-5097},
	type = {Article},
	abstract = {Carbon sources utilized by the active microbial communities in shallow groundwater systems underlying three petroleum service stations were characterized using natural abundance radiocarbon ((14)C). Total organic carbon (TOC) Delta(14)C values ranged from -314 to -972 parts per thousand and petroleum-extracted residues (EXT-RES) ranged from -293 to -971 parts per thousand. Phospholipid fatty acids (PLFAs)-biomarkers for active microbial populations-ranged from -405 to -885 parts per thousand and a comparison of these values with potential carbon sources pointed to significant microbial assimilation of (14)C-free fossil carbon. The most (14)C depleted PLFAs were found in the samples with the highest concentrations of total petroleum hydrocarbons (TPHs). A radiocarbon mass balance indicated up to 43\% of the carbon in microbial PLFAs was derived from TPHs, providing direct evidence for biodegradation at two of three sites. At lower levels of TPHs. Delta(14)C values of PLFAs were generally similar to or more enriched than all other carbon in the system indicating microbial utilization of a more (14)C-enriched carbon source and no resolvable evidence for microbial incorporation of petroleum-derived carbon. Results from this study suggest that it is possible to delineate petroleum biodegradation in groundwater systems using these techniques even in complex situations where there exists a wide range in the ages of natural organic matter (i.e., EXT-RES).},
	issn = {0013-936X},
	doi = {10.1021/es100080c},
	author = {Ahad, Jason M. E. and Burns, Leanne and Mancini, Silvia and Slater, Greg F.}
}
@article {1921,
	title = {14C methane and DIC in the deep terrestrial subsurface: implications for microbial methanogenesis},
	journal = {Geomicrobiology Journal},
	volume = {23},
	year = {2006},
	note = {id: 1100},
	month = {2006},
	pages = {453-462},
	author = {Slater, Greg F. and Lippmann-Pipke, Johanna and Moser, Duane P. and Reddy, Christopher M. and Onstott, T. C. and Lacrampe-Couloume, Georges and Lollar, Barbara Sherwood}
}
