Alkenones are common in prairie lakes of interior Canada
► Alkenones are common in prairie lakes of interior Canada. ► High concentrations of C37 alkenones are associated with anoxic deep meromictic lakes. ► Alkenone unsaturation is marginally correlated with spring temperature. Long chain alkenone (LCA) lipids produced by haptophyte algae are ubiquitous...
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Veröffentlicht in: | Organic geochemistry 2011-08, Vol.42 (7), p.707-712 |
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Sprache: | eng |
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Zusammenfassung: | ► Alkenones are common in prairie lakes of interior Canada. ► High concentrations of C37 alkenones are associated with anoxic deep meromictic lakes. ► Alkenone unsaturation is marginally correlated with spring temperature.
Long chain alkenone (LCA) lipids produced by haptophyte algae are ubiquitous in marine environments and are increasingly reported from enhanced conductivity, solute rich lakes worldwide. Following our survey of lakes in the United States (Toney et al., 10.1016/j.gca.2009.11.021), we examined surface sediments from 19 lakes in central Canada for alkenones and compared our data with lake characteristics. We found that 68% of surveyed lakes contained sedimentary LCAs, all have C37:4me dominated profiles. Lakes containing LCAs had salinities >1.5g/l and SO4/CO3 ratios >3.5. LCA concentrations were highly elevated (∑C37>500μg/g sediment) in sediments of meromictic lakes with permanently anoxic deep waters. Overall, the distribution of LCAs was consistent with a previous survey of lakes in the interior of the United States demonstrating that tetra-unsaturated lipids were most common in sulfate rich, saline lakes. Alkenone unsaturation indices (U37K) from the upper 10cm of the sediment column are weakly correlated with point sampled average spring water temperature (r2=0.30, p=0.067) and the range of inferred temperatures is in agreement with the average, long term potential evapotranspiration weighted temperature. |
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ISSN: | 0146-6380 1873-5290 |
DOI: | 10.1016/j.orggeochem.2011.06.014 |