Alcohol fraction, distribution sediments

Unlike the SMB, where a 6 C fatty acid anomaly was noted, the fatty acid fraction in the Antarctic sediments exhibits a value comparable to other fractions, but lower than the bulk extracted sediment and within the range of Cje and Cjg fatty acids characteristic of marine origin (UcHiDA et al., 2001). This conclusion is also consistent with the carbon number distribution of alkanes, alkenes, fatty acids, alcohols and sterols which reflects the predominance of marine-derived carbon with little recognizable higher plant debris in the sediment. Similar molecular distribution of the lipid classes has previously been reported in sediments from the same general locations in the McMurdo Sound (Venkatesan, 1988). 

Experimental and mathematical modeling studies were performed to evaluate the potential benefits and limitations associated with the use of nonionic surfactants to enhance the microbial transformation of hexachlorobenzene (HCB) by a dechlorinating mixed culture enriched from a contaminated sediment. In general. Tween series surfactants were shown to have little impact on methanogenesis, whereas, polyoxyethylene (POE) alcohols, Triton X-100 and SDS were found to strongly inhibit methanogenesis and HCB dechlorination. Subsequent experiments conducted with Tween 80 illustrated the ability of this surfactant to enhance the solubility of HCB and to reduce the HCB-soil distribution coefficient. Model simulations demonstrated, however, that the aqueous phase mass fraction of HCB was substantially reduced in micellar solutions, which corresponded with observed reductions in HCB dechlorination. These results indicate that the impacts of surfactants on both biological activity and contaminant phase distributions should be evaluated in order to accurately assess the potential for biotransformation of hydrophobic contaminants in the presence of surfactants. 

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