Stream periphytic biodegradation of the anionic surfactant C-12-alkyl sulfate at environmentally relevant concentrations

The effects of continuous exposure to C-12-alkyl sulfate on a periphytic microbial community were determined in an 8-week stream mesocosm study, C-12-alkyl sulfate concentrations ranged from environmentally relevant (<10-20 mu g/liter) to unrealistically high concentrations (>1500 mu g/liter). Endpoints evaluated included turnover rates, bacterial cell density, heterotrophic mixed amino acid uptake, and fatty acid profile evaluations, Predosed periphyton demonstrated a mean turnover rate for C-12-alkyl sulfate of 0.08/hr, During the 8-week dosing period, a significant increase in mean turnover rates was observed in streams dosed with greater than or equal to 61 mu g C-12-alkyl sulfate/liter, despite a 10 degrees C drop in stream temperature, A significant correlation between turnover rate and C-12-alkyl sulfate concentration was also observed, While bacterial cell density increased during the study, it was determined that the biodegradation acclimation to C-12-alkyl sulfate was not biomass-specific, Likewise, bacterial activity generally increased over the study, but it did not correlate with either biodegradation or bacterial cell density, Lastly, phospholipid fatty acid profiles indicate that a shift in the microbial community occurred in the high-dose stream as opposed to the control stream, This study demonstrates that C-12-alkyl sulfate is rapidly degraded and induces a biodegradative acclimation response at environmentally relevant concentrations. (C) 1997 Academic Press.