STREAM PERIPHYTIC BIODEGRADATION OF THE ANIONIC SURFACTANT C-12-ALKYLSULFATE AT ENVIRONMENTALLY RELEVANT CONCENTRATIONS

The effects of continuous exposure to C-12-alkyl sulfate on a periphyt ic microbial community were determined in an 8-week stream mesocosm st udy, C-12-alkyl sulfate concentrations ranged from environmentally rel evant (<10-20 mu g/liter) to unrealistically high concentrations (>150 0 mu g/liter). Endpoints evaluated included turnover rates, bacterial cell density, heterotrophic mixed amino acid uptake, and fatty acid pr ofile evaluations, Predosed periphyton demonstrated a mean turnover ra te 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 corr elation between turnover rate and C-12-alkyl sulfate concentration was also observed, While bacterial cell density increased during the stud y, it was determined that the biodegradation acclimation to C-12-alkyl sulfate was not biomass-specific, Likewise, bacterial activity genera lly increased over the study, but it did not correlate with either bio degradation 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 dem onstrates that C-12-alkyl sulfate is rapidly degraded and induces a bi odegradative acclimation response at environmentally relevant concentr ations. (C) 1997 Academic Press.