Stream Periphytic Biodegradation of the Anionic Surfactant C12-Alkyl Sulfate at Environmentally Relevant Concentrations☆

Abstract 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 ( 1500 μg/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 ≥61 μg C 12 -alkyl sulfate/liter, despite a 10°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.