Environmental chemistry for a surfactant ecotoxicology study supports rapid degradation of C12-alkyl sulfate in a continuous-flow stream Mesocosm

Abstract

Abstract Environmental chemistry is a vital part of ecotoxicology studies conducted in mesocosms. Quantification of exposure can be particularly challenging for biodegradable surfactants in once-through stream mesocosms like the Procter & Gamble Experimental Stream Facility (ESF). In the fall of 1991, a study was conducted with the anionic surfactant C12-alkyl sulfate (C12-AS). Analysis of chemical feed tank concentrates indicated that the in-stream concentrations should be very close to the nominal concentrations (26, 78, 233, 700, 2, 100 μg/L). However, measured concentrations were lower than expected. The concentrations at the head of the streams were 4 to 23% below nominal concentrations and there was an additional 14 to 33% decline in head to tail C12-AS concentrations. Total residence time in the streams is about 4.3 min. Because analytical losses had been minimized using individual sample recovery factors, it was concluded that these losses were due to rapid C12-AS biodegradation. The results of this analytical program are used to define the in-stream C12-AS concentrations to express subsequent community- and ecosystem-level no-observed-effect concentrations. In addition, the environmental chemistry program described will serve as the model for future programs in support of surfactant ecotoxicology studies conducted at the ESF.