Determination of biodegradation rates for surfactants and a fatty alcohol in aerobic sediment using a simplified test system

The development of specific regulatory persistence criteria and a growing need to conduct risk assessments in sediment have increased the need to better understand fate in this compartment. A simplified test approach was developed to assess the fate of chemicals in aerobic sediments and used to evaluate the biodegradation of (14) C-labeled representative analogs of alcohol sulfate, alcohol ethoxylate, alcohol ethoxy sulfate, linear alkylbenzene sulfonate, and tetradecanol in 2 different sediments. The method provides kinetic data on primary and ultimate biodegradation in sediments as well as information on biodegradation pathways and metabolites. All test materials exhibited extensive biodegradation in both sediments; disappearance of parent exhibited biphasic kinetics, described by a 2-compartment model, and mineralization was coupled to parent disappearance with little accumulation of metabolites. The first-compartment decay rates ranged from 10.8 d(-1) to 17.1 d(-1) for tetradecanol, 2.54 d(-1) to 24.8 d(-1) for alcohol sulfate, 0.17 d(-1) to 0.75 d(-1) for alcohol ethoxylate, 0.41 d(-1) to 0.71 d(-1) for alcohol ethoxy sulfate, and 0.26 d(-1) to 1.25 d(-1) for linear alkylbenzene sulfonate. These rates corresponded to half-lives ranging from 0.041 d to 4.08 d. This method's simplicity and focus on only sediment-associated processes offer potential benefits over the current Organisation for Economic Co-operation and Development 308 aerobic sediment-water test. Environ Toxicol Chem 2016;35:2199-2208. © 2016 SETAC.