Measurement of aquatic biodegradation rates by determining heterotrophic uptake of radiolabeled pollutants.

The heterotrophic uptake technique was modified to provide a rapid and simple technique for estimating the rates of biodegradation of organic pollutants under environmental conditions. The methodology is based on an evaluation of uptake into cells and subsequent respiration of radiolabeled organic substrates in short-term experiments. The resulting data can be used to calculate either turnover times or, if multiple concentrations of substrate are used, kinetic parameters. The procedure was applied to assess the biodegradation rates of m-cresol, chlorobenzene, nitrilotriacetic acid, and 1,2,4-trichlorobenzene in fresh, brackish, and marine water samples from the coastal areas of North Carolina. Saturation kinetics for uptake were obtained with each of the compounds tested. Rates of metabolism were shown to be dependent on sample location and time of year.