Inhibition of the biological self‐purification by chlorophenols, sodium dodecyl sulfate, and the complexing agents ethylenediaminetetraacetic acid and nitrilotriacetic acid

The determination of enzymatic activities in surface water allows the control of the biological selfpurification as well as being an indicator for microbial degradation of xenobiotics. As for this matter it is a good instrument for controlling alterations in the ecosystem. Inhibition of enzymatic activities (esterases, β-glucosidases, and alanin-aminopeptidases) were analyzed using linear dilution of the water under test, then correlating the resulting enzyme activities of each dilution step and the concentration of the sample. Because of the complex matrix of surface water, chemical analysis of inhibiting substances has been and still is very difficult. A characterization of these substances is therefore only possible by pretreatment of the samples. In order to simulate definite inhibition effects, surface water was spiked with 2-chlorophenol and 4-chlorophenol, as well as with the surfactant sodium dodecyl sulfate and the complex agents ethylenediaminetetraacetic acid and nitrilotriacetic acid. The simulated inhibition effects on the enzyme activities were characterized closely by an additional pretreatment of the water under test. The elimination of the inhibiting substances by adsorption on water-insoluble polyvinylpyrrolidone or activated carbon and the reduction of the inhibitory effect on the enzyme activities were investigated. The oxidation of inhibiting chemicals using stripping or treatment with H2O2 was also found to be a reliable method to diminish the inhibitory effects on the enzymatic activities. © 1994 by John Wiley & Sons, Inc..