A METHOD TO ASSESS THE TOXICITY OF POLLUTANTS ON ANAEROBIC MICROBIAL-DEGRADATION ACTIVITY IN SEDIMENTS

A method to assess the impact of toxicants on the actual anaerobic mic robial degradation activity in sediments is described. Under condition s closely related to in situ, the influence of isoproturon and three o f its known metabolites on the actual carbon dioxide release rate and the actual methane production rate was determined. For isoproturon onl y a slight inhibition (<10%) of the methane production rate was observ ed at concentrations up to 6.25 mg/L. All tested metabolites of isopro turon significantly inhibited the methane production rate (up to 70%) at concentrations of 50-500 mug/L. Complete inhibition of methanogenes is did not affect the anaerobic mineralization rate measured as carbon dioxide release in the investigated sediment. Neither isoproturon nor the tested metabolites affected the carbon dioxide release rate. (C) 1994 by John Wiley & Sons, Inc.