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 microbial degradation activity in sediments is described. Under conditions closely related to in situ, the influence of isoproturon and three of its known metabolites on the actual carbon dioxide release rate and the actual methane production rate was determined. For isoproturon only a slight inhibition ( < 10%) of the methane production rate was observed at concentrations up to 6.25 mg/L. All tested metabolites of isoproturon significantly inhibited the methane production rate (up to 70%) at concentrations of 50–500 μg/L. Complete inhibition of methanogenesis 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.