ATRAZINE BIOTRANSFORMATION IN WETLAND SEDIMENT UNDER DIFFERENT NUTRIENT CONDITIONS .2. AEROBIC

We investigated the aerobic biotransformation of atrazine under three different nutrient conditions, i.e., wetland water, D.I. water, and basal salt media (BSM), using the wetland sediment receiving wastewater from a local sugar mill in Louisiana. None of the well-known metabolites and their hydroxy analogs were detected, nor prevailing hydroxyatrazine. The atrazine biotransformation rate was the highest in the sample reactors with indigenous wetland water having some of necessary nutrients for the sediment microorganisms. The concentration of atrazine dropped from 10 mg/L to less than 10 mu g/L within three weeks of incubation at room temperature once the sediment microorganisms were adjusted to new environments. Contrary to our expectation, BSM significantly hindered the aerobic biotransformation rate, removing only 25 % of atrazine during 18 weeks of incubation. The high level of nitrogen source in the BSM was suspected for the cause of the inhibition.