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 ba sal salt media (BSM), using the wetland sediment receiving wastewater from a local sugar mill in Louisiana. None of the well-known metabolit es and their hydroxy analogs were detected, nor prevailing hydroxyatra zine. The atrazine biotransformation rate was the highest in the sampl e reactors with indigenous wetland water having some of necessary nutr ients for the sediment microorganisms. The concentration of atrazine d ropped from 10 mg/L to less than 10 mu g/L within three weeks of incub ation at room temperature once the sediment microorganisms were adjust ed to new environments. Contrary to our expectation, BSM significantly hindered the aerobic biotransformation rate, removing only 25 % of at razine during 18 weeks of incubation. The high level of nitrogen sourc e in the BSM was suspected for the cause of the inhibition.