Cocontaminant Effects on Degradation of Triazine Herbicides by a Mixed Microbial Culture

Abstract

In most pesticide-contaminated agrichemical facilities, atrazine is found in combination with other widely used agricultural chemicals, and remediation strategies must account for the multiple-contaminant environment. The ability of an atrazine-mineralizing culture to degrade other s-triazines in liquid culture was evaluated. Cyanazine and simazine, added to liquid culture, either alone or combined with atrazine, were degraded in 6 days. Cyanazine was degraded to persistent metabolite(s), as yet unidentified. Metribuzin was not degraded. The culture completely degraded atrazine in the presence of cocontaminants including alachlor, metolachlor, and trifluralin. Atrazine degradation was not affected when cocontaminant herbicides were introduced singly. Mixtures of cocontaminants increased half-life values of atrazine plus hydroxyatrazine 2−3 times. Nitrate presence did not affect atrazine. These results suggest that our mixed culture could be successfully used to bioaugment s-triazine contaminated systems, in the presence of nitrate and commonly detected cocontaminant herbicides. Keywords: Biodegradation; atrazine; simazine; cyanazine; cocontaminants