Degradation of isoproturon in biobeds

The fate of isoproturon (N,N-dimethyl-N '-[4-(1-methylethyl)phenyl]urea) in biobeds with and without inoculation with the white rot fungus Phanerochaete chrysosporium was studied. Total extractable isoproturon, its metabolites and formation of non-extractable residues were evaluated. Studies with C-14-isoproturon were also included. A strong decrease in isoproturon was observed in non-inoculated biobeds. Total extractable isoproturon decreased by 76% after 100 days. The decrease was even larger in biobeds inoculated with the white rot fungus P. chrysosporium. After 28 days, total extractable isoproturon decreased by 78%, and after 100 days > 99% had disappeared in the inoculated biobeds. However, the studies with C-14-isoproturon showed that 30% of the initially recovered C-14-isoproturon remained in the non-inoculated biobeds as non-extractable residues. As no studies with C-14-isoproturon were per formed in inoculated biobeds, it is unclear if the higher rate of disappearance was due to higher biodegradation or higher formation of bound residues.