Comparative biodegradation studies of pre-emergence broadleaf and grass herbicides in aqueous medium

The biodegradation of the herbicides hexazinone, metribuzin, metobromuron and propachlor was evaluated in liquid cultures of an adapted and a non-adapted mixed microbial culture obtained from a wastewater treatment plant. All herbicides were poorly degraded after 50 days (<50%). The adaptation of microbial culture prior to the biodegradation test shortened only the lag-time in degradation of hexazinone. The level of biodegradation correlated with the log Kow values of the molecules tested (R2=0.970). Metobromuron at 100 mg L-1 inhibited the metabolism of aniline by the mixed culture.