Enhanced soil degradation of alachlor by treatment with ultraviolet light and ozone

Alachor is a herbicide that is widely used to control grasses and certain broadleaf weeds, and therefore, is a common component in agricultural wastewater. The rates and mechanisms of alachor degradation by UV irradiation and ozone treatment have been investigated, as well as the effects of these treatments on subsequent biodegradation in soil. Labeling studies have shown that irradiation of alachor results in dechlorination with retention of the aromatic ring to generate at least six intermediates. Ozonation does not promote dechlorination, but rather oxidizes the alkyl side chains and opens the aromatic ring. Both treatments facilitated biodegradation of the herbicide in soil.