ABSTRACT
This chapter demonstrates that the imidazolinones can be rapidly degraded in aquatic systems, primarily through photolysis. The regioisomers of imazamethabenz-methyl are also hydrolyzed rapidly under basic conditions. The potential routes of entry of the imidazolinones, like those of other crop protection chemicals, into surface water bodies will be through spray drift or run-off. Volatilization of the imidazolinones from water bodies is not expected because of their high water solubilities and low vapor pressures, and thus their low Henry's law constants. Four possible environmental degradation processes — hydrolysis, photolysis, and aerobic and anaerobic biodegradation — are described. Hydrolysis of the acid imidazolinones is extremely slow at environmentally relevant pH and temperatures. In sharp contrast to the slow hydrolytic degradation of the imidazolinones, the compounds are rapidly degraded in water by light. Imazapyr and imazethapyr were stable under aerobic and anaerobic aquatic conditions.
