ABSTRACT
Diquat is released to the environment during its use as a herbicide, seed desiccant, and aquatic weed control agent. Diquat is rapidly adsorbed by clay constituents of soil and in the sorbed state is resistant to biodegradation and photodegradation. Diquat is intentionally applied to water to control aquatic weeds. Diquat disappeared from two experimental ponds within 14 and 30 days and was more persistent in the pond that had a lower average temperature of 18 °C. Diquat is listed as being a chemical which is unlikely to be removed during biological sewage treatment, even after prolonged exposure of the microorganisms. Diquat is stable in neutral or acid solutions; however, it hydrolyzes in the presence of alkaline materials including alkaline waters. Diquat dissolves and dissociates in aqueous solution to form cations. They are highly soluble and behave as strong electrolytes even under acid conditions.
