DEGRADATION KINETICS OF ORGANOPHOSPHORUS AND ORGANONITROGEN PESTICIDES IN DIFFERENT WATERS UNDER VARIOUS ENVIRONMENTAL-CONDITIONS

The evolution of a mixture containing 19 organophosphorus (OF) and org anonitrogen (ON) pesticides at ppb level was studied over a g-month pe riod in different water types (ultrapure water, natural seawater, rive r water, filtered Fiver water) and under various conditions. The degra dation kinetics were monitored in closed bottles in darkness at two te mperatures (T = 6 and 22 degrees C) and in a system exposed to natural sunlight (variable temperature). The mixture was analyzed by gas chro matography coupled with a nitrogen phosphorus detector (GC/NPD). Energ y activation (E(a)) and half-lifetimes (t(1/2)) were determined. Very different degradation behavior with respect to physicochemical conditi ons and molecular structures of the pesticides was observed. These exp eriments confirm that half-lives of OP pesticides can be more than sev eral months and consequently lead to lasting environmental pollution.