Effects of Ozone Treatment on the Degradation and Toxicity of Several Pesticides in Different Groups

The effects of ozone treatment on the degradation and toxicity of nine pesticides were determined with different chromatographic techniques, using bubbled ozone and distilled water and two different buffer solutions as test media. The toxicity experiments were performed using Daphnia magna, a cladoceran fresh water flea. The results revealed that thiacloprid and acetamiprid can only be degraded by ozonation to a limited extent (max 2.6%). The other seven pesticides were successfully degraded by ozone. The degradation rates (%) were found to be 93, 99, 95, 99, 87, 98, and 85 for fenazaquin, lambda cyhalothrin, azoxystrobin, chlorpyrifos, spiromesifen, clothianidin and thiamethoxam, respectively, after 5 minutes of ozone treatment in distilled water. The ozone treatment yielded reduced toxicity in fenazaquin, lambda cyhalothrin, azoxystrobin, chlorpyrifos and spiromesifen. However, the degradation products of clothianidin and thiamethoxam were found to be more toxic than the pesticide itself. In general, the use of buffer solutions has no significant effect on pesticide degradation compared to water as an ozonation medium.