Single And Combined Toxicity Of Pesticides On Earthworms

In this paper, the experiments of toxicity of pesticides on earthworm were done under laboratory conditions. Experiments showed that: (1) The single and combined toxicity of pesticides on earthworms were carried out by using the filter contact method. These pesticides include carbofuran, dimehypo, chlorpyrifos, methamidophos and atrazine. Carbofuran and dimehypo were selected as the target pesticides for further study after carefully analyzed. (2)The single and combined toxicity of pesticides, which include carbofuran,dimehypo and p'p-DDT, on earthworms were done in soil environment. (3) The residues of carbofuran and dimehypo in soil were detected by using the chromatographical analysis method, and some degradation mechanisms of pesticides in soil condition were obtain. Furthermore, some primary explains to the combined toxicity were made in experiments.By adopting filter paper contact method, the acute toxicology of pesticides on earthworm shows that different pesticides have different symptoms and dosage-response relationship on earthworm. And the acute toxicology of pesticides on earthworms increased according to the order of dimehypo, Methamidophos, chlorpyrifos, carbofuran and Atrazine under the condition of 10 centigrade and 72 hours, the LC₅₀(Lethal concentration for 50% of the test population) value of earthworm are 25.94μg/cm², 63.44μg/cm², 127.99μg/cm², 343.05μg/cm², and 737.69μg/cm² respectively. In addition, we find out that the morality of earthworms increased with the increasing temperature. When two pesticides were combined, the symptom and dosage-response relationship of earthworms demonstrate more complicated. The toxicity of pesticide on earthworms maybe affected by its chemical structure, function, toxicological mechanism, environmental behavior and other factors. After carefully studied, the pesticides of carbofuran and dimehypo were selected as the...