Status Of DDTs And BHCs Residue And Effect On Soil Microfauna

Ecological effects of typical pesticidal Persistent Organic Pollutants(POPs) on representative soil microfauna in soil were explored. Laboratory test, simulated ecosystem, and eco-survey methods were combined to depict integrative effects of the pesticidal POPs on soil microfauna, including earthworm, protozoa. Experiments were conducted based on a series of dosage and exposure time, and then the dose-response relationship and time-response relationship were estimated. The effect on the structure and function of real soil ecosystem by the pesticides residues were also studied, and the sensitive indicators to the Organic Chlorinated Pesticides (OCPs) pollution were screened.According to the situation of OCPs use and pollution in China, DDT and Lindane which are typical Persistent Organic Pollution that have been used as pesticides in China for long period and that have caused extensive pollution were selected as representative, and Endosulfan and Dicofol which are not being targeted for global control were also selected as study object. The precautionary effect by the soil microfauna as the indicators for OCPs pollution were analyzed.During the ecosystem investigation, DDTs and BHCs residues in the soil of garden and orchard were determinated by the method which was set up on the base of GB/T14550-93. The result showed that, compared with the research result of 1990s', the content of residus had declined greatly, but still exist. And the soil in the study aera could not absolutely up to the State Grade-A standard.The four pesticides had different toxic effects on the survival, growth and reproduction of soil microfauna in both individual and community level. DDT and Lindane had great and lasting toxicity on earthworm, while Dicofol had least toxicity. The acute toxicity of Endosulfan was great, and could not be reduced in the subtle exposure period. The growth inhibition effect of the pesticides on earthworms in the subtle period was a better indicator for evaluating the toxicity of pesticides. And the toxicity integrating the acute and subtle exposure on the growth of earthworms was in the order of Endosulfan> Lindane>DDT> Dicofol.The experiments in the simulated soil ecosystem indicated that the richness of soil flagellate, amoebae, and infusorian can be identified as the sensitive indicators to the pollution of OCPs in soil. All the four OCPs pesticides significantly reduced the richness of soil microfauna.