The Study On The Effects Of Simulated Acid Rain On The Degradation Of Chlorpyrifos

With China joins the World Trade Organization (WTO), peopleliving standard is improved constantly, it has been put more and moreattention on the food safety awareness regarding to the urban consumer.Therefore the quality and safety of agricultural products caught peoplemuch more attention. Particularly, the problem is the repellent remain.Chinese greengrocery is one of the most favorite vegetables by theChinese customers throughout years, and it can be grown in most parts ofChina. Greengrocery growing period is relatively long, and the leaves arestretch, which may cause the repellent can easily remain on thegreengrocery, and the residual is high. Therefore, the problem of pesticideresidue is quite common. The Chiorpyrifos, trading name as Lorsban, isdeveloped by the Dow Chemical Company in1965and it is a kind oforganophosphate pesticide used in pest control for grain, vegetables,fruits and cash crops worldwide. In2008January, with the cessation ofmethamidophos, parathion, methyl parathion, monocrotophos andphosphamidon, in total five kinds of highly toxic organophosphoruspesticide production, distribution and usage, Chiorpyrifos as analternative of the toxic organophosphorus pesticides has been widely usedin China. According to the Chinese governmental legislation, themaximum limit of the residual of Chiorpyrifos is1mgkg-1and the safetyinterval of7days. Severe acid rain pollution occurs in our countrycurrently, according to the monitoring statistics from2000to2010, andthe amount of cities that has acid rain pollution is more than50%. From2006to2010, the amount has heavy acid rain (pH <4.5) is more than8%.Previous studies have shown that acid rain pollution has a certainnegative impacts on crop seed germination, growth, yield and nutritionalquality. In consideration of the acidic conditions caused by acid rain mayreduce Chiorpyrifos amount to a certain extent, and result in the changeof the safety interval. However, there is no study on the impact of acidrain on the degradation of repellent, and therefore this study has a certainpractical meaning of acid rain on the residuals amount of the repellent of Chiorpyrifos in the greengrocery.In this study, the greengrocery were planted in the plasticgreenhouses, and the planting area was divided into5equal blocks. Whenthe greengrocery grows7to8leaf, the Chiorpyrifos was sprayed in thegrowing region, and thereafter simulated acid rain was sprayed atdifferent pH values. The residue of Chiorpyrifos was measured in0,1,3,7days in greengrocery and soil, afterwards analyzing of the impact ofsimulated acid rain on Chiorpyrifos residues in greengrocery, and finallythe goal of this research was reached.The results show that (1) the experimental results show that acid rainhas a certain amount of impacts on the degradation of Chiorpyrifos in thegreengrocery. In Chiorpyrifos degradation of the greengrocery, half-lifewas significantly longer than the using ultra-pure water spray. With thepH value of simulated acid rain getting lower, the Chiorpyrifosdegradation half-life in the greengrocery has increasing trend;(2) due tothe impact of simulated acid rain, spraying7days (safe interval) is muchlarger than the legislation prescribed1.0mg/kg, and therefore in regionswhere has serious acid rain pollution should have an appropriateextension of the safety interval is recommended.