The Residule Of Organochlorine Pesticides In Paddy Soil And The Bacteria Fitration For Chlorpyrifos Degradating

The residule and pollutant were attended by the whole world and the pesticides are yielded and used much in China.For this cause,the study of the residule and degradation of pesticides were significative.According to the situation of organochlorinated pesticides (OCPs) use and pollution in China,DDT and HCH which are typical Pesistent Organic Pollution that have been used as pesticides in China for long period and that have caused extensive pollution were selected as representative,and several other pesticides which are being targeted for global control were also selected as study object.According to US EPA method,A GC/MS/MS method was exploited to detected 20 kinds of OCPs.A series of matrix-spiked experiments that presented recoveries and MDL meet the request of pesticide residue detection of our country. 20 kinds organochlorine pesticdes in arable soils of seven regions of Hunan Province were analysed and the residues and distribution characteristic were studied. The results showed that the main residues of organochlorine pesticides in the paddy soil were HCHs and DDTs, the rang of HCHs content in the detected paddy soil was 1.7～25.3μg/kg with average content of 18.2μg/kg,and the rang of DDTs content in the detected paddy soil was 10.5～40.4μg/kg with average content of 23.8μg/kg.Theβ-HCH,DDT and DDE had comparative higher concentration and with average content of 12.9μg/kg, 11.4μg/kg and 9.8μg/kg, repectively. The other 13 kinds of organochlorine pesticides was also found with different content in the sample.The organochlorine pesticides contents in the paddy soil were lower than the limitation of national standard(HJ332-2006). Compared with the world's other region, these residual content were in medium level. Risk assessment indicated that the paddy soil in Hunan province posed a bit high risk to consumers of soil feeders.Chlorpyrifos was a organopHospHate pesticide which was developed by Dow Chemical Co.in US in 1965. Chlorpyrifos is a typical POPs and its potential hazards to people can't be ignorded. A bacterial strain designated as CH3 capable of degrading chlorpyrifos was isolated from sludges,and was identified as Hafnia sp. based on its biochemical-pHysiological characters. The strain of Hafunia sp. can grow with chlorpyrifos as its sole carbon source and degrade it at a rate of 78.5% within 6 days in the conditions of 30℃,pH7.0 and 200mg/L of the chlorpyrifos initial concentration.The optimal growth temperature, pH and concentration of chlorpyrifos for this strain of Hafunia sp. were 37℃,7.0 and 200mg/L repectively.Several carbon and nitrogen sources could be used by this strain and the optimal carbon sources were saccharose and grape sugar. Relatively, the choice to nitrogen sources of The strain of Hafunia sp. was feeblish and it could grow hearty in either inorganic or organic nitrogen sources.