Distribution Features And Risk Evaluation Of Organochlorine Pesticides In Facilities Agricultural Soil Of Shenyang

Organochlorine pesticides (OCPs), as typical persistent organic pollutants(pops),have the characteristics of high toxicity, persistence, mobility and bioaccumulation.There still has residual in the environment after30years prohibition. OCPs in the soilmay be a threat to human health through the food chain. Shenyang is the center of thenortheast and China’s major agricultural region. Now there has about665,000hm2cultivated land,70%of them were facilities agricultural land. Do research ondistribution features and risk evaluation of OCPs in facilities agricultural land ofShenyang area has practical significance.This study collected70topsoil samples in Shenyang facility agriculture area fromSeptember to November,2013. Determined the content of12OCPs residueconcentration, analyzed the statistical characteristics, spatial distribution and the causesof OCPs residues. The risk is also evaluated. The results are as follows:(1)The detection rate and concentration of12kinds OCPs are different. The totalOCPs concentration range from4.07to282.74ng/g,the mean value is65.31ng/g. HCHsand DDTs are main OCPs residues, detection rate are both over90%.Hexachlorobenzene has a high detection rate, but the concentration is low. Aldrin,dieldrin and endrin has lower detection concentration and detection rate. Shenyangsoutheast has the Maximum average concentrations of total OCPs, while Shenyangsouth and east keeps the minimum. Use geostatistical methods to draw the isoline mapof OCPs residues. Overall, Shenyang has a lower OCPs residues concentration, butdifferent kinds of OCPs have different spatial distribution.(2)As can be seen from the chart of frequency distribution of concentrationlogarithm, OCPs residues are affected by human activities in Shenyang suburb facilitiesagriculture area. According to the isomer ratio of HCHs and DDTs, the source of theOCPs can be found. The results show that HCHs mainly comes from lindane,industrialused HCH can also falling on soil becomes one of the source of HCHs in soil. Shenyangwest had no DDTs input in recent years, while the other3directions: Shenyang north,south and Shenyang southeast, had different degrees of DDTs input in recent years. (3)Ecological risk of HCHs is lower in the study area,46%of the sampling pointsDDTs has potential ecological risk for soil organisms and birdsand the ratio formammals is1%.Use RBCA model to evaluate soil health risk, the results showed thatthe OCPs comprehensive carcinogen risk value range from4.66×10-6to0.000279.Foursampling points has higher risk value over USEPA setting limits which is10-4.HCHs,DDTS and heptachlor are main contributes to comprehensive carcinogen risk.Oralintake risk is greater than skin contaction and breathing intake risk.