Pollution And Environmental Risk Assessment Of Polychlorinated Biphenyls In Soils Of The Jiefangzha Irrigation Area

Jiefangzha irrigation area was an important producing area of grain and veget able,which was of great significance to human health and safety.Because the wa ter body of the Yellow River is polluted by some organic pollutants,the polluted water of the Yellow River enters the irigation area of Jiefangzha irrigation area,and then pollutes the soil.Eight PCBs homologues were detected by GC-GCD in 49 surface soil samples collected from Jiefang sluice irrigation area.The occurrenc e level and composition characteristics of PCBs in soil were analyzed.The spatial distribution and source of PCBs were revealed.The effects of different factors o n PCBs in soil were discussed and the environmental risk assessment was carined out.Main conclusions were as follows:1.The concentrations of total PCBs in surface soil ranged from ND to 209.95 ng·g-1,with an average value of 15.09 ng·g-1,and the PCBs concentration in t his study was in a comparatively low level.In addition,the proportion of PCBs monomer content was as follows:tri-polychlorinated biphenyls>mono-polychlorinate d biphenyls>tetra-polychlorinated biphenyls>di-polychlorinated biphenyls>penta-po lychlorinated biphenyls,indicating that the surface soil in the Jiefangzha irrigation a rea was mainly contaminated with low-chlorobiphenyl.2.There are some spatial differences in PCBs distribution in surface soil of Jiefang sluice irrigation area,which shows that the distribution of PCBs in Northeast is higher than that in southwest,and the distribution of PCBs in southwest is sporadic.The high value area was mainly distributed in the northeast of the irigation area,The low value area is mainly distributed in the middle.Factor analysis was used to analyze the concentration of PCBs monomers.Factor analysis was used to analyze the source of PCBs monomer concentration.The results showed that PCBs in soil mainly came from leakage of capacitor and transformer oil.3.The correlation between PCBs distribution and soil properties was analyzed by correlation analysis method.The results showed that there was a significant correlation between pH and PCBs concentration.There was no significant correlation between PCBs concentration and organic matter,EC value,sand,silt and clay.The PCBs concentration distribution in surface soil of Jiefangzhai irrigation area was significantly different among different land use types,mainly as follows:wasteland>woodland>cultivated land.Irrigation mode had little effect on PCBs concentration distribution,and PCBs concentration tended to be the same.The PCBs concentration distribution in different crop soils is different,which was vegetable crop soil>grain crop soil.4.The ecological risk assessment of PCBs in topsoil of Jiefang sluice irrigati on area was carried out by means of low-median effect method and toxicity equiv alent factor method.The results showed that PCBs in topsoil of Jiefang sluice irri gation area had lower toxicity effect on organism and lower ecological pollution.The cumulative carcinogenic and non-carcinogenic risk coefficients of adults and c hildren in the soils of Jiefang sluice irrigation area were lower than those prescrib ed by UE EPA,and the cumulative carcinogenic and non-carcinogenic risk coeffici ents were small or negligible.Direct oral intake of PCBs in soil was the main ro ute of non-carcinogenic and carcinogenic risk.