Spatial Distribution Of HCHs In Surface Soil Based On Different Factors

HCHs is a typical persistent pollutant with high toxicity,long duration in the environment and the ability to migrate over a long distance.HCHs has a long history of application in the Yellow irrigated area of Inner Mongolia.In this study,the typical area of the Yellow irrigation area,the area of the Jie Fang Zha irrigation,was selected as the study area.The surface soil of the 50 sampling points in the irrigation area was detected.The residual condition,spatial distribution,source and risk of the HCHs in the soil were analyzed.The main conclusions of the study are as follows:1.The detection rate of HCHs is 96%,the concentration range is ND²3.04 ng·g^-1,the average value is 4.38 ng·g^-1,and the proportion of?-HCH residues in soil is less than that of the?-HCH.The spatial variability of HCHs in the topsoil of the irrigation area is strongly variable.The residual concentration of HCHs in soil is far less than the first grade standard value of HCHs in soil environmental quality standard.Irrigated soil in HCHs in the northeast and southwest of the town of unity of Chagan Aobao,Xiang Shuang Miao Zhen residues was the highest,and the residual concentration by the two direction to the central region showed a decreasing trend.?-HCH and?-HCH play a decisive role in the spatial distribution of total HCHs.2.On the influence factors of spatial distribution,the soil clay particles are positively correlated with the residual amount of HCHs.The residual concentration of HCHs in silty loam is higher than that in sandy loam soil.The residual concentration of HCHs is higher in the soil with relatively uniform particle gradation and poor grain gradation continuity.The residual concentration of HCHs increased with the increase of soil organic matter content,but there was no significant spatial correlation.There was no significant spatial correlation between HCHs concentration and pH distribution.Soil salinity has a certain effect on the spatial distribution of HCHs.HCHs had little effect on the distribution of land use types of irrigation,has certain influence on the distribution of different irrigation methods on HCHs,HCHs in the Yellow irrigation farmland is higher than the residual concentration of farmland irrigation.3.There may be new Lin Dan inputs in the area,and there may be a small amount of Lin Dan in the irrigation area.According to the results of principal component analysis,?-HCH and?-HCH are derived from the use of industrial grade HCHs and Lin Dan;?-HCH is derived from the isomerization of soil microbes,transforming the other isomers to?-HCH;?-HCH comes from human irrigation activities,and?-HCH comes from irrigation water.The most serious pollution point is located in the northeast of the sluice irrigation area,which may be the main source of HCHs pollution.4.No ecological risk of HCHs residue in the surface soil of irrigation area.The risk of inhalation and carcinogenesis,the risk of skin contact carcinogenesis,and the risk of oral carcinogenesis are all less than the lower limit of acceptable carcinogenic risk of HCHs(10^-6).The residue of HCHs in irrigation area does not pose a threat to human health.