Study On Heavy Metal(loid)s Pollution Characteristics And Environmental Criteria Of Agricultural Soil In Jiangsu And Zhejiang Provinces

With the rapid development of society and economy,the heavy metal（loid）s pollution of agricultural soil in China is becoming increasingly serious,posing a potential threat to the quality of agricultural products and human health.It is very important for soil pollution prevention and control to accurately and scientifically evaluate the characteristics of heavy metal（loid）s pollution in agricultural soil and to derive scientific soil environmental criteria based on regional characteristics and local parameters.In response to the above problems,this study selected the Yangtze River Delta as a typical study area,and selected agricultural soils in Jiangsu Province and Zhejiang Province as the study objects.Descriptive statistics,spatial interpolation,PMF model,CLEA model and other methods were used to analyze and compared the the content level,spatial distribution,and sources of heavy metal（loid）s in agricultural soils in Jiangsu and Zhejiang provinces.Based on the field investigation,the actual exposure scenarios in the two provinces were established.Based on the local exposure parameters,the soil environmental criteria for human health were derived.The main conclusions are as follows:（1）Both Jiangsu and Zhejiang had a certain degree of accumulation of heavy metal（loid）s in agricultural soils,and the degree of accumulation in Zhejiang might be greater than that in Jiangsu.The average content of heavy metal（loid）s in the two provinces did not exceed the risk screening value,only a few points exceeded the risk screening value;while the average content of heavy metal（loid）s in the two provinces was generally higher than their respective soil background values,the over standard rates were generally higher than 50%;compared with the results of Jiangsu and Zhejiang,the soil background values of Jiangsu were generally higher than that of Zhejiang.For Cd,Hg and Pb,although Jiangsu had higher background values,the average contents of Zhejiang were higher,indicating that Zhejiang had a higher degree of accumulation of Cd,Pb,and Hg.（2）The spatial distribution patterns of heavy metal（loid）s in agricultural soils in Jiangsu and Zhejiang were different,which was closely related to the industrial and agricultural development,industrial structure and regional differences in the two provinces.The spatial pattern of Jiangsu was as follows:Hg and Pb pollution were more serious in the economically developed areas of southern Jiangsu,Cd pollution was more serious in the agricultural developed areas of northern Jiangsu,As,Cr,Ni and Cu were mainly affected by the soil parent material,and the soil types in the regions with higher contents were mainly creep soil and organic soil.The spatial pattern of Zhejiang was:Pb and Zn pollution were serious in areas with dense Pb-Zn mines,Cd and Cu content were higher in areas with a high amount of organic fertilizer,and Hg pollution was more serious in areas with chemical fiber and pharmaceutical industries.As,Cr and Ni were mainly affected by the soil parent material,the soil types in the regions with higher content were mainly creep soil and organic soil.（3）Heavy metal（loid）s in agricultural soils in Jiangsu and Zhejiang were mainly derived from anthropogenic sources such as industrial and agricultural activities and traffic emissions.The contributions of anthropogenic sources accounted for 59.71%and 67.85%of the total amount of the two provinces,respectively.Moreover,the sources of soil heavy metal（loid）s were also different due to the differences of human activities in the two provinces.Among them,Pb and Zn mainly came from traffic emissions in Jiangsu,while in Zhejiang,they mainly came from mining and agricultural activities.The source of Hg in Jiangsu was coal,while the source of Hg in Zhejiang was industrial activities.For Cu,it was mainly derived from traffic emissions and soil parent material in Jiangsu,and mainly from agricultural activities in Zhejiang.（4）The criteria of Cd in Jiangsu province was 2.10 mg?kg^-1,the criteria of Cr（VI）was 27.8 mg?kg^-1,and the criteria of Cd in Zhejiang province was 2.32 mg?kg^-1,the criteria of Cr（VI）was 27.9 mg?kg^-1.The differences between Jiangsu and Zhejiang provinces were mainly reflected in the parameters,among which vegetable consumption rate and MDI might be the key parameters that affect the Cd criteria,while for Cr,the influence of parameters was not significant.The derived criteria of Cd and Cr（VI）were both higher than the risk screening values in GB15618-2018,indicating that GB15618-2018 might be conservative in protecting human health.Based on the experience of developed countries in Europe and America,farmers’exposure to soil should be regarded as occupational exposure.At present,the soil environmental quality standards for agricultural soil based on human health have not been established in China,and relevant researches should be carried out in light of the actual situation in China in the future.The results showed that although Jiangsu and Zhejiang were bordered,due to the large differences in the industrial and agricultural development level,industrial structure,agricultural land exposure scenario,and people’s living habits in the two provinces,the characteristics of agricultural soil heavy metal（loid）s pollution and soil environmental criteria also existed correspondingly differences.Therefore,to control soil pollution nationwide,regional control measures and soil environmental criteria are indispensable.The results of this study could provide important reference for soil environmental protection in the Yangtze River Delta,as well as other regions in China.