| Soil heavy metal pollution and its farm produce safety is becoming the hotspot. As investigated, about one fifth of Chinese farmland was polluted by heavy metal and farm produce safety is facing serious danger. Since 1980s, environmental pollution in Jiangsu province was more and more severe during the fast economy development, which resulted in soil quality degradation, especially the accumulation and activation of heavy metal. The north part of Jiangsu province is an important production bace of farm produce, and it is programming to develop green industry of safe, fine farm produce. Therefore, it is very important to study the heavy metal pollution in soil and the transfer and enrichment of heavy metal in rice in the north region of Jiangsu province, to access people's health risk of Jiangsu province with their food configuration.We analyzed the contents of As,Cd,Cr,Cu,Hg,Ni,Pb,Zn and water dissolved form of Cd,Cu,Ni,Pb,Zn in 98 entries of agricultural soils and corresponding rice samples in 6 countries of north region of Jiangsu; estimated the extent of soil heavy metal pollution and the food safety level of rice, according to the production bace standards of green food, no-social effects of pollution food and to the background value of heavy metal of local regions in 1980s; further more, we also evaluated the potential exposure risk of rice for people in these regions on the basis of RrD value recommended by WHO and USEPA, and of the average consume structure of Chinese resident; synchronously, we seted up the mathematic model of soil basic physical and chemical properties, forecast of heavy metal pollution in soil and rice, with the norm of solid-liquid distribution coefficient of heavy metal in soil(Kd, equal to the ratio of water-soluble heavy metal to total heavy metal in soil), soil basic physical-chemical property(including soil acidity, pH, SOM) and the enrichment coefficient of heavy metal in rice(BCF, equal to the ratio of certain concentration of heavy metal in plant to that in soil). The main results were as follows:The environmental quality of soil heavy metal in these regions was not polluted distinctively, which accorded with the request of constructing green food production base in the mass. The content of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn was 9.08 mg kg-1, 0.26 mg·kg-1,63.05 mg·kg-1,21.28 mg·kg-1,0. 05 mg·kg-1,30.25 mg·kg-1,20.04 mg.kg-1 and 72.13 mg.kg-1 separately; but the Ni content of rice on HuangChaoTu was 0.68 mg.kg-1, the Ni and Pb content of rice on ShaJiangHeiTu was 0.81 mg·kg-1 and 1.08 mg·kg-1, separately, which went beyond the food sanitation and safety standard of the nation partly. The potential exposure risk of rice for people in these regions evaluated on the basis of RrD value recommended by USEPA and of the average consume structure of Chinese resident showed that: As(4352%), Cr(505%), Pb(362%) and Ni(134%) in all the rices growed on the tested soils and Cd(150%) in rice of ShaJiangHeiTu in Donghai country existed potential food exposure risk to different extent.The relationship between solid-liquid distribution coefficient of heavy metal in soil and soil pH showed low capacity of soil on sequestrating Cd. The decrease of soil pH could increase heavy metal distribution in soil liquid evidently and further promoted the absorption and accumulation of heavy metal in crop. So Cd in soil occurred biggish potential pollution rish on crop with the major premise of global soil acidification. The regression equation between the enrichment coefficient(BCF) of Cd, Cu, Ni, Pb, Zn and content of soil total metals, soil pH, SOM content was as follows: log10(BeF)=a+b.pH+c.log10(Total)+d.log10(SOM) (BCF means enrichment coefficient, Total is content of soil total metals, a-d means constant, SOM means percentage of soil organic carbon). It was possible to forecast the heavy metal pollution in soil and rice by determining parameters upwards, thereby further speculate on the heavy metal trend of farm produce in food. |
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