Modeling And Risk Assessment Of Heavy Metal Transfer In Soil-rice System In Main Producing Areas Of Heilongjiang

After entering the soil,heavy metals will accumulate in the soil for a long time and cannot be degraded,and will be indirectly or directly transferred to crops through material conversion and energy cycling,endangering the growth of crops,and even enter the human body through the food chain.Over time,the content of heavy metals in the human body exceeds a certain concentration,which will cause damage to human functions and even cause cancer.The problem of heavy metal pollution in crops has become the most concerned issue at present,and it is also a focus of extensive research in recent years.In order to clarify the background data of heavy metals in the rice of Heilongjiang high-quality rice producing area,the soil and rice samples were collected from five major rice producing areas in Heilongjiang Province,including Chahayang,Wuchang,fangzheng,Xiangshui and Jiansanjiang to determine four heavy metal elements,As,Cr,and Cd,Pb,and the transfer of heavy metals from soil to rice was preliminarily modeled.,Finally,the risk assessment of heavy metal elements in polished rice was carried out.The findings are as follows:1.Among the 229 samples tested,the average values of Cr,As,Cd,and Pb in the soil were78.126 mg / kg,248.504 mg / kg,0.122 mg / kg and 24.287 mg / kg,respectively,and the other elements except arsenic did not exceed the standard.The average values of Cr,As,Cdand Pb in brown rice and polished rice were 0.122,0.203,0.007,0.023 mg / kg and 0.107,0.114,0.004and0.008 mg / kg,respectively.Among them,Cr element in brown rice in Xiangshui area exceeds the standard,and the exceeding standard rate is 8.1%.2.The R2 values of the fitting model in this experiment are between 0.325 and 0.433.The content of Cr,As and Cd in milled rice have a significant positive correlation with the content of corresponding elements in soil,and the Pb is negatively correlated with the pH value soil,Among them,The content of Cr is highly correlated with the content of Cr in soil..The content of Cr,As and Cd in soil can be well predicted,while the content of Pb is related to the pH of soil.Na,Cu,Al and Fe,the common nutrient elements in the soil,will greatly affect the absorption of C,Cd and Pb elements in milled rice,and their contents seriously affect the fitting degree of the model,which is also one of the important factors affecting the modeling of the soil-rice system model under the field conditions.3.There is no risk for exposure to arsenic and lead in adults and children in the study area;37.9% of adults and 0.6% of adults have exposure to chromium and cadmium,and children are not at risk for exposure to Cr and Cd.Among them,the exposure risk of Cr is the highest.In this paper,the contents of As,Cr,Cd and Pb in rice in the main producing areas of HeilongjiangProvince were studied.A preliminary simple linear model was established for the transfer of heavy metals in the soil-rice system.The risk assessment of heavy metal exposurein the way of local residents eating rice was conducted,and the research results provided theoretical guidance and decision-making basis for the food security and environmental protectionof Heilongjiang Province.