Enrichment And Health Risk Assessment Of Heavy Metals In Soil-mung Bean In Heilongjiang Province

Mung bean(Vigna radiata L.)is an important food of cash crop,and it is not only rich in nutrition,but also has medicinal effects,which is widely favored by people all over the world.It is widely cultivated in tropical and subtropical regions in the world.China is the main producer of mung bean,and has the most sown area and output in the world,in addition,Heilongjiang Province is one of the major producer in our country.To understand the contents of four important heavy metals in mung bean from the main producing areas in Heilongjiang Province.We collected three period samples of mung bean and related soild including branching,flowering and pod stages and maturation stage in four main producing areas in 2019.A total of 825samples(75 samples in each period)were collected.Then,7800 ICP-MS instrument was used to detect the contents of Pb,Cd,Cr and As,The distribution of heavy metals in soil,mung bean plants and seeds in three periods were analyzed.The linear regression model and SVM nonlinear regression model of soil-mung bean system were established.To evaluate the health risk of heavy metal content in mung bean seeds to residents.The basic distribution data of heavy metals in the soil and mung bean in the main producing areas of mung bean were obtained,which provided theoretical basis for government supervision and food safety guarantee.The results are as follows:(1)The contents of four heavy metals in the soil were As>Cr>Pb>Cd,As content is between screening value and control value of agricultural land soil risk.The contents of Cr,Pb and Cd were lower than the screening values of soil risk in agricultural land.(2)The heavy metals Cr,Pb and Cd were all enriched in the roots during the branching,while As was mainly enriched in the leaves.(3)For the same part,the comparison analysis of heavy metal content in different periods found that:In roots,stems and leaves,the content of Pb was higher at the maturity stage,the content of As was higher at the branching stage,and the content of Cr was higher at the maturity stage.However,the distribution of Cd was different from that of Cr,Pb and As.In roots,the content of Cd was higher at the flowering and pod stage,and in stems and leaves,the content of Cd was higher at the maturity stage.(4)Correlation analysis was conducted on the contents of four heavy metals in soil,root,stem,leaf and seed,respectively.The content of Cr and Pb was always significantly positively correlated.Correlation analysis of the contents of four heavy metals in seeds with soil p H and soil organic matter was carried out.The contents of Cr and Cd were negatively correlated with soil p H,while As and Pb were not significantly correlated with soil p H.There was a significant positive correlation between Cr content and soil organic matter,but no significant correlation between As,Cd,Pb and soil organic matter.(5)The stepwise linear regression model of a certain heavy metal in seeds and four heavy metals in soil and the SVM nonlinear regression model of a certain heavy metal in seeds and the same heavy metal in soil,root,stem and leaf were established,which could predict the heavy metal content in seeds by the heavy metal content in soil and plant.(6)Health risk assessment and exposure risk assessment of the four heavy metals As,Cr,Cd and Pb in mung bean seeds were carried out.The results showed that there was no health risk or exposure risk to adults and children in mung bean seeds from the main producing areas of Heilongjiang Province.