Study On Inventory And Changes Of Input/output Balance Of Heavy Metals In Farmland In China And Heavy Metals Pollution Risk Assessment

Heavy metals(HMs)in foods are important monitoring items in Global Environmental Monitoring system/Food and Chinese food contamination monitoring project as its characteristics of strong toxicity,accumulation,long half-life.Concentrations and distribution of HMs in foods are directly affected by HMs content and distribution in soil,therefore,HMs in soils,especially in agricultural soil are of serious concern.It is reported that HMs are the most serious pollutants in agricultural soil in China,and human activities like mining and agriculture are main causes.However,research on contributions of different pollutant sources on HMs input to agricultural soil in the nationwide is unavailable.Additionally,methods of risk assessment of agricultural soil HMs pollution are always not well enough to resolve HMs pollution in agricultural soil.Considering these two problems listed above,this report mainly focus on two study contents.(1)Make a systematical assessment on contributions of different pollutants sources to HMs input to agricultural soil in China based on published references and national statistics data.(2)Establish a new risk assessment method to assess HMs pollutant in agricultural soil.Important results are obtained as follows:(1)Inputs of HMs to agricultural soil from different pollutant sources are estimated.In terms of total input,the quantities of these eight HMs are Zn>Cu>Pb>Cr>Ni>As>Cd>Hg.In terms of contributions of different pollutant sources,atmospheric deposition is the main source of all HMs input to agricultural soil except Cu.Livestock is the main source of Cu input to agricultural soil.Atmospheric deposition and livestock make nearly same contribution to Zn input.(2)Compared with statistical data of Luo et al.2009,the net inputs of As,Cd,Cu,Hg,Pb are decreased,while the net inputs of Cr,Ni,Zn are increased.Livestock are main reason of decrease of Cd input,atmospheric deposition,livestock and fertilizers are reasons of decrease of Hg input.The growth of atmospheric deposition and fertilizers Ni input causes the total Ni input increase,and the increases of Cr and Zn are mainly from atmospheric deposition.(3)A new risk assessment method,which is focus on agricultural products safety,was established.Basic data of a typical Cd polluted agricultural soil in Zhuzhou city,Hunan province was collected,and risk assessment was carried on.Suggestions were proposed,that were:Cleaner Production,Irrigation water purification and soil remediation should be done to prevent agricultural soil Cd pollution.(4)Soil remediation experiments were carried on two typical agricultural soil Cd polluted area,Jiyuan city,Henan province and Jinan city,Shandong province.Results of Jiyuan experiment showed that a compound agent combined with foliar selenium fertilization obtained the most satisfied Cd reduction in wheat grain.Results of Jinan experiment showed that after fertilized with a compound agent(RMRS+,iron-based materials+rape stalk+amino acid+zinc fertilizer),Cd,Cr,and Pb in rape and maize were lower than the limited value.