The Health Risk Assessment Of Heavy Metals In Soils And Vegetables And The Phytoremediation Of Non-pollution Bases

In this paper, we evaluated heavy metals in organic vegetable soil and more than20more kinds of edible part of vegetables in Chaohu city, Anhui province.Using the grid method and the GPS,we have collected50soil samples and20more kinds of edible parts of vegetables.We analyzed the soil pH,organic matter content by conventional methods.We determinate the total content of heavy metals (Cu, Zn, Pb,Ni, Cr and Cd)in the greenhouse and open-air soil and edible parts of vegetables.Based on the different land using way and the difference of pH,We introduced single factor pollution index, Nemerow integrated index and Fuzzy mathematics method to evaluate and compare the the greenhouse and open-air soil and the edible part of vegetables.According to the standerds of International Commission on Radiological Protection(ICRP),we assessmented the edible parts of vegetables.The result of the analysis indicate:(1)Cd and Pb are the major pollutants in the study area.Pb, Cd, Zn contaminated sampling points up to19,16and1respectively in the Open-air study area while Cd, Pb, Zn, Cu, Cr contaminated sampling points up to26,21,11,7and1respectively in the greenhouse study area.(2) Nemerow integrated index evaluation showed that there are92%of open-air research areas belong to clean and the soil quality is good, while there are19%of the greenhouse study areas that is slightly polluted and58%research areas belong to clean according to the national secondary standard of heavy metal environmental quality.(3)The results of Fuzzy mathematics evaluation showed that the quality of open-air research area is good.24samples all belongs to the first level while there are96%and4%take up the first and second level separately in the greenhousestudy areas.(4)Based on the determined of the edible parts of vegetables and compared with he national food hygienic standards,The excessive rate of Ni、Zn、Cd、Pb、Cu in the edible parts of vegetables were100%、95%、80%、60%、55%、20%respectly.In general, the heavy metal content in leafy vegetables and beans are higher than other kinds of vegetables.As part of some heavy metals in some vegetables exceeded seriously so lead the overall pollution of the vegetables polluted seriously.(5)The order of the enrichment factor in the edible part of vegetables are:Cd>Zn>Cu>Ni>Cr>Pb.This basically the same with other researches on the enrichment factor.(6)the chemical carcinogens of the edible vegetables in the study area are surpass the ICRP recommendation,so there are potential threat risk to human health.While the annual non-chemical carcinogen is lower than the ICRP recommendation.Human health risks from heavy metals in vegetables were mainly caused by chemical carcinogens Cd and Cr.In particular,Cd and Cr concentration was high in Leafy vegetables.So we should strengthen prevention and control of soil Cd and Cr in this area,and local residents should reduce planting Leafy vegetables and intake them,or change to grow those fruits or cash crops,like ornamental flowers,which are weak in enrich heavy metals.then to ensure their food security.(7)The indoor pot simulation experiments showed that ryegrass has certain ability to accumulate Cd and Pb.So ryegrass is an ideal choice of phytoremediation for heavy metal contaminated soil,especially for Cd.