Accessment Of Heavy Metal Pollution In Farmland Soil And Agricultural Product In Zhejiang Province

The heavy metal pollution of soil is one of the main factors of quality decrease and safety issues of agricultural products.In this paper,the soil and crop in Zhejiang Province are selected as the research object,and the contents of heavy metals in soil and crop are collected.The heavy metal pollution degree of soil and crop are evaluated by heavy metal single factor index.method,over standard rate,enrichment coefficient and correlation analysis.And the assessment of heavy metals in soil is risked.It provides scientific basis for the control of heavy metal pollution and the production of pollution-free crops in Zhejiang Province,which has important practical significance and application prospect.On the whole,the content of heavy metals in crops in Zhejiang Province exceeds the content of heavy metal in farmland soils.Most of the soil samples accords with the "National Soil Environmental Standard".The heavy metal pollution of farmland soil in Jiaxing,Quzhou,Shaoxing and Taizhou is worse than that in Hangzhou,Huzhou,Jinhua,Ningbo and Wenzhou.The heavy metals such as Cd and Ni have the most serious pollution in Jiaxing,Quzhou,Shaoxing and Taizhou,followed by heavy metals Cu,Cr and Hg.The soil contaminated by rape is polluted most seriously,and Ni in the soil exceeds the standard most seriously.The excessive rate is 46.7%.The contents of Cu,Zn and Hg in crops in Zhejiang Province are almost no excessive,and the excessive situations of the rest of the heavy metals are different in various crops.The contents of heavy metals Pb and Ni in rice exceed the standard seriously and the excessive rates are 88%and 96%,respectively.The content of heavy metal Ni in rape exceeds the standard seriously and the excessive rate is 88%.The contents of heavy metals Pb and Ni in vegetable exceed the standard seriously and the excessive rates are 50%and 25.5%,respectively.The contents of heavy metals Cr and Ni in fruits exceed the standard seriously and the total excessive rates are 50%and 25.5%,respectively.Among the vegetable,the contents of heavy metal As in the green beans and tomatoes in Hangzhou are very high,respectively,10.11mg/kg and 2.39mg/kg.Among the fruits,the content of heavy metal As in grapes in Jinhua is extremely high,reaching 58.10mg/kg.The correlation analysis shows that the pH of soil had little effect on the content of heavy metals in rice,tea,rape and fruits,but has some effect on the total content of Zn,Pb,Cu,Hg in soil contaminated by vegetable.The heavy metals Cu,Cr and Ni in soil contaminated by fruit trees or tea trees have the same source.The heavy metals Zn and Cd in soil contaminated by rice have the same source.The heavy metals Cu,Zn and Cd in soil contaminated by vegetable have the same source.The absorption mechanisms of Ni and Cr in fruits and rice are similar.The absorption mechanisms of Zn,Pb,and Cr in rape are similar.The absorption mechanisms of Pb and Cr in vegetable are similar.The absorption mechanisms of Cr and Ni in vegetable are similar,too.And the absorption mechanisms of Cu,Zn and Ni in vegetable are similar as well.By heavy metal health risk assessment,it is found that heavy metals Pb,Cr and As cause serious safety problems in the diet children,young adults,middle-aged and elderly in Zhejiang Province,and it has a greater impact on children.The contribution rate of edible rice to the daily exposure of Pb,Cr and As is high.The contribution rate of edible vegetable and fruits to the daily exposure of As is high as well.The overall average risk of cancer caused by children's consumption of rice,vegetable and fruits containing Pb,Cr and As has exceeded the US Environmental Protection Agency standards,reaching 6.69E-3 a-1.So children still face a great risk of cancer.Among these heavy metals,Cr has the highest average carcinogenic risk(6.31E-3a-1),followed by As(3.71E-4a-1).The average carcinogenic risk of Pb(1.23E-6a-1)is lower than the standard of the US Environmental Protection Agency.