A Survey Of Heavy Metal Concentrations In Vegetables And Soils In Lanzhou And The Potential Risks To Human Health

A large scale survey of heavy metal levels in vegetable soils and vegetables planted or sold in Lanzhou was conducted. A total of 65 soil samples and 46 varieties of 118 fresh vegetable samples were collected. The results were showed as follow:1. Average content of Cd,Hg,Pb,As and Cr in Lanzhou,s vegetable cultivated soils was one time higher than the background values of Lanzhou,s agricultural soils. Compared with the background heavy metal concentrations, there appeared to be a significant accumulation of cadmium in soil collected from fields that produce vegetables, but below the soil environmental quality standard of secondary standard.2. Correlation analysis indicated that there was highly significantly positive correlation between As and Pb. There were significantly positive correlation between Cr and Cd,Cr and Pb,Cr and As. The coefficients of correlation between Hg and other elements weren't reach to the level of significant.3. The order of the comprehensive pollution index was As>Cd>Cr>Hg>Pb. The samples comprehensive pollution index was Qilihe>Yongdeng>Xigu>Anning>Gaolan>Honggu>Yuzhong. The samples comprehensive pollution index was less than 0.7, which indicated that pollution degree was safe.It was suitable for cultivation of vegetables.4. Lanzhou's indigenous vegetables were suffered from pollution of Pb,Cd and Cr, and Pb pollution was the most serious.The second was Cd. The nest was Cr.The exceeding standard rate of Pb was 17.8%, which was as 2.3 times and 10.5 times as that of Cd and Cr ,respectively.5. There was the highest content of heavy metal in leaf vegetables, and the lowest content of heavy metal in melons vegetables.6. The daily intakes of heavy metal in vegetable per capita in Lanzhou were less than ADI (Allow Daily Intakes).The highest daily intakes of Pb were 0.063 mg/day.people in leaf vegetables.7. Five kinds of heavy metals contribution rate range from 2.4% to 60% in different vegetables. Among, there was the highest contribution rate was 60.0% of Pb in leaf vegetables, and the lowest contribution rate was 49.2%of As in beans vegetables. If eating in this study is the most serious pollution of vegetable samples it may pose a health risk to local residents.8. Although the average contents of heavy metal far below the quality of farm produce safety non-pollution vegetables safety requirements, but for some people, the heavy metal may pose a health risk t is still worth attention.