Heavy metal accumulation of edible vegetables cultivated in agricultural soil in the suburb of Zhengzhou City, People's Republic of China.

摘要

A comprehensive study was performed on toxic heavy metals in 23 vegetable species grown in an agricultural soil under natural condition. The vegetable species were collected from four sampling sites located in the suburb of Zhengzhou City, Henan Province, China. Results showed that the mean concentrations of Cd, Pb, Cr and Cu were below the threshold levels in natural background soil as defined by China. The concentration of heavy metals in the vegetables was 87% for Cu and Cd, 96% for Pb, 65% for As and Cr and 100% for Hg, which exceeded the tolerance limit of Food Sanitary Regulation of China. The highest concentration of Hg was found in radish leaves. The highest Cr concentration was 15.38 mg/kg in leek. The highest Cu and Pb concentration was recorded in asparagus bean. The concentration of Cd was highest in Chinese cabbage. Radish and carrot leaves were efficient bioaccumulators of heavy metals, and the edible parts of radish and carrot were generally less contaminated than leaves. To appraise the bioaccumulation of vegetables, bioconcentration factors (BCF) values were calculated as the ratio between the concentration of heavy metals in the vegetable and soil for each vegetable at each site separately. The average BCF values were 5.31 for Cu, 0.65 for Cd, 0.45 for Pb, 0.20 for Cr, 0.16 for As and 0.062 for Hg. This indicates that mercury had the lowest bioavailability in the studied soil-vegetable system. Results indicated that 'yubaicai pakchoi' and 'pak choi' had the highest enrichment ability of As and Cr, and radish leaves had the highest enrichment ability of Pb, Cd and Hg among all studied vegetable species..