Mercury Contamination of Crops and Vegetables Around the Zinc Smelting Plant

The mercury contents in 3 kinds of crops, 22 kinds of vegetables, and the rhizosphere soil from eight sampling sites around zinc smelting plant in Huludao city, China are investigated. The results indicate that the edible parts of vegetable are also contaminated by mercury, with the range of mercury content 0.001~0.147mg·kg-1(dw). 37.1% leafy vegetable, 9% gourd vegetable, and 4% leguminous vegetable exceeded the maximum levels of contaminants in foods. Maize, bean and broomcorn are contaminated by mercury greatly, and the mercury contents of seed are 0.008 mg·kg-1, 0.006 mg·kg-1 and 0.057 mg·kg-1, respectively. The mercury content in plant tissue decrease in the order of leavesrootstalkgrain. The correlation analysis shows that the mercury in the root of plant mainly derives from soil, and uptake of gaseous mercury is the predominant pathway of mercury accumulation in the foliage. The average and maximal mercury daily intake(DI) of adult are 0.015 μg·kg-1·d-1, 0.051 μg·kg-1·d-1, and of child are 0.020 and 0.069 μg·kg-1·d-1 respectively. The World Health Organization(WHO) has established a provisional tolerable weekly intake(PTWI) of 5 μg·kg-1 body weight(bw) per week for total mercury. The average and maximal weekly intake of total mercury by consuming the vegetable around the Huludao Zinc Plant are 2.1%, 7.1% of PTWI for adult, and 2.8%, 9.7% of PTWI for child.