关键词: 北京市, 蔬菜, 锌, 健康风险, 抗污染品种

Abstract:

To assess the human health risk posed by elevated concentrations of zinc in vegetables,and to identify pollution-tolerant vegetable varieties,a large scale survey of zinc levels in soils and vegetables planted or sold in Beijing was conducted.Fifty-two soil samples were collected from gardens and fields used to grow vegetable plants.In addition,97 varieties of 402 fresh vegetable samples were obtained from vegetable stalls,supermarkets and wholesale outlets.Zinc concentrations were measured using flame atomic absorption spectrometry. Zinc concentrations in soils ranged from 24.9 to 307.5 mg kg^-1,with arithmetic,median,geometric and Box-Cox means of 79.29,63.81,70.7 and 68.01 mg kg^-1,respectively.Compared with the background zinc concentrations of soils from Beijing,there appeared a significant accumulation of zinc in soils collected from fields that produced vegetables.Zinc concentrations in the edible plant portions ranged from 0.005 to 25.6 mg kg^-1 fresh weight, with arithmetic,median and Box-Cox means of 3.11,2.24 and 2.55 mg kg^-1 fresh weight,respectively.In all of the samples and vegetable varieties,zinc was less than the Tolerance Limit of Zinc in Foods（TLCF） of 100 mg kg^-1 fresh weight for pulse and 20 mg kg^-1 for other vegetables.The TLCF is the maximum permissible concentration of zinc in vegetables that will be consumed by people.The highest level of zinc detected in a vegetable plant was 25.6 mg kg^-1,which was measured in a green soybean sample.Statistical analysis showed that the zinc concentration in leaf vegetables was significant higher than that of gourd and fruit vegetable.And the zinc concentration in vegetables from other places of China was significantly higher than the concentration of local vegetables,but there was no significantly difference between field-grown vegetables and those planted in a greenhouse. Results of hierarchical cluster analysis on the zinc bioconcentration factor（BCF） in vegetables indicated that the plants sampled could be separated into three groups based on BCF.Beans round trellis（Vigna unguiculata）,the first group,had the highest BCFs,and the following is the second group,including Chinese cabbage（Brassica pekinensis）,Pakchoi（Brassica chinensis） and radish（Raphanus）,had higher zinc BCFs while Chinese green onion,chili（Capsicum annuum） cucumber（Cucumis sativus）,eggplant（Solanum sp.）,tomato（Lycopersicon esculentum） and wax gourd（Beninacasa hispida） had lower zinc BCFs. The average ingestion rate of zinc from vegetables was 4.04 mg/individual/day for people of Beijing,making up 22.4% of the quantity demanded（18 mg/individual/day） and 7.4% of No-Observed-Adverse Effect-Level（NOAEL）.Consuming vegetables with elevated zinc concentrations may not pose a health risk to local residents.

Key words: Zinc, Beijing, vegetables, soil, bioaccumulation, human health risk, pollutant-resistant plants