云南个旧大屯镇蔬菜重金属污染现状及健康风险评价

In-situ heavy-metal pollution and health risks in the vegetables in Datun Town,Gejiu City,Yunnan

通过现场调查及室内分析,对云南省个旧市大屯镇的土壤和蔬菜重金属污染现状进行健康风险评价。对大屯镇蔬菜地土壤pH值、有机质等理化性质进行测定,通过Tessier连续提取法研究土壤重金属的分级形态,用原子吸收光谱仪测定土壤及蔬菜中Zn、Cu、Cd、Pb质量比,利用单因子污染指数法和内梅罗综合评价指数法进行蔬菜重金属污染评价。结果表明,土壤中只有Pb的质量比没有超出GB15618—1995《土壤环境质量标准》二级标准,Zn、Cu、Cd的质量比分别是国家土壤环境质量标准的1.65、1.33、5.32倍。15种蔬菜中Pb、Zn、Cu、Cd的平均质量比分别为3.63 mg/kg、71.04 mg/kg、22.70 mg/kg、0.81 mg/kg,分别是对应的食品安全限值的12.10、3.55、2.27、16.16倍。小青菜,菜花、薄荷、苤蓝、青蒜、大葱、芹菜、大白菜、莲花白、茼蒿、牛皮菜对Pb、Zn、Cu、Cd的吸收能力较低,适合在污染区继续种植;芋、菠菜、香菜、绿笋对4种重金属吸附能力较强,不适合在污染区继续种植。综合污染指数从大到小的重金属为Cd、Pb、Zn、Cu。居民经食用蔬菜途径日摄入Pb、Zn、Cu、Cd量分别为1.25 mg/d、24.51 mg/d、7.83 mg/d、0.28 mg/d,分别占暂定每日耐受摄入量(PTDI)的626.18%、74.27%、120.50%、387.17%。因此,经蔬菜途径摄入的Pb、Zn、Cu、Cd对当地居民健康构成潜在威胁。

The paper is to present our investigation results of the current situation and health risk of heavy-metal pollution in the soils and vegetables grown in Datun Town, Gejiu City, Yunnan. In our investigation, we have tested and measured the concentrations of lead（Pb）, zinc（Zn）, copper（Cu） and cadmium（Cd） contents in the soil and vegetables, the pH value and the organic matters in the soil by using a atomic absorption spectrometer. At the same time, we have inspected the distribution and forms of heavy metals in the soil through Tessier sequential extraction procedure, further providing our evaluation of such pollution in the vegetables in the single factor pollution index and Nemerow integrated index form. The results of our investigation indicates that among all the heavy metals mentioned above, only Pb content remains in the range of the ＂Environment Quality Standards for Soils＂ （GB 15618-1995） （Grade Ⅱ）. To be accurate, the average content concentrations of Pb, Zn, Cu and Cd in the soil account for 1.65, 1.33, 5.32 times as high as those listed in the corresponding standard whereas those of Pb, Zn, Cu, Cd in 15 vegetables are 3.63 mg/kg, 71.04 mg/kg, 22.70 mg/kg and 0.81 mg/kg, respectively, that is, 12.10, 3.55, 2.27 and 16.16 times higher than the safety limits for edible foods. Thus, it is only Brassica chinensis, Brassica oleracea, Mentha canadensis L., Brassica oleraces var.carlorapa, Allium sativum L., Allium fistulosum, Apium graveolens, Brassica rapa pekinensis, Brassica oleracea L.var.capitata L., Chrysanthemum cornarium var.spatisum and Beta vulgaris L., that are suitable for growth in the fields under survey for their tolerable metal accumulation, whereas Coiocasia esculenta, Spinacia oleracea, Herba Coriandri Sativi and Sinocalamus oldhami（Munro）McClure are not. The order of the comprehensive pollution indexes of the four vegetables stands as Cd〉Pb〉Zn〉Cu. According to the state-stipulated standard for tolerable daily intake （PTDI） of Pb, Zn, Cu and Cd, the contents for the four metals should be 1.25 mg/d, 24.51 mg/d, 7.83 mg/d and 0.28 mg/d, that is to say, the in-situ contents of these metals account for 626.18%, 74.27%, 120.50% and 387.17% higher than the state-stipulated standard. Therefore, a serious potential risk or threat which the local residents have to confront, when they consume the above mentioned vegetables with Pb, Zn, Cu and Cd contents.