湖南清水塘老工业区重金属污染特征及其在食物链的迁移富集研究

    Heavy metal pollution of the Qingshuitang old industrial area in Hunan Province: Characteristics and its migration and enrichment in food chains

    • 摘要: 湖南清水塘老工业区重金属污染对人体健康构成了高风险。为解析历史遗留工矿废弃地重金属在食物链中的迁移富集特征,本文采集了不同人群对应的食物链样品16组共128件样品,测试稻土、菜土、稻谷、蔬菜、饮用水、人体尿液、血液等样品中Cd、Hg、Pb、As 4种重金属元素的含量,运用污染指数法、内梅罗综合污染指数法和Pearson相关分析法,分析重金属在“土壤—农作物—人体”食物链中的迁移富集特征。结果表明:稻土和菜土中的Cd为重度污染,Pb为重度—中度污染,As为中度—轻度污染,Hg为轻度污染,总体上稻土综合污染程度高于菜土;稻谷中Cd、Pb、Hg为重度污染,As为轻度污染,蔬菜中Cd为重度污染,Hg和As为轻度污染,Pb为无污染,稻谷综合污染程度大于蔬菜;人体中,尿液Cd平均超标准限量2.73倍,血液Cd、Pb平均超标准限量1.73和2.73倍,血液As和尿液Hg含量基本低于临床诊断限量;Cd、Hg、Pb、As在“土壤—农作物(稻谷、蔬菜)”中的含量与Cd在“农作物(稻谷、蔬菜)—人体尿液”中的迁移富集相关性显著,但人体血液Cd、血液Pb的富集则另有其他迁移途径,As、Hg在“农作物(稻谷、蔬菜)—人体”迁移环节的富集规律不明显,为偶发的职业性中毒。本次研究成果将为工矿业废弃地重金属污染治理及其引起的人体健康风险防控提供参考。

       

      Abstract: Heavy metal pollution in the Qingshuitang old industrial area in Hunan province poses a high risk to human health. To investigate the migration and enrichment characteristics of heavy metals in the food chain of historical industrial and mining wastelands, this study collected 128 food chain samples comprising 16 groups corresponding to different populations. The contents of four heavy metals, including cadmium (Cd), mercury (Hg), lead (Pb), and arsenic (As), were tested in samples such as paddy soil, vegetable soil, rice, vegetables, drinking water, along with human urine and blood. Then, the migration and enrichment characteristics of heavy metals in the "soil-crop-human" food chain were investigated using the pollution index, Nemerow composite pollution index, and Pearson correlation analysis. The results show that the paddy and vegetable soils both exhibited heavy Cd pollution, heavy to moderate Pb pollution, moderate to mild As pollution, and mild Hg pollution. Overall, the paddy soil presented higher comprehensive pollution levels than the vegetable soil. Moreover, the rice displayed heavy pollution in Cd, Pb, and Hg and mild As pollution. In contrast, vegetables presented severe Cd pollution and mild pollution in Hg and As, with no Pb pollution observed. Generally, the comprehensive pollution level of rice was higher than that of vegetables. In addition, humans showed exceedances of standard limits for key biomarkers: Cd in urine (2.73 times), Cd in blood (1.73 times), and Pb in blood (2.73 times). In contrast, the As in blood and Hg in urine were generally below the clinical diagnostic limits. Significant correlations were determined between the Cd, Hg, Pb, and As contents in the "soil-crop (rice and vegetables)" and the migration and enrichment of Cd in the "crop (rice and vegetables)-human urine". However, the enrichment of Cd and Pb in human blood followed other migration pathways. No clear enrichment patterns of As and Hg were observed in the "crop (rice and vegetables)-human" transfer, indicating occasional occupational poisoning. These findings will provide a valuable reference for mitigating heavy metal pollution in industrial and mining wastelands and preventing and controlling associated human health risks.

       

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