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    赣西地区土壤-水稻系统中重金属Cd元素地球化学特征与健康风险评价

    Geochemical characteristics and health risk assessment of heavy metal Cd in soil-rice system inWestern Jiangxi Province

    • 摘要:研究目的】重金属元素主要通过食物链进入人体从而影响健康,开展土壤-水稻系统重金属元素地球化学特征研究,对科学管理耕地、保障粮食安全和健康中国战略的实施具有重要意义。【研究方法】系统采集水稻籽实及对应根系土样品129组,通过化学分析获取As、Cd、Hg、Pb、Cr、pH和土壤Cd形态等地球化学数据,采用人体健康风险模型评估研究区健康风险。【研究结果】 (1)研究区土壤Cd平均含量为0.49mg/kg,显著高于江西表层土壤背景值,有80件土壤Cd含量高于风险筛选值,占总样本的62%。水稻籽实有57件Cd含量超标,超标率为44%。(2)研究区土壤Cd的污染评价结果与农作物Cd的安全评价结果对应性较差。土壤pH值是主要的影响因素,随着土壤pH升高,土壤中Cd含量增加了2.26倍,但水稻籽实Cd含量降低了4.5倍。(3)土壤中Cd的水溶态、离子交换态和残渣态三种赋存形态对水稻籽实Cd含量具有显著影响,在强酸性土壤环境中,Cd生物有效性增强。(4)人体健康风险评价结果显示研究区儿童的健康风险大于成人,非致癌风险和致癌风险因子主要为Cd。【结论】研究区土壤Cd与水稻籽实Cd含量空间对应性较差,依照现行规范评价,存在一定的误判漏判具有一定的局限性;健康风险评价结果显示研究区存在因水稻Cd摄入引起的人体健康风险。

       

      Abstract: This paper is the result of land quality geochemical survey engineering. Objective Metal elements mainly enter the human body through the food chain, thus affecting health. Research on the geochemical characterization of heavy metal elements in the soil-rice system is significant for the scientific management of arable land, the guarantee of food security and the implementation of the strategy of a healthy China.Methods A total of 129 sets of rice seeds and root soil samples were systematically collected, analyzed by chemical analysis to obtain geochemical data such as As, Cd, Hg, Pb, Cr, pH, and soil Cd morphology, thus using the human health risk model to assess the health risk in the study area. Results (1) The average soil Cd content in the study area was 0.49 mg/kg, which was significantly higher than the background value of Jiangxi surface soil.There were 80 soil samples Cd content higher than the risk screening value, accounting for 62%.There were 57 rice seeds with excessive Cd content, the rate of exceeding the standard was 44%.(2) The results of the pollution evaluation of soil Cd and safety evaluation of rice seeds Cd in the study area were poorly correlated.Soil pH was the major influencing factor, with soil alkalinity increasing, soil Cd content increased by 2.3 times, but rice seeds Cd content decreased by 4.5 times.(3) The three fugitive forms of water-soluble, exchangeable and residual Cd in the soil had a significant effect on the Cd content of rice seeds, and the bio-efficacy of Cd was enhanced in a strongly acidic soil environment.(4) Children in the study area have greater health risks than adults, with non-carcinogenic and carcinogenic risk factors dominated by the heavy metal Cd.Conclusions The correlation between soil Cd and rice seeds Cd content in the study area is relatively poor, and there are some limitations of misjudgment and omission according to the current norms; the health risk evaluation results revealed that there is a human health risk caused by rice Cd intake in the study area.

       

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