ISSN 1000-3665 CN 11-2202/P

    承德市富硒土壤区镉的地球化学特征及生态风险评价

    Geochemical characteristics and ecological risk assessment of cadmium in selenium-rich soil of Chengde City in Hebei Province

    • 摘要: 硒是人体必需的生命元素,开发富硒农产品是提升人体硒摄入的安全有效途径,富硒土地资源是开发富硒农产品的基础。然而,近年来全国开展的多目标地球化学调查发现,富硒土壤中重金属元素镉通常较高,不利于富硒土地开发利用,因此,研究富硒土壤区镉的地球化学特征和生态风险状况对于富硒土地开发具有重要的指导意义。文章对承德市富硒土壤区表层土壤中主要的重金属元素镉的地球化学特征及生态风险进行评价,旨在为承德市富硒土地开发利用提供科学依据。采用“七步提取法”研究了表层土壤镉的形态特征。同时,配套分析了苹果、玉米样品中的重金属元素镉的含量,以了解其生物有效性。结果显示:承德市富硒土壤区表层土壤镉在全区均较富集,在新积土和中性粗骨土、水田中显著富集。研究区圈定了4处镉轻度污染土壤,均在表层土壤镉的高值区。表层土壤镉形态平均含量大小顺序为:水溶态 < 离子交换态 < 强有机结合态 < 腐殖酸结合态 < 铁锰氧化物结合态 < 碳酸盐结合态 < 残渣态,生态风险相对较低。表层土壤镉未对苹果和玉米样品产生影响,苹果和玉米中镉均不超标。承德市富硒土壤区表层土壤镉的生态风险较低,暂不影响承德市富硒土地开发利用。

       

      Abstract: Selenium is an essential bioelement for human being. It is a safe and effective way to increase the level of human selenium by selenium-enriched agricultural products. Selenium-enriched land resources are the main selenium source for selenium-enriched agricultural products. However, the multi-purpose geochemical surveys carried out nationwide in recent years have found that Cadmium, a heavy metal element, is usually relatively high in selenium-enriched soils. Therefore, the study on the geochemical characteristics and ecological risk status of Cadmium in selenium-enriched lands has an important guiding significance for the development of selenium-enriched soils. In this paper, the geochemical characteristics and ecological risks of Cadmium in the surface soil of selenium-rich soil area of Chengde city in Hebei province were evaluated, aimed at providing scientific basis for the development and utilization of selenium-rich land. The spatial distribution characteristics and environmental grades of Cadmium in topsoil were studied. The water-soluble, ion exchangeable, carbonates bound, humic acid bound, Fe-Mn oxides bound, tightly organic mater bound, residual of Cadmium were extracted step by step. At the same time, the contents of Cadmium in apple and corn were analyzed to understand their bioavailability. The results show that Cadmium is enriched in the surface soil in the selenium-rich soil area of Chengde city, and significantly enriched in the new accumulation soil, neutral coarse bone soil and paddy fields. In the study area, four piece of Cadmium lightly contaminated soils are delineated in the high value areas of Cadmium in the surface soil. The order of the average content of Cadmium in surface soil is water soluble < ion exchange < tightly organic mater bound < humic acid bound < Fe-Mn oxides bound < carbonates bound < residual fraction. The carbonates bound component is high and has potential environmental hazard. Cadmium in apple and corn is low. The ecological risk of Cadmium in surface soil in the selenium-rich soil area of Chengde city is low. The development and utilization of selenium-rich land in Chengde city is not affected by Cadmium in surface soil, temporarily.

       

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