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广西贺州烟区土壤重金属含量分析与评价

Analysis on soil heavy metal contents in Hezhou tobacco-growing areas in Guangxi

  • 摘要: 为降低土壤重金属污染对烟叶质量安全的影响,分析了广西贺州烟区土壤中As、Pb、Cd、Cr、Cu 5种重金属的含量及累积现状,并以GB 15618—1995土壤二级限量标准为评价依据,采用单因子污染指数法、内梅罗综合污染指数法和潜在生态风险指数法对贺州烟区土壤质量进行评价。结果表明:贺州烟区土壤中As、Pb、Cr、Cu含量均符合我国土壤环境质量标准二级限量要求,Cd含量存在超标现象。土壤中As、Pb、Cr累积指数分别为0.43、0.51、0.62,尚无累积;Cu、Cd累积指数分别为1.12、1.06,受人为活动影响而略有累积。贺州烟区91.1%土壤样品的内梅罗综合污染指数处于Ⅰ级(清洁)或Ⅱ级(尚清洁),所有土壤样品的多金属潜在生态风险指数RI < 150,烟区土壤整体处于清洁、尚清洁、低潜在生态风险水平。有5个取样点的Cd单因子污染指数>1.0,其中2个取样点的潜在生态风险等级为强,需对烟区进行合理规划,以规避高风险区域。

     

    Abstract: To reduce the influences of soil heavy metal pollution on the quality and safety of tobacco leaves, the contents and accumulation conditions of five heavy metals(arsenic, lead, cadmium, chromium and copper) were analyzed. On the basis of environmental quality standard for Grade Ⅱ soil as described in GB 15618-1995, a single-factor pollution index, Nemerow comprehensive pollution index and potential ecological risk index were used to assess soil environmental quality in Hezhou. The results showed that the contents of As, Pb, Cr and Cu in Hezhou tobacco-growing soils were lower than those specified by the environmental quality standard for Grade Ⅱ soil. However, the Cd content exceeded the standard. The accumulation index of As, Pb and Cr were 0.43, 0.51 and 0.62, respectively, suggesting no accumulation. The accumulation index of Cu and Cd were 1.12 and 1.06, respectively, indicating a slight accumulation due to human activities. The Nemerow comprehensive pollution index of 91.1% of the soil samples were at GradeⅠ(clean)or GradeⅡ(practically clean) in Hezhou tobacco-growing areas and the multi-metal potential ecological risk indexes(RI) of all the samples were less than 150, which indicated that the soil environmental quality in Hezhou tobacco-growing areas was at the level of"clean"or"practically clean"and low potential ecological risk. Single-factor pollution index of Cd from five sampling points were higher than 1.0, and potential ecological risk of Cd from two sampling points were at the strong level. Therefore, tobacco-growing areas should be selected in Hezhou to avoid Cd pollution areas.

     

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