富阳市不同类型农田土壤重金属变异特征及风险评价

    Characteristics and Risk Assessment of Heavy Metals Pollution of Farmland Soils Relative to Type of Land Use

    • 摘要: 以浙江省富阳市旱地、林地、水田和园地这4种类型农用地土壤为对象,研究0~20 cm表层土壤中Cu、Zn、Pb、Cd、Ni、Hg和As 的含量特征,并采用内梅罗综合指数法对土壤重金属污染状况进行评价,探讨农田土地利用类型对土壤重金属污染的影响。结果表明,研究区农用地土壤Cu、Zn、Pb、Cd、Ni、Hg和As含量平均值分别为26.01、108.41、36.42、0.26、21.85、1.66和94.81 mg•kg-1,其中土壤Hg和As单项污染指数较高。4种不同类型农用地土壤重金属污染的内梅罗综合指数从高到低依次为园地、旱地、水田和林地,旱地土壤Cu和Zn含量较高,园地土壤Pb含量较高,而Hg含量较低,Cd、Ni和As含量在4种类型农用地间差异不显著。析取克里格风险评价结果表明,w(Hg)>0.3 mg•kg-1w(As) >30 mg•kg-1的高风险区域主要集中在城镇和工矿企业周边农田,说明人为活动对土壤Hg和As高含量有重要影响。

       

      Abstract: Four different types of agricultural lands, i.e. upland field, woodland, paddy field and vegetable garden, were selected in Fuyang city, Zhejiang Province, as subjects for study on contents of seven heavy metals, i.e. Cu, Zn, Pb, Cd, Ni, Hg and As, in 0-20cm surface soils for assessment of heavy metals pollution of these soils using the Nemerow composite index method, and for exploration of effects of land use on the pollution. Results indicate that the average content of Cu, Zn, Pb, Cd, Ni, Hg and As in the soils was 26.01, 108.41, 36.42, 0.26, 21.85, 1.66 and 94.81 mg•kg-1, respectively, and the single pollution indices of Hg and As were much higher than the others’. In terms of the Nemerow composite index, the four types of land use are in the order of vegetable garden , upland field ,paddy field and woodland. The upland field is the higher in Cu and Zn content, and the vegetable garden was highest in Pb and the lowest in Hg. Differences between the lands in Cd,Ni and As were not significant. The disjunctive Kriging risk assessment shows that lands with w(Hg)>0.3 mg•kg-1 and w(As) >30 mg•kg-1 are high-risk areas, which are agricultural lands, distributed mainly around cities,towns and industrial and mining sites, suggesting that the Hg and As pollution is closely related to human activities.

       

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