| 地质高背景与污染叠加区不同土地利用方式下土壤重金属分布特征 |
| 摘要点击 2097 全文点击 704 投稿时间：2021-07-13 修订日期：2021-09-05 |
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| 中文关键词 地质高背景 铅锌冶炼 土壤重金属 土地利用方式 潜在生态风险指数 |
| 英文关键词 geological background lead-zinc smelter soil heavy metals land use type potential ecological risk coefficient |
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| 中文摘要 |
| 黔西北喀斯特地质高背景和历史遗留土法炼锌污染叠加，导致土壤重金属污染严重.为了解不同土地利用方式对土壤重金属分布的影响，选择威宁县某在产锌粉厂小流域为研究区域，共采集表层和剖面土壤样品126件，对农用地、荒地和林地土壤重金属（Cd、As、Pb、Cu和Zn）的空间分布、来源和生态风险进行分析和评价.结果表明，研究区表层土壤ω（Cd）、ω（As）、ω（Pb）、ω（Cu）和ω（Zn）平均值为8.14、45.07、263.97、41.36和716.98mg·kg-1，是背景值的1.29~12.33倍，除Zn外，土壤重金属表现为：农用地>荒地>林地；从空间分布上看，重金属含量高的土壤集中分布在锌粉厂和矿渣堆放点周边；在土壤剖面上，表层重金属普遍高于底层，荒地分布达显著差异水平，底层土壤重金属均高于背景值，表现出地质高背景的特征.相关分析和主成分分析结果显示，3种土地利用方式下表层土壤的Pb、Zn和As主要受到矿业和交通等人类活动的影响，Cd和Cu污染是地质高背景和人类活动共同作用的结果.土壤重金属Cd的单项生态风险系数最高，达到很强或极强风险，As、Zn、Cu和Pb达轻微或中等风险，研究区综合潜在生态风险指数总体表现为强生态风险，农用地风险强度高，荒地和林地相对较低.在喀斯特地质高背景区，铅锌冶炼对区域土壤重金属分布和累积的影响大于土地利用方式，土壤重金属污染叠加严重，生态风险高，应加强对重金属污染土壤的严格管控. |
| 英文摘要 |
| The high geological background and the residual pollution of historical zinc smelting in the karst area of northwest Guizhou has led to serious soil heavy metal pollution. In order to understand the characteristics of soil heavy metal pollution in agricultural land, wasteland, and forestland, 126 surface and profile soil samples were collected from a typical zinc powder factory-polluted small watershed in Weining County, Northwest Guizhou Province. The concentrations and distribution characteristics of Cd, As, Pb, Cu, and Zn in soils were studied. The results showed that the average ω(Cd), ω(As), ω(Pb), ω(Cu), and ω(Zn) in the surface soil were 8.14, 45.07, 263.97, 41.36, and 716.98 mg·kg-1, respectively, which were 1.29-12.33 times higher than the background values. The content of heavy metals in soil of different land uses in descending order was agricultural land, wasteland, and forestland. From the perspective of spatial distribution, the soil with high heavy metal concentration was concentrated around the zinc smelting plant and slag, and the accumulation of heavy metals in soil was greatly affected by the pollution sources of mining activities but less affected by the land use mode. In soil profile, heavy metals in the surface layer were generally higher than those in bottom layers, showing a significant difference (P<0.05) in wasteland. Five heavy metals in 80-100 cm soil were higher than the background value, reflecting the existence of a high geological background value. Correlation analysis and principal component analysis showed that Pb, Zn, and As in the surface soil were mainly affected by human activities such as mining and transportation, whereas Cd and Cu were both affected by high geological background and human activities. The single ecological risk coefficient of Cd in soil was the highest, which reached very strong or very strong risk, whereas As, Zn, Cu, and Pb reached slight or medium risk. The comprehensive potential ecological risk index indicated strong ecological risk, which in agricultural land was higher than that in wasteland and forestland. In the karst high geological background area, the influence of lead and zinc smelting on the distribution and accumulation of heavy metals in soils was greater than that of land use; soil heavy metal pollution was serious, and ecological risk was high in this area. Therefore, strict control of heavy metal-contaminated soil should be strengthened. |
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