| 摘要: |
| 为评估庆阳市市区与环江—泾河沿岸表层土壤中重金属含量与生态风险状况，本文采集了18组现代表层土壤样品，采用石墨炉原子吸收光谱法等方法测定了7种土壤重金属元素（Pb、As、Cd、Cr、Hg、Cu、Zn）的含量，利用单因子指数法、内梅罗综合污染指数法、地累积指数等评价方法，探讨了研究区土壤重金属含量、污染程度和生态风险，并利用皮尔逊相关分析和主成分因子分析对市区和河流进行源解析。结果表明：（1）对土壤重金属含量利用变异系数和峰度系数进行特征分析，显示人类活动干扰土壤环境比较明显；（2）与国家土壤环境标准（GB 36600—2018）对比发现，庆阳市市区Cr元素存在一定的富集，其余元素均处于安全范围之内；（3）各类污染指数表明，Cd和Pb在研究区的污染最为突出，均高于其他土壤重金属的污染水平，其余土壤重金属基本无污染；（4）对市区各土壤重金属进行相关性分析后，发现庆阳市市区的土壤重金属除与母质成分有关外，在很大程度上与强烈的人类活动密切相关；环江—泾河沿岸的土壤重金属元素间也具有相关伴生关系，经过主成分分析后土壤重金属富集主要是自然来源和农业生产。 |
| 关键词: 土壤环境 生态风险评价 重金属污染 庆阳市市区 环江—泾河沿岸 |
| DOI：10.7515/JEE222033 |
| CSTR： |
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| 基金项目:中央高校基本科研业务费专项资金项目（2019KYQD24） |
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| Ecological risk assessment of heavy metal content in soil along the urban area of Qingyang City and the Huanjiang — Jinghe River |
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LIU Fang, LIU Xiangjun, ZHANG Pengbo, TANG Daobin, ZHANG Shengqiang
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1. Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Northwest Normal University, Lanzhou 730070, China
2. College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China
3. School of Geography and Tourism, Jiaying University, Meizhou 514015, China
4. College of Education, Northwest Normal University, Lanzhou 730070, China
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| Abstract: |
| Background, aim, and scope Soil provides food production and living space for human beings and it will continuously receiving all kinds of pollutants discharged by human. As the most important persistent toxic pollutants in soil, heavy metals are difficult to degrade and will continue to accumulate in the soil, therefore posing potential risks to the ecosystem and human beings as a global problem. In this study we take 18 surface soil samples from the urban area of Qingyang City and along the Huanjiang—Jinghe River, measure the contents of seven heavy metals, then use single-factor index method, Nemerow comprehensive pollution index method, geo-accumulation index and potential ecological risk assessment method, to estimate pollution degree and ecological risk in the study area. The source analysis of urban areas and rivers is carried out by both Pearson correlation analysis and main component analysis. Materials and methods A total of 18 modern topsoil samples (with sampling depth of 0—3 cm) were collected from the urban area of Qingyang City and along the Huanjiang—Jinghe River. Seven metal contents of these samples were measured at the Analysis and Testing Center of Northwest Institute of Plateau Biology, Chinese Academy of Sciences. Pb, As, Cd and Cr were measured by graphite furnace atomic absorption spectrometry, Hg by atomic fluorescence spectrometry, Cu and Zn by ICP inductively coupled plasma emission spectrometry. Methods of single factor pollution index, geo-accumulation index, Nemerow comprehensive pollution index and potential ecological risk assessment were used to assess the ecological risks of heavy metals. The source analysis of urban areas and rivers is carried out by Pearson correlation analysis and main component analysis. Results There is no pollution of soil heavy metals along the Huanjiang—Jinghe River. Heavy metal pollution of soil has appeared in the urban area of Qingyang City, and the main source of pollution is traffic pollution. Potential ecological risks need to be properly monitored and corresponding measures to be taken. Discussion (1) The characteristics of soil heavy metals in this region were analyzed using the coefficient of variation and the coefficient of kurtosis, which indicate that the proportion of soil environment disturbed by human activities. (2) Compared to soil environmental quality risk control standard for soil contamination of development land (GB 36600—2018), there is a moderate enrichment of Cr element in the urban area of Qingyang City, and the other elements are within the safe range. (3) Various pollution indexes show that the pollution of Cd and Pb in the whole study area is the most prominent, which is higher than the pollution level of other heavy metals in the soil, and the pollution of other heavy metals in the soil is also on the warning line. (4) After analyzing the correlation between soil heavy metals in urban areas, it is found that soil heavy metals in the urban area of Qingyang City are closely related to strong human activities to a great extent, in addition to their maternal composition. There is also a correlation between soil heavy metals along the river, after analysis of the main composition soil heavy metal enrichment is mainly a natural source and agricultural production. Conclusions The pollution of heavy metals Cd and Pb in the topsoil of the urban area of Qingyang City and along the Huanjiang—Jinghe River was the most serious among the studied elements, followed by Cr, As, Cu, Zn and Hg. Subregionally, soil heavy metal pollution has occurred in the urban area of Qingyang, and there is a potential ecological risk, mainly human activities. River basins are pollution-free, and the sources of heavy metal enrichment are mainly natural sources and agricultural production. Recommendations and perspectives Although the urban area of Qingyang City and the Huanjiang—Jinghe River Basin as a whole are in a weak ecological risk, it is still necessary to give attention to their ecological risks, and make scientific evaluation and management. This is of great significance to support the benign and sustainable development of Qingyang City’s social economy and to accelerate the pace of ecological civilization construction. |
| Key words: soil environment ecological risk assessment heavy metal pollution the urban area of Qingyang City Huanjiang — Jinghe River Basin |
