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| DOI：10.13522/j.cnki.ggps.2019454 |
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| Distribution Characteristics and Risk Assessment of Heavy Metals in Qingshui River Basin of Ningxia |
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LI Shilong, ZHAO Zengfeng, QIU Xiaocong, GUO Qi, WU Yueling
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1.School of Civil and Hydraulic Engineering, Ningxia University, Yinchuan 750021, China；2.School of Life Science, Ningxia University, Yinchuan 750021, China
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| Abstract: |
| 【Objective】Arsenic (As), chromium (Cr), mercury (Hg) and lead (Pb) in water and surface sediments at 32 sampling sites in Qingshui River basin were monitored in April, July and November 2018 to explore the distribution characteristics and pollution of heavy metals there. 【Method】Principal component method and cluster analysis method were used to analyze the source of heavy metal pollution. The Nemerow comprehensive index method was used to evaluate the heavy metal pollution in water. The heavy metal pollution of surface sediments was evaluated by the potential ecological risk index. 【Result】The results indicated that the annual average contents of As, Pb, Hg, and Cr in Qingshui River water were 3.68, 0.37, 0.23, and 69.27 μg/L, only Cr more than surface water Ⅳ class standard. And the four heavy metal concentrations decreased in the order of November＞April＞July. The annual average contents of As, Cr, Pb, and Hg in surface sediments were 68.2%, 46.3%, 39.9%, and 130% of the standard values, with only Hg exceeded the soil background value. And the four heavy metal concentrations decreased in the order of November＞April＞July. The degree of heavy metal contamination in the water of Qingshui River decreased in the following order of Cr＞Hg＞As＞Pb with the method of Nemerow comprehensive pollution index, and Cr was the main pollution heavy metal. Potential Ecological Risk Index Method was used for evaluating the risk of four heavy metals in surface sediments of Qingshui River basin. The order of risk degree was Hg＞As＞Pb＞Cr, and Hg was the main ecological risk factor. Both principal component and cluster analysis method classified water and sediment heavy metals into three categories. Cr in water was mainly controlled by human factors,while As, Hg, and Pb were mainly affected by natural geological factors. As, Cr, and Pb in the sediments were mainly affected by natural geological factors, and Hg was mainly controlled by human factors.【Conclusion】In general, Cr pollution in water and Hg pollution in sediments should be paid attention to. |
| Key words: basin; heavy metal; distribution characteristics; risk assessment |
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