| 黄河干流沉积物重金属的赋存形态特征及污染评价 |
| 摘要点击 1162 全文点击 351 投稿时间：2023-01-13 修订日期：2023-02-18 |
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| 中文关键词 黄河 重金属(HMs) 沉积物 赋存形态 污染评价 |
| 英文关键词 Yellow River heavy metals(HMs) sediment chemical fraction pollution assessment |
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| 中文摘要 |
| 重金属毒性强、在环境中不易降解，可通过食物链在人体累积，进而对流域生态环境及人类健康产生严重影响.2019年9月，沿黄河干流调查了14个断面，分析了沉积物中6种重金属（As、Cd、Cr、Cu、Pb和Zn）的总量及其赋存形态，采用地累积指数法、潜在生态风险指数法和风险评价编码法对沉积物重金属污染程度和生物有效性进行风险评价，采用主成分分析和冗余分析解析了重金属的主要来源.结果发现，重金属的含量平均值排序为：Cr>Zn>Cu>Pb>As>Cd，相对于各河段的背景值，Cd的超标率最高，达到85.7%.沉积物中As、Zn、Pb和Cu均以可氧化态为主，Cd以弱酸溶解态和残渣态为主，Cr则以残渣态为主.As、Cr、Cu、Pb和Zn的生物有效性均表现出上游最低，中游升高，下游降低的趋势.风险评价表明Cd是黄河干流污染风险级别最高的元素，极易对生态环境造成严重的威胁，应当优先防控，尤其是干流内蒙古段.PCA和RDA分析揭示了细颗粒泥沙和总有机质对重金属污染的主控作用，因此在黄河流域应重点防控随土壤侵蚀和泥沙迁移流失的重金属污染. |
| 英文摘要 |
| Heavy metals(HMs) are highly toxic and do not easily degrade in the environment. They can accumulate in the human body through the food chain, with serious impacts on the ecological environment and human health. In this study, 14 sampling sites along the mainstream of the Yellow River were investigated, and the total content and chemical fractions of six heavy metals(As, Cd, Cr, Cu, Pb, and Zn) in sediments were analyzed. The geo-accumulation index, potential ecological risk index, and risk assessment coding were used to assess the contamination level and bioavailability of HMs in sediment. Principal component analysis and redundancy analysis were used to identify the main sources of HMs. The results showed that the average content of heavy metals was in the order of Cr>Zn>Cu>Pb>As>Cd. Cd had the highest excess rate relative to the background value of each reach, reaching 85.7%. In the sediments, As, Zn, Pb, and Cu were predominantly in the oxidizable fraction(F3:sulfide and organic matter-bound), Cd was mainly occupied by the acid-soluble(F1:exchangeable and carbonate-bound) and a residual fraction(F4:mineral matrix-bound), and Cr was predominantly in the residual fraction. As, Cr, Cu, Pb, and Zn showed the lowest bioavailability in the upstream, increased in the midstream, and finally decreased in the downstream. The risk assessment showed that Cd, the element with the highest pollution risk level in the Yellow River, was prone to pose a serious threat to the ecological environment and should be prevented and controlled first. The PCA and RDA analyses revealed that fine sediment and total organic matter controlled HMs contamination. Therefore, the prevention and control of soil erosion and sediment migration should be emphasized to control HMs pollution in the Yellow River Basin. |
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