College of Mining, Liaoning Technical University, Fuxin, China.
Research Station on Mechanics for Postdoctoral Fellows, Liaoning Technical University, Fuxin, China.
PLoS One. 2019 Aug 9;14(8):e0220409. doi: 10.1371/journal.pone.0220409. eCollection 2019.
Wetlands are recognized as one of the most important natural environments for humans. At the same time, heavy metal pollution has an important impact on wetlands. China's Raoyanghe Wetland is one of the most important natural wild species gene banks in China. Eight heavy metal elements (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in surface layer and deep layer soils were analyzed using statistical-, pollution index-, and Nemerow index-based methods, the Hakanson potential ecological risk index method, and principal component and cluster analyses. The results showed that the maximum concentrations of heavy metals exceeded the background values in the core area and buffer zone of the wetland, but the heavy metal content of the soils was generally low and did not exceed 30%. With the exception of Hg, heavy metal concentrations showed strong spatial differentiation. The differences between the surface layer and deep layer soils of the core area were smaller than in the buffer zone. With the exception of Cd, a clear vertical zonation in the buffer zone soils was observed, showing greater evidence of external influences in this zone than the core. With the exception of partial surface soils, which indicated a safe level of pollution in the core area, all other soils were classified as having a 'mild' level of pollution. Thus, the wetland is moderately polluted, with both the core area and the buffer zone presenting a low level of potential ecological risk. According to the results of the present study, heavy metal contaminants in the wetland soils were found to be derived mainly from the natural sources.
湿地被认为是人类最重要的自然环境之一。同时，重金属污染对湿地有重要影响。中国饶阳河湿地是中国最重要的自然野生物种基因库之一。本研究采用统计法、污染指数法、内梅罗指数法、Hakanson 潜在生态风险指数法以及主成分和聚类分析，对表层和深层土壤中的 8 种重金属元素（As、Cd、Cr、Cu、Hg、Ni、Pb 和 Zn）进行了分析。结果表明，在湿地核心区和缓冲区，重金属最大浓度超过了背景值，但土壤重金属含量普遍较低，未超过 30%。除 Hg 外，重金属浓度表现出较强的空间分异。核心区表层和深层土壤之间的差异较小，而缓冲区则较大。除 Cd 外，缓冲区土壤具有明显的垂直分带，表明该区域受外部影响较大。除部分表层土壤显示出核心区污染处于安全水平外，其余土壤均被归类为“轻度”污染。因此，湿地受到中度污染，核心区和缓冲区均表现出低水平的潜在生态风险。根据本研究结果，发现湿地土壤中的重金属污染物主要来源于自然源。
