College of Environmental Science and Engineering, Guilin University of Technology, Guilin, 541004, PR China.
College of Environmental Science and Engineering, Guilin University of Technology, Guilin, 541004, PR China.
Environ Pollut. 2021 Jan 15;269:116189. doi: 10.1016/j.envpol.2020.116189. Epub 2020 Nov 30.
The Lijiang River is of great ecological and environmental importance for Guilin City, which is located in the karst area of southeast China. Given its importance, a detailed evaluation of the heavy metals (HMs) in the river sediment is required. For the first time, 61 sediment samples were collected along the entire Lijiang River to determine pollution level and ecological risk posed by 10 HMs (Co, Cr, Cu, Mn, Ni, Pb, Zn, As, Hg, and Cd). These were assessed using the geo-accumulation index, potential ecological risk index, and modified degree of contamination. The results showed that the mean concentrations of the majority of HMs exceeded their corresponding background values and followed the trend: midstream > downstream > upstream. Based on the spatial distributions and pollution indices of the 10 HMs, the Lijiang River was found to have a high accumulation of Cd, Hg, Zn, and Pb in the sediments. The midstream area was the most polluted with respect to Cd and Hg, and also posed a relatively higher potential ecological risk than the downstream and upstream areas. The sources of the assessed HMs were inferred based on a correlation analysis and principal component analysis, which identified both natural and anthropogenic sources. A higher pollution potential was associated with Cd, Hg, Pb, and Zn in the midstream and downstream areas due to higher organic and carbonate content, urbanization, agricultural activities, and leisure activities (e.g., boating and cruises). In contrast, natural erosion and weathering processes were responsible for the HM concentrations in the upstream area. The findings of this study will help the local authorities to protect the important water resource of the Lijiang River.
漓江对位于中国东南部喀斯特地区的桂林市具有重要的生态和环境意义。鉴于其重要性，需要对河流沉积物中的重金属（HM）进行详细评估。这是首次在整个漓江采集了 61 个沉积物样本，以确定 10 种重金属（Co、Cr、Cu、Mn、Ni、Pb、Zn、As、Hg 和 Cd）对河流沉积物的污染水平和生态风险。这些通过地积累指数、潜在生态风险指数和修正的污染程度进行评估。结果表明，大多数重金属的平均浓度超过了相应的背景值，其趋势为：中游>下游>上游。根据 10 种重金属的空间分布和污染指数，发现漓江沉积物中 Cd、Hg、Zn 和 Pb 有很高的积累。中游地区 Cd 和 Hg 的污染最严重，与下游和上游地区相比，潜在生态风险也相对较高。根据相关性分析和主成分分析推断了评估的重金属来源，确定了自然和人为来源。由于较高的有机和碳酸盐含量、城市化、农业活动和休闲活动（如划船和游船），中游和下游地区的 Cd、Hg、Pb 和 Zn 具有更高的污染潜力。相比之下，上游地区的重金属浓度是由自然侵蚀和风化过程造成的。本研究的结果将有助于地方当局保护漓江这一重要的水资源。
