Li Guo-Zhan, Wang Xiao-Yu, Yan Meng-Xia, Chen Wen-Ke, Zhang Qing-Hui, Zhang En-Lou, Liu En-Feng
College of Geography and Environment, Shandong Normal University, Jinan 250358, China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
Huan Jing Ke Xue. 2023 Oct 8;44(10):5536-5545. doi: 10.13227/j.hjkx.202211058.
Based on the analysis of the total concentrations of 10 metals in the sediment core and total concentrations and chemical fractions of seven metals in the surface sediments of Qionghai Lake in Xichang City, Sichuan Province, the spatial-temporal characteristics of metal accumulation and pollution over the past century and the potential ecological risk of metals in surface sediments were studied. Before the 1970s, metal concentrations in the sediment core were stable. The total concentrations of Al, Fe, K, and Cr in the sediment core exhibited visible peaks in the 1970s, which were related to the enhanced input of fine-grained topsoil caused by increasing precipitation, lake reclamation, and deforestation. Since the 1990s, the total concentrations of Al, Fe, K, and Cr decreased with the reduced topsoil erosion, whereas the total concentrations of As, Cd, Cu, Pb, and Zn gradually increased or remained stable. The enrichment factor results showed that Cd, Pb, and Zn were the main contaminants, with Cd as the typical contaminant in the sediment core. The Cd contamination started in the 1960s and has remained at a moderate level since the 1990s. In the surface sediments, the total concentrations of Cd were higher in the northwest lake area, and no visible spatial concentration trends of the other metals were displayed. The bioavailable fractions of Cd, Pb, and Zn accounted for 95%, 63%, and 48% of the total metal concentrations on average. Among the bioavailable fractions, Cd was mainly in the acid-soluble fraction, and Pb and Zn were mainly in the reducible and oxidized fractions. The bioavailable fractions of the other metals were less than 27%. The results of total concentrations and bioavailable fractions of metals revealed that Pb and Zn in the surface sediments were slightly or moderately contaminated, and Cd was moderately contaminated on average. Cd contamination was at a severe level in the northwest lake area. The concentrations of anthropogenic Cd, Pb, and Zn in the surface sediments estimated from the total and bioavailable concentrations were comparable (>0.05), indicating that anthropogenic metals primarily existed in bioavailable fractions in the sediment. Integrating the assessment results from sediment quality guidelines, potential ecological risk index, and chemical forms of metals, Cd in surface sediments may pose a high ecological risk, whereas the other metals has a low ecological risk.
通过对四川省西昌市邛海湖沉积物岩芯中10种金属的总浓度以及表层沉积物中7种金属的总浓度和化学形态进行分析，研究了过去一个世纪金属积累和污染的时空特征以及表层沉积物中金属的潜在生态风险。20世纪70年代以前，沉积物岩芯中的金属浓度较为稳定。沉积物岩芯中Al、Fe、K和Cr的总浓度在20世纪70年代出现明显峰值，这与降水增加、围湖造田和森林砍伐导致的细颗粒表土输入增加有关。自20世纪90年代以来，随着表土侵蚀减少，Al、Fe、K和Cr的总浓度下降，而As、Cd、Cu、Pb和Zn的总浓度逐渐上升或保持稳定。富集因子结果表明，Cd、Pb和Zn是主要污染物，Cd是沉积物岩芯中的典型污染物。Cd污染始于20世纪60年代，自20世纪90年代以来一直保持在中等水平。在表层沉积物中，Cd的总浓度在湖西北区域较高，其他金属未呈现明显的空间浓度趋势。Cd、Pb和Zn的生物可利用态平均分别占总金属浓度的95%、63%和48%。在生物可利用态中，Cd主要存在于酸溶态，Pb和Zn主要存在于可还原态和氧化态。其他金属的生物可利用态小于27%。金属总浓度和生物可利用态的结果表明，表层沉积物中的Pb和Zn受到轻度或中度污染，Cd平均受到中度污染。Cd污染在湖西北区域处于严重水平。根据总浓度和生物可利用浓度估算的表层沉积物中人为源Cd、Pb和Zn的浓度具有可比性（>0.05），表明人为源金属主要以生物可利用态存在于沉积物中。综合沉积物质量准则、潜在生态风险指数和金属化学形态的评估结果，表层沉积物中的Cd可能构成高生态风险，而其他金属的生态风险较低。
