College of Agriculture, Guizhou University, Guiyang, 550025, China.
Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guiyang, 550025, China.
Environ Sci Pollut Res Int. 2022 Feb;29(10):14288-14298. doi: 10.1007/s11356-021-16824-9. Epub 2021 Oct 4.
Reservoir sediment contamination with heavy metals produced by mining activities has aroused widespread global concern owing to its potential threat to human health. In this study, the total concentrations and speciation of heavy metals (Cd, Pb, Zn) in the Lexi (LX) and Maoshui (MS) reservoirs around the historical artisanal zinc smelting area in Southwest China were determined, and pollution indices were applied to assess the pollution levels and potential ecological risks of the two reservoirs. The results showed that all the detected samples in the two reservoirs presented significant metal accumulation, especially for Cd, as compared with the soil background values in Guizhou Province. Between the two reservoirs, the vertical distribution characteristics of each metal in sediment columns were similar. The heavy metal concentrations of the three columns in the LX reservoir reached their maxima at 35, 15, and 10 cm and showed a trend of first increasing and then decreasing overall. However, the heavy metal contents of the three columns in the MS reservoir all exhibited wave-like characteristics in the vertical direction, and all of them reached a relatively obvious high point at approximately 5 and 30 cm. The geoaccumulation index (I) and potential ecological risk index (RI) indicated that Cd was strongly enriched and represented the main risk factor, and the pollution level of the MS reservoir was significantly higher than that of the LX reservoir. Furthermore, the effect coefficients (ERMQ) confirmed that the two reservoirs are likely to have toxic impacts on aquatic organisms and need to be controlled and mitigated. The speciation analysis of heavy metals revealed that Cd was primarily in the acid-extractable fraction (69.57%, 68.28%), Pb was chiefly in the reducible fraction (55.24%, 42.18%) and oxidizable fraction (22.60%, 38.02%), and Zn was mainly in the oxidizable fraction (32.54%, 37.65%) in the LX and MS reservoirs, respectively. The ratios of the secondary phase and primary phase (RSP) and risk assessment code (RAC) evaluation demonstrated that Cd in the sediments of the two reservoirs presents a very high potential ecological risk, and Pb and Zn were at medium to high ecological risk levels. This study highlighted that the artisanal zinc smelting activities had caused serious heavy metal pollution in reservoir sediments, posing a threat to the local ecological environment.
采矿活动导致的水库沉积物重金属污染引起了全球广泛关注，因为它可能对人类健康造成威胁。本研究测定了中国西南部历史手工炼锌区周边雷西（LX）和猫水（MS）水库中重金属（Cd、Pb、Zn）的总量和形态，应用污染指数评估了两个水库的污染水平和潜在生态风险。结果表明，与贵州省土壤背景值相比，两个水库的所有检测样本均表现出显著的金属积累，尤其是 Cd。两个水库沉积物柱中各金属的垂直分布特征相似。LX 水库中三个柱状物的重金属浓度在 35、15 和 10cm 处达到最大值，总体呈先增后减的趋势。然而，MS 水库中三个柱状物的重金属含量在垂直方向上均呈波浪状特征，且均在约 5 和 30cm 处达到一个相对明显的高点。地积累指数（I）和潜在生态风险指数（RI）表明 Cd 强烈富集，是主要的风险因素，MS 水库的污染水平明显高于 LX 水库。此外，效应系数（ERMQ）证实，两个水库可能对水生生物产生毒性影响，需要加以控制和缓解。重金属形态分析表明，Cd 主要以酸可提取态（69.57%，68.28%）存在，Pb 主要以可还原态（55.24%，42.18%）和可氧化态（22.60%，38.02%）存在，Zn 主要以可氧化态（32.54%，37.65%）存在于 LX 和 MS 水库中。次生相与原生相比值（RSP）和风险评估码（RAC）评价表明，两个水库沉积物中的 Cd 具有极高的潜在生态风险，Pb 和 Zn 处于中高生态风险水平。本研究表明，手工炼锌活动导致水库沉积物中重金属严重污染，对当地生态环境构成威胁。
