Lidman Johan, Olid Carolina, Bigler Christian, Berglund Åsa M M
Department of Ecology and Environmental Science, Umeå University, SE-90187 Umeå, Sweden.
Department of Ecology and Environmental Science, Umeå University, SE-90187 Umeå, Sweden; Department of Forestry and Management, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden; Department of Earth and Ocean Dynamics, University of Barcelona, ES-08028 Barcelona, Spain.
Sci Total Environ. 2023 May 10;872:162097. doi: 10.1016/j.scitotenv.2023.162097. Epub 2023 Feb 9.
The release of toxic metals from local mining activities often represents a severe environmental hazard for nearby lake ecosystems. Previous studies on the impact of mining have primarily focused on single lakes, with less emphasis on spatial and temporal recovery patterns of multiple lakes within the same catchment, but with different hydrological connection and distance to the pollutant source. This knowledge gap prevents us from assessing the real environmental risk of abandoned mines and understanding ecosystem recovery. This study explores the intensity and spatial patterns of sediment contamination and the potential for ecosystem recovery in three lakes in close vicinity of a lead (Pb) and zinc (Zn) mine in Sweden that has been inoperative for >20 years. Dated (Pb and Cs) sediment cores from each lake were used to reconstruct temporal patterns in trace element deposition and relate those with past mining activities. Results show that all lakes were affected by mining, indicated by increasing Pb and Zn concentrations and decreasing organic matter content, at the onset of mining. However, the extent and timing of mining impact differed between lakes, which was partly ascribed to differences in the historical use of tailings and settling ponds. Assessment of toxicity levels in sediments, based on normalized Probable Effect Concentration Quotient (PEC-Q) to organic matter content, provided more consistent results with the historical mining than conventional methods, showing a decreasing impact in lakes once the operations ceased. Still, sediment Pb concentrations were > 10 times higher than pre-mining values, evidencing the urgent need for remediation actions in the study lakes. This study highlights the importance of considering spatial heterogeneity in metal deposition, sediment organic matter content, and hydrological connectivity with tailings when risk assessments are performed in mining-impacted lakes. The use of normalized PEC-Q in toxic assessments is also recommended.
当地采矿活动中有毒金属的释放通常对附近的湖泊生态系统构成严重的环境危害。以往关于采矿影响的研究主要集中在单个湖泊，较少关注同一集水区内多个湖泊的时空恢复模式，这些湖泊具有不同的水文联系和与污染源的距离。这种知识空白阻碍了我们评估废弃矿山的实际环境风险并理解生态系统的恢复情况。本研究探讨了瑞典一座已停产20多年的铅（Pb）锌（Zn）矿附近三个湖泊中沉积物污染的强度和空间模式以及生态系统恢复的潜力。利用每个湖泊的年代测定（Pb和Cs）沉积物岩芯来重建微量元素沉积的时间模式，并将其与过去的采矿活动联系起来。结果表明，在采矿开始时，所有湖泊都受到了采矿的影响，表现为Pb和Zn浓度增加以及有机质含量下降。然而，各湖泊采矿影响的程度和时间不同，部分原因是尾矿和沉淀池的历史使用存在差异。基于归一化的可能效应浓度商（PEC-Q）与有机质含量对沉积物毒性水平进行评估，与传统方法相比，在反映历史采矿情况方面提供了更一致的结果，表明一旦采矿作业停止，湖泊受到的影响就会减小。尽管如此，沉积物中的Pb浓度仍比采矿前的值高出10倍以上，这表明研究湖泊迫切需要采取修复行动。本研究强调了在对受采矿影响的湖泊进行风险评估时，考虑金属沉积的空间异质性、沉积物有机质含量以及与尾矿的水文连通性的重要性。还建议在毒性评估中使用归一化的PEC-Q。
