Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Barcelona 08034, Catalonia, Spain; University of Barcelona, Barcelona 08028, Catalonia, Spain.
Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Barcelona 08034, Catalonia, Spain; University of Barcelona, Barcelona 08028, Catalonia, Spain.
Sci Total Environ. 2021 Sep 20;788:147579. doi: 10.1016/j.scitotenv.2021.147579. Epub 2021 May 7.
Adverse impacts of mine tailings on water and sediments quality are major worldwide environmental problems. Due to the environmental issues associated with the deposition of mine tailings on land, a controversial discussed alternative is submarine tailings disposal (STD). However, Fe(III) bioreduction of iron oxides (e.g., magnetite) in the tailings disposed might cause toxic effects on coastal environments due to the release of different trace elements (TEs) contained in the oxides. To study the extent and kinetics of magnetite bioreduction under marine conditions and the potential release of TEs, a number of batch experiments with artificial seawater (pH 8.2) and a marine microbial strain (Shewanella loihica) were performed using several magnetite ore samples from different mines and a mine tailings sample. The elemental composition of the magnetite determined in the tailings showed relatively high amounts of TEs (e.g., Mn, Zn, Co) compared with those of the magnetite ore samples (LA-ICP-MS and EMPA analyses). The experiments were conducted at 10 °C in the dark for up to 113 days. Based on the consumption of lactate and production of acetate and aqueous Fe(II) over time, the magnitude of Fe(III) bioreduction was calculated using a geochemical model including Monod kinetics. Model simulations reproduced the release of iron and TEs observed throughout the experiments, e.g., Mn (up to 203 μg L), V (up to 79 μg L), As (up to 17 μg L) and Cu (up to 328 μg L), suggesting a potential contamination of pore water by STD. Therefore, the results of this study can help to better evaluate the potential impacts of STD.
矿山尾矿对水和沉积物质量的不良影响是全球主要的环境问题。由于尾矿在陆地上沉积所带来的环境问题，人们对海底尾矿处置（STD）这一颇具争议的替代方案展开了讨论。然而，尾矿中氧化铁（如磁铁矿）的 Fe(III) 生物还原可能会由于氧化物中所含的不同痕量元素（TEs）的释放而对沿海环境造成毒害作用。为了研究海洋条件下磁铁矿生物还原的程度和动力学以及 TEs 的潜在释放，使用来自不同矿山的几种磁铁矿矿石样品和一种尾矿样品，在人工海水（pH 8.2）和一种海洋微生物菌株（希瓦氏菌属）中进行了一系列批处理实验。尾矿中磁铁矿的元素组成显示出相对较高含量的 TEs（例如 Mn、Zn、Co），与磁铁矿矿石样品相比（LA-ICP-MS 和 EMPA 分析）。实验在黑暗中于 10°C 下进行，最长达 113 天。基于随时间推移乳酸盐的消耗和乙酸盐和水合 Fe(II) 的生成，使用包括 Monod 动力学在内的地球化学模型计算 Fe(III) 生物还原的幅度。模型模拟再现了整个实验过程中观察到的铁和 TEs 的释放，例如 Mn（高达 203μg/L）、V（高达 79μg/L）、As（高达 17μg/L）和 Cu（高达 328μg/L），表明 STD 可能会污染孔隙水。因此，本研究的结果可以帮助更好地评估 STD 的潜在影响。
