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Remobilization of legacy arsenic from sediment in a large subarctic waterbody impacted by gold mining
Journal of Hazardous Materials ( IF 13.6 ) Pub Date : 2023-03-16 , DOI: 10.1016/j.jhazmat.2023.131230
John Chételat 1 , Michael J Palmer 2 , Katrina Paudyn 3 , Heather Jamieson 3 , Marc Amyot 4 , Reed Harris 5 , Raymond Hesslein 6 , Nicolas Pelletier 7 , Ines Peraza 1
Affiliation  

Arsenic contamination from mining poses an environmental challenge due to the mobility of this redox-sensitive element. This study evaluated arsenic mobility in sediments of Yellowknife Bay (Canada), a large subarctic water body impacted by gold mining during the 20th century. Short-term measurements of arsenic flux from sediment, arsenic profiling of the water column and sediment porewater, and mass balance modelling were conducted to assess the importance of sediment as an arsenic source. Sediment arsenic fluxes were highly variable throughout Yellowknife Bay and ranged from − 65–1520 µg m−2 day−1. Elevated fluxes measured near the mine site were among the highest published for well-oxygenated lakes. Redox boundaries were typically 2–3 cm below the sediment surface as indicated by porewater profiles of iron, manganese, and arsenic, with arsenic maxima of 65–3220 µg L−1 predominately as arsenite. Sediment arsenic flux was positively related to its solid-phase concentration. Modelling indicated sediment was a principal source of arsenic to the water column. Adsorption and precipitation processes in the oxidizing environment of near-surface sediments did not effectively attenuate arsenic remobilized from contaminated sediments. Internal recycling of legacy arsenic between sediment and surface water will impede a return to background conditions in Yellowknife Bay for decades.



中文翻译:

在受金矿开采影响的大型亚北极水体中从沉积物中再活化遗留砷

由于这种氧化还原敏感元素的流动性,采矿造成的砷污染对环境构成了挑战。本研究评估了耶洛奈夫湾(加拿大)沉积物中砷的流动性,耶洛奈夫湾是 20 世纪受金矿开采影响的大型亚北极水体。对沉积物中砷通量的短期测量、水柱和沉积物孔隙水的砷分析以及质量平衡模型进行了评估,以评估沉积物作为砷源的重要性。整个耶洛奈夫湾的沉积物砷通量变化很大,范围为 − 65–1520 µg m −2 day −1. 在矿区附近测得的通量升高是已发表的氧化良好湖泊中最高的通量之一。氧化还原边界通常在沉积物表面以下 2-3 厘米处,如铁、锰和砷的孔隙水剖面所示,最大砷含量为 65-3220 µg L -1 ,主要为亚砷酸盐。沉积物砷通量与其固相浓度呈正相关。模型表明沉积物是水柱中砷的主要来源。近地表沉积物氧化环境中的吸附和沉淀过程并不能有效减少从受污染沉积物中再活化的砷。沉积物和地表水之间遗留砷的内部循环将阻碍黄刀湾几十年来恢复到背景条件。

更新日期:2023-03-16
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