Laboratório de Traçadores em Ciências Ambientais Wolfgang Christian Pfeiffer, IBCCF, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373, CEP 21941-902, Rio de Janeiro, RJ, Brazil.
Norman B. Keevil Institute of Mining Engineering, University of British Columbia, Vancouver, BC, Canada.
Ecotoxicology. 2023 May;32(4):429-437. doi: 10.1007/s10646-023-02651-w. Epub 2023 Apr 13.
Artisanal and small-scale gold mining (ASGM) is the largest source of anthropogenic Hg emissions on the planet. In addition, Hg-contaminated tailings are often reprocessed with sodium cyanide (NaCN) to extract the residual gold remaining in the material. This leads to the formation of mercury cyanide (Hg(CN)) complexes, which are often discharged in untreated form into local drainages, leading to large amounts of free cyanide being released. However, data on mercury-cyanide interactions are scarce. In this study, we investigated the impact of cyanide and Hg bioavailability in zebrafish when added as Hg(CN). Different concentrations of Hg(CN) and NaCN were used, leading to an LC of 0.53 mg.L for NaCN and 0.16 mg.L for Hg(CN). Analyzing free cyanide concentrations in aquarium water, >40% dissociation was observed for NaCN and about 5% for Hg(CN). The accumulation of total Hg (THg) in the brain, gills, muscle and kidney was quantified. All fish exposed to Hg(CN) had higher THg levels than their controls and kidney was the tissue with higher Hg(CN) accumulation. Histological effects on the kidney and gills of both cyanides in D. rerio tissues were investigated, suggesting renal alterations in fish exposed to Hg(CN) and showing hyperplasia in the gills of animals exposed to NaCN and Hg(CN). The results alert to the risks of the presence of these complexes in aquatic environments.
手工和小规模采金（ASGM）是地球上人为汞排放的最大来源。此外，受汞污染的尾矿通常用氰化钠（NaCN）重新处理，以提取材料中残留的金。这导致形成汞氰化物（Hg(CN)）复合物，这些复合物通常未经处理就排放到当地的排水沟中，导致大量游离氰化物释放。然而，关于汞-氰化物相互作用的数据很少。在这项研究中，我们研究了当添加为 Hg(CN)时，氰化物和 Hg 生物利用度对斑马鱼的影响。使用了不同浓度的 Hg(CN)和 NaCN，导致 NaCN 的 LC 为 0.53 mg.L，Hg(CN)为 0.16 mg.L。分析水族馆水中的游离氰化物浓度，观察到 NaCN 有超过 40%的解离，而 Hg(CN)约有 5%的解离。定量了大脑、鳃、肌肉和肾脏中总汞（THg）的积累。所有暴露于 Hg(CN)的鱼的 THg 水平都高于其对照鱼，并且肾脏是积累 Hg(CN)的组织。研究了这两种氰化物在 D. rerio 组织中的肾脏和鳃的组织学效应，表明暴露于 Hg(CN)的鱼的肾脏发生了变化，并显示出暴露于 NaCN 和 Hg(CN)的动物的鳃增生。这些结果提醒人们注意这些复合物在水生环境中的存在所带来的风险。
