São Paulo State University-UNESP, Praça Infante Dom Henrique, São Vicente, São Paulo, Brazil.
School for Environment and Sustainability, University of Michigan, Ann Arbor, Michigan, USA.
Integr Environ Assess Manag. 2024 Jan;20(1):148-158. doi: 10.1002/ieam.4785. Epub 2023 Jun 7.
The Fundão mine tailings dam rupture of 2015, in the Rio Doce basin, Brazil, resulted in the deposition of tailings downstream of the dam. It has yet to be determined if metals associated with the tailings have contributed toxicity to organisms, burying a time bomb that could be ticking. Currently the data on toxicity to benthic and aquatic organisms have not been assessed sufficiently to allow an informed assessment using an approach based on weight-of-evidence. This study was conducted to ascertain if sediments at "hot spots" that received Fundão tailings reflected elevated concentrations of metals and if these concentrations were sufficient to result in toxicity to freshwater organisms. The lines-of-evidence considered included assessing metals concentrations in relation to sediment quality criteria, establishing biogeochemical characterizations, completing an evaluation of potential metal release upon resuspension to provide information on bioavailability, and identifying acute and chronic toxicity effects using sensitive native species for waters (water flea, Daphnia similis) and sediments (burrowing midge larvae, Chironomus sancticaroli). Only porewater concentrations of iron and manganese exceeded Brazilian surface water criteria, whereas most trace elements exhibited no enrichment or elevated environmental indexes. The concentrations of bioavailable metals were assessed to be low, and metal concentrations did not increase in the overlying water upon resuspension; rather, they decreased through time. Toxicity testing in resuspended waters and bulk sediments resulted in no acute or chronic toxicity to either benthic or aquatic species. The low metal bioavailability and absence of toxicity of the tailings-enriched sediments was attributed to the strong binding and rapid removal of potentially toxic metal ions caused by oxyhydroxides and particles in the presence of iron-rich particulates. The findings of these sediment hot-spot studies indicate the Fundão dam release of tailings more than six years ago is not causing the current release of toxic concentrations of metals into the freshwaters of the Rio Doce. Integr Environ Assess Manag 2024;20:148-158. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
2015 年巴西里约热内卢流域丰当矿尾矿坝溃坝，导致尾矿在坝下游沉积。目前还不能确定与尾矿有关的金属是否对生物产生了毒性，埋下了一颗可能正在滴答作响的定时炸弹。目前，关于底栖生物和水生生物毒性的数据还没有得到充分评估，无法使用基于证据权重的方法进行知情评估。本研究旨在确定接收丰当尾矿的“热点”沉积物中是否反映出金属浓度升高，以及这些浓度是否足以对淡水生物产生毒性。所考虑的证据线索包括评估金属浓度与沉积物质量标准的关系，确定生物地球化学特征，评估重新悬浮时潜在金属释放的情况，以提供生物可利用性信息，以及使用对水（水蚤，Daphnia similis）和沉积物（潜蝇幼虫，Chironomus sancticaroli）敏感的本地物种来识别急性和慢性毒性效应。只有铁和锰的孔隙水浓度超过了巴西地表水标准，而大多数痕量元素没有富集或环境指数升高。生物可利用金属的浓度被评估为低，并且重新悬浮时上层水中的金属浓度没有增加，而是随着时间的推移而减少。重新悬浮水和原状沉积物的毒性测试对底栖或水生物种均未产生急性或慢性毒性。尾矿富集中的沉积物金属生物可利用性低且没有毒性，这归因于在富含铁颗粒的存在下，铁氧化物和颗粒对潜在有毒金属离子的强烈结合和快速去除。这些沉积物热点研究的结果表明，丰当大坝尾矿的释放已经超过六年，不会导致里约热内卢河淡水目前释放出有毒浓度的金属。《综合环境评估与管理》2024 年；20：148-158。©2023 作者。综合环境评估与管理由 Wiley Periodicals LLC 代表环境毒理与化学学会（SETAC）出版。
