Gabriel Fabrício Â, Hauser-Davis Rachel Ann, Soares Lorena, Mazzuco Ana Carolina A, Rocha Rafael Christian Chavez, Saint Pierre Tatiana D, Saggioro Enrico, Correia Fabio Verissimo, Ferreira Tiago O, Bernardino Angelo F
Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo, Brasil.
Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brasil.
PeerJ. 2020 Oct 28;8:e10266. doi: 10.7717/peerj.10266. eCollection 2020.
The Rio Doce estuary, in Brazil, was impacted by the deposition of iron mine tailings, caused by the collapse of a dam in 2015. Based on published baseline datasets, the estuary has been experiencing chronic trace metal contamination effects since 2017, with potential bioaccumulation in fishes and human health risks. As metal and metalloid concentrations in aquatic ecosystems pose severe threats to the aquatic biota, we hypothesized that the trace metals in estuarine sediments nearly two years after the disaster would lead to bioaccumulation in demersal fishes and result in the biosynthesis of metal-responsive proteins.
We measured As, Cd, Cr, Cu, Fe, Mn, Pb, Se and Zn concentrations in sediment samples in August 2017 and compared to published baseline levels. Also, trace metals (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb, Se and Zn) and protein (metallothionein and reduced glutathione) concentrations were quantified in the liver and muscle tissues of five fish species (, , , and sp.) from the estuary, commonly used as food sources by local populations.
Our results revealed high trace metal concentrations in estuarine sediments, when compared to published baseline values for the same estuary. The demersal fish species and had the highest concentrations of As, Cr, Mn, Hg, and Se in both, hepatic and muscle, tissues. Trace metal bioaccumulation in fish was correlated with the biosynthesis of metallothionein and reduced glutathione in both, liver and muscle, tissues, suggesting active physiological responses to contamination sources. The trace metal concentrations determined in fish tissues were also present in the estuarine sediments at the time of this study. Some elements had concentrations above the maximum permissible limits for human consumption in fish muscles (e.g., As, Cr, Mn, Se and Zn), suggesting potential human health risks that require further studies. Our study supports the high biogeochemical mobility of toxic elements between sediments and the bottom-dwelling biota in estuarine ecosystems.
巴西的多西河河口在2015年一座大坝坍塌后受到铁矿尾矿沉积的影响。根据已发表的基线数据集，自2017年以来，该河口一直受到慢性痕量金属污染影响，存在鱼类生物累积和人类健康风险。由于水生生态系统中的金属和类金属浓度对水生生物群构成严重威胁，我们推测灾难发生近两年后河口沉积物中的痕量金属会导致底栖鱼类生物累积，并引发金属响应蛋白的生物合成。
我们于2017年8月测量了沉积物样本中的砷、镉、铬、铜、铁、锰、铅、硒和锌浓度，并与已发表的基线水平进行比较。此外，还对河口的五种鱼类（、、、和sp.）的肝脏和肌肉组织中的痕量金属（砷、镉、铬、铜、铁、汞、锰、铅、硒和锌）和蛋白质（金属硫蛋白和还原型谷胱甘肽）浓度进行了定量，这些鱼类是当地居民常用的食物来源。
与同一河口已发表的基线值相比，我们的结果显示河口沉积物中痕量金属浓度很高。底栖鱼类和在肝脏和肌肉组织中砷、铬、锰、汞和硒的浓度最高。鱼类中的痕量金属生物累积与肝脏和肌肉组织中金属硫蛋白和还原型谷胱甘肽的生物合成相关，表明对污染源有积极的生理反应。本研究时在鱼类组织中测定的痕量金属浓度在河口沉积物中也存在。一些元素在鱼类肌肉中的浓度高于人类消费的最大允许限值（如砷、铬、锰、硒和锌），表明存在潜在的人类健康风险，需要进一步研究。我们的研究支持了河口生态系统中沉积物和底栖生物群之间有毒元素的高生物地球化学流动性。
