Instituto de Biofísica Carlos Chagas Filho, Laboratório de Estudos Ambientais Olaf Malm, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, RJ, 21941-900, Brazil.
Instituto de Ciências Biológicas. Laboratório de Limnologia, Ecotoxicologia E Ecologia Aquática, Universidade Federal de Minas Gerais, Belo Horizonte, MG, 31270-901, Brazil.
Environ Monit Assess. 2024 Oct 22;196(11):1089. doi: 10.1007/s10661-024-13199-5.
The increase of mercury (Hg) concentrations in abiotic and biotic compartments of aquatic ecosystems following the river impoundment for building a hydroelectric reservoir is one of many environmental and social impacts that the construction of hydroelectric plants can trigger. Yet, long-term studies in Amazon reservoirs are still scarce. The present study aimed to understand the effects of dam impoundment in THg concentrations in an Amazon reservoir up to 35 years of its creation. On March 2019 (35th year after filling), samples of fish, soil, and sediments were collected in the Tucuruí reservoir. Total mercury (THg) concentrations were determinate in those samples and compared with data extract from previous studies referring to the 6, 16 and 18 years after the reservoir filling. Fish from different guilds at the 6th year after filling the Tucuruí reservoir had high THg concentrations, and those decreased in the 16 and 18 years, then the concentrations increased again in the 35 year after filling. For soils and sediments, a decline in THg concentrations was observed. These results differ from previous studies that predicted that Hg concentrations in fish would return to natural concentrations within 30 years in temperate zones and no decline of THg concentrations would be observed for Amazonian reservoirs. The Tocantins river drainage basin has been subjected to multiple anthropic disturbances and land use changes over the past decades, such as the implementation of new hydroelectric plants, deforestation, and fires, which can explain our observations. This study contributes valuable long-term insights into the dynamics of Hg concentrations in an Amazonian reservoir, highlighting the complex interactions between environmental changes and Hg accumulation over decades.
随着为建造水电站而进行的河流蓄水，水生生态系统的非生物和生物部分的汞（Hg）浓度增加，是水电站建设可能引发的许多环境和社会影响之一。然而，亚马逊水库的长期研究仍然很少。本研究旨在了解大坝蓄水对一个亚马逊水库中总汞（THg）浓度的影响，该水库自建成以来已经有 35 年的历史。2019 年 3 月（蓄水 35 年后），在图库鲁伊水库采集了鱼类、土壤和沉积物样本。测定了这些样本中的总汞（THg）浓度，并与之前关于水库蓄水后 6、16 和 18 年的数据进行了比较。在蓄水后的第 6 年，来自不同类别的鱼类的总汞浓度较高，然后在第 16 年和第 18 年下降，然后在蓄水后的第 35 年再次上升。对于土壤和沉积物，THg 浓度呈下降趋势。这些结果与之前的研究不同，之前的研究预测在温带地区，鱼类中的汞浓度将在 30 年内恢复到自然浓度，而亚马逊水库不会观察到 THg 浓度的下降。在过去几十年里，托坎廷斯河流域经历了多次人为干扰和土地利用变化，例如新的水电站建设、森林砍伐和火灾，这可以解释我们的观察结果。本研究为亚马逊水库中汞浓度的动态提供了有价值的长期见解，强调了环境变化和几十年来汞积累之间的复杂相互作用。
