Department of Environmental Science, Stockholm University, 106 91 Stockholm, Sweden.
Laboratório de Ecologia Aquática, Programa de Pós-Graduação em Biodiversidade e Conservação da Natureza. Universidade Federal de Juiz de Fora, 36036 900, Juiz de Fora, Brazil.
Environ Sci Process Impacts. 2021 Oct 20;23(10):1542-1553. doi: 10.1039/d1em00156f.
Thousands of dams are currently under construction or planned worldwide to meet the growing need for electricity. The creation of reservoirs could, however, lead to conditions that promote the accumulation of mercury (Hg) in surface sediments and the subsequent production of methylmercury (MeHg). Once produced, MeHg can bioaccumulate to harmful levels in organisms. It is unclear to what extent variations in physical features and biogeochemical factors of the reservoir impact Hg accumulation. The objective of this study was to identify key drivers of the accumulation of total Hg (THg) in tropical reservoir sediments. The concentration of THg in all analyzed depth intervals of 22 sediment cores from the five contrasting reservoirs investigated ranged from 16 to 310 ng g ( = 212, in the different sediment cores, the maximum depth varied from 18 to 96 cm). Our study suggests reservoir size to be an important parameter determining the concentration of THg accumulating in tropical reservoir sediments, with THg ranging up to 50 ng g in reservoirs with an area exceeding 400 km and from 100 to 200 ng g in reservoirs with an area less than 80 km. In addition to the reservoir size, the role of land use, nutrient loading, biome and sediment properties (, organic carbon content) was tested as potential drivers of THg levels. The principal component analysis conducted suggested THg to be related to the properties of the watershed (high degree of forest cover and low degree of agricultural land use), size and age of the reservoir, water residence time and the levels of nutrients in the reservoir. A direct correlation between THg and tested variables was, however, only observed with the area of the reservoir.
目前，全球有成千上万座大坝正在建设或规划中，以满足日益增长的电力需求。然而，水库的建设可能导致一些条件，促进汞（Hg）在表层沉积物中的积累，并随后产生甲基汞（MeHg）。一旦产生，MeHg 可以在生物体内积累到有害水平。目前还不清楚水库的物理特征和生物地球化学因素的变化在多大程度上影响 Hg 的积累。本研究的目的是确定影响热带水库沉积物中总汞（THg）积累的关键驱动因素。在对五个具有代表性的水库中的 22 个沉积物芯的所有分析深度间隔中，THg 的浓度范围为 16 至 310ng g（平均值为 212ng g），在不同的沉积物芯中，最大深度从 18 至 96 厘米不等。我们的研究表明，水库面积是决定热带水库沉积物中 THg 积累浓度的一个重要参数，面积超过 400 平方公里的水库中 THg 浓度高达 50ng g，面积小于 80 平方公里的水库中 THg 浓度在 100 至 200ng g 之间。除了水库面积外，土地利用、养分负荷、生物群落和沉积物特性（如有机碳含量）等因素也被认为是影响 THg 水平的潜在驱动因素。进行的主成分分析表明，THg 与流域的特性（森林覆盖率高，农业用地少）、水库的面积和年龄、水停留时间以及水库中的养分水平有关。然而，THg 仅与水库的面积呈直接相关。
