Molisani M M, Rocha R, Machado W, Barreto R C, Lacerda L D
Instituto de Ciências do Mar, Universidade Federal do Ceará, Fortaleza, CEP 60185-081, Fortaleza, Brazil.
Braz J Biol. 2006 Feb;66(1A):101-7. doi: 10.1590/s1519-69842006000100013. Epub 2006 May 2.
This paper reports on a study to determine the Hg content in the five most abundant aquatic macrophyte species (Elodea densa, Sagittaria montevidensis, Salvinia auriculata, Pistia stratiotes and Eichhornia crassipes) in two artificial reservoirs flooded by water diverted from the Paraíba do Sul river, SE Brazil. The potential of these species for Hg accumulation and their role in Hg transport along the river system due to macrophyte management were evaluated. Mercury concentrations were higher in free-floating than in rooted species. Roots were also richer in Hg than were leaves. Dry weight Hg concentrations in leaves and roots from all species varied from 46-246 ng.g(-1) to 37-314 ng.g(-1), respectively. These values are higher than those reported for uncontaminated lakes in Brazil and in other tropical areas and similar to those reported for moderately contaminated sites. Mercury concentrations can be attributed to fluvial transport from the heavily industrialized Paraíba do Sul river basin. Intensive sampling of Pistia stratiotes from two sites in the Vigário reservoir was performed to evaluate the capacity of Hg incorporation in short periods of time. The results showed a significant negative correlation between Hg content and size class of individual plants, demonstrating the importance of juveniles, fast growing plants in absorbing Hg. The foremost impact related to Hg contents in the studied area concerns the periodic removal of macrophytes for reservoir management, followed by disposal in nearby areas. This results in the mobilization of 0.52 to 1.3 Kg of Hg per year, a significant fraction of the Hg burden present in reservoir waters. Disposal of such material may result in Hg leaching to river systems, affecting the Hg transfer throughout the basin.
本文报道了一项研究，旨在测定巴西东南部帕拉伊巴河分流形成的两个人工水库中五种最常见的水生大型植物（伊乐藻、蒙特维的亚慈姑、耳叶满江红、大薸和凤眼莲）中的汞含量。评估了这些物种积累汞的潜力以及由于大型植物管理而在汞沿河流系统传输中的作用。自由漂浮物种中的汞浓度高于扎根物种。根部的汞含量也比叶子高。所有物种叶子和根部的干重汞浓度分别在46 - 246 ng.g(-1)至37 - 314 ng.g(-1)之间变化。这些值高于巴西和其他热带地区未受污染湖泊的报告值，与中度污染地点的报告值相似。汞浓度可归因于工业化程度高的帕拉伊巴河流域的河流输送。对维加里奥水库两个地点的大薸进行了密集采样，以评估短时间内汞的吸收能力。结果表明，汞含量与单株植物的大小等级之间存在显著负相关，这表明幼体、快速生长的植物在吸收汞方面的重要性。研究区域内与汞含量相关的最主要影响涉及为水库管理定期清除大型植物，随后在附近地区处置。这导致每年有0.52至1.3千克汞的迁移，这是水库水体中汞负荷的很大一部分。处置此类物质可能导致汞渗入河流系统，影响整个流域的汞转移。
