Achterberg Eric P, Herzl Veronique M C, Braungardt Charlotte B, Millward Geoff E
Department of Environmental Sciences, Plymouth Environmental Research Centre, University of Plymouth, Plymouth PLA 8AA, UK.
Environ Pollut. 2003;121(2):283-92. doi: 10.1016/s0269-7491(02)00216-6.
The concentrations of dissolved and suspended particulate Cd, Cu and Zn have been determined in water samples obtained during two axial transects of the Rio Tinto-Huelva Ria system in south-west Spain, which is severely impacted by acid mine drainage. Although the metal concentrations in both phases were elevated, dissolved metals were dominant and, in the upper estuary, constituted > 99% of total metal in the water column. Dissolved metals behaved non-conservatively on each transect, with maximum concentrations in the low salinity region. There was no evidence of metal adsorption within the turbidity maximum zone, despite the high specific surface areas of resuspending particles. Measurements of electrophoretic mobility showed that the suspended particulate matter (SPM) had a positive surface charge in the salinity range 0-4, where the waters had a pH < 3. Desorption experiments were carried out in which SPM from the turbidity maximum zone was resuspended in coastal seawater. The desorption of the metals was monitored for 24 h, using anodic stripping voltammetry (ASV) to detect the variation in total dissolved Cd, Cu and Zn and the species of Cu and Zn. Total dissolved Cd concentrations doubled during the incubation period, whereas the concentration of total dissolved Cu declined and that of Zn remained rather constant. The ASV-labile fraction of dissolved Cu and Zn showed an initial sharp release followed by a slower uptake. However, desorption was shown to be a minor source of dissolved metals and made little contribution to the non-conservative behaviour in the low salinity zone. The results are used to predict the effects of acid mine drainage on estuarine ecology.
在西班牙西南部受酸性矿山排水严重影响的力拓-韦尔瓦河口系统的两条轴向断面采集的水样中，测定了溶解态和悬浮颗粒物中镉、铜和锌的浓度。尽管两相中的金属浓度都有所升高，但溶解态金属占主导地位，在上游河口，溶解态金属占水柱中总金属的比例超过99%。在每个断面上，溶解态金属的行为都不保守，在低盐度区域浓度最高。尽管再悬浮颗粒的比表面积很大，但在最大浊度带内没有金属吸附的迹象。电泳迁移率测量表明，在盐度范围为0-4（此处水体pH<3）时，悬浮颗粒物（SPM）带正表面电荷。进行了解吸实验，将来自最大浊度带的SPM重新悬浮在沿海海水中。使用阳极溶出伏安法（ASV）监测金属的解吸情况24小时，以检测总溶解镉、铜和锌的变化以及铜和锌的形态。在孵育期间，总溶解镉浓度增加了一倍，而总溶解铜浓度下降，锌浓度保持相当稳定。溶解铜和锌的ASV-不稳定部分最初急剧释放，随后吸收较慢。然而，解吸被证明是溶解态金属的一个次要来源，对低盐度区域的非保守行为贡献不大。这些结果用于预测酸性矿山排水对河口生态的影响。
