Campaner Veridiana P, Luiz-Silva Wanilson, Machado Wilson
Departamento de Geologia e Recursos Naturais, Instituto de Geociências, Universidade Estadual de Campinas, Campinas, São Paulo, Brasil.
Campus do Valonguinho, Departamento de Geoquímica, Instituto de Química, Universidade Federal Fluminense, Niterói, RJ, Brasil.
An Acad Bras Cienc. 2014 Jun;86(2):539-554. doi: 10.1590/0001-37652014113712. Epub 2014 May 14.
Acid drainage influence on the water and sediment quality was investigated in a coal mining area (southern Brazil). Mine drainage showed pH between 3.2 and 4.6 and elevated concentrations of sulfate, As and metals, of which, Fe, Mn and Zn exceeded the limits for the emission of effluents stated in the Brazilian legislation. Arsenic also exceeded the limit, but only slightly. Groundwater monitoring wells from active mines and tailings piles showed pH interval and chemical concentrations similar to those of mine drainage. However, the river and ground water samples of municipal public water supplies revealed a pH range from 7.2 to 7.5 and low chemical concentrations, although Cd concentration slightly exceeded the limit adopted by Brazilian legislation for groundwater. In general, surface waters showed large pH range (6 to 10.8), and changes caused by acid drainage in the chemical composition of these waters were not very significant. Locally, acid drainage seemed to have dissolved carbonate rocks present in the local stratigraphic sequence, attenuating the dispersion of metals and As. Stream sediments presented anomalies of these elements, which were strongly dependent on the proximity of tailings piles and abandoned mines. We found that precipitation processes in sediments and the dilution of dissolved phases were responsible for the attenuation of the concentrations of the metals and As in the acid drainage and river water mixing zone. In general, a larger influence of mining activities on the chemical composition of the surface waters and sediments was observed when enrichment factors in relation to regional background levels were used.
在巴西南部的一个煤矿区，研究了酸性排水对水和沉积物质量的影响。矿井排水的pH值在3.2至4.6之间，硫酸盐、砷和金属浓度升高，其中铁、锰和锌超过了巴西法规规定的废水排放限值。砷也超过了限值，但只是略超。活跃矿山和尾矿堆的地下水监测井显示出与矿井排水相似的pH值区间和化学浓度。然而，城市公共供水的河水和地下水样本的pH值范围为7.2至7.5，化学浓度较低，尽管镉浓度略超过巴西法规规定的地下水限值。总体而言，地表水的pH值范围较大（6至10.8），酸性排水对这些水体化学成分的影响不太显著。在局部地区，酸性排水似乎溶解了当地地层序列中存在的碳酸盐岩，减弱了金属和砷的扩散。溪流沉积物呈现出这些元素的异常，这强烈依赖于尾矿堆和废弃矿山的距离。我们发现，沉积物中的沉淀过程和溶解相的稀释导致了酸性排水与河水混合区中金属和砷浓度的降低。总体而言，当使用相对于区域背景水平的富集因子时，观察到采矿活动对地表水和沉积物化学成分的影响更大。
