Mineralogy and geochemistry of alluvium contaminated by metal mining in the Rio Tinto area, southwest Spain
Mineralogy and geochemistry of alluvium contaminated by metal mining in the Rio Tinto area, southwest Spain
复制标题
DOI：
10.1016/s0883-2927(99)00008-6
复制
发表时间：
1999-11-01
影响因子：
3.4
通讯作者：
Macklin, MG
中科院分区：
文献类型：
--
作者：
Hudson-Edwards, KA;Schell, C;Macklin, MG
西班牙西南部的力拓开采铜矿和黄铁矿，这些矿至少从青铜时代就开始运营。大规模的金属开采，尤其是 1873 年至 1954 年间，导致力拓冲积层受到砷、铜、铅、银和锌的污染。 X 射线衍射 (XRD)、波长色散 X 射线测绘、扫描电子显微镜岩相学和 X 射线能量色散 (EDX) 分析表明，冲积层中存在 4 类主要的污染金属和含砷矿物，包括硫化物、Fe-As 氧化物、Fe 氧化物/氢氧化物/羟基氧化物和 Fe 羟基硫酸盐。硫化物矿物主要产于矿区附近的冲积层中，包括黄铁矿、黄铜矿、毒砂、闪锌矿等。氢氧化铁和羟基氧化物（例如针铁矿和可能的水铁矿）存在于矿区和下游冲积层的水泥中，并含有少量的砷、铜和锌。羟基硫酸铁，包括黄钾铁矾、铅黄铁矿和可能的施威特曼石，是矿区下游冲积层中最常见的矿物，是仅次于铁砷矿物的铜、铅、锌和砷的主要宿主。这项工作和其他观察表明，（1）由于冲积层和矿山废料尖端中黄铁矿和其他硫化物的氧化，以及二次氧化物和羟基硫酸盐的形成，河水的极端酸度和高金属浓度可能会维持一段时间； (2) 可溶性羟基硫酸铁，例如在冲积层上形成的科皮阿皮特，是污染物金属的临时储存物，但在高降雨量或洪水期间溶解，将污染物释放到水系统中； (3) 相对难溶的羟基硫酸铁和氢氧化物，例如黄钾铁矾和针铁矿，可能是冲积污染物金属的主要长期储存； (4) 提高河流 pH 值可能会导致 Fe 羟基氧化物和氧化物/氢氧化物/羟基氧化物沉淀，从而对水质产生积极影响，但这种作用可能会破坏这些污染物中的一些含金属矿物的稳定性，将金属释放回水系统。 (C) 1999 Elsevier Science Ltd. 保留所有权利。
The Rio Tinto in SW Spain drains Cu and pyrite mines which have been in operation since at least the Bronze Age. Extensive metal mining, especially from 1873 to 1954, has resulted in contamination of the Rio Tinto alluvium with As, Cu, Pb, Ag and Zn. X-ray diffraction (XRD), wavelength-dispersive X-ray mapping, scanning electron microscope petrography and X-ray energy-dispersive (EDX) analysis has revealed that 4 major groups of contaminant metal and As-bearing minerals, including sulphides, Fe-As oxides, Fe oxides/hydroxides/oxyhydroxides, and Fe oxyhydroxysulphates, occur in the alluvium. Sulphide minerals, including pyrite, chalcopyrite, arsenopyrite and sphalerite, occur in alluvium near the mining areas. Iron hydroxides and oxyhydroxides such as goethite and possibly ferrihydrite occur in cements in both the mining areas and alluvium downstream, and carry minor amounts of As, Cu and Zn. Iron oxyhydroxysulphates, including jarosite, plumbojarosite and possibly schwertmannite, are the most common minerals in alluvium downstream of the mining areas, and are major hosts of Cu, Pb, Zn and of As, next to the Fe-As minerals. This work, and other held observations, suggest that (1) the extreme acidity and elevated metal concentrations of the river water will probably be maintained for some time due to oxidation of pyrite and other sulphides in the alluvium and mine-waste tips, and from formation of secondary oxide and oxyhydroxysulphates; (2) soluble Fe oxyhydroxysulphates such as copiapite, which form on the alluvium, are a temporary store of contaminant metals, but are dissolved during periods of high rainfall or flooding, releasing contaminants to the aqueous system; (3) relatively insoluble Fe oxyhydroxysulphates and hydroxides such as jarosite and goethite may be the major long-term store of alluvial contaminant metals; and (4) raising river pH will probably cause precipitation of Fe oxyhydroxides and oxides/hydroxides/oxyhydroxides and thus have a positive effect on water quality, but this action may destabilise some of these contaminant metal-bearing minerals, releasing metals back to the aqueous system. (C) 1999 Elsevier Science Ltd. All rights reserved.