Lecomte K L, Maza S N, Collo G, Sarmiento A M, Depetris P J
Centro de Investigaciones en Ciencias de la Tierra (CICTERRA) CONICET, Universidad Nacional de Córdoba, Av. Vélez Sarsfield 1611, X5016CGA, Córdoba, Argentina.
Dpto. Geodinámica y Paleontología, Universidad de Huelva, 21071, Huelva, Spain.
Environ Sci Pollut Res Int. 2017 Jan;24(2):1630-1647. doi: 10.1007/s11356-016-7940-2. Epub 2016 Oct 28.
The Amarillo River (Famatina range, Argentina, 29° S and ~67° W) is unusual because acid mine drainage (AMD) is superimposed on the previously existing acid rock drainage (ARD) scenario, as a Holocene paleolake sedimentary sequence shows. In a markedly oxidizing environment, its water is currently ferrous and of the sulfate-magnesium type with high electrical conductivity (>10 mS cm in uppermost catchments). At the time of sampling, the interaction of the mineralized zone with the remnants of mining labors determined an increase in some elements (e.g., Cu ~3 to ~45 mg L; As ~0.2 to ~0.5 mg L). Dissolved concentrations were controlled by pH, decreasing significantly by precipitation of neoformed minerals (jarosite and schwertmannite) and subsequent metal sorption (700 mg kg As, 320 mg kg Zn). Dilution also played a significant role (i.e., by the mixing with circumneutral waters which reduces the dissolved concentration and also enhances mineral precipitation). Downstream, most metals exhibited a significant attenuation (As 100 %, Fe 100 %, Zn 99 %). PHREEQC-calculated saturation indices (SI) indicated that Fe-bearing minerals, especially schwertmannite, were supersaturated throughout the basin. All positive SI increased through the input of circumneutral water. PHREEQC inverse geochemical models showed throughout the upper and middle basin, that about 1.5 mmol L of Fe-bearing minerals were precipitated. The modeling exercise of mixing different waters yielded results with a >99 % of correlation between observed and modeled data.
阿马里洛河（位于阿根廷法马蒂纳山脉，南纬约29°，西经约67°）不同寻常，因为正如全新世古湖泊沉积序列所示，酸性矿山排水（AMD）叠加在先前已有的酸性岩石排水（ARD）之上。在明显氧化的环境中，其水体目前富含亚铁，属于硫酸 - 镁类型，电导率高（最上游集水区>10 mS/cm）。在采样时，矿化带与采矿作业遗迹的相互作用导致某些元素增加（例如，铜从约3 mg/L增至约45 mg/L；砷从约0.2 mg/L增至约0.5 mg/L）。溶解浓度受pH值控制，通过新形成矿物（黄钾铁矾和施韦特曼石）沉淀以及随后的金属吸附（砷约700 mg/kg，锌320 mg/kg）显著降低。稀释也起到了重要作用（即与中性水混合，这降低了溶解浓度并促进了矿物沉淀）。在下游，大多数金属表现出显著衰减（砷100%，铁100%，锌99%）。PHREEQC计算的饱和指数（SI）表明，含铁矿物，尤其是施韦特曼石，在整个流域都处于过饱和状态。所有正的SI值通过中性水的输入而增加。PHREEQC反演地球化学模型显示，在整个流域的上游和中游，约1.5 mmol/L的含铁矿物沉淀。混合不同水体的模拟实验结果显示，观测数据与模拟数据之间的相关性>99%。
