Placencia-Gómez Edmundo, Parviainen Annika, Slater Lee, Leveinen Jussi
Aalto University, School of Engineering, Department of Civil and Environmental Engineering, P.O. Box 16200, FI-00076 Aalto, Finland.
Universidad de Granada, Facultad de Ciencias, Dpto. de Mineralogía y Petrología, Avda. Fuente Nueva s/n, C.P. 18002 Granada, Spain.
J Contam Hydrol. 2015 Feb;173:8-24. doi: 10.1016/j.jconhyd.2014.12.002. Epub 2014 Dec 9.
Mine tailings impoundments are a source of leachates known as acid mine drainage (AMD) which can pose a contamination risk for surrounding surface and groundwater. Methodologies which can help management of this environmental issue are needed. We carried out a laboratory study of the spectral induced polarization (SIP) response of tailings from the Haveri Au-Cu mine, SW Finland. The primary objectives were, (1) to determine possible correlations between SIP parameters and textural properties associated with oxidative-weathering mechanisms, mineralogical composition and metallic content, and (2) to evaluate the effects of the pore water chemistry on SIP parameters associated with redox-inactive and redox-active electrolytes varying in molar concentration, conductivity and pH. The Haveri tailings exhibit well defined relaxation spectra between 100 and 10,000Hz. The relaxation magnitudes are governed by the in-situ oxidative-weathering conditions on sulphide mineral surfaces contained in the tailings, and decrease with the oxidation degree. The oxidation-driven textural variation in the tailings results in changes to the frequency peak of the phase angle, the imaginary conductivity and chargeability, when plotted versus the pore water conductivity. In contrast, the real and the formation electrical conductivity components show a single linear dependence on the pore water conductivity. The increase of the pore water conductivity (dominated by the increase of ions concentration in solution) along with a transition to acidic conditions shifts the polarization peak towards higher frequencies. These findings show the unique sensitivity of the SIP method to potentially discriminate AMD discharges from reactive oxidation zones in tailings, suggesting a significant advantage for monitoring threatened aquifers.
矿山尾矿库是酸性矿山排水（AMD）渗滤液的一个来源，这种渗滤液会对周围地表水和地下水构成污染风险。因此需要有助于管理这一环境问题的方法。我们对芬兰西南部哈弗里金铜矿的尾矿进行了光谱诱导极化（SIP）响应的实验室研究。主要目标是：（1）确定SIP参数与与氧化风化机制、矿物成分和金属含量相关的质地特性之间可能存在的相关性；（2）评估孔隙水化学对与氧化还原惰性和氧化还原活性电解质相关的SIP参数的影响，这些电解质在摩尔浓度、电导率和pH值方面各不相同。哈弗里尾矿在100至10000Hz之间呈现出明确的弛豫谱。弛豫幅度受尾矿中硫化物矿物表面的原位氧化风化条件控制，并随氧化程度降低。尾矿中由氧化驱动的质地变化导致相角、虚部电导率和充电率的频率峰值在与孔隙水电导率作图时发生变化。相比之下，实部电导率和地层电导率分量与孔隙水电导率呈单一线性关系。孔隙水电导率的增加（主要由溶液中离子浓度的增加主导）以及向酸性条件的转变会使极化峰向更高频率移动。这些发现表明SIP方法在潜在区分尾矿中反应性氧化区的AMD排放方面具有独特的敏感性，这表明在监测受威胁含水层方面具有显著优势。
