The role of surface water and mine groundwater in the chemical stratification of an acidic pit lake (Iberian Pyrite Belt, Spain)
The role of surface water and mine groundwater in the chemical stratification of an acidic pit lake (Iberian Pyrite Belt, Spain)
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DOI：
10.1016/j.jhydrol.2013.03.018
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发表时间：
2013-05
影响因子：
6.4
通讯作者：
E. Santofimia;E. López-Pamo
中科院分区：
文献类型：
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作者：
E. Santofimia;E. López-Pamo
Concepcion矿的液压系统由露天矿和地下矿组成，目前这两个矿都被淹了，并通过液压连接。Concepcion坑湖表现出永久性的化学分层(浅成湖)，其中可区分出两个不同密度和化学成分的层：(I)厚的浅层，11±2m深，溶解固体(混合体)浓度低；(Ii)薄的底层，从11±2m深到16m深(单晶层)，其物理化学参数垂直变化，氧化还原电位降低，T、pH和溶解固体含量随深度增加。Concepcion坑湖层的分布取决于补给过程和系统中的水损失。在冬季，降雨和径流导致湖泊水位迅速上升。每当通过一个旧的矿坑失去水时，湖水就会恢复到最初的水位，因为走廊和竖井是进出水的优先通道。这一网络与湖底相连，导致了化跃层的逐步下移。此外，径流产生了密度较低的浅层，这触发了混合层中短暂的化跃层的发展。在夏季，混合层通过蒸发失去水分，这部分被从湖底流入的地下水所补偿，导致永久化学跃层向上移动。在此期间，系统中的水位低于出水口水位，因此导致水的流出不活跃。在这一阶段，混合层保持均匀，浅层化跃层消失。考虑到该坑湖的水化学特征和所识别层位的空间分布，提出了一个解释其季节性湖相演化的模型。
The hydraulic system of the Concepción mine is made up of an open pit and an underground mine, which are currently flooded and hydraulically connected. The Concepción pit lake has shown permanent chemical stratification (meromictic lake), where two layers with different density and chemical composition can be differentiated: (i) a thick superficial layer of 11±2m deep, with a low concentration of dissolved solids (mixolimnion) and (ii) a thin bottom layer from 11±2m to 16m deep (monimolimnion), exhibiting vertical changes in its physico-chemical parameters, with decreasing redox potential and increasing T, pH and dissolved solids content with depth. The distribution of the Concepción pit lake layers depends on recharge processes and the loss of water from the system. In winter, rainfall and runoff result in a rapid increase of lake levels. The lake regains its initial level whenever water is lost through an old mine adit, since galleries and shafts act as preferential pathways for inflowing and outflowing water. This network is connected to the bottom of the lake, resulting in the progressive downward movement of the chemocline. Furthermore, runoff generates a less dense superficial layer, which triggers the development of an ephemeral chemocline in the mixolimnion. In summer, the mixolimnion loses water by evaporation which is partially compensated by groundwater inflowing from the lake bottom, resulting in the upward movement of the permanent chemocline. During this period the water level in the system is below the outlet level, which therefore renders the outflow of water inactive. During this stage, the mixolimnion remains homogeneous and the shallow chemocline disappears. Taking into consideration the hydrochemical characteristics of this pit lake and the spatial distribution of the layers identified, a model that explains its seasonal limnological evolution is presented.