Man-Technology-Environment Research Centre, Örebro University, 70182, Örebro, Sweden,
Environ Sci Pollut Res Int. 2014;21(11):6930-8. doi: 10.1007/s11356-013-2026-x. Epub 2013 Aug 3.
A former open pit where black shale (alum shale) was excavated during 1942-1965 has been water filled since 1966. The water chemistry was dominated by calcium and sulphate and had a pH of 3.2-3.4 until 1997-1998, when pH was gradually increasing. This was due to the intrusion of leachates from alkaline cement waste deposited close to the lake. A stable pH of around 7.5 was obtained after 6-7 years. The chemistry of the pit lake has changed due to the neutralisation. Concentrations of some dissolved metals, notably zinc and nickel, have gone down, as a result of adsorption/co-precipitation on solid phases (most likely iron and aluminium hydroxides), while other metals, notably uranium and molybdenum, are present at elevated levels. Uranium concentration is reaching a minimum of around pH 6.5 and is increasing at higher pH, which may indicate a formation of neutral and anionic uranyl carbonate species at high pH (and total carbonate levels around 1 mM). Weathering of the water-exposed shale is still in progress.
一个曾经的露天矿坑，在 1942 年至 1965 年间开采过黑色页岩（明矾页岩），自 1966 年以来已被水填满。水质主要由钙和硫酸盐组成，pH 值在 3.2-3.4 之间，直到 1997-1998 年，pH 值逐渐升高。这是由于靠近湖泊的碱性水泥废物浸出液的侵入。经过 6-7 年，pH 值稳定在 7.5 左右。由于中和作用，坑湖的化学性质发生了变化。一些溶解金属的浓度，特别是锌和镍，由于吸附/共沉淀在固相上（很可能是铁和氢氧化铝）而下降，而其他金属，特别是铀和钼，浓度升高。铀的浓度在 pH 值约为 6.5 时达到最小值，并在较高 pH 值时增加，这可能表明在高 pH 值下形成中性和阴离子铀酰碳酸盐物种（以及总碳酸盐水平约为 1 mM）。暴露在水中的页岩的风化仍在进行中。
