Water@leeds, School of Geography, University of Leeds, Leeds LS2 9JZ, UK.
Environ Sci Process Impacts. 2017 Aug 16;19(8):1061-1074. doi: 10.1039/c7em00171a.
Point and diffuse pollution from metal mining has led to severe environmental damage worldwide. Mine drainage is a significant problem for riverine ecosystems, it is commonly acidic (AMD), but neutral mine drainage (NMD) can also occur. A representative environment for studying metal pollution from NMD is provided by carboniferous catchments characterised by a circumneutral pH and high concentrations of carbonates, supporting the formation of secondary metal-minerals as potential sinks of metals. The present study focuses on understanding the mobility of metal pollution associated with historical mining in a carboniferous upland catchment. In the uplands of the UK, river water, sediments and spoil wastes were collected over a period of fourteen months, samples were chemically analysed to identify the main metal sources and their relationships with geological and hydrological factors. Correlation tests and principal component analysis suggest that the underlying limestone bedrock controls pH and weathering reactions. Significant metal concentrations from mining activities were measured for zinc (4.3 mg l), and lead (0.3 mg l), attributed to processes such as oxidation of mined ores (e.g. sphalerite, galena) or dissolution of precipitated secondary metal-minerals (e.g. cerussite, smithsonite). Zinc and lead mobility indicated strong dependence on biogeochemistry and hydrological conditions (e.g. pH and flow) at specific locations in the catchment. Annual loads of zinc and lead (2.9 and 0.2 tonnes per year) demonstrate a significant source of both metals to downstream river reaches. Metal pollution results in a large area of catchment having a depleted chemical status with likely effects on the aquatic ecology. This study provides an improved understanding of geological and hydrological processes controlling water chemistry, which is critical to assessing metal sources and mobilization, especially in neutral mine drainage areas.
点源和扩散污染导致了全球范围内的严重环境破坏。矿山排水是河流生态系统的一个重大问题，通常呈酸性（AMD），但也可能出现中性矿山排水（NMD）。石炭纪流域为研究中性矿山排水导致的金属污染提供了一个代表性环境，其特点是 pH 值接近中性，碳酸盐浓度高，有利于形成次生金属矿物，成为金属的潜在汇。本研究重点研究了与石炭纪高地流域历史采矿相关的金属污染的迁移性。在英国高地，在 14 个月的时间里采集了河水、沉积物和废矿渣样本，对样本进行了化学分析，以确定主要金属来源及其与地质和水文因素的关系。相关测试和主成分分析表明，基岩中的石灰岩控制着 pH 值和风化反应。对来自采矿活动的重要金属浓度进行了测量，锌（4.3mg/L）和铅（0.3mg/L）的浓度较高，这归因于开采矿石的氧化过程（例如闪锌矿、方铅矿）或沉淀的次生金属矿物的溶解过程（例如白铅矿、菱锌矿）。锌和铅的迁移性表明，在流域特定地点，其对生物地球化学和水文条件（例如 pH 值和流量）有很强的依赖性。锌和铅的年排放量（分别为 2.9 吨和 0.2 吨）表明这两种金属都是下游河流水域的重要污染源。金属污染导致流域内大面积地区的化学物质匮乏，这可能对水生生态系统产生影响。本研究提高了对控制水质的地质和水文过程的认识，这对于评估金属来源和迁移至关重要，尤其是在中性矿山排水区。
