Variability in Mine Waste Mineralogy and Water Environment Risks: a Case Study on the River Almond Catchment, Scotland

The River Almond catchment contains coal, oil shale and ironstone mine waste and displays widespread surface water metals pollution. Mineralogical investigations and geochemical modelling at four mine waste sites identified pyrite oxidation and jarosite, siderite and aluminosilicate dissolution reactions as the primary sources of metal pollutants (Fe, Mn, Al). Carbonate dissolution reactions control drainage pH. Pyrite is absent in burnt oil shale waste, however, trace content in unburnt shale horizons is implicated as a source of Fe in drainage waters. Site specific water quality and load assessments indicate pyrite bearing coal and ironstone sites present the greatest water environment risks.