Flow dependent water quality impacts of historic coal and oil shale mining in the Almond River catchment, Scotland

Simon Haunch, Alan MacDonald, Neil Brown, Christoper McDermott

Research output: Contribution to journalArticlepeer-review

Abstract

The Almond River Catchment in Central Scotland has experience significant historic coal and oil shale mining during the last 300 years. Detailed spatial analysis of the catchment has identified over 300 abandoned mine and mine waste sites, comprising a significant potential source of mine related contamination. River water quality data, collected over a 15 year period from 1994 to 2008, indicates that both the coal and oil shale mining regions detrimentally impact shallow groundwater and surface water quality long after mine abandonment, due to the continued release of iron and sulphate associated with pyrite oxidation at abandoned mine sites. Iron and sulphate display significant concentration-flow dependence in surface waters: iron increases at high flows due to the re-suspension of river bed iron precipitates (Fe(OH)3); sulphate concentrations decrease with flow as a result of dilution. Further examination of iron and sulphate loading at low flows indicates a close correlation of iron and sulphate with mined areas; cumulative low flow load calculations indicate that coal and oil shale mining regions contribute 0.21 and 0.31 g/s of iron, respectively, to the main Almond tributary. A decrease in iron loading in river sections in non mined areas of the catchment demonstrates the deposition and diffuse storage of iron within the river. River bed iron is re-suspended with increased flow, resulting in load values of up to 50 g/s iron. Interpretation of major ion chemistry data for 2005-6 indicates significant increases in Ca2+, Mg2+ and HCO3- in coal mined areas probably as a result of the buffering of proton acidity in mine waters; this is not observed in the oil shale areas. The study demonstrates the cumulative impact of point and diffuse contamination sourced from numerous small and several large coal and oil shale mine sites on surface water Fe load and whole water quality.
Original languageEnglish
JournalApplied geochemistry
VolumeEarly Online
Early online date25 Jun 2013
DOIs
Publication statusPublished - 2013

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