Stormflow hydrochemistry of a river draining an abandoned metal mine: the Afon Twymyn, central Wales

摘要: Contaminated drainage from metal mines is a serious water-quality problem facing nations that exploit mineral resources. Measurements of river hydrochemistry during baseflow are common at mine sites, whilst detailed hydrochemical information regarding stormflow limited and often confined to single event. This study investigates the seasonal evolution an abandoned in central Wales, UK, possible sources mechanisms release. Significant flushing metals was observed events, resulting concentrations severely exceeded guidelines. The relationship between discharge suggests dissolution efflorescent sulphates on surface spoil as principal source contamination. High fluxes Pb stormflows linked extended periods dry weather prior storm events produced water table drawdown encouraged oxidation sulphide spoil. However, some also occurred following wet antecedent conditions. It suggested Fe oxide reduction translatory flows involving metal-rich pore waters results wetter periods. Detailed measurements sites essential for accurate forecasting long-term trends flux understand release, assess potential risks quality instream ecology, gauge effectiveness remediation. In order protect riverine riparian ecosystems, it routine monitoring becomes part catchment management mining-impacted regions.