The hidden costs of unmanaged abandoned mines in water-scarce regions: an extreme case of arsenic legacy in the Mediterranean

Due to their dramatic environmental impacts, especially on natural water bodies, legacy pollution from abandoned mines has become a major issue, now exacerbated by increasing water scarcity and economic pressure. Among them, arsenic-rich mining legacies are particularly challenging to mitigate, as prolonged neglect can lead to severe, long-lasting contamination of soils, rivers and groundwater. The Matra mine (Corsica, France), abandoned since 1945, stands out as one of the most severe yet poorly documented arsenic legacies in Europe. Arsenic concentrations reach up to 4 mg/L in surface waters, far beyond the threshold of 10 µg/L, with contamination spreading from the headwaters of the Bravona River basin to the sea, threatening ecosystems, drinking water resources and local development. Decades of non-management, combined with unfavourable hydrogeological and geomorphological conditions, have made the Matra site a long-term environmental hazard with multi-scale impacts on human health and regional development. In the current context of water scarcity, this study highlights the urgent need for site-specific remediation strategies for historical abandoned mines. Based on the case of Matra, it emphasizes that integrated governance – accounting for hydrogeological dynamics, contaminant behaviour and socio-economic constraints – is essential to address these persistent legacies and prevent future environmental and public health crises.