A geochemical, mineralogical and sulphur isotopic study on the impact of acid mine drainage on the water quality of the Odiel river (Huelva, SW Spain).

At 20 km from the riverhead, the Odiel river receives four discharges of acid mine drainage emanating from Concepción, San Platón, Esperanza and Poderosa-El Soldado mines. Two field studies performed in October 2003 and May 2004 showed that these acidic waters (0.2-8.5 L/s, pH 2.3-2.8) transfer to the Odiel river (pH=7-8.3, 220-1,000 L/s) significant quantities of acidity and dissolved metals, affecting the water quality in the region. The geochemical, mineralogical, and sulphur isotopic composition of the discharges were analyzed to understand their impacts on the Odiel river ecosystem. Results indicated that the acid mine drainage contributes substantial levels of pollutants, leading to an alteration in the aquatic environment. The study aimed to quantify the degree of contamination and its implications for local water quality, which is crucial for environmental management and remediation efforts in mining-affected areas. This research highlights the necessity for ongoing monitoring and the development of strategies to mitigate the impacts of acid mine drainage on water bodies.