The abandoned antimony-mines of SE Sardinia: impact on surface waters

This study investigates the impact of abandoned Sb-mines on the Flumendosa River, which is the most important water resource in southern Sardinia. Hydrogeochemical surveys carried out in 2005 and 2006 indicated a significant impact of waters flowing out from adits, slag, tailings and waste materials on surface waters. The contaminated waters show alkaline pH, and high dissolved SO4, Sb and As (up to 1900, 9.6 and 3.5 mg/L, respectively). Although the flow rates of drainages from the mining area are usually low (in the range of < 0.1 to 1 L/s), the contribution to dissolved concentrations of Sb in the streams downstream of mines is high. Sampling under high flow conditions in the Flumendosa River before the confluence with the contaminated streams showed Sb concentrations below the limits established by the guidelines of World Health Organization for drinking water (i.e. 20 g/L), while downstream of the confluence dissolved Sb was 32 g/L. Contamination in the Flumendosa extended 16 km, and attenuation (15 g/L Sb) was only observed close to the Flumendosa mouth.