In southwestern Sardinia the areas around Iglesias and Guspini–Arbus represent the heart of the former mining industry. Lead and zinc ores were extensively exploited from 1850 to 1995. Geochemical studies in these areas have identified the main sources of contamination to be from drainage of flooded mines, mining wastes and tailings abandoned in settling ponds, and exposed ores. The transport of the fine materials eroded from the tailings ponds contributes to spreading pollution over larger areas downstream. Concentrations of Pb, Cd and Zn in the streams draining the mining area (up to 1, 1.7, and 1000 mg l−1, respectively) are several orders of magnitude higher than those observed in rivers outside the mining areas in Sardinia (Pb: <0.004 mg l−1, Cd: <0.001 mg l−1, and Zn: <0.02 mg l−1), and greatly exceed the Italian drinking water standards (Pb: 0.01 mg l−1, Cd: 0.005 mg l−1, and Zn: 3 mg l−1).
- © 2002 AAG/The Geological Society of London