Potential environmental hazard in the mining district of southern Iglesiente (SW Sardinia, Italy)

A stream sediment survey carried out in southern Iglesiente, southwestern S ardinia, comprised 249 samples which were analysed for 35 elements. The dat a from 83 samples derived from a previous survey by Ente Minerario Sardo we re also used. Maps showing element distribution were created using the GIS program Are View 3.1. For the compilation of potential risk maps, the regio nal distribution of the elements has been reclassified using as thresholds the Italian intervention criteria for residential/recreational and commerci al/industrial land use. The main concentrations of heavy elements mainly fo llow the carbonate lithologies, hosting most of the ore deposits of Mississ ippi Valley and Sedimentary Exhalative types. Fairly high contents of Pb, Z n, Cd, and As are reflected in the stream sediments sampled along the carbo nate ridges bordering the mining district along the Iglesias syncline. Trea tment plants, tailings and dumps are also located in this area. Another are a with high metal values is the swampy river mouth of Rio Sa Masa, near Gon nesa, draining not only the main mining sites of the Iglesias syncline, but also the small industrial areas around the town of Iglesias and a few vill ages. Potential risk maps have been compiled for four elements: Zn, Pb, Cd and As. Among those, the state of geochemical pollution is very serious for Cd, Pb, and Zn, which are the main elements contained in the stratabound o rebodies, but less so for As. If even only partly transferred to the soils, the concentration in these elements should limit any further development i n this area, unless remediation is carried out. (C) 1999 Elsevier Science B .V. All rights reserved.