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A preliminary investigation into mining and smelting impacts on trace element concentrations in the soils and vegetation around Tharsis, SW Spain

Abstract Toxic trace elements present an environmental hazard in the vicinity of mining and smelting activities. However, the processes of transfer of these elements to groundwater and to plants are not always clear. Tharsis mine, in the Iberian pyrite belt (SW Spain), has been exploited since 2500 BC, with extensive smelting taking place from the 1850s until the 1920s. Sixty four soil (mainly topsoils) and vegetation samples were collected in February 2001 and analysed by ICP-AES for 23 elements. Concentrations are 6-6300 mg kg-1 As and 14-24800 mg kg-1 Pb in soils, and 0.20-9 mg kg-1 As and 2-195 mg kg-1 Pb in vegetation. Trace element concentrations decrease rapidly away from the mine, with As and Pb concentrations in the range 6-1850 mg kg-1 (median 22 mg kg-1) and 14-31 mg kg-1 (median 43 mg kg-1), respectively, 1 km away from the mine. These concentrations are low when compared to other well-studied mining and smelting areas (e.g. 600 mg kg-1 As at 8 km from Yellowknife smelter, Canada; >100 mg kg-1 Pb over 270 km2 around the Pb-Zn Port Pirie smelter, South Australia; mean of 1419 mg kg-1 Pb around Aberystwyth smelter, Wales, UK). The high metal content of the vegetation and the low soil pH (mean pH 4.93) indicate the potential for trace element mobility which could explain the relatively low concentration of metals in Tharsis topsoils and cause threats to plans to redevelop the Tharsis area as an orange plantation.