Effects of water and wind erosion on metal pollution of surrounding areas of a Mediterranean mining area

Resumen

Heavy metal pollution of soils causes a wide range of health and environmental problems in most of the countries. Cartagena-La Union Mountains, SE Spain, is a Mediterranean area with more than 2500 years of mining tradition. Piles from ancient times, when less developed technologies we reused, and especially more recent ones from large scale exploitations, are rich in content of various metals. On the other hand, soils of surrounding areas seems to be highly enriched in heavy metals such as Pb and Zn, but also other elements such as Cd and As. Water, but also wind erosion in this area could be considered extremely high and hazards associated to this eroded sediments seems to be high because the huge amount of metals present in the mining wastes. Therefore, combination of high erosion rates and high metal concentration in this mining waste, make those environmental risks can be considered high for the surrounding ecosystems, but also for public health of the nearby villages and towns.Our research has been focused on Zn mobility from the mining area to the surrounding farmlands.The total contents of zinc in studied soils ranged from 33 to 7055 mg/kg, while DTPA extractable metals in soils ranged from 2 to 375 mg/kg. Sequential chemical extraction methodologies, such as BCR, have been applied in order to determine the solid speciation for trace metals present in the considered soils.It was observed high concentration of the most mobile exchangeable fraction of Zn in soils located near the mine. Finally, the studied soils contained significant amounts of mobile and potentially labile fractions of this heavy metal that could be acting as a potential toxic element because of its high concentration and availability.