Biogeochemistry in Neves Corvo mining region, Iberian Pyrite Belt, Portugal

The study was conducted in the Neves Corvo Cu–Sn mine, and in six old Mn, Cu and pyrite mines, situated in the same volcano-sedimentary formations of the Portuguese Iberian Pyrite Belt, namely Courela das Ferrarias, Cerro da Cachaçuda, Herdade do Castelo, Cerro das Guaritas, Cerro do Algaré and Brancanes and in Lombador at the surface of a unexploited deep orebody. The objective was to compare the pathway of specific chemical elements in the present Neves Corvo mine, and in the other study areas. Consequently, soils, plants and sediments were sampled and analyzed for Cu, Pb, Zn, Fe and Mn. The pH was measured in the soils. Data compiled from other studies from soils, plants, rocks, and mine waste dumps was also used.The Neves Corvo area is still in a reactive state, that is, acid generating minerals are released from the orebodies and mobilised into the surrounding soils both by chemical processes and wind erosion. The acidity generated in contact with water may cause mobilisation of the metallic elements, increasing the bioavailable fraction and, consequently, contributes to plants uptake.The northwestern mines are in an intermediate state, that is, with partial mobilisation of metals from orebodies into superficial environment. Although, a natural attenuation process in the study area appears to have started in the soil–plant system in Brancanes, and in the previously mentioned northwestern mines (Cerro do Algaré, Cerro das Guaritas, Herdade do Castelo, Cerro da Cachaçuda, Courela das Ferrarias), no attenuation processes occur in waters and sediments, which have metals that are still being released from dump materials.