Suchergebnisse

Soil, water and plant geochemistry was studied around the Miguel Vacas copper mine (Alentejo, SE Portugal), which stopped its exploitation and processing activities in 1991. After closure waste-rock piles remained exposed to weathering. The copper ore was mainly composed of copper phosphates and carbonates. Remediation actions were insufficient to prevent the spreading of waste-rock materials to surrounding farmed fields. The latter caused contamination of soils and water. Based on overall characteristics water from wells and surface stream water mostly can be classified as of the sulphate magnesium type. The application of a chemical equilibrium model to the sampled water showed that copper, phosphate and sulphate concentrations are controlled by copper(II) secondary minerals (pseudomalachite, libethenite and malachite) and gypsum. Nevertheless, groundwater can be used for irrigation and cattle based on quality parameters. Soils and plants (Prunus domestica L., Olea europaea L. spp. europaea and Quercus ilex L.) were collected southeast of the open pit and the exploitation substructures. The soils located in the influence of drainage water that percolated through waste material or exploitation substructures were contaminated with Cu, and Ni was close to the maximum value allowed by Portuguese legislation. These soils, however, did not show elevated Zn and Mn concentrations. The trace element content in plants was within the normal range, with Q. ilex being able to accumulate Mn and to some extent also Ni. Dispersion of trace elements seemed to be limited to a distance 1500 m down from the waste dumps in southeastern direction.

Santa Margarida Military Camp (S.M.M.C.) is the only one Portuguese military training area, including firing ranges for tactical military manoeuvres of mechanised divisions. For this reason, various negative effects on the environment were expected due to the military activities, as the Military Camp's area is classified as a high vulnerability area to pollution of its multilayer porous aquifers. The aim of this study was to identify and characterise local/regional geochemical impacts caused by the continuing military training activities performed at S.M.M.C. in the course of 52 years. An overview of the geochemical research issues as a basis for risk assessment is presented. A special attention has been put on the quality of local and regional surface waters, shallow groundwaters and groundwaters. Local soils and sediments as well as fragments of shells and bullets were sampled and analysed. The results so far obtained, indicated that none pollution effects were a consequence of the military training activities. Till now, the geochemical signatures such as, high levels of K, Cl and NO3 in waters, detected in particular sites, should be faced as tracers of diffuse pollution ascribed to urban waste disposal and cattle breading.