Groundwater pollution by heavy metals in historical mining area of Lavrio, Attica, Greece

This article deals with the impacts of past mining activities and inefficient water resources management on groundwater quality in the Lavrio area. Thirty-three water samples were collected during March 1998 and were analyzed for major ions (Ca, Mg, Na, K, HCO3, Cl, NO3, SO4, PO4), trace elements (Fe, Pb, Ni, Zn, Mn, Cu, Cr, Cd) and water parameters (Temperature, pH, conductivity, hardness and SiO2). High concentrations of heavy metals (lead, cadmium, zinc, nickel) are recorded in groundwater samples in the Lavrio area. The highest concentrations are recorded in the unconfined aquifer (alluvial deposits and schists), due to mining activities. Quality deterioration of groundwater is also decumented and attributed to seawater intrusion and nitrate pollution of agricultural origin. The data were subjected to simple correlation analysis and R-mode factor analysis in order to examine the relationships between the parameters. There is a relationship between the elements participating in the sulfide (Pb, Zn, Cu, Cd) and iron-manganese mineralization and a strong relationship between Ni-Cr. In the factor analysis a four-factor model is suggested, which can explain 72.5% of the total variance. The contribution of each factor at every site is also computed and maps showing the geographical distribution are illustrated. The areas with high concentrations of heavy metals are defined from these maps.