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

This article deals with the impacts of past mining activities andinefficient water resources management on groundwater quality inthe Lavrio area. Thirty-three water samples were collectedduring March 1998 and were analyzed for major ions (Ca, Mg, Na,K, HCO sub(3), Cl, NO sub(3), SO sub(4), PO sub(4)), trace elements(Fe, Pb, Ni, Zn, Mn, Cu, Cr, Cd) and water parameters (Temperature,pH, conductivity, hardness and SiO sub(2)). High concentrationsof heavy metals (lead, cadmium, zinc, nickel) are recorded ingroundwater samples in the Lavrio area. The highestconcentrations are recorded in the unconfined aquifer (alluvialdeposits and schists), due to mining activities. Qualitydeterioration of groundwater is also decumented and attributedto seawater intrusion and nitrate pollution of agriculturalorigin. The data were subjected to simple correlation analysisand R-mode factor analysis in order to examine the relationshipsbetween the parameters. There is a relationship between theelements participating in the sulfide (Pb, Zn, Cu, Cd) andiron-manganese mineralization and a strong relationship betweenNi-Cr. In the factor analysis a four-factor model is suggested,which can explain 72.5% of the total variance. The contributionof each factor at every site is also computed and maps showingthe geographical distribution are illustrated. The areas withhigh concentrations of heavy metals are defined from these maps.