Geochemical exploration of a volcano-sedimentary aquifer system in northern Greece

In this note, hydrochemical data from a volcano-sedimentary aquifer of the Skydra region, Northern Greece, are analysed following an integrated approach, where results obtained with classical hydrochemical methods (saturation index, mixing diagram, characteristic relationships) are compared with those obtained from multivariate statistical technique correspondence analysis (R-mode factor analysis). From several groundwater samples collected from bore-wells the pH, the total dissolved solid, the electrical conductivity, the temperature and the major ions (Ca, Mg, Na, K, SO4, NO3, HCO3, Cl and SiO2) were measured. Within the investigated area, different hydrochemical facies have been recognised, basically generated by different geological formations but also induced by human activities. In order to characterise the different facies and to infer the relationships among them, thirteen parameters are chosen and elaborated by applying multivariate analyses. Accordingly, the chemical data of the aquifers can be grouped following five major factors which best fit the total variance of the data. These factors indicate the alimentation area and the influence of the regional geology for the hydrochemical characteristics of the principal aquifer systems.