Γεωχημική Περιβαλλοντική μελέτη των υπόγειων υδάτων από γεωτρήσεις του δήμου Δέλτα Θεσσαλονίκης=Geochemical and environmental study of the underground water by boreholes of the Municipality of Delta in Thessaloniki, N. Greece

Περίληψη

The present undergraduate dissertation refers to the geochemical and environmental study of the underground water in the area of the Municipality of Delta in Thessaloniki through the results of the regular and audit monitoring in boreholes and pumping stations. This study is based on the Municipal Communities of Kalochori (results from 2006 to 2011), Anatoliko, Vraxia, Kymina, Malgara and Chalastra (2011 results). This region consists mainly of Neogene-Quaternary sediments and is located at the western suburban district of Thessaloniki, in northern Greece. The study area is characterized by a versatile system of river deltas and estuaries, swamps, salt marshes and wetlands, while the morphology is chiefly influenced by the rivers Axios and Gallikos and the associated sediments. During the last decades this area has been affected by various human activities such as the improper disposal of wastewater, solid waste and debris. This environmental burden is evident mainly due to the rapid industrial development of the region, which renders it one of the largest industrial zones of Greece. However an organized plant for processing the industrial waste has not been constructed so far. Furthermore, the excessive use of pesticides has created additional environmental problems in the region. The purpose of this research is to study the physicochemical composition of the underground potable water in the area. More specifically the main objective is the assessment of the physical parameters (pH, TDS, conductivity, taste, turbidity, total hardness, odor, residual chlorine, color) and the chemical composition in compounds (NH4+, NO2-, ΝΟ3-, SO42-, PO43) and elements (Ca, K, Mg, Na, Br, Cl, F, B, Sb, Se) including heavy metals (Ag, As, Cd, Co, Cr, Fe, Hg, Mn, Ni, Pb, Zn) in the waters of the study area, in order to define the degree of a possible pollution. According to the physicochemical characteristics of the groundwater, most of them are characterized as “very hard” and “fresh” waters, with an accepted turbidity level and with normal pH values and conductivity level. As far as the results of potable water analyses are concerned, it is shown that the concentrations, mainly of calcium (Ca), sodium (Na) and chlorine (Cl) are elevated at the most studied locations. Furthermore, very rather high levels of arsenic (As) and iron (Fe), exceeding the upper legal limits, are observed only in the underground water of Chalastra, making the drinking water of the region inappropriate for human consumption.