Groundwater contamination by nitrates and seawater intrusion in Atalanti basin (Fthiotida, Greece)
The aim of the present essay is to evaluate the groundwater quality in the coastal alluvial aquifer of the Atalanti basin (Fthiotida, Greece). For this reason, data from the physical and chemical analyses of groundwater samples for eight sampling periods were collected and nitrate pollution was studied thoroughly. The period of June 2005 is the most appropriate and representative as far as dispersion and number of samples are concerned. The most dominant water type is Mg-(Ca)-HCO3, due to the presence of dolomite and ultrabasic rocks. Moreover, the Na-Cl hydrochemical type is recorded near the coast line, due to seawater intrusion. Furthermore, it can be concluded that a) the high nitrates concentration values are related with the intensified agricultural production, the applied fertilizers and the absence of sewage systems, b) higher Mg concentration and Mg/Ca ratio values are observed near the coastline due to high Mg concentration in sediments and seawater intrusion, c) high Cl and Ca concentration in the southern area are connected with the discharge of the karst, saline spring in Tragana and seawater intrusion, d) according to factor analysis there are three main factors that are related with the aquifer salinization, the dolomite/ultrabasic rocks dissolution and the nitrate pollution with intense use of fertilizers, e) according to the cluster analysis, there are two clusters of water samples in Atalanti: the ones near the coastline with increased hardness, that are affected by salts and the ones in the central basin with reduced hardness, due to the short residence time in the ground Finally, some recommendations are proposed in order to protect and improve the groundwater quality in the study area.
KeywordsSeawater Intrusion Groundwater Contamination Aquifer Salinization Ultrabasic Rock Nitrate Pollution
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