Seawater intrusion and nitrate pollution in coastal aquifer of Almyros - Nea anchialos basin, central Greece

Abstract

The exploitation of groundwater resources is of high importance and has become very crucial the last decades especially in coastal areas of Central Greece, due to urbanization, tourist development and intensive agriculture. The phenomenon of seawater intrusion in coastal aquifers is a significant environmental issue in Greece that nowadays is considered as pollution of groundwater, which could pose a threat to human's health through direct consumption or through irrigation processes. The objectives of this study are to identify and investigate the extent of seawater intrusion in the Nea Anchialos basin in Central Greece. For this purpose, 45 groundwater samples were collected from the study area and analyzed for certain parameters that indicated salinisation of the aquifers. Specifically, water chemical analysis were conducted and statistical analysis regarding spatial distribution were performed. The results demonstrated increased values of the parameters which can be attributed to seawater intrusion. Laboratory analyses indicated that Electrical Conductivity, concentration for the basic cations (Ca+2, Mg+2, Na+ and K+), HCO3 -, Cl-, and SO4 -2 varied greatly. Furthermore, maximum NO3 -concentration was 138 mg/L and this can be attributed to overexploitation of coastal aquifer for agricultural activities. The results indicated seawater intrusion in the north-eastern part of the study area. Hydrochemical maps were compiled using SURFER version 7 Software, based on models Shepard and Inverse Distance to a Power (IDP), in order to present the results in an integrated way and demonstrate the "hotspots" of pollution.