Evaluating toxic element contamination sources in groundwater bodies of two Mediterranean sites

The Driver-Pressure-State-Impact-Response (DPSIR) framework is applied for assessing the pressures and impacts on groundwater bodies of two Mediterranean sites (Megara and Oropos-Kalamos basins). The study areas present joint driving forces (drivers) and pressures. The main driving forces in the areas studied mainly include geology, agricultural activities, and urban development, while the main pressures mainly include the weathering of ultramafic rock masses, application of agrochemicals, and groundwater abstractions for irrigation and drinking uses. Hexavalent chromium (Cr⁺⁶), chromium total (Cr_total), manganese (Mn), and nitrate (NO₃^-) contamination of groundwater bodies are attributed to both anthropogenic and lithological sources. Elevated Cr_total (up to 70.3 μg L^-1), Mn (up to 87.7 μg L^-1), and NO₃^- (up to 411 mg L^-1) contents are recorded for groundwater samples in Megara basin. High Cr_total (up to 34.3 μg L^-1), Cr⁶⁺ (up to 27.9 μg L^-1), Mn (up to 132.5 μg L^-1), and NO₃^- (up to 30 mg L^-1) are also observed for groundwater samples in the Oropos-Kalamos basin. The major response actions needed for the management options of groundwater bodies are discussed. Among the proposed remedial measures, the installation of a continuous groundwater monitoring network and the control in the usage of nitrogen fertilizers seems to be the most effective and tangible for immediate action.