A modified SINTACS method for groundwater vulnerability and pollution risk assessment in highly anthropized regions based on NO₃^- and SO₄^2- concentrations

Groundwater vulnerability and risk assessment are worldwide tools in supporting groundwater protection and land planning. In this study, we used three of these different methodologies applied to the Campanian Plain located in southern Italy: SINTACS, AVI and LOS. However, their capability to describe the observed chemical pollution of the area has resulted quite poor. For such a reason, a modified SINTACS method has been then implemented in the area in order to get a more reliable view of groundwater vulnerability. NO₃^- and SO₄^2- from more than 400 monitoring wells were used for specific vulnerability assessment. Land use was chosen as key parameter to infer the risk of groundwater pollution in our area. The new methodology seems to show a higher correlation with observed NO₃^- concentrations and a more reliable identification of aquifer's pollution hot spots. The main sources of NO₃^- were found in sub-urban areas, where vulnerability and risk are higher than in other areas. Otherwise due to reducing conditions triggered by the presence of elevated sedimentary organic matter and peat, concentrations below agricultural areas were lower than in sub-urban areas. The SO₄^2- specific vulnerability map showed a positive correlation with observed concentrations, due to geogenic and anthropogenic SO₄^2- sources present in the area. The combination of both NO₃^- and SO₄^2- derived risk maps becomes essential to improve the conceptual model of aquifer pollution in this severely anthropized area. The application of this new and original approach shed light on the strengths and weaknesses of each of the described previous methods and clearly showed how anthropogenic activities have to be taken into account in the assessment process.