Rainfall and temperature variability causes changes in groundwater recharge that can also influence groundwater quality by different processes. The aim of this study is the analysis of the hydrogeochemical variations over time due to meteorological variability in two different study areas in Italy: an alluvial aquifer in the Piedmont Po plain and an alluvial-pyroclastic aquifer in the Campanian plain. The examined plains show groundwater with natural quality not satisfying the European drinking water standards, or anthropogenic contamination. The peculiar natural quality is due, in the Campanian plain, to the closeness of volcanic areas, and to the presence of reducing conditions. In Piedmont plain a test site is characterized by a point-source contamination by heavy metals, due to the presence of past industrial activities. In all the examined areas there is a diffuse nitrate contamination. The fluctuations of the ions As, F, Fe, Mn, Cr VI, NO₃, and Cl were analyzed and compared, using statistical methods, with the variations over time in precipitation, temperature, and piezometric levels, sometimes significant. Results highlight the importance of the groundwater and meteorological monitoring and the key role of the recharge variation in the hydrogeochemical processes. The linking degree between rainfall/temperature variability and hydrogeochemistry is variable, in function of the typology of chemical species, their origin, and of the aquifer characteristics. The fluctuation of climate variables determines sudden changes in the geochemistry of shallow unconfined aquifers (e.g., in the Piedmont plain), while semiconfined or confined aquifers (e.g., in the Volturno-Regi Lagni plain) react with a greater delay to these variations. Moreover, natural quality is more affected by climatic variations than anthropogenic contamination, which is the result of multiple environmental and anthropic factors.

This paper deals with the environmental characterization of a large and densely populated area, with a poor reputation for contamination, considering the contribution of environmental features (air, soil, soil hydraulic and groundwater) and the potential effects on human health. The use of Geographic Information System (GIS) has made possible a georeferenced inventory and, by overlaying environmental information, an operational synthesis of comprehensive environmental conditions. The cumulative effects on environmental features were evaluated, taking into account superposition effects, by means of the Spatial MultiCriteria Decision Analysis (S-MCDA). The application of the S-MCDA for converging the combination of heterogeneous factors, related to soil, land and water, deeply studied by heterogeneous groups of experts, constitutes the novelty of the paper. The results confirmed an overall higher potential of exposure to contaminants in the environment and higher mortality rates in the study area for some tumours, but hospital admissions for tumours were generally similar to the regional trend. Besides, mortality data may be strictly dependent on the poor socioeconomic conditions, quality of therapy and a lack of welfare in the area relative to the rest of Italy. Finally, as regards the possible relationship between presence of contaminants in the environment and health conditions of the population no definite conclusions can be drawn, although the present study encourages the use of the new proposed methods, that increase the possibilities for studying the combined effect of more environmental factors.

Many methods for evaluating the aquifer’s vulnerability to pollution have been developed in the past four decades by using geographic information system (GIS) tools. However, even if the aquifer vulnerability concept is well defined and the methods have been constantly tested and compared, the problem of the choice of the best “standard” method remains. To meet these objectives, aquifer vulnerability maps are of crucial importance. The choice of method depends on several factors, including the scale of the project, the hydrogeological characteristics of the area, and data availability. Among the many methods, the AVI (Aquifer Vulnerability Index) method has been widely used as it considers only two physical parameters. The AVI Index represents the hydraulic resistance of an aquifer to vertical flow, as a ratio between the thickness of each sedimentary unit above the uppermost aquifer (D, length), and the estimated hydraulic conductivity (K, length/time) of each of these layers. The AVI Index has a time dimension and is divided into five classes. In order to avoid a widespread presence of the higher vulnerability classes, especially in shallow aquifers, the AVI classification has been modified using statistical methods. The study reports the application of the modified AVI method for groundwater pollution vulnerability, in three different areas of southern Italy, highlighting the limitations of the method in alluvial aquifers and the differences with other methods.

This paper deals with the environmental characterization of a large and densely populated area, with a poor reputation for contamination, considering the contribution of environmental features (air, soil, soil hydraulic and groundwater) and the potential effects on human health. The use of Geographic Information System (GIS) has made possible a georeferenced inventory and, by overlaying environmental information, an operational synthesis of comprehensive environmental conditions. The cumulative effects on environmental features were evaluated, taking into account superposition effects, by means of the spatial multicriteria decision analysis (S-MCDA). The application of the S-MCDA for converging the combination of heterogeneous factors, related to soil, land and water, deeply studied by heterogeneous groups of experts, constitutes the novelty of the paper. The results confirmed an overall higher potential of exposure to contaminants in the environment and higher mortality rates in the study area for some tumours, but hospital admissions for tumours were generally similar to the regional trend. Besides, mortality data may be strictly dependent on the poor socioeconomic conditions, quality of therapy and a lack of welfare in the area relative to the rest of Italy. Finally, as regards the possible relationship between presence of contaminants in the environment and health conditions of the population no definite conclusions can be drawn, although the present study encourages the use of the new proposed methods, that increase the possibilities for studying the combined effect of more environmental factors.

Increased variability in precipitation and more extreme weather events caused by climate change can lead to more extended periods of droughts and floods, which directly affects the availability of groundwater. The consequent fluctuation of the water table can also affect groundwater quality. Particularly, a higher recharge, and the resultant increase of the piezometric level, can have, as a positive result, the dilution of the contaminants in aquifers and a decrease of the concentrations. On the other side, water that infiltrates can leach pollutants that are present in the unsaturated zone, with an increase of groundwater pollution. Even, the rise of the piezometric level can have negative consequences on groundwater quality, also due to groundwater that leach the capillary fringe and the previously unsaturated zone; if a contaminant is present in these sectors, it can lead to an increase of the aquifer pollution.The increase or decrease in contaminants levels depend on a complex balance between all the described phenomena, and contaminant behaviour. This study wants to analyse the hydrogeochemical variations in time due to climate variability to define the role of different processes.Two different hydrogeological environments were chosen as test fields: an alluvial aquifer in the Piedmont Po Plain (NW Italy) and an alluvial-pyroclastic aquifer in the Campanian plain (S Italy).Piedmont Po plain shows a diffuse nitrate contamination, due to intensive agricultural and livestock activities. A nickel contamination is locally present, due to natural causes, namely the presence of basic and ultrabasic rocks debris in the supply basins, containing high amount of nickel-bearing femic minerals. Consequently, nitrate and nickel fluctuation were analysed and compared with precipitation and piezometric levels.The hydrogeochemistry of the Campanian plain is influenced by the closeness of volcanic active areas (Phlegrean Fields and Vesuvius), bringing high As and F values, and by the presence of reducing conditions, bringing high Fe and Mn values. Moreover, there is a widespread nitrate contamination, prevalently due to intensive agricultural and livestock activities. The fluctuations of these 5 ions (As, F, Fe, Mn and NO3) have been observed during almost twenty years and compared with the differences in recharge, sometimes significant due to the climate change.The monitoring and analyses of the chemical concentrations of ions of anthropogenic and natural origin in a context of climate variability represent a key element to offer a new and different research perspective in the field of groundwater chemistry.

This hydrogeological study has been performed in the framework of a\ud LIFE + project (LIFE11/ENV/IT/275 – ECOREMED ). The study area is\ud a large flat area (> 1500 km2) located in Campania region (Southern Italy).\ud In the first phase, completed in 2014, the study consisted in the synergetic\ud approach among different scientists to attain to the environmental\ud characterization of the whole area. The second phase, started in 2015, was\ud focused on the hydrogeological characterization of small sites (from 3000\ud m2 to 4500 m2), and it included a detailed investigation survey, based on\ud boreholes drilling, slug tests, pumping tests, hydrogeochemical\ud monitoring, etc. The site-scale study showed the important role of small\ud lenses of impervious materials together to the differences in the flowpath\ud for groundwater above and under impervious materials and the flowpath at\ud regional scale. Finally, the hydrogeochemistry gave important results\ud about the groundwater quality and the contamination state