Defining natural background levels (NBL) of geochemical parameters in groundwater is a key element for establishing threshold values and assessing the environmental state of groundwater bodies (GWBs). In the Apulia region (Italy), carbonate sequences and clastic sediments host the 29 regional GWBs. In this study, we applied the Italian guidelines for the assessment of the NBLs, implementing the EU Water Framework Directive, in a south-European region characterized by the typical Mediterranean climatic and hydrologic features. Inorganic compounds were analyzed at GWB scale using groundwater quality data measured half-yearly from 1995 to 2018 in the regional groundwater monitoring network (341 wells and 20 springs). Nitrates, chloride, sulfate, boron, iron, manganese and sporadically fluorides, boron, selenium, arsenic, exceed the national standards, likely due to salt contamination along the coast, agricultural practices or natural reasons. Monitoring sites impacted by evident anthropic activities were excluded from the dataset prior to NBL calculation using a web-based software tool implemented to automate the procedure. The NBLs resulted larger than the law limits for iron, manganese, chlorides, and sulfates. This methodology is suitable to be applied in Mediterranean coastal areas with high anthropic impact and overexploitation of groundwater for agricultural needs. The NBL definition can be considered one of the pillars for sustainable and long-term groundwater management by tracing a clear boundary between natural and anthropic impacts.

Coastal areas are characterized by considerable demographic pressure that generally leads to groundwater overexploitation. In the Mediterranean region, this situation is exacerbated by a recharge reduction enhanced by climate change. The consequence is water table drawdown that alters the freshwater/seawater interface facilitating seawater intrusion. However, the groundwater salinity may also be affected by other natural/anthropogenic sources. In this paper, water quality data gathered at 47 private and public wells in a coastal karst aquifer in Apulia (southern Italy), were interpreted by applying disparate methods to reveal the different sources of groundwater salinity. Chemical characterization, multivariate statistical analysis, and mixing calculations supplied the groundwater salinization degree. Characteristic ion ratios, strontium isotope (⁸⁷Sr/⁸⁶Sr), and pure mixing modelling identified the current seawater intrusion as a main salinity source, also highlighting the contribution of water–rock interaction to groundwater composition and excluding influence from Cretaceous paleo-seawater. Only the combined approach of all the methodologies allowed a clear identification of the main sources of salinization, excluding other less probable ones (e.g., paleo-seawater). The proposed approach enables effective investigation of processes governing salinity changes in coastal aquifers, to support more informed management.

The disposal of municipal solid wastes in landfills represents a major threat for aquifer environments at the global scale. The aim of this study was to explore how groundwater geochemical characteristics can influence the microbial community functioning and the potential degradation patterns of selected organic substrates in response to different levels of landfill-induced alterations. Groundwaters collected from a landfill area were monitored by assessing major physical-chemical parameters and the microbiological contamination levels (total coliforms and fecal indicators—Colilert-18). The aquatic microbial community was further characterized by flow cytometry and Biolog EcoPlates^TM assay. Three groundwater conditions (i.e., pristine, mixed, and altered) were identified according to their distinct geochemical profiles. The altered groundwaters showed relatively higher values of organic matter concentration and total cell counts, along with the presence of fecal indicator bacteria, in comparison to samples from pristine and mixed conditions. The kinetic profiles of the Biolog substrate degradation showed that the microbial community thriving in altered conditions was relatively more efficient in metabolizing a larger number of organic substrates, including those with complex molecular structures. We concluded that the assessment of physiological profiling and functional diversity at the microbial community level could represent a supportive tool to understand the potential consequences of the organic contamination of impacted aquifers, thus complementing the current strategies for groundwater management.

Arsenic is a potentially toxic element (PTE) that is widely present in groundwater, with concentrations often exceeding the WHO drinking water guideline value (10.0 μg/L), entailing a prominent risk to human health due to long-term exposure. We investigated its origin in groundwater in a study area located north of Rome (Italy) in a volcanic-sedimentary aquifer. Some possible mineralogical sources and main mechanisms governing As mobilization from a representative volcanic tuff have been investigated via laboratory experiments, such as selective sequential extraction and dissolution tests mimicking different release conditions. Arsenic in groundwater ranges from 0.2 to 50.6 μg/L. It does not exhibit a defined spatial distribution, and it shows positive correlations with other PTEs typical of a volcanic environment, such as F, U, and V. Various potential As-bearing phases, such as zeolites, iron oxyhydroxides, calcite, and pyrite are present in the tuff samples. Arsenic in the rocks shows concentrations in the range of 17–41 mg/kg and is mostly associated with a minor fraction of the rock constituted by FeOOH, in particular, low crystalline, containing up to 70% of total As. Secondary fractions include specifically adsorbed As, As-coprecipitated or bound to calcite and linked to sulfides. Results show that As in groundwater mainly originates from water-rock interaction processes. The release of As into groundwater most likely occurs through desorption phenomena in the presence of specific exchangers and, although locally, via the reductive dissolution of Fe oxy-hydroxides.

The data value of hyperspectral measurements on ice and snow cover is strongly impacted by the availability of data services, where spectral libraries are integrated to detailed descriptions of the observed surface cover. For snow and ice cover, we present an updated version of the Snow/Ice Spectral Archive (SISpec 2.0), which has been integrated into a web portal characterized by different functionalities. The adopted metadata scheme features basic geographic data, information about the acquisition setup, and parameters describing the different surface types. While the implementation of the IACS Classification of Seasonal Snow on the Ground is the core component for snow cover, ice cover is approached using different parameters associated with its surface roughness and location. The web portal is not only a visualization tool, but also supports interoperability functionalities, providing data in the NetCDF file format. The availability of these functionalities sets the foundation for sharing a novel platform with the community and is an interesting tool for calibrating and validating data and models.