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Water resources represented by coastal aquifers are very important for regions characterized by a relevant request of freshwater, but limited rainfall, lack of surface water bodies and intrusion of the seawater through the sediments which host groundwater. Therefore some coastal areas, like the Salento peninsula (southern Italy), are subjected to the risk of desertification and a proper management of groundwater resources requires tools to analyze and predict the water balance and the evolution of the physical system in response to human activities (e.g., ground water withdrawals) and climatic factors. The Salento peninsula is a typical Mediterranean basin, where the main water resource is the aquifer hosted in Cretaceous carbonatic rocks (Calcare di Altamura, Altamura limestone): this is a fractured and karst aquifer, with a poor recharge and complex relationships with the sea. In order to develop a tool to assess the water balance at regional scale for the considered aquifer system, a groundwater flow model was developed by Giudici et al. (2012a); it is based on a conceptual model obtained from a reconstruction of the hydrostratigraphic architecture of the region, which includes the main aquifer and the overlaying rocks characterized by low permeability which can host local and relatively thin aquifers. In this paper that work is updated, by improving the reconstruction of the hydraulic head and of the conceptual model, above all in those areas that the previous model evidenced as critical for the absence of fresh water along the whole aquifer thickness. Moreover, since the estimate of some model’s input parameters is affected by high uncertainty, a sensitivity analysis is performed to evaluate the effects of this uncertainty on the model’s results.

The Salento Peninsula (south-eastern Italy) is characterized by sedimentary rocks. The carbonatic nature of the rocks means they are affected by karst phenomena, forming such features as sinkholes, collapsed dolines and caverns, as a result of chemical leaching of carbonates by percolating water. The instability of these phenomena often produces land subsidence problems. The importance of these events is increasing due to growing urbanization, numerous quarries affecting both the subsoil and the surface, and an important coastline characterized by cliffs. This paper focuses on geological and geophysical methods for the characterization of soft sedimentary rock, and presents the results of a study carried out in an urban area of Salento. Taking the Q system derived by Barton (2002) as the starting point for the rock mass classification, a new approach and a modification of the Barton method are proposed. The new equation proposed for the classification of sedimentary rock mass (Qsrm) takes account of the permeability of the rock masses, the geometry of the exposed rock face and their types (for example, quarry face, coastal cliff or cavity), the nature of the lithotypes that constitute the exposed sequence, and their structure and texture. This study revises the correlation between Vp and Q derived by Barton (2002), deriving a new empirical equation correlating P-wave velocities and Qsrm values in soft sedimentary rock. We also present a case history in which stratigraphical surveys, Electrical Resistivity Tomography (ERT), and seismic surveys were applied to in situ investigations of subsidence phenomena in an urban area to estimate rock mass quality. Our work shows that in the analysis of ground safety it is important to establish the rock mass quality of the subsurface structures; geophysical exploration can thus play a key role in the assessment of subsidence risk.

In the framework of the Italian Special Network for Mercury (ISNM) “Reti Speciali”, a sampling campaign to monitor atmospheric mercury (Hg) was carried out at Monte Sant’Angelo (MSA). This is a coastal monitoring station in the Apulia region, representative of the Southern Adriatic area, within the Mediterranean basin. This work presents continuous Gaseous Elemental Mercury (GEM) measurements over about three years at MSA, using the Lumex RA-915AM mercury analyzer. The aim was to obtain a dataset suitable for the analysis of Hg concentrations in terms of source and transport variation. Diurnal cycles of GEM were evaluated to observe the influence of local atmospheric temperature and wind speed on potential re-emissions from surrounding sea and soil surfaces. Data were also analyzed in terms of long-range transport, using backward trajectory cluster analysis. The spatial distribution of potential sources, contributing to higher measured GEM values, was obtained employing Potential Source Contribution Function (PSCF) statistics. The influence of major Hg anthropogenic point sources, such as mining activities and coal-fuel power plants, both regionally and continentally, from mainland Europe, was observed. The role of the vegetation GEM uptake in modulating the seasonal GEM variability was also investigated. The potential of wildfire influence over the highest detected GEM levels was further examined using active fire data and the evaluation of the vegetation dryness index during the selected episodes. Graphical abstract

Abstract. This work sets out a physical – stratigraphical reconstruction of the superficial aquifer in the Brindisi area; this site is recognized to be at significant environmental risk (Law no. 426/98) by the Italian government. Geological, hydrogeological and geophysical methodologies were applied. The geological characterisation consisted of surface and subsoil surveys. The existing stratigraphical, geotechnical and hydrogeological data were collected, processed and homogenised, and the information inserted in a database managed with a specific software (arcview). Hydrogeological surveys were conducted in a number of boreholes uniformly distributed over the studied area. Geophysical prospecting was conducted in the most industrialized part of the area, adjacent to a combined industrial road/conveyor belt – the "Asse Attrezzato" – in order to better describe the site and evaluate the impact of this structure on the environment. This research enabled us to characterise the superficial aquifer of the Brindisi area. The groundwater is of the phreatic type. In the upper part of the deposit, the presence of low permeability sediments (recent continental deposits) means that the groundwater is confined. Subapennine Clays (Lower Pleistocene), present across the whole of the area, form the impermeable base of the aquifer. The deposits that make up the superficial aquifer vary greatly in their permeability. The greatest permeability is associated with the calcarenite deposits (Terraced Deposits, Middle-Upper Pleistocene). The higher the proportion of slime in the granulometric assortment, the lower the permeability of the deposit. The lower section of the aquifer, characterized by the presence of slimy-sandy sediments (Brindisi sands, Lower-Middle Pleistocene), has a lower permeability. The results of the geophysical investigations enabled us to reconstruct in detail the lateral and vertical lithological variations of the geological formations. Furthermore, by supplementing the data from boreholes (direct surveys), the geophysical surveys proved to be useful in that they reduce the need for perforations of the ground, which are potential conduits of pollution.

Abstract. This work sets out a methodology of integrated geological, hydrogeological and geophysical surveys for the characterization of contaminated sites. The flow model of the shallow aquifer in the Brindisi area (recognized to be at significant environmental risk by the Italian government) and the impact of an antrophic structure on the groundwater flow have been evaluated. The stratigraphic and hydrogeological targets used for the calibration phase of the flow model provide a means of assessing calibration quality. The good calibration of the model point out the key role of a detailed knowledge of the physical-stratigraphycal attributes of the area to be studied and field data collection. Geoelectrical tomography focus the attention on an area resulted of particular interest by the flow model obtained. This method permit to reconstruct in detail the lateral and vertical lithological variations in the geological formations improving the spatial resolution of the data and consequently the scale of observation. Besides, anomaly resistivity values have been correlated with pollution. Chemical analysis have confirmed this correlation.