The Alcantara River Basin is located in North-Eastern Sicily (Italy), encompassing the north side of Etna Mountain, the tallest active volcano in Europe. On the right-hand side of the river, the mountain area is characterized by volcanic rocks with a very high infiltration. Here, precipitation and snow melting supply a big aquifer whose groundwater springs at the mid/downstream of the river, mixing with surface water and contributing to feeding the river flow also during the dry season. In the upstream a maximum of 520 l/s are extracted for municipal use through wells and an infiltration gallery supplying the Alcantara Aqueduct. In summer 2020 and 2021, the river suffered a prolonged dry phenomenon in the middle-valley stretch with a serious loss of fish fauna, due to significant spring depletion along the stream most likely determined by a meteorological drought. Since this anomaly is of great concern, the need arises to better understand whether the interaction between the water abstraction to supply the Alcantara aqueduct and the natural recharge of the aquifer is compatible with maintaining the balance of aquatic ecosystems in the middle-downstream valley of the Alcantara River also during dry years; or if the observed changes may also be partly due to other mechanisms, such as illegal or unaccounted water abstractions or hydrogeological modification due to the volcanic activity. To this end, in this study, an attempt was made to analyze changes in the groundwater level and in the interconnection between surface and groundwater by using the widely accepted MODFLOW 6, a finite-difference numerical model that in principle can provide constraints to reduce uncertainty and address field activity in data scarce case studies. The model was calibrated in steady state by comparing simulated and observed water heads as well as the groundwater budget. Then the simulation was run in transient mode for the period 2014-2021. The model outcome showed a depletion rate compatible with the one observed during the recent dry summers, thus suggesting that more sustainable and comprehensive strategies, also including groundwater extraction regulations, should be implemented to preserve this natural resource for in-stream water use and ecosystem services.

The Alcantara River Basin is located in North-Eastern Sicily (Italy), encompassing the north side of Etna Mountain, the tallest active volcano in Europe. On the right-hand side of the river, the mountain area is characterized by volcanic rocks with a very high infiltration. Here, precipitation and snow melting supply a big aquifer whose groundwater springs at the mid/downstream of the river, mixing with surface water and contributing to feeding the river flow also during the dry season. In the upstream a maximum of 520 l/s are extracted for municipal use through wells and an infiltration gallery supplying the Alcantara Aqueduct. In summer 2020 and 2021, the river suffered a prolonged dry phenomenon in the middle-valley stretch with a serious loss of fish fauna, due to significant spring depletion along the stream most likely determined by a meteorological drought. Since this anomaly is of great concern, the need arises to better understand whether the interaction between the water abstraction to supply the Alcantara aqueduct and the natural recharge of the aquifer is compatible with maintaining the balance of aquatic ecosystems in the middle-downstream valley of the Alcantara River also during dry years; or if the observed changes may also be partly due to other mechanisms, such as illegal or unaccounted water abstractions or hydrogeological modification due to the volcanic activity. To this end, in this study, an attempt was made to analyze changes in the groundwater level and in the interconnection between surface and groundwater by using the widely accepted MODFLOW 6, a finite-difference numerical model that in principle can provide constraints to reduce uncertainty and address field activity in data scarce case studies. The model was calibrated in steady state by comparing simulated and observed water heads as well as the groundwater budget. Then the simulation was run in transient mode for the period 2014-2021. The model outcome showed a depletion rate compatible with the one observed during the recent dry summers, thus suggesting that more sustainable and comprehensive strategies, also including groundwater extraction regulations, should be implemented to preserve this natural resource for in-stream water use and ecosystem services.

Aquifers of coastal areas are impaired by saline water intrusion owing to either natural or anthropogenic causes. Different inputs of surface and marine salt waters can consistently affect the local hydrological, geochemical, and biological settings, with direct consequences on groundwater quality, the aquifer ecological status, and related ecosystem services. The aquatic microbial community represents a fundamental component of the groundwater resident biota by playing a major role in carbon and nutrient cycling through rapid structural and functional adaptations to changing environmental conditions. However, the structural and functional traits of the aquatic microbial community in coastal aquifers were largely disregarded in the current literature. The present work aimed to explore the groundwater quality in a coastal karst aquifer located in southern Italy (Region Apulia) and the microbial community responses to groundwater salinization. The target area (1227 km2) is located in a semi-arid climate region with agricultural vocation. Water withdrawal for irrigation is among the major factors promoting saline intrusion. A total of 200 samples, collected during four sampling campaigns, were analyzed in situ for the main physical-chemical parameters (oxidation reduction potential, pH, electrical conductivity, T, dissolved oxygen) together with UV-VIS determinations of ammonia, nitrites, and cyanides. Chemical analysis in the laboratory included major anions/cations, trace elements, and dissolved organic carbon (DOC). The groundwater microbial community was characterized by assessing the total microbial load (flow cytometry), the microbiological contamination of fecal origin (Colilert- 18 assay), the microbial metabolic potential (Biolog EcoPlates), the heterotrophic respiration (Biolog MT2 MicroPlates), the extracellular enzyme expression (API ZYM test), and the phylogenetic community composition (16rRNA gene amplicon sequencing). Preliminary results from 47 sampling sites allowed identifying four major groups of waters with different salinity levels according to Cl concentration patterns. The aquatic microbial load and fecal contamination levels were generally low and not significantly affected by salinization. However, the microbial functional activities were likely stimulated at increasing salt concentration and the phylogenetic community profiles changed consistently during the water withdrawal period. The observed changes can have potential repercussions on biogeochemical cycling and ecosystem services. The approach here utilized can represent a fast, reliable and sensitive tool for tracking saline water impact in the groundwater environment in view of better management of the water resource.

The analysis of pressures and impacts on the Apulian aquifers, as required by the EU WFD, has evidenced physical and chemical parameters related to groundwater salinization, particularly along the coastal strip. Predisposing factors such as lithology, tectonic evolution, aquifer over-exploitation (Passarella et al., 2017), and the ongoing climate change are various. Therefore, distinguishing natural from anthropogenic sources of salinization becomes a fundamental issue for assessing the aquifer's chemical status. In this framework, isotopic measures of O, H, B, and Sr, suitably support distinguishing different sources of salinity, water-rock interaction processes, and the origin of the water molecules (Pennisi et al., 2006). This study focuses on the coastal sector of the Murgia aquifer located on the Adriatic side of the Apulia region (south Italy). It is made up of several hundred-meter-thick Mesozoic calcareous and calcareous-dolomite rocks affected by fracturing and karst phenomena. The aquifer is confined and characterized by irregular geometry. Groundwater flows to the sea where it rises in numerous coastal springs. Paleo-seawater as an additional source of salinity has been suggested by previous studies. 87 Sr/86Sr, 11B/10B, (expressed as ?11B permil), ?18O, ?2H determined with overall chemistry in about 50 samples collected in autumn 2019 in the study area, range from 0.70768 to 0.70884, from +15.3? to +43.0?, from -7.78? to -3.40? and from -49.50? to -23.30?, respectively. The coupled chemical and isotopic approach evidenced that different mixing processes concur in the water, highlighting hydrogeologic zoning and complex groundwater circulation patterns. Some samples reveal Sr and B isotopic compositions typical of the local Cretaceous carbonate rocks implying a prolonged water-rock interaction. Chemistry and isotopes in 6 samples, where chlorine ranges from 3162 to 9684 mg/L indicate a significant contribution from modern seawater. Water>s intermediate compositions are explained by a different mixing degree of known endmembers, such as meteoric, marine, and rock-interacting water. ?11B values, 87 Sr/86Sr ratios, and Cl, B, and Sr contents seem to exclude the contribution of fossil seawater to the studied groundwater. Further studies on high conductivity samples are ongoing to better detail the zoning based on the isotopic and hydrogeological characteristics and to confirm or deny the occurrence of fossil marine waters.

Questo manuale, frutto della collaborazione IRSA-CNR, ISPRA, ARPAV, è specificamente dedicato ai "modelli di flusso in acquiferi porosi" ed ha come scopo principale di proporre degli schemi operativi, elaborati nella forma di schede di valutazione, che guidino passo per passo il modellista nel lavoro di sviluppo del modello e il valutatore nel formulare un giudizio basato su elementi condivisi. Il documento complessivo fornisce gli elementi necessari per un uso efficace di tali schemi operativi. Esso può quindi essere utilizzato con diversi obiettivi: 1. supportare il modellista nella implementazione del modello evidenziando gli elementi critici e le eventuali lacune esistenti; 2. consentire un agevole scambio di informazioni tra committente e modellista, per una verifica puntuale del lavoro sia in corso d'opera che alla consegna; 3. fornire al committente elementi utili per una valutazione critica del lavoro del modellista.

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. Moni-toring 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 overexploi-tation 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.

Relazione conclusiva del monitoraggio delle acque di falda nella rete piezometrica dell'impianto di discarica in loc. Cerreto (FR). Lo studio mette in evidenza la relazione tra la migrazione del gas di discarica (metano e CO2 con tracce di VOC) dall'invaso alla falda e la dissoluzione riduttiva di ossi-idrossidi di ferro e manganese con arsenico adsorbito che porta all'aumento della loro concentrazione in falda. Alla fine dello studio, quando le concentrazioni si stanno stablizzando a seguito della migliorata efficienza della captazione dei gas, sono stati stabiliti dei livelli di guardia (in conformità con la Direttiva Discariche e il Dlgs 36/2003) per questi elementi per ciascun piezometro.

Groundwater resources are of utmost importance in sustaining water related ecosystems, including humans. The long-lasting impacts from anthropogenic activities require early actions, owing to the natural time lag in groundwater formation and renewal. The European Union (EU) policy, within the implementation of the Water Framework Directive (WFD), requires Member States to identify and reverse any significant and sustained upward trend in the concentration of pollutants, defining specific protection measures to be included in the River Basin Management Plans (RBMP). In Italy, official guidelines for trend and trend reversal assessment have been published recently. Statistical methods, such as the Mann-Kendall test for trend analysis and the Sen's method for estimating concentration scenarios, should be applied at the fixed terms stated by the WFD implementation cycles to identify upward trends, while the Pettitt test is proposed for the identification of trend reversal. In this paper, we present an application of a slightly modified version of the Italian Guidelines to a groundwater body in Northern Italy featuring nitrate pollution and discuss its advantages and limitations. In addition to Pettitt test, for the trend reversal analysis, we apply the MannKendall test in two sections and compare the results. We conclude that this method seems more reliable than Pettitt test to identify a reversal point in quality time series. The overall procedure can be easily applied to any groundwater body defined at risk across Europe, for the assessment of the upward trends of pollutants and their reversal, even with little chemical monitoring data. Although focused on the EU legislative framework, this procedure may be relevant for a wider context, allowing to individuate upward trend as early warning for contamination processes in an integrated water resources management context.

Inorganic compounds in groundwater may derive from both natural processes and anthro-pogenic activities. The assessment of natural background levels (NBLs) is often useful to distinguishthese sources. The approaches for the NBLs assessment can be classified as geochemical (e.g., thewell-known pre-selection method) or statistical, the latter involving the application of statisticalprocedures to separate natural and anthropogenic populations. National Guidelines for the NBLsassessment in groundwater have been published in Italy (ISPRA 155/2017), based mainly on thepre-selection method. The Guidelines propose different assessment paths according to the samplesize in spatial/temporal dimension and the type of the distribution of the pre-selected dataset, takingalso into account the redox conditions of the groundwater body. The obtained NBLs are labelled witha different confidence level in function of number of total observations/monitoring sites, extensionof groundwater body and aquifer type (confined or unconfined). To support the implementationof the Guidelines, the on-line tool evaluation of natural background levels (eNaBLe), written inPHP and using MySQL as DBMS (DataBase Management System), has been developed. The maingoal of this paper is to describe the functioning of eNaBLe and test the tool on a case study incentral Italy. We calculated the NBLs of As, F, Fe and Mn in the southern portion of the MountsVulsini groundwater body, within the volcanic province of Latium (Central Italy), also separating thereducing and oxidizing facies. Specific results aside, this study allowed to verify the functioning andpossible improvements of the online tool and to identify some criticalities in the procedure NBLsassessment at the groundwater body scale

The vulnerability to salinization is a major issue for coastal aquifers. The resulting rapid modifications of hydro-geochemical characteristics, driven by the different origin of water inputs, can modify the properties of the resident biological communities. The study of structural and functional properties of groundwater microbial community, posed at the base of the heterotrophic food web, assumes an increasing importance to describe the effect of water quality on C-cycling and the resilience of groundwater systems to changes. Within the framework of the VIOLA project, this study was entailed to explore the groundwater quality and the functional responses of the microbial community across the gradient of salinity in a coastal karst aquifer located in Apulia Region (Southern Italy). The investigated area (1227 km2) is located in a semi-arid climate region with predominantly agricultural vocation. In this area, an excess of withdrawals for irrigation and other uses, often results in a significant decline of the water table, facilitating saline intrusion. The main physical-chemical parameters of 47 groundwater sampling sites (T, pH, oxidationreduction potential, electrical conductivity, major anions/cations, trace elements, dissolved oxygen, ammonia, nitrites, cyanides and dissolved organic carbon) were measured, along with microbial community analyses including the total cell abundance, the High Nucleic Acid and Low Nucleic Acid content cell ratio (Flow Cytometry), the total coliform and Escherichia Coli contamination (Colilert-18 assay), the microbial metabolic potential (Biolog EcoPlates), and the microbial respiration (Biolog MT2 MicroPlates). The preliminary results allowed identifying two major groups of waters with different salinity levels and concentrations of Cl, Na, Mg and SO4. Prokaryotic cell abundance (mean 3.5 x 104 ± 4.6 x 104 cells/ml) showed higher values in saline waters, so as HNA cell percentages and total coliforms. Saline waters were also characterised by relatively higher metabolic potential and respiration values. In conclusion, the observed groundwater quality changes induced the stimulation of the functional microbial properties and the functional diversity. These changes in the metabolic potential of the resident communities could alter the ability to exploit the available resources and modify the related groundwater biogeochemical cycling.metabolic adaptation to a condition of high salinization level.

La Banca Dati delle Risorse Idriche (WRdB) nasce allo scopo di facilitare le elaborazioni dei dati raccolti nel corso delle attività relative ai progetti di ricerca condotti sui Corpi Idrici Sotterranei del Lazio dal Gruppo di Idrogeologia e Geochimica attivo nell'Istituto di Ricerca sulle Acque. La Banca dati e le procedure di gestione sono state progettate al fine di: - Consentire agli operatori l'accesso costante alle informazioni di base e alle elaborazioni, anche sul terreno; - Armonizzare le procedure di elaborazione grafiche e statistiche più utilizate; - Centralizzare le attività di gestione dei dati; La struttura relazionale della Banca Dati è stata progettata tenendo conto di tali finalità e della diversa tipologia dei dati raccolti (dati relativi a pozzi/piezometri o a sorgenti). Le tabelle raccolgono non solo i dati chimici e chimico-fisici ma, per facilitarne l'interpretazione, anche i dati di supporto (localizzazione, tipologia del punto di campionamento, caratteristiche costruttive nel caso di pozzi/piezometri, dati della captazione nel caso di sorgenti, modalità di campionamento e strumentazione utilizzata). Attualmente sono presenti nel sistema circa 750 analisi chimiche relative a circa 350 pozzi/piezometri e 30 sorgenti, raccolte nell'ambito di 14 diversi Progetti di Ricerca. I corpi idrici investigati con un numero di punti di campionamento significativo sono: Monti Vulsini, Monti Cimini e Vicani, Monti Sabatini, Colli Albani, Versante sinistro della media valle del Tevere, Valli dei Fiumi Sacco, Liri e Garigliano. L'accesso completo al sistema è riservato al personale dell'Istituto. Attraverso le pagine relative alle elaborazioni di sintesi è possibile consultare dati aggregati relativi ai Corpi Idrici investigati, sopra indicati. Il sistema è implementato sui server dell'Istituto. Il gestore di database relazionali (DBMS) utilizzato è mySQL e le procedure lato server sono scritte impiegando PHP come linguaggio di programmazione. Per facilitare le interazioni con gli utenti dal lato client, le procedure contengono codice in Javascript.

T he European Water Directives (WDs, 2000/60/EC; 2006/118/EC) force Member States to proceed to the characterization of groundwater bodies in order to define their quantitative and chemical status and their environmental objectives. Since the earlier years of this century, the Department of Water Resources Management of the Apulia Region implemented the WDs by setting a wide groundwater monitoring network, delineating regional groundwater bodies and characterizing their status. The groundwater bodies characterization showed that the risk of not achieving a good status was generally related to salt contamination and the exceedance of the threshold values or the quality standards for some parameters (e.g., NO3, Fe, Mn), as expected for regions with a predominantly agricultural vocation and characterized by extensive coastal development. The main regional aquifers reside in the carbonate bedrock characterized by intense fracturing and karstification. The groundwater Directive 2006/118/EC allows the evaluation of Natural Background Levels (NBLs) to be taken into account when establishing the relevant threshold values. During the last years, the IRSA-CNR collaborated with the National Environmental Protection Agency (ISPRA) in defining scientifically based guidelines for the NBLs assessment and clarifying some methodological aspects. These guidelines suggest excluding water samples characterised by high levels of specific markers clearly indicating anthropogenic inputs. The project "VIOLA - Natural background levels for the groundwater bodies of Apulia Region ", has been funded by the Department of Water Resources Management of the Apulia Region for carrying out the application and validation of the above mentioned methodologies and to develop and test methodologies better tailored for coastal aquifers. In particular, isotopic techniques will be used to discriminate between the anthropogenic and natural origin of the salinization and historical data of groundwater salinization will be processed in order to study its evolution in time. . Finally, the investigation of innovative microbiological techniques is envisaged to evaluate how changes in groundwater quality will affect the resident microbial community properties involved in C-flux. The VIOLA project will last three years during which the IRSA-CNR will: - collect and order all the background knowledge relating to the hydro-geo-chemical characteristics of the Apulian groundwater bodies, - define adequate groundwater sampling procedures and assessment protocols for the NBLs, carry out field activities, aimed at sampling groundwater at a specific monitoring network and measuring values of main physico-chemical and microbiological parameters, in the study area of the coastal Murgia groundwater body, and - produce tools to support the planning and management of groundwater resources integrated in a GIS environment. This contribution aims at providing an overview at the ongoing activities at the regional scale, illustrating the groundwater bodies setting, the main pressures and the preliminary derivation of NBL using the historical data.

C oastal areas worldwide are often highly impacted due to the concurrence of aquifer exploitation for irrigation, human consumption exacerbated during touristic seasons and industrial activities. In order to meet the objectives of the GWD, European groundwater bodies' status (chemical and quantitative) is evaluated every 6 years. Criteria for good status include chemicals exceeding standards and threshold values, saline intrusion and others. Apulian region features a very high ratio coastline/area (44 m/km2, for Italy is 25 m/km2) thus seawater intrusion is a very common phenomenon, due to both natural and anthropogenic drivers. In this contribution, the first results of the VIOLA project (Natural Background Values for the Apulian groundwater bodies) are presented, supplying a preliminary geochemical characterization of the coastal Murgia groundwater body. This is part of a fractured and karstified calcareous-dolomitic aquifer with groundwater naturally flowing to the Adriatic sea. Exceedances were reported for nitrates, as well as for EC, Cl, SO4, Fe, Mn. The main objective for this groundwater body is to assess the natural background levels for the aforementioned parameters, and discriminate between the natural and anthropogenic origin of saline intrusion. Four sampling campaigns have been planned, and we present here the result of the first two sampling rounds carried out in spring and fall 2019. Groundwater sampling was performed at 47 wells with submergible pumps or with a water depth sampler. Field parameters (T, EC, pH, DO, ORP) were measured with a multiparametric probe in a flow through cell. Ammonia, cyanides and nitrites were measured in the field (UV-VIS). Laboratory analysis were performed for major anions, major cations, minor and trace elements, environmental isotopes, DOC and microbial parameters. Natural background values (NBLs) for the critical parameters have been provisionally assessed using the preselection method. Sampled waters show neutral/weakly alkaline and mostly oxidizing conditions, with conductivity values between about 700 and 20.000 ?S/cm. The high salinity detected in some water points (chlorides up to 10 g/L, sulphates up to 1 g/L) is clearly linked to mixing with seawater. On a Piper diagram, the samples show a clear transition from earth alkaline bicarbonate water towards mean seawater composition. A clear trend from coastline to inland can be recognized, with the most extended contamination in the northern and southern sectors. Trace elements (B, Sr, Ba), show a similar pattern. From spring (beginning of the irrigation season) to fall (end of the irrigation season) only a slight increase in salinity/chloride concentration can be observed. Nitrates are widespread in the study area, as well as the agricultural pressures, with values even higher than 100 mg/L without a specific spatial pattern. As for the NBLs derivation, classic indicators of anthropogenic contamination (e.g. nitrates, ammonia, NaCl) for the pre-selection of uninfluenced samples failed, due to the extensive distribution of saline groundwaters in the study area. Thus, new solutions, including environmental isotope analysis, for discriminating the anthropogenic and natural origin of the salinity are under evaluation.

In a volcanic-sedimentary aquifer in central Italy, we investigate the co-existence of arsenic and fluoride in groundwater, aiming at identifying the most probable processes deductible at regional/groundwater body scale leading to the observed co-contamination in groundwater. Further, the areas at risk for human health where high concentrations can produce a significant risk to human health have been investigated. The study area is located in Latium (Central Italy) where silica-undersaturated alkali-potassic formations of Plio-Pleistocene age largely outcrop above marine and continental sand and clay deposits (Neogene) and continental alluvial deposits (Lower Pleistocene-Middle Pleistocene). Geochemical data from groundwater at 322 wells and 76 springs have been analyzed through statistical methods including clustering/PCA and geostatistical analysis. The results show exceedances of the drinking water standards for F (1.5 mg/L) and As (10.0 ?g/L) in 29% and 55% of the sampled groundwater, respectively. Multivariate statistics suggest a widespread process of water-rock interaction with the K-alkaline volcanic formations releasing As, F, K, Si, V, Rb and PO to the groundwater. As and F show a good correlation (Pearson's r = 0.61, Spearman's r = 0.59) and define a separate PCA component, confirming that their background in groundwater might be governed by a common process. Kriging interpolations have been used to study the spatial distribution of the two parameters, identifying areas with the highest concentrations and highest probability of exceeding the standards for human consumption. Moreover, by resampling the As-F data with the jackknife technique it was possible to identify the variations of their correlation index in the study area, due to specific As or F anomalies. While in the peripheral areas of the volcanic districts, dominated by sedimentary deposits, the As-F correlation index does not present important fluctuations, Indicator Kriging shows specific As or F correlation anomalies within the volcanic groundwater bodies and along the Tyrrhenian coastline. These anomalies seem to correspond to the zones with the highest thermal flux and/or are located near important structural lineaments. Fluoride correlation anomalies close to mining sites (fluorite) have also been observed. We hypothesize that, unlike the regional co-contamination, these local anomalies are related to the upwelling of geothermal fluids along fracture/fault systems that mix with cold groundwater, or to the interaction with mineral deposits particularly enriched of these elements.

This study explores the co-existence of arsenic and fluoride in a volcanic-sedimentary aquifer in central Italy, aiming at identifying the risk areas for human health and the most likely processes deductible at regional/groundwater body scale leading to the observed co-contamination in groundwater. The study area is located in Latium (Central Italy) where undersaturated alkali-potassic formations largely outcrop, belonging to three different volcanic apparatus of Plio-Pleistocene age. Geochemical data from groundwater at 398 wells or springs are analyzed through statistical methods including clustering/PCA and geostatistical analysis. 29% of the sampled groundwaters exceeds the drinking water standard for F (1.5 mg/L), while 55% exceeds that for As (10.0 g/L). Multivariate statistics suggest a widespread process of water-rock interaction with the K-alkaline volcanic formations releasing As, F, K, Si, V, Rb and PO4 to the groundwater. As and F show a good correlation (Pearson's r = 0.61) and define a separate component, suggesting that their background in groundwater might be governed by a common process. While in the peripheral areas of the volcanic districts, dominated by sedimentary deposits, the As-F correlation index does not present important fluctuations, Indicator Kriging shows specific As or F anomalies within the volcanic groundwater bodies and along the Tyrrhenian coastline. These anomalies seem to correspond to the zones with the highest thermal flux and/or are located near important structural lineaments. Fluoride anomalies close to mining sites (fluorite) have also been observed. We hypothesize that, unlike the regional co-contamination, these local anomalies are related to the upwelling of geothermal fluids along fracture/fault systems that mix with cold groundwater, or to the interaction with mineral deposits particularly enriched of these elements.

At an urban landfill facility located in central Italy, we investigate the processes leading to moderate amounts of VOC in groundwater (benzene), at one downgradient monitoring well. Increased alkalinity and sulfates, lower pH and high levels of redox-sensitive elements (Mn, Fe, As), might support both the hypothesis of leachate loss to groundwater or landfill gas-to-water transfer. In this study, we analyze the available information concerning geochemistry, organic contaminants, environmental isotopes and landfill gas in groundwater to shed light on the possible mass transfer processes. We test the hypothesis that landfill gas migrating from the landfill at the downgradient end of the plant be responsible for high dissolved organic carbon (from methane and other organic compounds), lower pH (due to CO2), and the presence of limited amounts of VOCs transferred from the landfill gas to the groundwater. Periodical groundwater monitoring campaigns have been conducted since 2016 at the site. Field parameters (T, EC, pH, DO, ORP) are measured with probes in a flow-through cell. Groundwater sampling is performed with an in-line device in order to minimize sample disturbance. Lab analysis are performed for major and trace elements. Organic compounds include DOC, PAH, PCB, VOC. Ammonia and sulphide are measured in the field with a portable UV-VIS. Environmental isotopes (18O, 2H, Tritium, 13C) have been assessed twice. The pressure of CH4, CO2, O2 in the piezometer free gas phase are measured in situ with Draeger X-am 7000 (CO2, O2) and laser INSPECTRA® LASER (GAZOMATTM) (CH4); dissolved gas in groundwater is analyzed by gas cromatography on the headspace. Groundwaters are mostly anoxic (DO < 1 mg/L), with neutral to slightly basic pH and calcium-bicarbonate facies. Iron, manganese and arsenic are above national standards for groundwater. PAH, PCB and VOC were always below the standards except benzene at one downgradient well. The downgradient well stands out also for high EC, high alkalinity, low pH, very high As, Fe and Mn, above average DOC. Preliminary results on the landfill gas measurements indicate that methane is present both in the free phase in the wells' headspace and as dissolved phase in groundwater. The high values of methane support the hypothesis of a gas-phase transport of VOC localized at the downgradient end of the facility. Landfill gas CO2 might enhance the dissolution of carbonate minerals and increase alkalinity. The reducing capacity of CH4 favours the high levels of redox sensitive elements in groundwater. While the plant manager has already improved the gas extraction system, a sampling campaign is planned in spring 2019 to further investigate the impact of landfill gas on groundwater and verify the efficacy of the gas recovery measures.

Deliverable del progetto VIOLA (Valori di Fondo Naturale per i Corpi Idrici Sotterranei Pugliesi, PO FESR 2014-2020 - Azione 6.4 - Attività 6.4.1 ) Scopo di questo report è di definire il modello concettuale preliminare, esteso a tutti i Corpi Idrici della Regione Puglia, attraverso la ricostruzione dell'assetto geologico e idrogeologico, l'analisi dello stato delle acque sotterranee, sulla base di dati pregressi, e studio delle pressioni esistenti. Un modello concettuale (MC) è la base per decisioni affidabili nella valutazione e gestione del rischio nelle acque sotterranee e può essere utilizzato per molteplici scopi. In questo studio il MC ha per scopo principale la facilitazione della comprensione del sistema delle acque sotterranee; valutazione dei rischi relativi alle acque sotterranee; visualizzazione dove e come i rischi possono avere un impatto sulle acque sotterranee; pianificazione di sistemi di monitoraggio e di adeguate misure di protezione delle acque sotterranee.