Arsenic-fluoride co-contamination in groundwater: Background and anomalies in a volcanic-sedimentary aquifer in central Italy

Abstract 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 μg/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 PO4 to the groundwater. As and F show a good correlation (Pearson's r = 0.61, Spearman's rs = 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

Proposal for an integrated method of natural background levels assessment in groundwater

Natural Background Level (NBL), geochemical approach, statistical methods

A proposal for groundwater sampling guidelines: application to a case study in Southern Latium

Groundwater monitoring , body status,  best sampling techniques,  quaternary alluvial,  pyroclastic deposit

[Procedures for the environmental remediation of contaminated sites in Italy: food for thought from the Roundtable at Flowpath 2021 in Naples]

[This technical note follows the discussion that took place during the Roundtable on "Experiences and perspectives on groundwater contamination: from characterization to legal implications", held during the National Conference Flowpath 2021, which was attended by experts in the field of contaminated sites from the academic, professional, and public sectors. This contribution aims at summarizing and discussing the critical points emerged during the Roundtable, starting from the description of the technical-administrative procedure currently required by the Italian legislation and the measures suggested for each phase of the environmental remediation process.] [In Italian

Physiological Profiling and Functional Diversity of Groundwater Microbial Communities in a Municipal Solid Waste Landfill Area

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 EcoPlatesTM 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

Linee guida per lo sviluppo di modelli numerici di flusso in acquiferi porosi: Una proposta IRSA-ISPRA

A livello nazionale, nell'ambito dei procedimenti di bonifica dei siti contaminati, disciplinati dalla parte Quarta – Titolo V del decreto legislativo 152 del 2006, l'implementazione di modelli matematici di flusso e di trasporto dei contaminanti è uno strumento che ha acquisito con il tempo sempre maggiore importanza, soprattutto ai fini della definizione e progettazione degli interventi di messa in sicurezza e bonifica delle acque di falda. Modelli matematici sono utilizzati anche a scala di bacino o sottobacino per la caratterizzazione e la gestione delle risorse idriche sotterranee [...]

Assessing Natural Background Levels in the Groundwater Bodies of the Apulia Region (Southern Italy)

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

A Novel Method for Y Photons Depth of Interaction Discrimination on Monolithic LYSO Crystals for Brain PET/MRI

The MindView European Project pursues the development of a high efficiency and high resolution brain dedicated PET detector, simultaneously working with a Magnetic Resonance Imaging (MRI) system. Since the PET scanner is based on a small diameter ring and on thick monolithic scintillation crystals to assess high efficiency, the parallax error related to off-center positron annihilation is a critical issue. The Depth of Interaction (DoI) discrimination can reduce the blurring due to this phenomenon. In this work, we propose a novel DoI estimator, based on the ratio of the integral of scintillation light distribution to its maximum (named N/I). In a preliminary way, by means of Monte Carlo simulation, we have validated the correlation between this parameter and the DoI. Furthermore, we have experimentally tested the capability of such DoI estimator on a monolithic 20mm-thick LYSO crystal optically coupled to a 12x12 silicon photomultipliers (SiPMs) array. Thanks to the proposed method, it is possible to select interaction events coming from different depths of the crystal. The DoI discrimination capability has been confirmed by using a collimated slanted pencil-beam: the proposed estimator allows to produce different images coming from events belonging to different depths of the crystal. From the experimental results a DoI discrimination resolution ranging from 4mm to 6mm has been obtained. The proposed method is expected to reduce the parallax error and, consequently, the width of lines of response coming from off- center positron annihilation of about 70% respect to the method without DoI discrimination