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Mongelli, Giovanni
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Mongelli, Giovanni
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- PublicationRestrictedREEs and U distribution in P-rich nodules from Gelasian Apulian Tethyan carbonate: A genetic recordIn the Tethyan realm the carbonate-dominated Meso-Cenozoic South Tethyan Phosphogenic Province is ofconsiderable economic importance since it represents the greatest accumulation of sedimentary phosphorites. Insouthern Italy, in the Salentine peninsula (the southern part of the Apulian Carbonate Platform, ACP), is welldocumented the occurrence of Cenozoic P-rich levels consisting of nodules and pebbles and showing a large P2O5fluctuation (4.07–22.07 wt%), due to variable calcite abundance. The mainly observed P-bearing minerals arehydroxyapatite and carbonatefluorapatite and U, together with Sr and Pb, preferentially acts as Ca substitutes inboth lattices. Minor authigenic monazite (LREE-bearing phosphate) and xenotime (HREE+Y-bearing phos-phate), likely formed during sediment burial compaction and diagenesis. The total REEs' abundances and theshape of the shale-normalized REE-patterns in the P-rich nodules are in the range of those typically observed inPaleocene-Eocene through Pleistocene-Recent P-rich sediments, supporting the idea of a broadly consistentocean chemistry in this span of geological time. The (La/Yb)Nproxy is within the modern seawater range,signifying early diagenetic adsorption played only a minor role in affecting the REEs' distribution. The Ce and Pranomalies suggest some P-rich nodules experienced very localized hypoxic to anoxic conditions promoting Ce/Ce* spurious results in a generally oxic to hypoxic environment causing real negative Ce anomaly. This scenariois reinforced by the lack of the coupled uranium-vanadium enrichment typically observed in an anoxic en-vironment. Since the Pliocene the eastern Mediterranean was variously affected by oxygenation and productivityand it is likely the ACP phosphate-rich sediments formed under low sedimentation rates and authigenesis in abottom current-dominated regime, as also indicated by the glauconite occurrence. Transgressions and sea levelsrising following major glaciations may have favored the deposition of phosphate sediments by creating newrestricted basin configurations and increased nutrient input promoted by upwelling processes.
55 3 - PublicationRestrictedRare earth elements distribution and geochemical behaviour in the volcanic groundwaters of Mount Vulture, southern Italy(2020-04-20)
; ; ; ; ; ; ; The Mount Vulture basin, which mainly consists of pyroclastic and subordinate lava flow layers, is one of the most important aquifers for drinking water and irrigation supply in southern Italy. In this study, we investigated the geochemical behaviour of the rare earth elements (REEs) in the groundwater of this aquatic system, assessing fractionation patterns and performing speciation calculations to elucidate the geochemical processes affecting the REEs' distribution. The groundwater collected was separated into two subsets corresponding to recharge and discharge water. Overall, the groundwater exhibited REE concentrations well below 1000 ng/l, and the average content measured in the discharge water is approximately three times higher than that of the recharge water. In the recharge water, the shale normalised patterns are characterised by a more negative average Ce anomaly, a more positive average Eu anomaly, and a larger average (La/Yb)PAAS. The observed relationship between Ce anomalies and dissolved oxygen (DO) supports the idea that Ce oxidative scavenging has a role in determining the size and shape of the Ce anomaly. Further, the less negative average size of the Ce anomaly in the discharge zone also suggests Ce desorption due to changes in redox conditions. As for the Eu anomalies, the largest Eu* are associated with the recharge zone, characterised by higher average Eh and DO values. The volcanics in the Mt. Vulture lithologies have post-Archean average shale (PAAS) normalised patterns showing positive Eu anomalies due to feldspars occurrence. This indicates that the Eu* of groundwater in the recharge zone is mostly produced by the dissolution of feldspars. In the discharge zone, most samples are in equilibrium with smectite and Eu2+ adsorption onto the clay phase surface or its inclusion in the mineral structure as exchangeable cations likely lead to the smaller average size of Eu*. The possible occurrence of secondary minerals preferentially scavenging light REEs may also explain the difference in the (La/Yb)PAAS index observed between the recharge and discharge zones. Speciation calculations indicate that dissolved REEs consist mainly of carbonato complexes (LnCO3 +) whereas the percentage of dicarbonato complexes (Ln(CO3)2 −) increases in samples with circa-neutral pH. At acidic pH, the Ln3+ species are numerous and, in samples with large amounts of dissolved sulphate, derived by feldspathoids dissolution, from the discharge zone, the percentage of LnSO4 + species is not negligible.45 4 - PublicationOpen AccessGroundwater Quality in the Mediterranean RegionIn recent decades, the percentage increase in water use on a the global scale has exceeded twice that of population growth. This has led to more, and larger, regions in the world being subject to water stress where the current restricted rates of water use and consumption, let alone the desired rates, are unsustainable [1, 2]. In the Mediterranean area, water availability is a main economic and social target for most countries since most of them share several features including, for instance, similar water and land resources, agricultural development, demographic pressure coupled with tourism increase and, last but not least, a climate change evolving toward semiarid to arid conditions [3–5]. This precious resource, widely exploited, is not distributed, at a regional level and within each country, in a homogeneous fashion. The increase in groundwater exploitation poses a severe risk for the availability of water resources, and the resulting resource scarcity is a major concern in most countries of the Mediterranean region. Groundwater paucity often occurs in combination with poor groundwater quality, not only in areas heavily conditioned by human activities [6] or in the often highly saline coastal aquifers [7–9] but also in zones characterized by geogenic contamination sources. In such areas, although human pressure is absent, water-rock interaction processes, as those promoting, for instance, geogenic Cr(VI) water contamination [10], may cause pollution with critical effects on the public health
59 14 - PublicationRestrictedGeochemistry of two contrasting deep fluids in the Sardinia microplate (western Mediterranean): Relationships with tectonics and heat sources(2017-02-24)
; ; ; ; ; ; ; ; ; The Sardinia microplate in the western Mediterranean represents an ideal example for examining the relationship between fluid geochemistry, tectonic and heat sources in hydrothermal circuits. It consists of a portion of Variscan basement partly covered by sedimentary (mainly carbonate) and volcanic successions that record significant Permian to Pliocene geodynamic events within the southern European margin. The regional structure of the northern Sardinia is dominated by Tertiary ENE–WSW trending strike-slip and NNW–SSE trending normal faults, both capable of controlling deep and shallow fluid circulation. In this paper, results of a detailed geochemical investigation of waters and gases coming from a W-E trending section of central-north Sardinia are presented in order to explain the contrasting thermal and geochemical features of two - already known groups - of fluids. The Volcanic Logudoro Waters (VLW) is a group of cold to hypothermal Na–HCO3 waters characterised by high CO2 contents and mantle-derived He, that are localized in the volcanic-dominated Tertiary grabens. The He mantle signature within the VLW waters is associated with Plio-Pleistocene Quaternary volcanism where the outgassing of mantle-derived fluids is reasonably due recently active magma sources at depth. The currently active emission of mantle-derived gas linked to cold and hypothermal waters, provides evidence that the heat diffusion associated with the Plio-Pleistocene volcanism has already ended. In contrast, the Granite Variscan Basement Waters (GBW) group is characterised by hot-NaCl-rich waters, containing high concentrations of both dissolved N2 and radiogenic 4He. The high contribution of 4He produced by radiogenic decay of U and Th in the crust indicates a supply of radiogenic heat to the hydrothermal system localized within the granitic basement or in the tectonic contact between granite and Tertiary covers.123 3 - PublicationOpen AccessDepth influence on the distribution of chemical elements and saturation index of mineral phases in twins maar lakes: The case of the Monticchio lakes (southern Italy)(2016)
; ; ; ; ; ;; In this paper we provide a systematic geochemical study of the Monticchio maar lakes, on the Mt. Vulture volcano, southern Italy, to understand the processes affecting the distribution of chemical elements. A high-resolution conductivity–temperature–depth profile was obtained, and water samples were collected at various depths for analyses of major and trace elements. Although the two lakes are separated by less than 200 m, they exhibit different behaviour. The Ca–Na–HCO3 composition of “Lago Grande” water suggests that low-temperature fluids are leached from the host volcanic rocks. Na–Ca–HCO3 in near-surface “Lago Piccolo” water is derived from the dissolution of local volcanic rocks, while the deepest water samples are bicarbonate alkaline-earth in composition and generally show an enrichment in solutes with respect to the epilimnion layer (except for SO42 − content). The hypolimnion water is principally governed by both the input of saline groundwater from the lake bottom and authigenic processes within bottom sediments. In addition, the occurrence of anoxic conditions and microbial activity is responsible for the transformation of sulphates to hydrogen sulphide, and for the precipitation of Fe sulphide phases. Both processes cause a change in the chemical composition of saline groundwater as it moves upwards. Overall, the water chemistry of the Monticchio lakes is principally affected by: i) the input of CO2-rich volcanic gas; ii) evaporative processes that deplete near-surface water in some elements; and iii) the occurrence of chemical, physical and biological conditions causing the transformation of molecular complexes and consequently promoting mineral precipitation.66 438 - PublicationRestrictedSource and mobility of minor and trace elements in a volcanic aquifer system: Mt. Vulture (southern Italy)(2011)
; ; ; ; ;Parisi, S.; University of Basilicata, Department of Geological Sciences, Campus Macchia Romana, 85100 Potenza, Italy ;Paternoster, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Perri, F.; University of Calabria, Department of Earth Sciences, Via Pietro Bucci 87036 Rende, Italy ;Mongelli, G.; University of Basilicata, Department of Chemistry, Campus Macchia Romana, 85100 Potenza, Italy; ; ; In this paper we provide a geochemical investigation on 34 groundwater samples in the Mt. Vulture volcanic aquifer representing one of the most important groundwater resources of the southern Italy pumped for drinking and irrigation supply. The present study includes the first data on the abundance and mobility of minor and trace elements and the thermodynamic considerations on water–rock interaction processes in order to evaluate the conditions of alkali basalt weathering by waters enriched in magma-derived CO2. The results highlight the occurrence of two hydrofacies: bicarbonate alkaline-earth and alkaline waters deriving from low-temperature leaching of volcanic rocks of Mt. Vulture, and bicarbonate-sulfate-alkaline waters (high-salinity waters) related to prolonged water circulation in alkali and feldspathoids-rich pyroclastic layers interbedded with clay deposits. The Al-normalized relative mobility (RM) of metals in Vulture's aquifer varies over a wide range (10− 1 < RM < 104), confirming that the basalt weathering is not a congruent and isochemical process. Chemical equilibrium studies show that the bicarbonate alkaline-earth and alkaline waters, having a short interaction with silicate minerals, plot very close to the kaolinite–smectite stability boundary, whereas the high-salinity waters fall in the stability field of smectite and muscovite because of prolonged interaction with alkali and feldspathoids-rich pyroclastic layers. Overall, for the bicarbonate alkaline-earth and alkaline waters, the release of toxic metals in solutions is related to the spatial variation of host-rock geochemistry, the high-salinity waters, collected near urban areas, show values higher than legal limits for Ni and As, likely as a consequence of anthropogenic contribution.178 20 - PublicationRestrictedNatural Hexavalent Chromium in the Pollino Massif Groundwater (Southern Apennines, Italy): Occurrence, Geochemistry and Preliminary Remediation Tests by Means of Innovative Adsorbent Nanomaterials(2021)
; ; ; ; ; ; ; ; ; ; ; In this study Cr(tot), Cr(VI), major and trace elements were determined in groundwater of northern sector of the Pollino Massif (southern Italy). The investigated area is characterized by ophiolitic rocks consisting of metabasites, shales and calcschists and fractured serpentinites. Two main hydro-facies were observed, reflecting low temperature water-rock interaction. The Mg-HCO3 hydrofacies is due to the weathering of serpentinites, Ca-HCO3 groundwaters are linked to the interaction with calcschist and metabasites. High Cr(VI) concentrations were detected, exceeding the maximum admissible concentrations by Italian regulation, due to the release of Cr(III) from ophiolitic rocks into water and its oxidation to the hexavalent state. Remediation tests were carried out using two synthetized nanomaterials, Fe(0) and magnetite, characterized by a mean size lower than 50 nm. The experiments were conducted at fixed nanoparticles/Cr(VI) molar ratio and according to previous studies. In addition, the kinetic data were interpreted with a suitable mathematical model.57 6 - PublicationOpen AccessGenesis of carbonate-rich veins in the serpentinites at the Calabria-Lucania boundary (southern Apennines)(2018)
; ; ; ; ; ; ; ; ; ; ; ; ;; ;; ; ; ;In the northern sector of the Pollino massif (southern Apennines, Italy) well-exposed lens-shaped bodies of serpentinites and sediments of the Frido Unit belonging to the Liguride Complex crop-out. Most serpentinite rocks are cross-cut by carbonate and quartz-carbonate veins with different thickness. This study focuses on petrographic, mineralogical, geochemical, and isotopic analysis of the carbonate veins embedded in serpentinite rocks, collected at the Fosso Arcangelo site and at the Pietrapica quarry (Calabria-Lucanian boundary). The paragenesis of the carbonate veins from the Fosso Arcangelo site is dominantly made by calcite and aragonite with minor amount of rhodochrosite. In quartz-carbonate veins from Pietrapica quarry, dolomite, Mg-calcite, quartz, with minor ankerite were observed. The ?13CV-PDB isotope ratios of carbonates in the carbonate veins are in the range from +2.16? to -3.66? and corresponding ?18OV-SMOW values are between +15.02? and +21.53?. The ?13CV-PDB values of carbonates in quartz-carbonate veins are in the range from -3.60? to -1.78? and the corresponding ?18OV-SMOW average value is around +21.3?. The results suggest that the carbonate at both site occurredunder the same environmental conditions from crustal-derived and low-moderate temperatures hydrothermal fluids having different chemical composition.147 163 - PublicationOpen AccessMineralogy and heavy metal assessment of the Pietra del Pertusillo reservoir sediments (Southern Italy)(2021)
; ; ; ; ; ; ; ; ; ; ; ; ; The Pietra del Pertusillo freshwater reservoir is a major artificial lake of environmental, biological, and ecological importance located in the Basilicata region, southern Italy. The reservoir arch-gravity dam was completed in 1963 for producing hydroelectric energy and providing water for human use, and nearby there are potential sources of anthropogenic pollution such as urban and industrial activities. For the first time, the minero-chemistry of the lake and fluvio-lacustrine sediments of the reservoir have been evaluated to assess the environmental quality. Moreover, the composition of fluvial sediments derived from the peri-lacual zone of the reservoir and of local outcropping bedrock were also studied to understand the factors affecting the behavior of elements in the freshwater reservoir, with particular attention paid to heavy metals. In Italy, specific regulatory values concerning the element threshold concentration for lake and river sediments do not exist, and for this reason, soil threshold values are considered the standard for sediments of internal waters. The evaluation of the environmental quality of reservoir sediments has been performed using enrichment factors obtained with respect to the average composition of a reconstructed local upper continental crust. We suggest this method as an innovative standard in similar conditions worldwide. In the studied reservoir sediments, the trace elements that may be of some environmental concern are Cr, Cu, Zn, As, and Pb although, at this stage, the distribution of these elements appears to be mostly driven by geogenic processes. However, within the frame of the assessment and the preservation of the quality of aquatic environments, particular attention has to be paid to As (which shows median value of 10 ppm, reaching a maximum value of 26 ppm in Quaternary sediments), constantly enriched in the lacustrine samples and especially in the fine-grained fraction (median = 8.5 ppm).77 29 - PublicationOpen AccessHydrogeochemistry and Groundwater Quality Assessment in the High Agri Valley (Southern Italy)(2021-06-25)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; The High Agri Valley (southern Italy) is one of the largest intermontane basins of the southern Apennines affected by intensive agricultural and industrial activities. The study of groundwater chemical features provides much important information useful in water resource management. In this study, hydrogeochemical investigations coupled with multivariate statistics, saturation indices, and stable isotope composition (δD and δ18O) were conducted in the High Agri Valley to determine the chemical composition of groundwater and to define the geogenic and anthropogenic influences on groundwater quality. Twenty-four sampling points ( including well and spring waters) have been examined. The isotopic data revealed that groundwater has a meteoric origin. Well waters, located on recent alluvial-lacustrine deposits in shallow porous aquifers at the valley floor, are influenced by seasonal rainfall events and show shallow circuits; conversely, spring waters from fissured and/or karstified aquifers are probably associated to deeper and longer hydrogeological circuits. The R-mode factor analysis shows that three factors explain 94% of the total variance, and F1 represents the combined effect of dolomite and silicate dissolution to explain most water chemistry. In addition, very low contents of trace elements were detected, and their distribution was principally related to natural input. Only two well waters, used for irrigation use, show critical issue for NO3 - concentrations, whose values are linked to agricultural activities. Groundwater quality strongly affects the management of water resources, as well as their suitability for domestic, agricultural, and industrial uses. Overall, our results were considered fulfilling the requirements for the inorganic component of the Water Framework Directive and Italian legislation for drinking purposes. The water quality for irrigation is from “good to permissible” to “excellent to good” although salinity and relatively high content of Mg2+ can occasionally be critical.37 15