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DatoValore
TitleWater-Rock Interaction Processes: A Local Scale Study on Arsenic Sources and Release Mechanisms from a Volcanic Rock Matrix
AbstractArsenic is a potentially toxic element (PTE) that is widely present in groundwater, with concentrations often exceeding the WHO drinking water guideline value (10.0 ?g/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 ?g/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.
SourceToxics 10 (6)
Keywordspotentially toxic elementsaquifervolcanic tuffsequential extractionFe oxyhydroxidessorption
JournalToxics
EditorMDPI, Basel, Svizzera
Year2022
TypeArticolo in rivista
DOI10.3390/toxics10060288
AuthorsDaniele Parrone, Stefano Ghergo, Elisabetta Preziosi, Barbara Casentini
Text468080 2022 10.3390/toxics10060288 potentially toxic elements aquifer volcanic tuff sequential extraction Fe oxyhydroxides sorption Water Rock Interaction Processes A Local Scale Study on Arsenic Sources and Release Mechanisms from a Volcanic Rock Matrix Daniele Parrone, Stefano Ghergo, Elisabetta Preziosi, Barbara Casentini Water Research Institute National Research Council, IRSA CNR, Via Salaria km 29.300, PB 10, 00015 Monterotondo Rome , Italy 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 g/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 g/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. 10 Published version https //www.mdpi.com/journal/toxics 25/05/2022 Articolo in rivista MDPI 2305 6304 Toxics Toxics Toxics danieleparrone PARRONE DANIELE stefano.ghergo GHERGO STEFANO elisabetta.preziosi PREZIOSI ELISABETTA barbara.casentini CASENTINI BARBARA