title: Dynamics of natural contamination by aluminium and iron rich colloids in the volcanic aquifers of Central Italy.
abstract: The dynamics of natural contamination by Al and Fe colloids in volcanic aquifers of central-southern Italy were investigated. Localized perched aquifers, and their relative discharges, are strongly affected by the presence of massive suspended solids, which confer a white-lacteous coloration to the water. This phenomenon occasionally caused the interruption of water distribution due to the exceeding of Al and Fe concentrations in aquifers exploited for human supply. The cause was ascribed to water seepage from perched aquifers. Water discharges affected by such contamination was investigated for the Rocca Ripesena area (north-eastern sector of Vulsini Volcanic District) and for the Rianale Stream Valley (Roccamonfina Volcanic Complex). Hydrogeological survey of both areas confirmed the presence of perched aquifers not previously considered due to their low productivity. Pluviometric data and chemical parameters were periodically monitored. Water mineralization decreased with increasing rainfall, conversely Al and Fe concentrations increased. Statistical analysis confirmed the dependence of all the chemical variables on rock leaching, with the sole exception of Al and Fe which were imputed to colloids mobilization from local, strongly pedogenized pyroclastic material. The similarities in hydrogeological settings and mobilization dynamics in both areas suggest that the Al and Fe colloidal contamination should be more abundant than currently known in quaternary volcanic areas.
authors.affiliation: Science Department, Roma Tre University, Largo S. Leonardo Murialdo 1, Rome, Italy. stefano.viaroli@uniroma3.it.
authors.forename: Stefano
authors.initials: S
authors.lastname: Viaroli
authors.affiliation: Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Second University of Naples, Caserta, Italy.
authors.forename: Emilio
authors.initials: E
authors.lastname: Cuoco
authors.affiliation: Science Department, Roma Tre University, Largo S. Leonardo Murialdo 1, Rome, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Mazza
authors.affiliation: Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Second University of Naples, Caserta, Italy.|National Institute of Geophysics and Volcanology (INGV), Via di Vigna Murata, Rome, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: Tedesco
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry*; D060587:Groundwater / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D007558:Italy; D018707:Volcanic Eruptions / Q000032:analysis*
chemical_list: D003102:Colloids; D000535:Aluminum; D007501:Iron
keywords: Al and Fe natural contamination; Groundwater; Hydrogeological conceptual models; Mineral colloids; Perityrrhenic quaternary volcanoes; Volcanic aquifers