title: Occurrence of Cr(VI) in drinking water of Greece and relation to the geological background.
abstract: This study provides a survey on potential Cr(VI) exposure attributed to drinking water in Greece. For this reason, a wide sampling and chemical analysis of tap waters from around 600 sites, supplied by groundwater resources, was conducted focusing on areas in which the geological substrate is predominated by ultramafic minerals. Results indicate that although violations of the current chromium regulation limit in tap water are very rare, 25% of cases showed Cr(VI) concentrations above 10 μg/L, whereas Cr(VI) was detectable in 70% of the samples (>2 μg/L). Mineralogy and conditions of groundwater reservoirs were correlated to suggest a possible Cr(VI) leaching mechanism. Higher Cr(VI) values are observed in aquifers in alluvial and neogene sediments of serpentine and amphibolite, originating from the erosion of ophiolithic and metamorphic rocks. In contrast, Cr(VI) concentration in samples from ophiolithic and metamorphic rocks was always below 10 μg/L due to both low contact time and surface area, as verified by low conductivity and salt concentration values. These findings indicate that under specific conditions, pollution of water by Cr(VI) is favorable by a slow MnO2-catalyzed oxidation of soluble Cr(III) to Cr(VI) in which manganese products [Mn(III)/Mn(II)] are probably re-oxidized by oxygen.
authors.affiliation: Laboratory of Analytical Chemistry, Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
authors.forename: E
authors.initials: E
authors.lastname: Kaprara
authors.affiliation: Laboratory of Engineering Geology and Hydrogeology, Department of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
authors.forename: N
authors.initials: N
authors.lastname: Kazakis
authors.affiliation: Department of Mechanical Engineering, University of Thessaly, 38334 Volos, Greece.
authors.forename: K
authors.initials: K
authors.lastname: Simeonidis
authors.affiliation: Laboratory of Analytical Chemistry, Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
authors.forename: S
authors.initials: S
authors.lastname: Coles
authors.affiliation: Laboratory of General and Inorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
authors.forename: A I
authors.initials: AI
authors.lastname: Zouboulis
authors.affiliation: Department of Food Technology, Alexander Technological Educational Institute of Thessaloniki, 57400 Thessaloniki, Greece.
authors.forename: P
authors.initials: P
authors.lastname: Samaras
authors.affiliation: Laboratory of Analytical Chemistry, Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece. Electronic address: manasis@eng.auth.gr.
authors.forename: M
authors.initials: M
authors.lastname: Mitrakas
mesh_terms: D002857:Chromium / Q000032:analysis*; D060766:Drinking Water / Q000032:analysis*; D004784:Environmental Monitoring; D055593:Geological Phenomena; D006115:Greece; D060587:Groundwater / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D060766:Drinking Water; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion
keywords: Drinking water; Hexavalent chromium; Natural origin; Ultramafic rocks