Trace element distribution and Cr(VI) speciation in Ca-HCO3 and Mg-HCO3 spring waters from the northern sector of the Pollino massif, southern Italy

Origin and concentration profile of chromium in a Greek aquifer

“…6). The high correlation between Cr(VI) and Crtot has been frequently observed in geogenic environments [6,51] and is related to predominance of Cr(VI) over Cr(III), since Cr(III) would be insoluble as hydroxides and completely adsorbed onto clay surfaces at these pH values [43]. The difference of Crtot and Cr(VI) values obtained might be attributed to differences in the analytical methods employed.…”

“…These concentrations are among the highest measured globally in similar geological backgrounds. For instance, Fantoni et al [6] and Margiotta et al [51] in Italy, observed Cr(VI) concentrations up to 73 g/L in groundwater and 30 g/L in spring water interacting with ophiolitic rocks, respectively. Morrison et al [52] and Izbicki et al [53] reported Cr(VI) concentrations in California groundwater up to 50 and 62 g/L, respectively.…”

Fate of transition metals during passive carbonation of ultramafic mine tailings via air capture with potential for metal resource recovery

“…Trace metal concentrations may be particularly elevated in surface and ground waters around ultramafic environments and chrysotile deposits, and in some cases concentrations exceed local water quality thresholds (Fantoni et al, 2002;Margiotta et al, 2012;McClain and Maher, 2016;Natali et al, 2013;Schreier, 1987). For instance, up to 73 µg/L Cr 6+ has been reported in ground water associated with an ophiolite in Italy, where the local permissible value is 5 µg/L Cr 6+ (Fantoni et al, 2002).…”

“…These are typically found within the crystal structures of Mgsilicate, Mg-hydroxide, sulphide, and oxide minerals as well as within alloy minerals such as awaruite (Ni2-3Fe) and wairauite (CoFe) (Challis and Long, 1964;Goff and Lackner, 1998;Kmetoni, 1984;Margiotta et al, 2012;Natali et al, 2013;Schreier, 1987;Sciortino et al, 2015). First row transition metals may be mobilised by dissolution of their mineral hosts during either natural weathering reactions or the artificially accelerated reactions that can be used to enhance mineral carbonation rates (Margiotta et al, 2012;Oelkers et al, 2008;Olajire, 2013;Olsson et al, 2014a,b;Schreier, 1987;Teir et al, 2007a). Because first-row transition metals can be toxic to biota in elevated concentrations, concern has been raised that the release of metalliferous waters from mineral carbonation facilities or geoengineered landscapes could adversely affect natural systems (Olsson et al, 2014b).…”

“…Previous studies have reported elevated concentrations of trace metals (particularly Ni,Cr 3+ and carcinogenic Cr 6+ ) in soils and waters associated with serpentinites (Margiotta et al, 2012;McClain and Maher, 2016;Morrison et al, 2015;Schreier, 1987;Schreier and Lavkulich, 2015). Uptake of these trace metals by Fe-hydroxide and clay minerals has been documented in serpentinites (Morrison et al, 2015), but the influence of hydrated Mgcarbonate minerals on trace metal mobility within ultramafic environments is relatively unexplored.…”