Arsenic speciation in synthetic gypsum (CaSO4·2H2O): A synchrotron XAS, single-crystal EPR, and pulsed ENDOR study

Incorporation of arsenic into gypsum: Relevant to arsenic removal and immobilization process in hydrometallurgical industry

“…Arsenic can be incorporated into gypsum lattice structure via isomorphic substitution for sulfate as unambiguously evidenced by neutron diffraction [16,17]. This finding is confirmed by a latest study using singlecrystal electron paramagnetic resonance spectroscopy (EPR) and pulsed electron nuclear double resonance spectroscopy (ENDOR) [18]. This is similar to the incorporation of arsenate ions into jarosite structure by substitution of sulfate [19] and vice versa incorporation of sulfate ions into scorodite structure by substitution of arsenate [20,21].…”

Tracking the transformation and transport of arsenic sulfide pigments in paints: synchrotron-based X-ray micro-analyses

“…The arsenate ion is known to substitute for the sulfate group in the gypsum crystal. 38,39 This process is favorable under highly alkaline conditions. The sulfate group is replaced by not only As 5+ as […”

Distribution of Arsenic and Risk Assessment of Activities on Soccer Pitches Irrigated with Arsenic-Contaminated Water

“…Questions remain on the processes that take place after addition of As to the soil and those that control the percolation of As downwards at the study site. While As is known to incorporate in calcite and gypsum by surface adsorption and/or (co)precipitation [ 17 , 18 , 19 , 20 , 21 ], high transport of As has been otherwise reported in carbonate-rich soils, in which Fe and Al oxyhydroxide fractions are limited [ 65 ]. Cycles of dissolution and precipitation of secondary arsenate minerals formed in soil after irrigation may also account for the accumulation of As in the topsoil and the vertical migration of As.…”

“…In aerated soil, As is strongly retained by adsorption on iron (III) oxyhydroxides as well as other soil constituents, such as organic matter [ 13 , 14 ] and clay minerals with surface and edge charges [ 15 ]. In calcareous and gypsic soils, however, As may show high bioaccessibility [ 16 ], as it adsorbs and/or precipitates on either calcite or gypsum [ 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. Pollution of soils due to the release of soluble As in water that is used for land irrigation is a major concern in areas located under arid or semi-arid conditions, such as the Comarca Lagunera [ 24 ], Zimapan [ 25 ], and Matehuala [ 16 ] in Mexico, Antofagasta in Chile, and the Chaco-Pampean area in Argentina, Pakistan, India, and China [ 26 , 27 , 28 , 29 ].…”