Arsenic mobility controlled by solid calcium arsenates: A case study in Mexico showcasing a potentially widespread environmental problem

作者：Martinez Villegas Nadia^*; Briones Gallardo Roberto; Ramos Leal Jose A; Avalos Borja Miguel; Castanon Sandoval Alan D; Razo Flores Elias; Villalobos Mario

来源：Environmental Pollution, 2013, 176: 114-122.

DOI：10.1016/j.envpol.2012.12.025

• Arsenic pollution
• Arsenic mobility
• Arsenate dissolution
• Arsenate retention
• Calcium arsenates

An As-contaminated perched aquifer under an urban area affected by mining was studied over a year to determine the contamination source species and the mechanism of As mobilization. Results show that the dissolution of calcium arsenates in residues disposed on an inactive smelter has caused high levels of As pollution in the adjoining downgradient 6-km perched aquifer, reaching up to 158 mg/L of dissolved As, and releasing a total of ca. 7.5 tons of As in a year. Furthermore, free calcium ion availability was found to control As mobility in the aquifer through the diagenetic precipitation of calcium arsenates (Ca5H2(AsO4)(4)center dot cH(2)O) preventing further mobilization of As. Results shown here represent a model for understanding a highly underreported mechanism of retention of arsenate species likely to dominate in calcium-rich environments, such as those in calcareous sediments and soils, where the commonly reported mechanism of adsorption to iron(III) oxyhydroxides is not the dominant process.

• 出版日期2013-5