Understanding arsenic-ulexite interactions in evaporite environments: Evidence from XRPD, micro-XRF, micro-FT-IR, and XPS studies.

World-class borate deposits often form from As-rich waters, this study addresses the understudied association of arsenic (As) species with evaporite borates, focusing on the Puna region's borate deposits (Central Andes of Argentina). The research aims to characterize the association between borate minerals and high As concentrations in brines and thermal waters. To achieve this, five borate samples were collected from the Olaroz salt flat nucleus and thermal springs, alongside associated water samples.

Dispersion of arsenic species from highly explosive historical volcanic eruptions in Patagonia.

Andean volcanic rocks typically have low to moderate arsenic (As) concentrations. However, elevated levels of As in groundwaters of southern South America have been reported as a consequence of weathering of volcanic glass. This study discusses the abundance, speciation and dispersion of As species in fresh volcanic ash from highly explosive (Volcanic Explosivity Index: 4-5) Patagonian eruptions, as well as the potential of As release to aqueous reservoirs.

The role of efflorescent salts associated with sulfide-rich mine wastes in the short-term cycling of arsenic: Insights from XRD, XAS, and µ-XRF studies.

The evaporation of As-rich leachates generated by the weathering of sulfide-rich mine wastes accumulated in abandoned tailing dams of the La Concordia mine, triggers the widespread precipitation of saline crusts and efflorescences. Because these salts are highly soluble, they may release high concentrations of arsenic after rainfall events. Thus, the goal of this work is to assess the solid speciation of As in these efflorescences, which may help to understand the short-term cycling of As in the site.

Synchrotron XAS study on the As transformations during the weathering of sulfide-rich mine wastes.

This paper describes the weathering processes that occurred across two tailing dumps in the Concordia mine (Puna of Argentina) with the purpose of evaluating the formation of secondary As-bearing minerals due to arsenopyrite alteration. After 30 years of exposure, the gradual oxidation of the wastes produced a number of secondary mineral phases containing As in different chemical arrangements. Synchrotron-based X-ray absorption spectroscopy was used to determine both, As and Fe solid speciation and to identify the formed As-bearing minerals.

Long term metal release and acid generation in abandoned mine wastes containing metal-sulphides.

The sulphide-rich mine wastes accumulated in tailing dumps of La Concordia Mine (Puna of Argentina) have been exposed to the weathering action for more than 30 years. Since then, a series of redox reactions have triggered the generation of a highly acidic drainage -rich in dissolved metals-that drains into the La Concordia creek. The extent of metal and acid release in the site was analysed through field surveys and laboratory experiments.