As-Fe-S systems

Aqueous As-S complexes are important species in sulfidic systems, which have been shown to exist under natural conditions (Yellowstone NP, Mono Lake). Under oxic (natural) conditions thioarsenates were determined by IC-ICP-MS. Contrary, under anoxic conditions thioarsenites can be formed, which were recently only determined in synthetic, anoxic arsenite-sulfide mixes by XAS.

However, As-S complexes exist and thus there is a need for information about their stability and possible stabilization methods. Furthermore, in natural systems arsenic is associated with solid phases as sorbed species on iron(hydr)oxides or incooperated in mineral phases, such as the sulfides orpiment and arsenopyrite.

Leaching processes release As, S, and Fe, and thus the question has to be solved if As-S complexes are formed through oxidative dissolution - also in iron-containing systems and how these kind of waters (containing iron, sulfides, arsenic) can be preserved.

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• Fe-As-S systems