Natural arsenic and its distribution in global geothermal systems

This paper highlights the occurrence and distribution of geothermal As worldwide and its mobilization in geothermal fluids focusing different geological settings and processes. The mobilization of As from rocks and mineral phases into geothermal fluids depends on existing As sources, geochemical conditions and microbiological activity. In deep geothermal reservoirs, As mobilization is predominantly occurred from As-bearing pyrite at low temperatures (150–250°C), whereas at higher temperatures (>250°C), from arsenopyrite. The highest As concentrations were found in the volcanic geothermal systems of Los Humeros (Mexico) with up to 162,000 μg/L. Hence, updated and novel information on the present topic would be very much beneficial in order to understand the role of geothermal As in the genesis of As-rich ground- and surface water resources which are used for human consumption worldwide.