期刊
SCIENCE OF THE TOTAL ENVIRONMENT
卷 429, 期 -, 页码 57-75出版社
ELSEVIER
DOI: 10.1016/j.scitotenv.2011.08.043
关键词
Arsenic; Geothermal system; Latin America, Volcanic fluids; Geothermal fluids
资金
- Fundacion Amigos del Lago de Ilopango
- Swedish International Development Cooperation Agency (Sida) [7500707606]
- Swedish International Development Cooperation Agency [SWE-2005-P18]
- Convenio de Desempeno Universidad de Tarapaca (UTA-MINEDUC)
- CYTED Proyect Red Tematica [406RT0282 Iberoarsen]
Numerous volcanoes, hot springs, fumaroles, and geothermal wells occur in the Pacific region of Latin America. These systems are characterized by high As concentrations and other typical geothermal elements such as Li and B. This paper presents a review of the available data on As concentrations in geothermal systems and their surficial discharges and As data on volcanic gases of Latin America. Data for geothermal systems in Mexico, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, Ecuador, Bolivia, and Chile are presented. Two sources of As can be recognized in the investigated sites: Arsenic partitioned into volcanic gases and emitted in plumes and fumaroles, and arsenic in rocks of volcanic edifices that are leached by groundwaters enriched in volcanic gases. Water containing the most elevated concentrations of As are mature Ma-Cl fluids with relatively low sulfate content and As concentrations reaching up to 73.6 mg L-1 (Los Humeros geothermal field in Mexico), but more commonly ranging from a few mg L-1 to tens of mg L-1. Fluids derived from Na-Cl enriched waters formed through evaporation and condensation at shallower depths have As levels of only a few mu g L-1. Mixing of Na-Cl waters with shallower meteoric waters results in low to intermediate As concentrations (up to a few mg L-1). After the waters are discharged at the ground surface, As(III) oxidizes to As(V) and attenuation of As concentration can occur due to sorption and co-precipitation processes with iron minerals and organic matter present in sediments. Understanding the mechanisms of As enrichment in geothermal waters and their fate upon mixing with shallower groundwater and surface waters is important for the protection of water resources in Latin America. (C) 2011 Published by Elsevier B.V.
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