Arsenic in volcanic geothermal fluids of Latin America

Dina L. López, Jochen Bundschuh, Peter Birkle, Maria Aurora Armienta, Luis Cumbal, Ondra Sracek, Lorena Cornejo, Mauricio Ormachea

Research output: Contribution to journalArticlepeer-review

118 Scopus citations

Abstract

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 Na-Cl fluids with relatively low sulfate content and As concentrations reaching up to 73.6mgL-1 (Los Humeros geothermal field in Mexico), but more commonly ranging from a few mgL-1 to tens of mgL-1. Fluids derived from Na-Cl enriched waters formed through evaporation and condensation at shallower depths have As levels of only a few μgL-1. Mixing of Na-Cl waters with shallower meteoric waters results in low to intermediate As concentrations (up to a few mgL-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.

Original languageEnglish
Pages (from-to)57-75
Number of pages19
JournalScience of the Total Environment
Volume429
DOIs
StatePublished - 1 Jul 2012
Externally publishedYes

Bibliographical note

Funding Information:
The authors want to acknowledge the support of different organizations for portions of this work: Fundación Amigos del Lago de Ilopango, Swedish International Development Cooperation Agency (Sida Contribution: 7500707606 ), Swedish International Development Cooperation Agency project to Costa Rica on Arsenic in Geothermal Waters, Central America ( SWE-2005-P18 ), Convenio de Desempeño Universidad de Tarapacá (UTA-MINEDUC, 2008–2010), and the CYTED Proyect Red Temática 406RT0282 Iberoarsen. We thank Dr. John Farmer and Dr. Elizabeth Gierlowski-Kordesch for editorial help.

Keywords

  • Arsenic
  • Geothermal fluids
  • Geothermal system
  • Latin America, Volcanic fluids

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