Alluvial and gypsum karst geological transition favors spreading arsenic contamination in Matehuala, Mexico

• Published in: The Science of the total environment Vol. 707; p. 135340
• Main Authors: Gómez-Hernández, Andrea, Rodríguez, Rodrigo, Lara del Río, Antonio, Ruiz-Huerta, Esther Aurora, Armienta, María Aurora, Dávila-Harris, Pablo, Sen-Gupta, Bhaskar, Delgado-Rodríguez, Omar, Del Angel Ríos, Andrés, Martínez-Villegas, Nadia
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10-03-2020
• Subjects: Arsenic transport; Exposure; Groundwater; Risk; Semiarid environment; Surface water; Risk; Exposure; Groundwater; Arsenic transport; Semiarid environment; Surface water
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.135340

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•Arsenic contamination in Matehuala is mostly linked to a shallow aquifer.•Shallow lithosphere configuration plays a key role in arsenic transport in Matehuala.•Exposure to arsenic contaminated groundwater causes accumulation in human hair.•Arsenic transport is more rapid and extent in a gypsum karst than in alluvial aquifers.
Arsenic transport in alluvial aquifers is usually constrained due to arsenic adsorption on iron oxides. In karstic aquifers, however, arsenic contamination may spread to further extensions mainly due to favorable hydrogeochemical conditions. In this study, we i) determined the spatial and temporal behavior of arsenic in water in an alluvial-karstic geological setting using field and literature data, ii) established whether a contaminated aquifer exists using field and literature piezometric data and geophysical analysis, iii) studied the local geology and associated arsenic contaminated water sources to specific aquifers, iv) revealed and modeled subsoil stratigraphy, and v) established the extent of arsenic exposure to the population. We found arsenic contamination (up to 91.51 mg/l) in surface and shallow groundwater (<15 m), where water flows from west to east through a shallow aquifer, paleochannels and a qanat within an alluvial-karst transition that favors the spreading and transport of arsenic along 8 km as well as the increase of arsenic exposure to the population (up to 3.6 mgAs/kghair). Results from this study contribute to understanding arsenic transport in semi-arid, mining-metallurgical, and urban environments, where the presence of karst could favor arsenic transport to remote places and exacerbate arsenic exposure and impact in the future.