7 Geochemical Influences on Metal Contaminants in Subsurface Systems

Monday, 19 April 2021
8:00 AM - 12:00 PM
Missouri Geological Survey Room

TRACING NATURAL SOURCES OF F- IN GROUNDWATER: CASE NORTHERN MEXICO

Paper number: 7-5
Program: Theme Sessions
Time: 9:05 AM – 9:25 AM

Authors

Abstract

Groundwater in arid and semi-arid areas of northern Mexico contain high concentrations of fluoride (F), a toxic element that causes dental and skeletal fluorosis and bone fractures, among other health problems. A previous (2020) study identified Durango, Zacatecas and Chihuahua as the Mexican states with highest F concentrations. The source and the factors that cause its enrichment were investigated here. To this purpose, F and related water parameters (As, TDS, T, U) were acquired from groundwater quality databases of samples collected in 2019. A map showing the sites with highest concentrations in the region (north-central Mexico and bordering region in the USA) was constructed. The analysis shows that the origin of F is mostly natural, likely caused by weathering of silica-rich volcanic rocks contained in the alluvial fill. High alkalinity and evaporation concentrate F further. The chemical species under alkaline conditions and present solutes are F-, MgF+, and AlF2+. F showed a strong correlation to As and correlated weakly with TDS. Both temperature and U data were too fragmented to show a trend.

Geological Society of America Abstracts with Programs. Vol. 53, No. 3

doi: 10.1130/abs/2021NC-362517

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