Relationship of Fluoride Concentration to Well Depth in an Alluvial Aquifer in a Semiarid Area

Abstract

Groundwater of northern Mexico contains high concentrations of geogenic fluoride (F?), a contaminant known to affect human health. The origin of F? in groundwater in this region has been related to the weathering of rhyolite and other volcanic rocks present in the alluvium. However, the relationship of F? concentration to water depth has not been established. F? concentrations, pH, and total dissolved solids (TSD) were determined for 18 wells within the Meoqui-Delicias aquifer in 2021. The F concentrations varied between 0.62 mg L?1 and 4.84 mg L?1, and 61% of the wells exceeded the 1.5 mg L?1 guideline. F? concentrations did not correlate to TDS but correlated to well depth (r = ?0.52, p < 0.05). Because of the less-than-strong correlation coefficient value obtained, a diagram of F? concentrations vs. well depth was constructed. The diagram showed a distinct enrichment of F? in shallow wells, suggesting that groundwater residence time and evaporation may be important factors in explaining the F? content within the aquifer. This pattern was confirmed after plotting 2003 and 2006 data for the same wells. These findings are important to better understand the distribution of F? in neighboring alluvial aquifers as well as in alluvial aquifers elsewhere.

Department(s)

School of Earth, Environment and Sustainability

Document Type

Article

DOI

10.3390/environments9120155

Keywords

basin-fill aquifer, Chihuahua, evaporation, fluoride, groundwater withdrawal

Publication Date

12-1-2022

Journal Title

Environments Mdpi

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