Natural controls validation for handling elevated fluoride concentrations in extraction activated Tóthian groundwater flow systems: San Luis Potosí, Mexico.

Autor: Cardona, Antonio, Banning, Andre, Carrillo-Rivera, José Joel, Aguillón-Robles, Alfredo, Rüde, Thomas R., Aceves de Alba, Jorge
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Zdroj: Environmental Earth Sciences; Feb2018, Vol. 77 Issue 4, p0-0, 1p, 1 Diagram, 2 Charts, 5 Graphs, 1 Map
Abstrakt: Fluoride concentration in groundwater supply above the guideline value of 1.5 mg/L is a health hazard for the population living in two thirds of the Mexican territory. Enhanced groundwater extraction in the city of San Luis Potosí (SLP), Mexico, led to a substantial territorial increase in water with high fluoride (F−) which originates from thermal water-rock interaction with regional rhyolites. Previous knowledge of the Tóthian groundwater flow systems around SLP City and their F− concentrations from 1987 data provided an insight into natural F− controls for the construction and operation of boreholes. During the period 1987-2007, the number of new boreholes increased as well as the relocation of boreholes whose production diminished. Overall estimated extraction augmented from 2.6 to 4.1 m3/s. Results obtained for 2007 suggest that F− controls defined for 1987 data (e.g., variable portions of F−-rich deep thermal water in borehole yields) are also valid in newly constructed boreholes. Water authority actions related to groundwater extraction lack consideration of proposed F− controls, so constructed boreholes progressively tapping the high F− groundwater flow system resulted in a 85% increase in the F− affected territory (> 2 mg/L) between 1987 and 2007. Reduction in F− extraction following the proposed natural control mechanisms (e.g., fluorite precipitation) was also confirmed. Applying geochemical and mineralogical analysis, rhyolites surrounding the SLP graben basin and contributing to its volcano-clastic sedimentary filling were identified as the primary F− source for elevated concentrations in groundwater of the area under investigation. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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