Abstract

CORTES, Alejandra; DURAZO, Jaime  and  KRALISCH, Stefanie. Rapid isotopic changes in groundwater, upper Rio Guanajuato catchment, Mexico. Geofís. Intl [online]. 2007, vol.46, n.1, pp.75-82. ISSN 2954-436X.

Significant changes in the isotopic composition of groundwater in the upper catchment of Rio Guanajuato, Mexico, were detected in two independent sets of samples for 3 % of the 1600 high-production wells in the area. Sampling was done in December 1998 (53 samples), and in July - August 2003 (41 samples). Average deuterium concentration did not change between 1998 and 2003 but the average oxygen-18 concentration suggested a generalized dilution from deep water from infiltrated local precipitation. This regional change occurred within 56 months, indicating a highly dynamic hydrogeologic system. Fast replenishment of aquifer storage, or non sustainable over-pumping of old aquifer reserves, are possible explanations.

Keywords : Recent isotopic change in oxygen-18 and deuterium in groundwater; rapid aquifer evolution; Guanajuato; Mexico.

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