Estudio hidrogeoquímico isotópico de manantiales en la Cuenca de México

Abstract

Isotope and hydrochemical seasonal variations for 38 springs, two wells, three shallow wells and two lakes, mostly in the recharge areas in the Basin of Mexico were examined. Global chemical trends of major-ions show wáter of type HC03-Ca and HCOrNa+K. According to the concentration ofTotal Dissolved Solids (TDS) a short residence time was inferred through basalts and andesites. Chemical anomalies (TDS in mg/l) were found at Peñón de los Baños (> 2500, sample 1), Poza de Reyes (> 900, sample 6), Copilco (>540, sample 4) and Pocito La Villa (>700, sample 21). For the rest of the springs the TDS concentrations range from 13 - 460 mg/l. Two termal anomalies were detected: Peñón de los Baños (sample 1), with 450 C, and Castañeda (> 250, sample 18) with a maximum temperature of 46 0C. Stable isotopes (S¹⁸O= -10.7 y SD and 8D) for sprinis fit a line determined by SD = (5.94 ± 0.56)S¹⁸0- (9.77 ± 6.00). Isotope means for these samples are S¹⁸ 0= -10.7 and SD = -73, lighter than the means for wells, possible due to evolution and different recharge conditions of the latter. Precipitation data of the basin were plotted on the local meteoric water line with slop and intercept as was reported for Sierra de las Cruces.