Abstract

DOMINGUEZ MARIANI, Eloísa et al. Determination of hydrogeochemical processes associated with the composition of water from supply wells for the inhabitants of the Iztapalapa District, D.F., Mexico. Bol. Soc. Geol. Mex [online]. 2015, vol.67, n.2, pp.299-313. ISSN 1405-3322.

The water supply issues for Basin of Mexico residents have been constant; recently they have increased in Iztapalapa because of the groundwater withdrawal. The most significant concentrations, obtained from 17 wells, were: Fe²⁺ (0.004 - 0.6 mg/L), Mn²⁺(0.003 - 0.96 mg/L), Na⁺ (91 - 598 mg/L) and Cl^- (59.5 - 372 mg/L), COD (3 - 63.8 mg/L) and specific conductivity (620 - 2503 µS/cm), in addition with turbidity and bad odour. The following hydrogeochemical processes were determined: mixing between different groundwater flow components induced by heavy pumping, and brackish water of overlying aquitard, increasing of the ionic content of groundwater until the precipitation of minerals like carbonates, phosphates and silicates on supply network and turbidity of the water extracted. This was demonstrated by calculating saturation index with the software PHREEQC. Redox conditions are consequence of organic matter oxidation, and therefore sulfate reduction, denitrification and presence of gases such as CO₂ and H₂S, the latter associated with corrosion in the drinking water network.

Keywords : water quality; hydrochemistry; water extraction; iron; salinization; sulfate reduction.

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