Hydrochemistry of groundwater in the Duero River basin and regulations for domestic use.

Abstract

This work was carried out in the Duero River basin, in the northwest portion of the State of Michoacán. Its main objective was to evaluate the chemical composition of groundwater for domestic use, with an emphasis on heavy metals due to their potential effects on human health. Regulations for drinking water quality control were reviewed so as to discuss the implications and limitations of their implementation based on the results obtained. The physicochemical composition of samples from 17 sites was analyzed on two different sampling dates to determine pH, EC, t(oC), major ions and heavy metals using standard methodologies. Data was processed using multivariate statistical analysis techniques (principal components analysis, PCA). EC varied from 135 to 880 mS cm-1and pH ranged from 6.28 to 7.83. The main water families found were: magnesium-bicarbonate, calcium-bicarbonate and sodium-calcium-bicarbonate.  Zn, Mn, Cu and Fe concentrations were within safe limits for human consumption. Pb was detected at all the sampling sites and exceeded the maximum allowable limits for human consumption. The factors associated with the source of the chemical components of the water were: basaltic rocks with olivine and feldspars minerals and calcite. Pb concentration was associated with volcanic clasts (siliceous sands).