HIDROQUÍMICA DE LAS AGUAS SUBTERRÁNEAS EN LA CUENCA DEL RÍO DUERO. Elementos para una gestión sustentable del recurso

Abstract

The study was done in the Zamora aquifer zone, in the northwestern part of Michoacan state, in the so-called Mexican Volcanic Belt. The objectives of this work was to evaluate the hidro-chemistry of groundwater, to determined the heavy metals concentrations and link these with the potential hazards on human health by consumption of these flows and also, to make some observations about the limitations and scope of the application of these rules in the study area. The water physical and chemical composition in 17 sites and in two sampling dates, were analyzed using standardized methodologies. The data were processed using multivariate statistical analysis (CJA ascending hierarchical cluster and principal components analysis ACP). The electrical conductivity ranged from 135 to 880 μS cm-1, while the pH ranged from 6.28 to 7.83. In this study, the main families of water that were found were: magnesium-bicarbonate, calcium- bicarbonate and sodium-calcium-bicarbonate. Water sources were grouped into three categories, depending mainly on the electrical conductivity. The lead was detected in all studied sites and during the two sampling dates, in concentrations that ranged from 8 to 220 mg L-1, was exceeding twenty times the maximum limit allowed for drinking water. The concentration of Zn, Mn, Cu and Fe were found it within allowable limits for water of use and human consumption. Factors associated with the origin of the chemical components of water were: basaltic rocks with minerals type olivine, feldspar and calcite. The Pb concentration was associated with volcanic clasts (silicious sand) where possibly there are reefs of PbS. The water used as drinking water in the area, regularly only is chlorine and are not carried out checks on its physic-chemical quality. The evidence indicates the need to make monitors and introduce additional measures to protect the health of those people who drink water with high levels of lead.