Geochemical evolution and Boron sources of the groundwater affected by urban and volcanic activities of Puebla Valley, south central Mexico

Abstract

The geochemical evolution of groundwater of the Puebla aquifer was investigated using chemistry and isotopic data with special emphasis on the geochemistry of Boron to decipher the natural and anthropogenic sources. This study measured 70 groundwater samples that are potentially impacted by the urban and rural anthropic, volcanic and glaciation activities. Based on the distribution of anions and cations water samples were classified into three groups using Piper Diagram. Group1 showed to have high HCO3 than SO4, Group 3 high SO4 than HCO3 and Group 2 revealed intermediate composition. Radiometric studies show the presence of Pleistocene groundwater; however, there was no definite relationship between the radiometric dates to the groups except that enrichment in δD and δ13C values were noted with respect to age. Average Boron concentrations in some wells were observed to be higher (>5000 μg/L) than that of the permissible limit for human consumption. Results also indicated that the sources of Boron were more natural than anthropogenic that comprised the local geological conditions, volcanic activity and hydrothermal processes. The study also validated that the groundwater wells from the southwestern part of the study area are suitable for extraction of groundwater, considering its quality and residence time; whereas, in the wells located in the central-eastern zone of the metropolitan area, it is recommended that groundwater exploitation must be gradually reduced.