239-3 Hydrogeochemical Modelling of a Springs System, Xalapa, East Central MEXICO

Tuesday, 7 October 2008: 8:30 AM
George R. Brown Convention Center, 352DEF
Rocio Salas, Posgrado Ciencias de la Tierra, UNAM Mexico, Mexico, Mexico, Alejandro Carrillo-Chávez, Centro de Geociencias, UNAM, Queretaro, Mexico, Alejandra Cortes, NATURAL RESOUCES, GEOPHYSICS INSTITUTE, Mexico, D.F, Mexico, Sergio Rodriguez, Regional Geology, Geology Institute, Mexico, D.F, Mexico and Juan Perez-Quezadas, Posgrado en Ciencias de la Tierra, UNAM, Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Mexico, D.F, Mexico
Twenty three water springs were sampled along a mountainous section of some 50 km from 1185 m to 131 m altitude above sea level. Total dissolved solids from the water samples vary from 54 to 1,200 mg/l, in general increasing downhill. The groundwater goes through volcanic rock (mostly basalts and pyroclasts) first, and then through limestone. Hydrogeochemical evolution of groundwater using PHREEQC, was used to analyse water-rock interaction and possible different flow paths for groundwater. The results show a deeper flow with higher temperatures and higher rock-water interaction, and some shorter shallow flow-paths with lower temperatures and lower rock-water interaction. Water chemistry from some springs could only be explained with an anthropogenic component in a mixing system. A conceptual model for groundwater circulation is presented, indicating chemical reactions along the paths.