GEOCHEMISTRY AND ENVIRONMENTAL ASSESSMENT OF A SYSTEM OF WATER-SPRINGS IN JALAPA, EAST CENTRAL MEXICO

This system of water springs is located on the east sector of the Mexican Volcanic Belt, close to two major volcanoes (Pico de Orizaba and Perote). There are also several small monogenetic volcanoes which locally affect the hydrologic characteristics for groundwater flow. The altitudes in the springs area vary from 3,500 m to 140 m (above sea level). The discharges of the water springs vary from 0.03 to 60 litres per second, and these springs are the only water source for 52 communities in the area (central-west Veracruz). The objective of this study is to determine the source of water for the springs, the chemical and hydrological characterization of the springs and to assess the environmental sensibility of the system and the current anthropogenic impact. So far, the methodology involved consists of: 1) location of springs and their geologic setting (general geologic and hydrologic map), 2) measurement of discharges and some water parameters (hydrogeology and hydrogeochemistry of the system), 3) installation of 10 rain water collector stations (isotopic studies for mass balance and recharge evaluation), 4) selection of 25 water springs for detailed chemical and isotopic analysis (hydrogeochemical evolution modelling and hydrogeological flow). Preliminary results indicate that the springs are the result of changes in lithology, fractures and permeability in the aquifers. Based on hydrogeochemistry data, there are at least three flow systems. Some chemical parameters are above the standards for drinking water due to anthropogenic (waste water) impact on the natural system.