Description of Chemical Changes in a Large Karstic System: Montebello, Mexico☆

Abstract Lake complex “Lagunas de Montebello” is a karstic system composed by sixty lakes, all apparently connected. This system is localized at south of Chiapas state, SE Mexico. It is considered one of most beauties landscapes of the country. Main importance is due to climatic and hydrological regulation of this region. However anthropic activities as deforestation and waste water spills begin to produce risky conditions to water quality. This work presents spatial and temporal variability of water quality considering the study of ten lagoons through three sampling periods. Two of these periods of field work, (april and september 2013) consider sampling of only one point at surface in each lagoon. A very extensive sampling was developed in august 2014 in ten lagoons. Results show that this karstic system can be divided in two groups of water quality. First group of lakes contains calcic-magnesic-bicarbonated-sulfated waters and second group contains calcic-magnesic-bicarbonated waters. At first group, is possible to identify impacts related to inlet of waters high in sulfates and chlorides, these solutes dilutes along two first lagoons. An independent flow system rich in sulfates, probably of groundwater that circulates deeply was identified.