Geochemical Characterization and Saturation Index (Si) in the Montebello Lagunar System Liquidamber Lagoon, Chiapas Mexico

Abstract

The “Lagunas de Montebello” National Park located in Chiapas, Mexico, is well known for its crystal blue water bodies, some of which, in 2003, started to change color from crystalline to cloudy brown, and occasionally emit a foul smell, contains white-yellowish supernatant debris and dead fish. To determine the causes of the changes in the water characteristics of the “Liquidambar” lagoon of the Montebello lagoon system, a physicochemical characterization was carried out over the first six meters of the water column, together with geochemical speciation analysis and the saturation index calculation for different minerals. Water was classified as calcium-sulfated and the main mechanism that controlled its chemistry was rocks dissolution. Sulfide was found at all sampled depths in the range of 0.11 to 1.13 mg.L-1. The concentration of sulfate in the water column ranged from 249.21 to 298.7 mg.L-1, carbonate ranged from 140.5 to 261.4 mg.L-1, calcium and magnesium ranged from 94.5 to 146.9 mg.L-1 and 34.2 to 38.3 mg.L-1, respectively. Likewise, oxygen was also found to be oversaturated on the surface with a value of 9.32 mg.L-1. The speciation results and SI indicated that the mineral phases calcite, aragonite, and dolomite were oversaturated, being greater on the surface. The results suggested the possibility that the turbidity, the coloration change, and the whitish supernatant were due to the precipitation of carbonate minerals, microbiologically influenced by the photosynthetic activity in the upper layer of the lagoon water.

Keywords

• agricultural waste, erosion risk, loss of fertile soil, water quality