The present study is conducted with
the purpose of determining the chemical characteristics of groundwater that
supplies 16 wells in the state of Coahuila, which are used for different human
activities. Sampling was conducted in January 2011. For 56% of the fifteen
wells tested, analysis did not detect the presence of aluminum; however, wells
2, 3, 6, 8 and 13 had concentrations above the permissible limit established by
the Mexican standard NOM-127-SSA1-1994. For cadmium, only the well 3 was above
the Norm. Meanwhile, iron was above the permissible limit in eight wells (2, 4,
5, 6, 9, 12, 13 and 15). Lead exceeded the limit in wells 6, 7, 9, 10, 11 and 12. In general, for the rest
of the parameters listed in the Norm, values were below allowable limits. By
using Piper diagrams, it was observed that in general, the waters tested showed
characteristic calcium bicarbonate. By establishing a matrix of correlations
between chemical parameters, it was observed that the highest significant
correlations occurred among carbonate hardness, calcium, lead and total
alkalinity, with r2 values greater than 0.82. Also, high
correlations were found between some metal species, suggesting a common origin.
The allowed Principal Component Analysis and Cluster Analysis establish the
associations between all analyzed physicochemical parameters, and they also determine the wells with similar characteristics.