Anthropogenic Contamination in the Free Aquifer of the San Luis Potosi Valley

Abstract

Abstract The valley of San Luis Potosí is an endorheic basin formed by three aquifers: shallow hanging, alluvial material on a hardened horizon known as "tepetate", two deep, free and confined type. Population growth has led to gradual contamination of the surface aquifer. Recent studies documented anthropogenic, biogenic and heavy metal contamination. A recent phenomenon of settlement has affected houses and buildings in the urban area, extending to parts of the valley that are still used for agriculture, developing "faults" affecting the tepetate that supports the superficial aquifer, facilitating the infiltration of contaminated water into the aquifer. free type. This investigation reports detection of nitrogen (N-NO3), with a concentration of 15 mg/L (milligram liter) its maximum allowable limit is 10 mg/L. Twelve samples with fecal coliforms from 5 to 17 MPN/100 (the most probable number in one hundred milliliters of the sample). Thirteen samples showed total coliform concentrations, one sample reported a too high concentration of 150 NMP/100, compared to the rest with concentrations of 5 to 17 NMP/100, indicating less contamination. Some trace elements with concentrations in parts per million (ppm) that were also detected were manganese (Mn), arsenic (As), cadmium (Cd), and mercury (Hg). Results that give the first sign of attention to the contamination of the deep free aquifer, derived from anthropic activity in the valley of San Luis Potosí.