An adapted groundwater quality index including toxicological critical pollutants

Abstract

Water supply for population is mainly supported by groundwater. Its quality for drinking purposes is a worldwide major issue. Groundwater quality indexes are tools to assess its appropriateness for human consumption. This study evaluates the WAWQI index in North-Central Mexico with reported toxicological critical pollutants (arsenic, fluoride, and uranium) and put forward an adapted and optimized Groundwater Quality Index (GWQI). The research utilizes a dataset of groundwater parameters to analyze the chemical composition and suitability of groundwater (n = 121 samples) for drinking purposes. Arsenic concentrations fluctuate between 7.78 and 9798, average of 154 μg/L and only three samples within the Mexican guideline. Fluoride concentrations range from 0.01 to 2.2, average of 0.8 mg/L and 64% of the sample within the Mexican guideline. Uranium, not previously described in the region, show elevated concentrations in the range of 1.01–93.7 average of 11.4 μg/L and 88% within the WHO guideline. The WAWQI Index, applied to water samples, categorized samples as excellent and good status. However, 95%, 33%, and 11% of the samples are above As, F^-, and U guidelines; therefore, a tailored GWQI for drinking water was proposed and optimized considering the WAWQI limitations. The outcome of the GWQI shows that only two samples classified with excellent status and are safe to drink without treatment. However, 119 samples were classified as poor, very poor, and unsuitable for drinking purposes. The GWQI provides a valuable tool for assessing groundwater quality in regions with similar hydrogeological conditions to the study area, and to identify areas requiring urgent attention to ensure safe drinking water supply. The study highlights the urgent need for sustainable water management practices to address the region's water quality challenges and ensure the long-term well-being of its population and fulfill the Sustainable Development Goal 6.