Evaluation of Groundwater Quality for Human Consumption and Irrigation in Relation to Arsenic Concentration in Flow Systems in a Semi-Arid Mexican Region

Abstract

The supply of drinking water to the population is an important challenge facing humanity, since both surface and underground sources present a great variability of water storage with respect to space and time. This problem is further aggravated in arid and semi-arid areas where rainfall is low and torrential, which makes groundwater the main source of supply; therefore, it is necessary to carry out studies that allow evaluating the evolution of the quantity and quality of water. This study addresses the behavior of groundwater in a semi-arid region, considering the theory of flow systems to identify movement as well as water quality, es determined by a water quality index (WQI), calculated considering arsenic and fluorine. In addition, a quality irrigation classification is used, employing the norms in accordance with international standards and the Mexican Norm, which allows for a comparison. Local, regional, intermediate and mixed flow systems are identified, and the evolution of cations and anions in addition to temperature is examined. It is observed that the drinking water quality index classifies them as excellent in most of the monitored wells (<50), but with a negative evolution. Regarding irrigation, most of the water samples are classified without restriction for the establishment of any type II crop (C2S1) and with restrictions for horticultural crops. It is observed that arsenic had values between 0.49 and 61.40 (µg/L) in 2005, while in 2015 they were between 0.10 and 241.30 (µg/L). In addition, fluoride presented values between 0.00 and 2.6 (mg/L) in 2005, while in 2015 they were between 0.28 and 5.40 (mg/L). The correlations between arsenic and fluorine are noted as well as WQI and SAR. A finding in this research was to include arsenic and fluorine in the calculation of the WQI allowing a better interpretation of the quality of water for both human consumption and for agricultural use to based on this make the best decision to control any harmful effects for the population, in addition to identifying the appropriate purification treatment required to control pollutants. It is concluded that arsenic is an element of utmost importance when considering water quality, so it is necessary to examine its evolution and continue to monitor its levels constantly.

Aqueous Arsenic Speciation with Hydrogeochemical Modeling and Correlation with Fluorine in Groundwater in a Semiarid Region of Mexico

“…Water in this region is not suitable for any of the activities mentioned above. Ortiz-Letechipia et al [29], reaffirms this, according to the water quality index. Considering the concept of total arsenic and the spatial and temporal distribution observed in this work, very few investigations report this [30,64].…”

“…Water in this region is not suitable for any of the activities mentioned above. Ortiz-Letechipia et al [29], reaffirms this, according to the water quality index.…”

“…This demonstrates the contribution of this research, that with a space-time analysis of the elements, the application of specific remediations is improved, thereby achieving significant savings of money and human resources for decision-makers on the use of groundwater. There are only a few studies that analyze this behavior, as well as the toxicity of fluoride with arsenic, two elements that have potentially harmful effects on public health [29,77] .…”

“…In the space-time comparison of arsenic speciation, it is found that in 2015, an As III plume was identified in the north of the study area; however, by 2020, it disappeared (Figures 4 and 5). This is probably due to evolution from As III to As V due to the mixture of flows resulting from the extraction of water [8,29,73] . This change can also be attributed to mobilization/retention processes, dissolution, bacteria-mediated electrochemical evolution, geology, and ion exchange [33,46,74,75] ].…”

“…Several investigations have been carried out to understand the mechanism of evolution of ions in groundwater [7,8,29,33,38] and, based on this, to determine its trajectory and the geological environment through which it has passed. This allows identifying elements that can generate health issues using water in different activities.…”