Analysis of the heterogeneity of the Pampeano aquifer sediments: towards a better understanding of the behavior of arsenic and fluoride in the Chacopampeana Plain

GUALDE, S.; DIETRICH, S.; ZABALA, M.E.

Conferencia; Proceedings of The First International Student Conference on Medical Geology and Environmental Health: Latin America; 2021

Although considerable progress has been made in the study of arsenic and fluoride in groundwater, the number of people affected by this problem in Argentina is still high1. The city of Azul in the province of Buenos Aires is located in the Chacopampeana Plain and is supplied with water from wells in the Pampeano aquifer. This aquifer is composed of Pampean and post-Pampean sediments that have high concentrations of arsenic and fluoride in the first few meters2. These chemical species originate from several primary sources and are mobilized and transported by various factors and mechanisms, both physical and chemical3. In addition, there are local factors such as lithology, geomorphology, topography, hydraulic parameters and residence time of groundwater. In particular, aquifer heterogeneity is an issue that is not well understood. This, in turn, leads to heterogeneity in hydraulic conductivity and temporal variations in water flow that affect arsenic and fluoride behavior. The main objective of this study is to determine which sections of the Pampeano aquifer contain water with low arsenic and fluoride concentrations and to isolate them through an analysis of the subsurface geology. The methodology used to characterize the aquifer sediments includes analysis of drilling logs and geophysical measurements. The use of isotopic techniques is proposed to understand the hydrodynamic. The use of a software is proposed to assess the degree of mixing of water due to lithological heterogeneity with uncertain end members4.It is planned to create a conceptual model and establish criteria for water quality in the city of Azul. It is expected that we will be able to provide scientific guidelines for hydrogeological exploration with the lowest concentrations of these ions. Undoubtedly, this progress will have a positive impact on the health of the population, providing them with better quality water.