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

GUALDE, MARÍA SOLEDAD; DIETRICH, SEBASTIÁN; ZABALA, MARÍA EMILIA

San Pablo

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

Geological Survey of Brazil, IMGA, GSA's Geology and Health Division, Clay Mineral Society, Springer Publishing

Although considerable progress has been made in the study of arsenic (As) and fluoride (F) ingroundwater, the number of people affected by this problem in Argentina is still high1. The cityof Azul in the province of Buenos Aires is located in the Pampean Plain and is supplied withgroundwater from the multilayer Pampeano Aquifer, whose thickness is about 100 m. Theaquifer has a complex geological heterogeneity that leads to important variations in hydraulicconductivity, which in turn affects As and F behavior. It has been shown that Pampeano Aquiferhas high concentrations of As and F, but distributed erratically, both laterally and in depth2.These chemical species originated in several sources and are mobilized and transported byvarious mechanisms, both physical and chemical3. In addition, there are local factors such aslithology, geomorphology, topography and hydraulic parameters that affect these processes.The main objective of this study is to determine which layers of the Pampeano Aquifer containwater with low As and F concentrations and to relate them to heterogeneity in subsurfacegeology.The methodology used to characterize the aquifer sediments includes analysis of drilling logsand geophysical measurements. The use of chemical and isotopic techniques is intended to helpin the understanding of hydrodynamics. The use of specific software EMMA-MIX is proposed togain insights into the degree of mixing of water due to lithological heterogeneity andgroundwater pumping4.An hydrogeological conceptual model it is planned to be developed which allow us to establishsome criteria for water quality in the city of Azul. It is expected that this model provide scientificguidelines for hydrogeological exploration with the lowest concentrations of these ions aspossible. Undoubtedly, this progress will have a positive impact on the health of the population,providing them with better water quality.