Hydrogeochemical and Isotopic Evaluation of Heavy Metal Contamination in Rural Groundwater: A Case Study from Tonosí, Panama

The primary source of drinking water for the people of Tonosí, Panama, is groundwater. This research evaluates the presence of heavy metals and possible hazards by combining geochemical and isotopic analyses. Total Reflection X-ray Fluorescence (TXRF) was used to measure metal levels in water and soil near wells and springs, while stable isotope ratios (δ2H and δ18O) identified the source of groundwater recharge. Isotopic signatures closely aligned with the Local Meteoric Water Line (LMWL), suggesting meteoric origin and limited evaporation. An analysis of Enrichment Factor (EF) for soil samples, utilizing background values from Coiba and Montijo, showed moderate to substantial enrichment of arsenic, chromium, and copper. Soil enrichment suggests possible dangers with environmental shifts like changes in land use or heavy rainfall. These findings highlight the necessity for continual groundwater observation in rural areas and show the benefits of integrating isotopic and geochemical methods to detect sources of contamination and guide protection strategies. This research improves comprehension of heavy metal exposure in tropical aquifers and offers evidence to aid environmental and public health policymaking.