A novel hydrogeochemical approach to delineate the origin of potentially toxic elements in groundwater: Sophisticated molar ratios as environmental tracers

Environ Sci Pollut Res Int. 2023 Jun;30(30):74771-74790. doi: 10.1007/s11356-023-27721-8. Epub 2023 May 20.

Abstract

The occurrence, mobilization, and origin of Potentially Toxic Eelements (PTEs) in the environment is always a difficult research question that has not been fully addressed to date; solving this problem would be a major achievement for environmental science and pollution research, a significant scientific breakthrough, and an important contribution to environmental analysis and monitoring. The lack of a holistic methodology that uses chemical analysis to determine the origin of each PTE in the environment is the main motivation for this project. Therefore, the hypothesis tested here is to develop a scientific approach applied to each PTE to determine whether its origin is geogenic (i.e., water-rock interaction with dominance of silicate or carbonate mineral phases) or anthropogenic (i.e., agricultural practices, wastewater, industrial activities). A total of 47 groundwater samples from the Psachna Basin in central Euboea, Greece, were used and plotted on geochemical mole ratio diagrams (i.e., Si/NO3 vs. Cl/HCO3) and used to perform a robust geochemical modeling analysis. The proposed method showed that elevated groundwater concentrations of various PTEs in groundwater were mainly related to intensive fertilization (e.g., Cr, U), water-rock interaction (e.g., Ni), and saltwater intrusion. (i.e., As, Se). This work highlights that a comprehensive framework with sophisticated molar ratios combined with modern statistical methods, multi-isotope signatures, and geochemical modeling could provide answers to unresolved scientific questions about the origin of PTEs in water resources and improve environmental resilience.

Keywords: Euboea; Fate and transport; Groundwater; PHREEQC; Potentially toxic elements; R-mode hierarchical cluster analysis.

MeSH terms

  • Agriculture
  • Environmental Monitoring / methods
  • Groundwater* / analysis
  • Water / analysis
  • Water Pollutants, Chemical* / analysis

Substances

  • Water Pollutants, Chemical
  • Water