Potentially Toxic Element (PTE) Sources in the Middle Eocene Carbonate Aquifer, East El Minia, Egypt

Abstract

Water pollution with potentially toxic elements (PTEs) becomes a major threat to the validity of that water for drinking and agriculture and hence human life. The current study aims to evaluate the carbonate aquifer groundwater PTE content, sources, and impact on water quality. To achieve this goal, drilling cutoff of two wells and 30 groundwater samples were collected and chemically analyzed. The groundwater has TDS values ranged from 271.2 to 971.8 mg/l. Freshwater recharge process led to the continuous freshening of the aquifer and enhanced the forward ion exchange reactions. Carbonate and evaporate mineral dissolution/precipitation processes are the main controller of groundwater chemistry. Cd and As represented the most hazardous elements in these rocks followed by Pb. The presence of high concentrations of PTEs (As, Cd, Cr, and Pb) in water-bearing carbonate rocks has led to detritus of water quality and its unsuitability for drinking owing to the occurrence of these harmful elements in water. Even though the high concentrations of PTEs in the studied water, these elements occurred in low mobility and toxicity species: Fe(OH)3, Mn2+, (HAsO4)−2, Cd2+, Cr2O3, Cu2O, CuO, and PbCO3. This reflects the importance of studying element species rather than total concentration. Even though the unsuitability of this water for drinking owing to high concentrations of some PTEs, all of the samples were found to be suitable for irrigation.