Comprehensive investigation of groundwater quality in the north-west of Iran: Physicochemical and heavy metal analysis

The suitability of rural groundwater quality for drinking purposes were investigated in the north west of Iran. Major anions, cations and heavy metals were measured in 39 water wells during the summer and spring seasons. The spatial distribution of major parameters and hydro-chemical faces were described by developing GIS-based maps and Piper and Gibbs diagrams. According to the results, the EC values were in the range of 461 and 2600 mu s/cm with the hardness contents between 220 and 720 mg/L as CaCO3. It was found that, the total hardness is highly correlated with the magnesium concentration than calcium in all samples. The dominant cations and anions were in the order of Mg2+ > Na+ > Ca2+ > K+ and HCO3- > SO42- > Cl- > NO3- > F-, respectively. The major water types in the area were fresh (Ca-HCO3) and saline (Ca-Mg-Cl). Based on Gibbs plot, the main mechanisms controlling groundwater chemistry were rainfall dominance, rock weathering dominance, and evaporation-participation dominance. The lower quality of water resources sited in the southern and northern parts of the area was observed according to the GIS maps. It was found that aluminum, boron, iron and manganese concentrations, in some cases, were higher than the guideline values however, it can be concluded that groundwater quality in the study area, apart from some cases, is suitable for drinking purposes without any specific treatment processes. The present study gives a comprehensive status of groundwater quality for proper management in the area.