Hydrogeochemical evaluation with emphasis on nitrate and fluoride in urban and rural drinking water resources in western Isfahan province, central Iran.

Nitrate (NO3-) and fluoride (F-) are two major potential contaminants found in the groundwater of Iran. These contaminants are highly dangerous to humans if consumed more than the safe limit prescribed by the WHO. Therefore, in this study, the urban and rural drinking water resources of Isfahan province (central Iran) were investigated to evaluate the quality of groundwater from the perspective of NO3- and F-. The calculated saturation index (SI) shows that the majority of samples are mainly undersaturated or in equilibrium with respect to potential minerals. The most likely interpretation for undersaturation with respect to most minerals is either that the minerals are not present if they are reactive or if they are present, then they are not reactive. This study reveals that the majority of the groundwater samples belong to the Ca-Mg-HCO3 water type. Further, in this study, potential physicochemical variables have been used to calculate entropy weighted water quality index (EWQI). The EWQI reveals that the majority of the groundwater in the area is of good quality. Results show that the water chemistry in the area is largely governed by the water-rock interaction. This study based on large data sets reveals that the majority of drinking water resources are uncontaminated by F-. However, the groundwater is found to be largely contaminated by NO3-. The bivariate plot suggests that the unscientific farming practices and overuse of manures and fertilizers are largely responsible for high content of NO3-. Therefore, emphasis should be given on the cost-effective environmentally friendly fertilizers. The findings from this study will aid the governing authorities and concerned stakeholders to understand the hydrogeochemical evolution of groundwater in this region. The results will help formulate policies in the area for sustainable water supply.

Assessing the chemical behavior and spatial distribution of yttrium and rare earth elements (YREEs) in a coastal aquifer adjacent to the Urmia Hypersaline Lake, NW Iran.

This study aims to shed light on the seasonal behavior of yttrium and rare earth elements (YREEs) in the Urmia Aquifer (UA), in the immediate vicinity of Urmia Lake (UL) in Iran. Samples of groundwater, collected under dry and wet conditions in coastal wells of UA, suggest a large degree of variability in both YREE abundance and normalized patterns. Although weathering or water-rock interactions (between the surface/groundwater and rock samples) were predicted to be the most probable source in explaining YREEs in groundwater samples, results to the contrary indicate that the groundwater do not inherit aquifer rock-like YREE signatures in the study area; this might be due to the relative stability of YREEs during the process of water-rock interactions, which suggest that methods based on YREEs can be beneficial in discrimination of water sources. Furthermore, findings demonstrated no significant relationship between Ce/Ce* and salinity (0.08 and 0.05 in wet and dry seasons, respectively), and between Eu/Eu* and salinity (0.1 and -0.04 in wet and dry seasons, respectively). Dissimilarity of patterns of YREEs in rock and water samples reveals YREEs as no conservative tracers in determining the UL saltwater intrusion into coastal groundwater. Therefore, the groundwater YREE concentrations and fractionation patterns in UA warrant controlling by coastal aquifer need to be controlled by other chemical weathering, adsorption, desorption, and solution complexation reactions. Finally, comparison of REE concentration values in groundwater samples with corresponding indicative admissible drinking water concentrations (IAC) demonstrated their suitability for drinking purposes.