The evaluation of groundwater quality and geochemistry have an important role in the management of water resources in arid and semi-arid regions. In the present study, the spatio-temporal assessment of groundwater quality and hydrogeochemical processes, as well as, statistical analyses in the Azarshahr and Ajabshir planes located in the Urmia Lake basin were investigated. The results revealed that within six years (from 2014 to 2019), the value of total hardness was higher than the permissible level and the quality of groundwater for drinking was very hard and fresh in both planes. In 2019, 84 and 67% of the samples fell within the range of good to poor groundwater quality in the Azarshahr and Ajabshir planes, respectively. The temporal assessment with the help of water quality index values for both planes revealed a good groundwater quality for the Azarshahr plane and a good to poor groundwater quality for the Ajabshir plane. However, deterioration of water quality was observed in both planes from 2014 to 2019. The level of water quality for irrigation was better in the Azarshahr plane than in the Ajabshir plane, due to the presence of fewer salty sites. In addition, Ca–Mg–HCO3 and rock dominance were identified as hydrochemical facies and controlling factor in the groundwater of both planes, respectively. Multivariate statistical analyses indicated both natural and anthropogenic sources (such as weathering, fertilizers, and wastewater) for hydrochemical parameters. It was suggested to develop a comprehensive regulation to control the entry of pollutants into the groundwater of the study area.

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This study was aimed at investigating the effectiveness of starch‐modified magnetic nanoparticles for the removal of naphthalene, which is a polycyclic aromatic hydrocarbon present in the majority of water sediments, from water resources. Magnetic Fe0 nanoparticles have recently been considered because of their high efficiency for contaminant removal. In the present study, Fe0 nanoparticles were synthesized using sulfate method and starch was used as a stabilizer. The size of the Fe0 nanoparticles was measured as approximately 45 nm using X‐ray diffraction and scanning electron microscopy analyses. The removal efficiency of naphthalene from water using the nanoparticles was evaluated based on various factors including the viscosity of naphthalene dissolved in water, and operation factors such as nanoparticle dosage, contact time, initial naphthalene concentration and pH in non‐continuous reactors were optimized. The results revealed that the starch‐modified nanoparticles have high efficiency for removal of dissolved naphthalene from aqueous solution. Under the optimum conditions, more than 99% of naphthalene at a pH of 5.0 with nanoparticle dosage of 0.05 g was removed from aqueous solution in 5 min. The equilibrium adsorption data were interpreted in terms of Langmuir, Freundlich and Temkin isotherm models and the goodness of fit was inspected using linear regression analysis. Our results indicated that the Langmuir model with maximum adsorption capacity was best fitted, suggesting monolayer adsorption. Moreover, it was found that the adsorption process followed the pseudo‐second‐order kinetic model. In addition, a thermodynamic study indicated that the adsorption process of naphthalene from aqueous solution by the starch‐modified nanoparticles was spontaneous and exothermic.

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