Effective Factors on Hydrochemical Characteristics of Maragheh-Bonab Plain Aquifer

The aim of this study is to assess the hydrochemical characteristics of the groundwater system of Maragheh-Bonab plain aquifer, its contamination and effective factors on it. For this purpose, graphical methods and also water quality index (WQI) are used. The study area contains three major groundwater types, namely Ca–Mg–HCO3, Na–Cl, and non-dominant water types based on Piper diagram. Considering the water quality index, there is an evolutionary trend in the water resources in the study area, such that the mixing process of the excellent and poor classes’ waters has caused degradation of water quality from recharge to discharge areas. However, there are some areas in the south of the plain with poor WQI which are affected by polluted wastewater. Industrial factories are located in the recharge area, and in this research, the effect of industrial wastewater on the quality of groundwater has been considered. The electric conductivity of wastewater is very high and based on hydrochemical analysis; the most important ions in wastewater are Cl-, Ca2, and Na, respectively. The concentration of these ions has unusually increased in samples taken from wells located near the wastewater site. Noting the stiff diagrams for several successive years, hydrochemical properties of these samples are the same as industrial wastewaters and the chemical anomalies created in the plain are resulted from wastewater recharge into groundwater resources. Furthermore, the main factors were determined that affect hydrochemistry of water resources in the study area using multivariate statistical analysis and Factor Analysis. Therefore, the most effective factor in hydrochemistry of the study area is the pollutant industrial wastewater that overshadowed the influence of geological formations and general sequence of groundwater hydrochemistry.