Determination of Sources of Groundwater Pollution in the Southern Plain of Arak by Contamination Indices and Fractal Geometry Methods

The southern plain of Arak with 47 wells is used to provide part of Arak drinking water. The assessment of the quality of water in terms of chemical constituents and toxic metals and their origin are important issues in this plain. About 52% of wells have Ca-HCO3, 26% Ca-Cl and 20% Na-Cl type. The maximum concentration of some of the compounds, including NO3, Na, Ca, Mg, PO4, HCO3, SO4 and Cl, indicates that they are higher than Iranian drinking water standard and WHO standard. On the other hand, by determining the pollution indices in heavy metals, it was found that the waters have good drinking quality. Since the region's waters are desirable compared to drinking water standards, but the fractal threshold examination showed that the concentration of chemical constituents in most waters is higher than normal and is at the threshold of contamination. This study showed that chemical compounds are the result of two natural contaminants (weathering, and chemical dissolution of carbonate rocks and saline water penetration) along with human contamination. The high concentrations of Ca, HCO3 and Mg in the Arak plain are due to the dissolution of calcareous and dolomitic rocks of southern highlands. The high concentrations of Na, SO4 in the Aman-abad plain are due to the influence of saline water in the Mighan wetland of Arak. Also, the landfill of Amanabad plain, the wastewaters of the industrial park and the city in Arak plain are the source of toxic metals such as Cu, Zn, As and Pb in the regional waters.