The effect of Arak Mighan Plain Salt on groundwater quality by multivariate statistical method

Mighan playa is the most important extraction point of sodium sulfate in Iran. The playa consists of two parts, the island in the center and the lake in the margin. Extraction of sodium sulfate on the island is associated with the formation of artificial ponds. Sodium sulfate company effluent and treated wastewater are the most important sources of surface water in Mighan playa. The effects of salinity over groundwater quality is one of the objectives in this article. The univariate and multivariate statistics such as mean comparison test, factor, cluster and discriminant analysis was used to compare saline playa with groundwater resources. In 22 samples, it was determined variables of electrical conductivity, alkalinity, total soluble solids, pH, calcium, magnesium, potassium, sodium, chlorine, sulfate and bicarbonate. It identified three water groups such as pond brine, lake brine and groundwater by differences in total soluble solids, pH, sulfate and chlorine. Multivariate analysis showed that qualitative variables are of several origins. The salinity of Mighan playa water and groundwater is related to anions and cations that originate from the gypsum and saline layers of the northern part, alkalinity and bicarbonate due to the dissolution of limestone in the southern floors of the Mighan catchment. Recent compounds are the result of groundwater and the entry of treated Arak municipal wastewater into the playa. Evaluation of the sodium to chlorine ratio and Gibbs diagram show the influence of infiltration Mighan playa saline water on the groundwater, especially in the playa margin.