Hydrogeochemistry and Quality Monitoring of the Gypsum- Karst Barm-e- Shour Pond in the Khuzestan Province

The Barme-e-Shoor permanent pond has formed on the Gachsaran evaporative formation in a closed water catchment area with standing water body during the whole year. The purpose of this study is to assess the pond water hydrogeochemical and quality properties during the months of March and August 2015. The water samples were taken starting from the main stream path on the Gachsaran Formation to its entrance point to the pond, and different locations and depths (1-3 m) inside the pond area to evaluate the concentration of the major elements and heavy metals during the two periods. The electrical conductivity (EC) of the water changes considerably from the value of 920 µs/cm in the farthest point on the stream, to the value of 2030 µs/cm at the stream entrance point to the pond, increasing to the maximum value of 4290 µs/cm inside the pond in September 2015. The water type of the all surface, deep and inlet water samples in the both periods is the calcium sulfate due to the dissolution of gypsum along the stream path, inside the pond and also severe evaporation in the region.There is a good correlation between calcite, dolomite and gypsum saturation indexes versus sulfate concentration during the March, while in contrast and in the September, there is a low correlation between saturation Indices and sulfate concentration, which conforms again the evaporation effects on the pond water hydrochemistry during the high temperature season. The Gibbs diagram showed that the water-rock interaction in the pond and stream path is the main hydrochemical process affecting the water body. The heavy metals concentration abundance relation in the pond is Zn> Pb> Fe> As at 6 sampling locations.The Zn, As, Pb concentration of the whole samples are above the WHO standard ranges but lower than the ranges of FAO standards.