آرتمیا-شیلات و محیط زیست

A study on fluctuation of five ions of Urmia Lake at the rainy and dry periods

LATIF ESMAEILI DAHESHT1*, AMIR SHOA HASANI, REZA AHMADI1, SIAVASH GANJI

Abstract

     Urmia Lake is one of the two large hypersaline lakes in the world which have Artemia [1]. In the recent years due to decrease in water inflow and volume, the salinity of Urmia Lake has increased to more than 300 ppt since 2001 [2]. The salinity of Urmia Lake was about160 ppt in 1993 and 180 ppt in 1996 [3], and up to 300 ppt at the present, it has greatly influenced ecological aspects of the lake, and caused the critical condition. The aim of present research is to investigate the fluctuation of five ions of Urmia Lake in rainy (1993-1996) and dry periods (1996-2007). Eleven sampling sites with geographical coordinates were selected for this study. Sampling was performed monthly for 8 months of 2007. A portion of the filtered water samples were used to measure concentrations of Ca²⁺, SO₄^2-, Mg²⁺, Cl^- and HCO₃^- . The average concentrations of these ions showed that according to the changes in water volume and its salinity the fluctuations occurred of these ions on the rainy years (1992 to1996) was less than the dry years (1996- 2007) and the ratio of the Ca²⁺, SO₄^2-, Mg²⁺, Cl^- and HCO₃^- fluctuation on the recent decade were 2.5, 1.5 ,3 ,4 and 4.5 times more than the rainy years respectively.

.