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Thermodynamic Analysis of the Temporal Changes in Salt Concentration in Saline Lakes (the case of Urmia lake)

Emami, Neda | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51082 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Tajrishi, Masoud
  7. Abstract:
  8. Urmia Lake is a strong electrolyte containing various salts, with a thermodynamic identity. Changes in the temperature and volume of lake water cause a change in the concentration of ions in this brine as well as the composition and precipitation of salts in the lake. As a result of these changes, the thermodynamic properties of brine are also changed. The purpose of this study was to investigate the effect of mixing the rivers entering the lake and calculate and analyze the changes in the quality and hydrogeochemical characteristics of Urmia Lake and the amount of precipitation and dissolution of the main minerals in Urmia Lake during the period of 2007-2013 per month. For this purpose, the Pitzer equations and the PHREEQC software have been used to calculate the hydrogeochemical characteristics of the lake and the rivers entering it. To calculate the composition of water from mixing the lake and rivers entering it from the Mixing model and the amount of precipitation and solubility dissolution in each month, the Inverse model and the software PHREEQC have been used. The results of the modeling showed that the rivers, with the exception of the seasons with very high water inputs, had no effect on the chemical composition of the lake. Based on the results of the studied period, the main mineral in the lake is sodium chloride, which is deposited in high evaporation months and is re-dissolved with fresh water entry due to the high solubility factor of this mineral. Ultimately, the mass and rate of precipitation and dissolution of sodium chloride are determined each month. The results of this study show that from September 2007 to June 2013 total 97 million tons of sodium chloride salts were precipitated and 140 million tons of salts were dissolved in the lake. The highest amount of precipitation of halite in the lake occurred in August 2009 and 2011 at a height of about 6 mm and at a rate of 0.74 g/cm2
  9. Keywords:
  10. Dynamics Models ; Inverse Modelling ; Urumieh Lake ; Brine Leaching ; Mineral Precipitation ; Inverse Method ; Mixing

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