Depositional environments and brine composition of Urmia lake: implications on appropriate solution to restoration
Document Type : Research Paper
Authors
1 Assistant professor, Research institute for earth sciences, Geological Survey of Iran
2 Master sience, in sedimentology, Center of Geology and Mineral Exploration Abadan,geological survey of Iran.
Abstract
Recent environmental crisis and drying lake Urmia, now is considered as one of the biggest geological hazards in Iran. In this research, remote sensing study for a period of 35 years, 55-year climatic data processing and their relationship with lake water fluctuations were implemented, hydrogeochemical monitored for 6 years and undisturbed sedimentary cores of western lake sediments were prepared by Auger coring method. 23 cores having a maximum depth of 9 meters and totally 140 m of the lake sub floor sediments were verified. According to the results of the coring, the main part of the lake atleast 13,000 years ago had been lake environment and are visible continuous lacustrine sedimentation. Anthropogenic (human)factors is important factors in decrease of Urmia lake water level that including the irregular development agriculture, the use of ground water and dams construction and construction of Shahid Kalantari causeway. Therefore, climate change and increase evaporation, especially in recent years, is considered a factor in reducing the water level, but it is not the main reason in drying of the Urmia lake. On the other hand, process brine evolution has expired in the Urmia lake and amount of brines magnesium has been more than sodium. In these conditions, with huge increase in evaporation rate, lake has become to playa or salt pan (high thickness of salt in the lake bed is more than 6 meter)and is in verge of annihilation. Entry fresh water as sectional and not once into it, with out help to save it, is cause of destruction sources of water. Thus limiting the lake, extracting of economical salt from its brine and salts reduction part of the salt lake, before dewatering is the most appropriate lake reclamation solution. The northern part of the lake due to the inherent depth, appropriate for restoration in first phase and southern part appropriate for extraction salt and economic minerals.
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