Document Type : Research Paper
Author
Assistant Professor, Department of Natural Resources-Environment, Ardabil Unit, Islamic Azad University, Iran
Abstract
In this study, rainfall, percolation and hydrogeological processes relationship were evaluated using geochemical tracers to determinate paleoclimate in the Ardabil Plain. The occurrence of dry and wet periods was also determined with the help of tracer used in six profiles. The Dry and wet periods were then evaluated by the Edmund-Allison equations based on interpretation of soil water chloride concentrations and long–term precipitation measured in different periods. Applying the chloride mass balance technique to soil water chloride profiles improved the boundary conditions associated with wetter and drier climate in last times. The estimated ages through sediment cores chemistry varied from 737 years in Imijah core to 4511 years in Gharahlar core with two recorded dry and wet periods. Precipitation of recently drier climate was estimated around 202 mm in 116 last years and second drier climate was estimated around 83 mm in 473 last years. Precipitation of recently wetter climate was also estimated around 451 mm in 210 last years and second wetter climate was estimated around 703 mm in 735 last years. The second wetter had the highest amount of precipitation in 3600 years period. The Ardabil plain had a moderate drier climate since 1100 to 2900 years ago. In addition, the results showed that the wetter climate happened during last 2900 to 3550 years. According to this results, the present climate moves towards drier climate. A comparative analysis of data from six profile sites indicated that there were short term oscillations of wetter and drier climate.
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