Document Type : Research Article
Authors
Department of Soil Science, Faculty of Agriculture, Urmia University
Abstract
Abstract
The availability of heavy metals in the soil is related to their partitioning between solution and solid phases and expressed by sorption isotherm. Twenty surface soil samples (0-30 cm) belonging to five soil subgroups were taken from agricultural regions of Western Azerbaijan province. The sorption isotherms of Pb were determined by equlibrating the soil with solutions containing 0, 100, 300, 500, 700, 900, 1100 and 1300 mg Pb L-1 from Pb-nitrate source in 0.01 M NaNO3 as background electrolyte. Illite was the dominant clay mineral in Typic Calcixerepts (TC), Typic Haploxerepts (TH) and Typic Endoaquepts (TE) whereas in Vertic Calcixerepts (VC) and Vertic Endoaquepts (VE) the clay mineralogy was dominated by smectite. Active and equivalent calcium carbonate and clay contents ranged from 4.3 to 7.8%, 6.2 to 16% and 31 to 45%, respectively. The linaer, Langmuir and Freundlich isotherm equations were fitted to the experimental data of Pb sorption and desorption. Both the Freundlich (0.98< R2
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