Pedosphere 23(2): 185--193, 2013
ISSN 1002-0160/CN 32-1315/P
©2013 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Time-dependent zinc desorption in some calcareous soils of Iran
Department of Soil Science, College of Water and Soil Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan (Iran)
      Desorption of zinc (Zn) from soil is an important factor governing Zn concentration in the soil solution and Zn availability to plants. Batch experiments were performed to study the kinetics of Zn desorption by diethylenetriaminepentaacetic acid (DTPA) from 15 calcareous soil samples taken from Golestan Province in northern Iran. Soils were equilibrated with 0.005 mol L-1 DTPA solutions for 0.25 to 192 h. The results showed that the extraction process consisted of rapid extraction in the first 2 h followed by much slower extraction for the remainder of the experiment. Desorption kinetic data was fitted to pseudo-first-order kinetic model. The experimental data were found to deviate from the straight line of the pseudo-first-order plots after 2 h. The model of two first-order reactions was fitted to the kinetic data and allowed to distinguish two pools for Zn: a labile fraction (Q1), quickly extracted with a rate constant k1, and a slowly labile fraction (i>Q2), more slowly extracted with a rate constant k2. The applicability of pseudo-second-order model in describing the kinetic data of Zn desorption was also evaluated.
Key Words:  diethylenetriaminepentaacetic acid, kinetic models, labile fraction, zinc availability
Citation: Baranimotlagh, M. and Gholami, M. 2013. Time-dependent zinc desorption in some calcareous soils of Iran. Pedosphere. 23(2): 185-193.
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