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International Journal of Agronomy
Volume 2014 (2014), Article ID 428569, 7 pages
http://dx.doi.org/10.1155/2014/428569
Research Article

Exchange Characteristics of Lead, Zinc, and Cadmium in Selected Tropical Soils

1Forestry Research Institute of Nigeria, P.M.B. 5054, Ibadan 234-02, Oyo State, Nigeria
2Federal College of Wildlife Management, P.M.B. 268, New Bussa 234-02, Niger State, Nigeria
3Federal College of Forestry, P.M.B. 5054, Ibadan 234-02, Oyo State, Nigeria

Received 31 July 2013; Revised 17 October 2013; Accepted 4 November 2013; Published 16 January 2014

Academic Editor: Silvia Imhoff

Copyright © 2014 Tope O. Bolanle-Ojo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Conducting binary-exchange experiments is a common way to identify cationic preferences of exchangeable phases in soil. Cation exchange reactions and thermodynamic studies of Pb2+/Ca2+, Cd2+/Ca2+, and Zn2+/Ca2+ were carried out on three surface (0–30 cm) soil samples from Adamawa and Niger States in Nigeria using the batch method. The physicochemical properties studies of the soils showed that the soils have neutral pH values, low organic matter contents, low exchangeable bases, and low effective cation exchange capacity (mean: 3.27 cmolc kg−1) but relatively high base saturations (≫50%) with an average of 75.9%. The amount of cations sorbed in all cases did not exceed the soils cation exchange capacity (CEC) values, except for Pb sorption in the entisol-AD2 and alfisol-AD3, where the CEC were exceeded at high Pb loading. Calculated selectivity coefficients were greater than unity across a wide range of exchanger phase composition, indicating a preference for these cations over Ca2+. The values obtained in this work were all positive, indicating that the exchange reactions were favoured and equally feasible. These values indicated that the Ca/soil systems were readily converted to the cation/soil system. The thermodynamic parameters calculated for the exchange of these cations were generally low, but values suggest spontaneous reactions.