Pedosphere 14(2): 253--257, 2004
ISSN 1002-0160/CN 32-1315/P
©2004 Soil Science Society of China
Published by Elsevier B.V. and Science Press
NH4+ adsorption in a eum-orthic anthrosol at different solution/soil ratios and temperatures
WANG Yu and ZHANG Yi-Ping
Department of Natural Resources and Environmental Sciences, Northwest Science and Technology University of Agriculture and Forestry, Yangling, Shaanxi 712100 (China). E-mail: wangyu5@pub.xaonline.com
ABSTRACT
      Effects of NH4+ concentration, solution/soil ratio and temperature on NH4+ adsorption were studied in a Eum-Orthic Anthrosol. The slopes of the soil NH4+ adsorption isotherms and the fitted n, the coefficient for the adsorption intensity, and k, the coefficient related to adsorption capacity, of the Freundlich equation increased with increasing solution/soil ratio (SSR) and with decreasing temperature (T). For the range of experimental conditions, the value of ∂q/∂c, the rate of change of the amount of NH4+ adsorbed in the soil solid phase (q) with respect to the equilibrium concentration of NH4+ in soil solution (c), was 0.840, indicating that q increased with increasing c. From 2 to 45 ℃, ∂q/∂SSR, the rate of change of q with respect to SSR, decreased from 2.598 to 1.996, showing that q increased with increasing SSR, while its increasing rate decreased with temperature. From SSR 1:1 to 20:1, ∂q/∂T, the rate of change of q with respect to T, decreased from -0.095 to -0.361, indicating that q decreased with increasing temperature, and at the same time the negative effect of temperature became larger as SSR increased. Thus under the experimental conditions the order of importance in determining the amount of NH4+ adsorbed in the soil solid phase was ∂q/∂SSR > ∂q/∂c > |∂q/∂T|, indicating that the greatest effect on the amount of NH4+ adsorbed was with the solution/soil ratio; the equilibrium concentration of NH4+ had a lesser effect; and temperature had the least effect.
Key Words:  NH4+ adsorption, solution/soil ratio, temperature
Citation: Wang, Y. and Zhang, Y. P. 2004. NH4+ adsorption in a eum-orthic anthrosol at different solution/soil ratios and temperatures. Pedosphere. 14(2): 253-257.
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