HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Elgawhary, S. M. Articles by Kemper, W. D. Search for Related Content PubMed Articles by Elgawhary, S. M. Articles by Kemper, W. D. Agricola Articles by Elgawhary, S. M. Articles by Kemper, W. D.

Effect of EDTA on the Self-Diffusion of Zinc in Aqueous Solution and in Soil¹

ABSTRACT

Self-diffusion coefficients for Zn and ZnEDTA (zinc ethylenediaminetetraacetic acid) were determined in aqueous solution and in soil. Those in solution were estimated from diffusion measurements in agar-agar gel and were found to be 8.8 x 10^-6 cm² sec^-1 for Zn and 6.8 x 10^-6 cm² sec^-1 for ZnEDTA. The apparent diffusion coefficient of Zn in soil increased from 0.36 x 10^-9 cm² sec^-1 to 3.0 x 10^-9 cm² sec^-1 with addition of 1.53 x 10^-8 mole of EDTA/g soil and to 9.0 x 10^-9 cm² sec^-1 with addition of 1.53 x 10^-8 mole of ZnEDTA/g soil. The true diffusion coefficient D_p of Zn in soil was fairly constant at different levels of EDTA, averaging 1.81 x 10^-7 cm² sec^-1.

Addition of EDTA to soils increased the diffusion of Zn; this increase was explained by the transformation of the solid phase soil Zn into soluble ZnEDTA complexes, thereby increasing the concentration gradient of total diffusible Zn. Chelating agents were shown to play an important role in overcoming the rate-limiting steps of solution and diffusion which are largely responsible for the movement of micronutrient cations in soils.

¹ Contribution from the Dep. of Agronomy, Colorado State University, Fort Collins and Northern Plains Branch, Soil and Water Conservation Res. Div., ARS, USDA. Part of a dissertation submitted by the senior author in partial fulfillment of a graduate program in soil science for the Ph.D. degree. Published with the approval of the director of the Colorado Agr. Exp. Sta. as Scientific Series Paper no. 1357. This work was supported in part by the Div. of Agr. Devel., TVA, Muscle Shoals, Ala.

² Graduate Research Assistant; Professor of Soil Science; Professor of Soil Science and Soil Scientist, USDA, Colorado State University, Fort Collins. Senior author is now Post-doctoral Fellow, Department of Agronomy, Purdue University, Lafayette, Ind.

Received for publication September 2, 1968. Accepted for publication September 15, 1969.