Author(s): M.A. Mustafa, I.A. Ayed and O.A. Mahgoud
Article publication date: 1988-04-01
Vol. 6 No. 1 (yearly), pp. 9-20.
120
Keywords
zinc, soil samples, Saudi Arabia
Abstract
Zinc sorption was characterized for samples of twenty-two agriculturally important soils in Saudi Arabia. The soil samples had CaCo3 contents ranging from 0.6- 35.4%, and DTA-extractable Zn contents ranging from 0.19-2.42 ug/g. The latter correlated significantly (r=0.469) with the organic matter content of the samples.
Zinc sorption data, obtained by a batch equilibrium technique, conformed to both Freundlich and Langmuir equations. The adsorption maxima were very high and ranged from 1260- 22390 with a mean of 9910 ug/g. Apart from four samples lowest in CaCO3 percentage the adsorption maxima were in excess of the cation exchange capacities (CEC) of the samples. Zinc potentials indicated that, in most cases, Zn did not precipitate as hydroxide or carbonate.
Calcium carbonate percentage and DTPA- extractable Zn originally present in the soil samples accounted for 75% (τ0.001= 0.652) and 26% (τ0.05=0.423) of the variability of the adsorption maxima (Sm), respectively. Furthermore, the accountability of CaCO3% was improved to 87% if it and Sm were divided by CEC (i.e., Sm/CEC versus percentage CaCO3/CEC)