Effect of soil solution composition on cadmium transport through variable charge soils

Saved in:
Authors:Kookana, Rai S.; Naidu, Ravendra
Author Affiliations:Primary:
Cooperative Research Centre for Soil and Land Management, Glen Osmond, South Aust., Australia
Volume Title:Contaminants and the soil environment
Volume Authors:Naidu, R., editor
Source:Geoderma, 84(1-3), p.235-248; First international conference on Contaminants and the soil environment, Adelaide, South Aust., Australia, 1996, edited by R. Naidu. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0016-7061
Publication Date:1998
Note:In English. 15 refs.; illus., incl. 2 tables
Summary:Cadmium (Cd) is of no known essential biological function and is toxic to plants and animals. Leaching of Cd through soil profiles has implications for both its accumulation in subsoil or contamination of ground-water. We measured adsorption and transport of Cd in the presence of Ca and Na salts of varying ionic strengths using batch and miscible displacement techniques. Two variable charge soils, an Oxisol and an Alfisol, were used in this study. The Alfisol, despite its lower clay content, showed an adsorption coefficient (K) that was four times higher than the clay-rich Oxisol. Such a difference in adsorption was attributed to the presence of 2 : 1 layer silicate minerals in the Alfisol and the consequent high surface negative charge density. In column experiments, a marked effect of ionic strength on the breakthrough curves (BTCs) of Cd was observed when the concentrations of NaNO3 were increased from 0.03 M to 0.15 M in the background solutions. This increase caused nearly four times faster movement of Cd through the Oxisol soil column. The effect of increasing Ca(NO3)2 concentration on Cd adsorption and transport was relatively less pronounced than that recorded for the NaNO3 solution. In the Alfisol, the increase in Ca(NO3)2 ionic strength from 0.05 M to 0.25 M resulted in four-fold smaller adsorption coefficient. For both soils, the movement of Cd at a constant ionic strength was, however, an order of magnitude faster in the presence of Ca(NO3)2 than that in the presence of NaNO3. To describe the combined effect of ionic strength and pH, we used the K values calculated from the BTCs with CXTFIT model to develop a simple theoretical relationship between Cd adsorption and [H+], [Ca2+] and [Cd2+] in solution. The relation was found to be consistent with other published studies. The study demonstrated that Cd mobility in soils is strongly affected by the soil solution composition (ionic strength and type of cations). Abstract Copyright (1998) Elsevier, B.V.
Subjects:Adsorption; Alfisols; Cadmium; Electrochemical properties; Experimental studies; Geochemistry; Heavy metals; Ions; Isotherms; Measurement; Metals; Mobility; Oxisols; PH; Physicochemical properties; Pollutants; Pollution; Pore water; Soil profiles; Soils; Sorption; Temperature; Toxic materials; Transport; Australasia; Australia; New Zealand
Record ID:1998041091
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands
Tags: Add Tag
No Tags, Be the first to tag this record!
Be the first to leave a comment!
You must be logged in first