Significance of Aqueous Cation Composition on Heavy Metal Mobility in a Natural Clay
Abstract:Heavy metal mobility in soils is influenced by various soil variables and environmental factors, including the composition of the soil-aqueous phase. This study used the sequential extraction technique to study how major cations could affect heavy metal sorption and speciation in a natural clay. The sorption of Zn, Pb, and Cd by the soil in the presence of Na+ and Ca2+ and the resulting metal speciation in the sorbed phases were examined. Sorption experiments were performed at pH levels of 3 to 8. Sorptions occurring in both single and multiple heavy metal systems were investigated. The results show that Na+ and Ca2+ significantly inhibited Zn, Pb, and Cd sorption in the acidic pH range only. The reduction in the exchangeable sorption was responsible for a large part of the reduction in the total Zn, Pb, and Cd sorption in the presence of Na+ and Ca2+. Specific adsorptions of heavy metals in other fractions of sorbed phases were only marginally affected by the composition of cations. The reduction in the exchangeable sorption increased with increasing concentration of Na+ and Ca2+. In the presence of a major cation, the competitive adsorption among the heavy metals seemed to have only a minor effect on individual heavy metal sorption.
Document Type: Research Article
Publication date: 2002-07-01
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Water Environment Research� (WER�) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
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