Contribution of Individual Sorbents to the Control of Heavy Metal Activity in Sandy Soil

• Published in: Environmental science & technology Vol. 35; no. 22; pp. 4436 - 4443
• Main Authors: Weng, Liping, Temminghoff, Erwin J. M, Van Riemsdijk, Willem H
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.11.2001
• Subjects: Absorption; Adsorption; Applied sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Pollution - prevention & control; Exact sciences and technology; Hydrogen-Ion Concentration; Iron - chemistry; Metals, Heavy - chemistry; Models, Chemical; Organic Chemicals; Pollution; Pollution, environment geology; Sectie Bodemkwaliteit; Silicates - chemistry; Silicon Dioxide; Soil; Soil and sediments pollution; Soil Pollutants - analysis; Sub-department of Soil Quality; WIMEK; Clay; Cadmium; Organic matter; Pollutant behavior; Acidification; Geochemistry; Silicates; Sandy soil; Soil pollution; Modeling; Zinc; Iron Hydroxides oxides; Heavy metal; Sorption; Adsorption; Medium effect; Lead; pH; Soil interaction; Nickel; Copper; Humic acid
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es010085j

A multisurface model is used to evaluate the contribution of various sorption surfaces to the control of heavy metal activity in sandy soil samples at pH 3.7−6.1 with different sorbent contents. This multisurface model considers soil as a set of independent sorption surfaces, i.e. organic matter (NICA-Donnan), clay silicate (Donnan), and iron hydroxides (DDL, CD-MUSIC). The activities of Cu2+, Cd2+, Zn2+, Ni2+, and Pb2+ in equilibrium with the soil have been measured using a Donnan membrane technique. The metal activities predicted by the model agree with those measured reasonably well over a wide concentration range for all the metals of interest except for Pb. The modeling results suggest that soil organic matter is the most important sorbent that controls the activity of Cu2+, Cd2+, Zn2+, and Ni2+ in these sandy soils. When metal loading is high in comparison with soil organic matter content, the contribution of clay silicates to metal binding becomes more important. Adsorption to iron hydroxides is found not significant in these samples for Cu, Cd, Zn, and Ni. However, for Pb the model estimates strong adsorption on iron hydroxides. The model predicts that acidification will not only lead to increased solution concentrations but also to a shift toward more nonspecific cation-exchange type binding especially for the metals Cd, Zn, and Ni. Lowering the pH has led to a loss of 56% of Cd, 69% of Zn, and 66% of Ni during 16 years due to increased leaching.