Copper and Cadmium Adsorption Characteristics of Selected Acid and Calcareous Soils

Abstract

Samples of two New York soils, an acid and a neutral silt loam, were equilibrated with Cu2+ and Cd2+ solutions in concentrations ranging from 10−5 to 10−4M in distilled water and in 0.01M CaCl2. The extent of complexation and adsorption of the heavy metals was measured using specific ion electrodes and atomic absorption. The data were found to fit the Langmuir adsorption model, and the Cu2+ adsorption maxima were greater than those of Cd2+ for both soils. Acid soils demonstrated much less ability to retain the heavy metals than neutral soils. In the presence of 0.01M CaCl2, adsorption of the metals was much reduced, suggesting Ca2+ competition for adsorption sites. A considerable amount of Cu2+ was complexed in the soil solutions, but Cd2+ complexation was much less evident. The results support an ion exchange mechanism of adsorption in the surface soils, and suggest that precipitation occurs in calcareous subsoils.

Caracterização química e física de turfa litorânea e avaliação da adsorção competitiva por cobre e zinco

“…Pode-se atribuir as maiores concentrações de zinco, nas camadas mais superficiais da turfa, as maiores porcentagens de matéria orgânica nestas camadas. Por outro lado, as pequenas variações das concentrações de cobre, em função da profundidade examinada, pode ser devida a maior afinidade deste elemento pela matéria orgânica 25 . A matéria orgânica de solos e sedimentos geralmente é oxidada com água oxigenada para determinação de micronutrientes 26 .…”

Interactive Effects of Copper on Alfalfa Growth, Soil Copper, and Soil Bacteria

“…When present in calcareous soils, it has been shown that increasing OM content (0.4 to 4.8%; within the range of our study) decreases the quantity of plant-available Cu (Ghasemi-Fasaei et al, 2006) due to Cu complexation with organic species. Between 80 and 100% of Cu added to neutral or calcareous soils has been shown to be organically complexed (Cavallaro and McBride, 1978;McBride and Blasiak, 1979).…”

Copper Impacts on Corn, Soil Extractability, and the Soil Bacterial Community

“…When present in calcareous soils, it has been shown that increasing OM content decreases the quantity of plant-available Cu (Ghasemi-Fasaei et al, 2006) because of Cu complexation with organic species. Between 80% and 100% of Cu added to neutral or calcareous soils has been shown to be organically complexed (Cavallaro and McBride, 1978;McBride and Blasiak, 1979).…”

“…In soils with pH values greater than 7.0, soluble Cu can react to form CuO, CuCO 3 , or mixed hydroxycarbonate mineral species (McBride and Bouldin, 1984;Ponizovsky et al, 2007), although most of the Cu is strongly adsorbed to soil organic matter (OM) in basic soils because of greater OM solubility and increasing pH-dependent charge associated with increasing soil pH (McBride and Blasiak, 1979). Cavallaro and McBride (1978) showed that more than 80% of Cu added to neutral pH soil was in complexed form, whereas McBride and Blasiak (1979) showed that 99.9% of total soluble Cu was complexed with organic phases at pH 8. McBride and Bouldin (1984) found evidence of malachite precipitation in a Cu-contaminated calcareous soil (~3%Y4% free carbonate), yet the soil contained 5.3% OM, and greater than 95.5% of the Cu in soil solution was complexed with organic species.…”