assessment of cadmium availability in cadmium-contaminated soils using isotope exchange kinetics

• Published in: Soil Science Society of America journal Vol. 68; no. 4; pp. 1210 - 1217
• Main Authors: Gray, C.W, McLaren, R.G, Gunther, D, Sinaj, S
• Format: Journal Article
• Language: English
• Published: Madison Soil Science Society of America 01.07.2004; Soil Science Society; American Society of Agronomy
• Subjects: Agronomy. Soil science and plant productions; Analysis methods; Applied sciences; Biological and medical sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Biosolids; Cadmium; Contaminants; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Fertilizers; Fundamental and applied biological sciences. Psychology; ions; Isotopes; Kinetics; Metals; Nutrient availability; polluted soils; Pollution; Pollution, environment geology; prediction; Soil amendment; Soil and sediments pollution; Soil and water pollution; Soil contaminants; Soil contamination; Soil science; Soil solution; Soil testing; Topsoil; Phosphates; Phosphate fertilizer; Soil pollution; Sewage sludge; Environmental engineering; POLLUTED SOIL; Soil science; Ion exchange; Quantitative analysis; Method study; Analytical chemistry; Soil chemistry; Cadmium; Ecotoxicology; Nuclear method; Ion transfer; Isotope exchange; Property of soil; Agricultural soil; Mineral soils; Bioavailability; Experimental study; Heavy metal; Pollutant; Analysis method; Poison; Physicochemical properties; Chemical contamination
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj2004.1210

There has been much research conducted to find suitable methods for the determination of available Cd in soils. In recent years, an isotope exchange kinetics (IEK) technique has been tested to describe the kinetic transfer of ions from the soil solution to the solid phase. Although the IEK technique has been successful in describing nutrient availability in soils, it has not been widely applied to study contaminant availability. In this study, experimental conditions to determine exchangeable Cd in soils using IEK were determined along with a measurement of Cd availability using the IEK technique for 20 topsoils. The results indicated that isotopically exchangeable Cd [E(t) values] predicted from short-term isotopic kinetics (less than or equal to 60 min) were only successful in predicting exchangeable Cd up to 24 h of exchange. After 24 h, E(t) values were significantly overestimated when compared with measured E(t) values. A compartmental analysis revealed that there were differences in the distribution of Cd in exchange pools between soils contaminated with Cd from different sources. The percentage of Cd located in the E(1 min) pool, was on average 21% of total Cd for the P-fertilizer soils compared with 13% for the biosolids-amended soils. In contrast, the biosolids-amended soils had on average 42% of total Cd located in the E(1 min-24 h) pool compared with 25% for the P-fertilizer soil. The E(>24 h) pool averaged 57% for the P-fertilizer soil compared with 46% for the biosolids-amended soil. The IEK technique may be a useful tool to provide information on Cd availability in soils.