Changes in Partitioning of Cadmium-109 and Zinc-65 in Soil as Affected by Organic Matter Addition and Temperature
- Å. R. Almås *a,
- B. Salbub and
- B. R. Singha
Soil collected from the A horizon of a soil developed from alum shale was added organic matter at the rate of 0 and 4% (w/w) and placed in temperature-controlled climate chambers at 9 and 21°C. After spiking the soil with 109Cd and 65Zn, sequential extraction of the tracers was performed on soil subsamples collected at time intervals ranging from 0.5 to 8760 h (1 yr). The activity concentrations of 109Cd and 65Zn determined in the seven extracts were used in a three-component model to calculate the kinetics of 109Cd and 65Zn transfer between the water-soluble, reversibly sorbed and irreversibly sorbed model components. The rates and the time-dependent distribution coefficient constants for 109Cd and 65Zn distribution among the three components were determined, and the impacts of organic matter addition and increasing temperature on these constants were assessed. The reversible sorption of the tracers occurred rapidly, within 0.5 h, while the transfer of reversibly sorbed 109Cd and 65Zn into the irreversibly sorbed fractions was a significantly slower process. The addition of organic matter reduced the rate of 109Cd and 65Zn transfer into the irreversibly sorbed fractions, whereas the transfer rate increased with increasing temperature. The interaction between organic matter and temperature affected both the rates and the pseudoequilibrium constants, and the temperature regimes and rate of organic matter addition may thus influence the potential mobility of the investigated metals.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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