|MadSci Network: Chemistry|
Heavy metals adsorb to organic materials largely due to surface charges on the colloidal organic particles. In the case of peat there is some additional retention simply due to the enormous water holding capacity of the peat. Because the retention of metals is charge dependent it is also to some degeree pH dependent and redox dependent. Metals form different secondary compunds in a reducing environment than in an oxidizing environment. In any event, as the peat decomposes, the metals may be released back into the environment as salts or incorporated into decomposer biomass. The degree of decomposition in the peat is also important as it will influence the surface area and net charge of the organic substances. If you want to look at the scientific literature on this there has been work done on organic ammendments to soils, but I am not immediately aware of specific citations.
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