Rhizosphere metal contaminant complexation

In the rhizosphere, activities of free metal ions may be decreased through uptake by plants and microbes. Metal contaminants are complexed substantially with biomolecules in the rhizosphere due to higher concentrations of complexing... 

Weis, 2004). If the rhizosphere plays an important role in the sequestration of metals in wetland soils, fluxes of potentially toxic metals out of the wetland to adjacent aquatic systems will, in theory, be reduced. However, plants may also increase metal mobilization through rhizosphere acidification and the oxidation of metal-sulfide complexes (Jacob and Otte, 2003). They may also represent only a temporary sink for metals if rhizosphere Fe plaque is reduced following plant senescence. Furthermore, metals can be exported from the ecosystem if contaminated plant parts are consumed by people or wildlife. The pathways and possible health effects of metal consumption have been especially well studied in Southeast Asia, where metal contamination (notably As) of rice crops is a serious public health issue (e.g., Meharg and Rahman, 2003 Meharg, 2004). 

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