PRIMARY MINERAL 



WEATHERING 



UPTAKE BY 

 PLANTS 



% 



/ 



INSOLUBLE ORGANIC 

 MATTER 



SOLUTION 

 FREE I ON -*=^. COMPLEX 



UPTAKE BY 

 MICROBES 



// 



\^ SUR 



OXIDATIONS 

 REDUCTION 



FACE 

 ADSORPTION 



SOLID STATE 

 DIFFUSION INTO 

 SOIL MINERALS 



P.P.T. OF OXIDES OR PHOSPHATES 

 FOR FeANDMn 



Figure 1. Potential sites for competitive uptake of metals in the marsh (from Dunstan and 

 Windom 1975). 



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