Sorption reactions on particle surfaces can dramatically affect the speciation, cycling and bioavailability of essential micronutrients (i.e. PO43-, Cu, Zn etc.) and toxic metals and metalloids (i.e. Pb, Hg, Se, As) in soils and aquatic environments. Considerable attention has been focused on understanding metal sorption reactions at a molecular/mechanistic level and the effects of metal concentration, pH, ionic strength, and complexing ligands on the ways in which metal ions bind to the surfaces of common mineral phases such as Fe-, Mn- and Al-(hydr)oxides and clays. However, a significant fraction of mineral surfaces in natural environments are extensively colonized by microbial organisms, which can also be potent sorbents for metals due to the large number of reactive functional groups that decorate the cell walls and outer membranes of bacterial surfaces.
