The Role of Colloids in Estrogen Transport through Soil.

Soils with any appreciable organic carbon will exhibit high sorption capacities for environmental estrogens from manures or bio-solids.  It is because of this that many have thought them to be immobile in soil systems.  However, they continue to show up in surface water, ground water, and agricultural drainage water.  This is likely due to physical and chemical non-equilibrium as well as the presence of conjugated estrogen forms (with greater solubility and mobility), but this is not the whole picture.  Colloidal material presents a potentially mobile sorptive phase that protects estrogen from degradation while speeding it along a transport path through only the larger soil pores.  Our study showed Kd values approximately 3 to 5 times greater for soil colloids than bulk soil.  Sorption kinetic processes to soil and colloidal material also appear to exhibit the possibility for multiple sorptive phases.