Sorption of Estrogens to Colloidal Material: Of Swine Manure and Soil Origin.

Soil and manure colloidal sized material may be a vector for estrogen transport in the environment.  Estrogens, like 17-β estradiol (E2) and estrone (E1), are strongly bound to soil organic matter with log K_oc values varying from approximately 3 – 4 L g^-1 and miscible transport experiments showing very limited movement.  Colloidal materials present a possibly mobile sorptive phase in soil when present with physical and chemical non-equilibrium conditions.  Swine manure colloids differ from soil derived colloids in the type and amount of organic carbon present leading to different sorption behaviors and different potential for transport of bound estrogens.  Swine manure colloids exhibited K_d values of 214 L kg^-1(E2) and 224 L kg^-1 (E1) in contrast to soil derived colloids which varied from 55 - 140 L kg^-1 in the three soils tested.  Soil and manure colloid sorption kinetics also varied in the apparent number of processes.  Total carbon (TC) of swine manure colloids was ~ 350 g kg^-1 and total nitrogen (TN) was ~ 63 g kg^-1 an order of magnitude higher than those for soil colloids TC ~ 40-55 g kg^-1 and TN ~ 4-6 g kg^-1.