Impacts of Environmental Colloids On the Transport of 17-B Estradiol in Intact Soil Cores.

Estrogens such as 17-β estradiol are known to have biological effects on aquatic organisms.  Because of this it is important to understand the mechanisms of their transport in the environment.  17-β estradiol and its daughter product estrone are both strongly sorbed by soil organic matter and have relatively short half-lives provided oxygen is available.  Thus, conditions that reduce contact time with soil potentiate greater transport.  It has been suggested that the transport of estrogenic compounds in soils is dominated by preferential flow with the possibility of a colloid mediated pathway.  In this study intact soil cores, from three Iowa soils were used to compare the transport of 17-β estradiol by itself with its transport in the presence of colloidal material fractionated from soil or swine manure.  Chemical breakthrough experiments were conducted and estrogens were measured in solution and attached to suspended solids in soil column effluent using high-pressure liquid chromatography.  Colloids were able to carry 17-β estradiol through soil.  Additionally, the presence of colloids decreased the time of 17-β estradiol first arrival as compared to a bromide tracer in two soils.  The presence of colloids also created a condition where higher peak 17-β estradiol solution concentrations were eluted from the soil columns in those same two soils.  Colloids also contributed to greater total loads of estrogen transport over the course of these experiments.