Submitted to: Journal of Environmental Quality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/10/2005
Publication Date: 6/1/2005
Citation: Casey, F., Lee, J., Simunek, J., Larsen, G.L., Hakk, H. 2005. Sorption, mobility and transformation of estrogenic hormones in natural soil. Journal of Environmental Quality 34:1372-1379. Interpretive Summary: Domestic animal manures that are applied to soils as nutrients can contain endocrine disrupting hormones. To prevent their unwanted effects in the environment, it is necessary to understand the fate and transport of hormones in agricultural soils. The movement and fate of the female hormone estradiol and its degradation product estrone was studied using a column of soil by application of a single pulse of estradiol and washing the estradiol throught the soil with a large volume of the water solution. The total duration of the column experiment was approximately 42 h, and estradiol and estrone were the predominant compounds detected in the water exiting the column. The amount and timing of the estrogens exiting the column showed that the absorption of estradiol was dependent on the organic content of the soil. That is, the more organic content of the soil, the most of the estradiol was absorbed by the soil. The organic content also affected how fast the estradiol was absorbed by the soil and released back into the water as it moved through the soil column. The absorption of estradiol or estrone to soil was also studied by mixing soil, water and estradiol or estrone in vials then sampling the amount of hormone remaining in the water at various time points. It was found that a constant amount of absorption of both estrogens to soil was observed with time, but a time point was reached where the amount of each estrogen absorbed to the soil and the amount remaining in the water was constant. For estradiol this time point was 5 hours and 24 hours for estrone. These studies showed that there is an important interaction between the absorption and the degradation of these hormones that needs to be considered, which may help explain why hormones are consistently detected in the environment despite their strong soil absorption and ease of degradation.
Technical Abstract: Domestic animal manures that are applied to soils as nutrients can contain endocrine disrupting hormones. To prevent their unwanted effects in the environment, it is necessary to understand the fate and transport of hormones in agricultural soils. In this study comprehensive batch sorption and a long-term column study were used to study the fate and transport of 17 -estradiol and its primary metabolite, estrone. Kinetic and equilibrium batch experiments were done using radiolabeled 17 -estradiol and estrone. It was found that equilibrium sorption for both estrogens was achieved between 5 and 24 h and that the equilibrium sorption isotherms were linear. The Log Koc values for 17 -estradiol (3.07) and estrone (3.10) were consistent with previously reported values, and was consistent with hydrophobic sorption theory also proposed by other researchers. Additionally, it was found that there was rate-limited sorption for both 17 -estradiol (0.178 h-1) and estrone (0.210 h-1), and it was influenced by the organic matter content. Long term, Steady-state, saturated column experiments were used to study the transport of radiolabeled 17 -estradiol, which was applied in a 5[g L-1 solution pulse of 44 pore volumes. The total duration of the column experiment was approximately 42 h, and 17 -estradiol and estrone were the predominant compounds detected in the effluent. The effluent breakthrough curves were asymmetric and the transport modeling indicated that sorption was fully kinetic. The kinetic sorption of the estrogens was similar for the column and batch experiments. There is an important interaction between the sorption and the degradation of these hormones that needs to be considered, and may help explain why hormones are consistently detected in the environment despite their strong sorption and readily degradable nature.