Monday, November 5, 2007

Transport of 17-Estradiol and Testosterone in a Field Lysimeter.

Francis Casey1, Peter Oduor1, Heldur Hakk2, and Gerald L. Larsen3. (1) North Dakota State University, Dept. of Soil Science, North Dakota State Univ, Fargo, ND 58105, (2) Animal Metabolism Unit, Bioscience Research Lab, Animal Metabolism Unit, Bioscience Research Lab, Biosciences Research Laboratory, USDA-ARS, Fargo, ND 58105, (3) Animal Metabolite and Ag. Chemical Unit, Animal Metabolite and Ag. Chemical Unit, Bioscience Research Lab, Fargo, ND 58105

17β-estradiol (E2) and testosterone (T) are naturally present in manures and have the potential to disrupt aquatic organisms at low concentrations. Laboratory studies indicate that E2 and T have limited mobility and attenuate rapidly in soils; however, these hormones are consistently detected in the environment. A steady-state, near-saturated, field lysimeter (2.4m length × 2.4 m width × 2.3m deep) study was done to identify the fate and transport of E2 and T, to try to understand why E2 and T are consistently detected in the environment. The transport of E2 and T were compared to the transport of a conservative, non-sorbing tracer, pentafluorobenzoic acid (PFBA). Concentration redistributions of water extractable E2, T, and PFBA through depth were determined. Also, lysimeter effluent drainage concentrations of water-dissolved E2, T, and PFBA were determined. Effluent concentrations of PFBA were modeled with the convective-dispersive equation assuming no sorption, and indicated that there was no preferential transport. The mass recovery of PFBA in the effluent was 100%. The mass recoveries of the E2 and T in the lysimeter profile were calculated to be 0.46% and 0.02%, respectively. The effects of porosity (Φ) and percent saturation (%sat) were significant in explaining E2 and T redistribution in the lysimeter, where lower Φ and higher %sat corresponded to higher E2 and T concentrations. This result likely indicated greater persistence of E2 and T (i.e., less degradation) where soil oxygen levels were low. In the lysimeter effluent, the mass recoveries of E2 and T were 1.3% and 0.2%, respectively. 17β-estradiol and T were detected before the PFBA in the effluent, which suggests antecedent presence of E2 and T. Also, E2 and T concentrations were correlated to lysimeter drainage, which may indicate significant colloidal facilitated transport. This study helps to bridge the understanding between laboratory fate and transport studies on E2 and T in soil, and reported environmental observations.