| The objectives of this study were to identify the sorption, fate, and transport of manureborne hormones (i.e., 17beta-estradiol and testosterone) in soil-water systems. Various incubation, batch, and miscible-displacement experiments were conducted to isolate and discern the physical, chemical, and biological processes governing the degradation, sorption, and transport of these hormones in soil-water systems.; The incubation experiments indicated that 1-6% of 17beta-estradiol and 46-63% of testosterone could be mineralized to CO2 in native soils under anaerobic and aerobic conditions, respectively. The results also indicated that the degradation of testosterone was exclusively through a biological process while the degradation of 17beta-estradiol was through both a biological (to estrone) and a chemical (to an unidentified polar metabolite) process.; The batch and miscible-displacement experiments indicated that degradation and sorption processes occurred simultaneously in the static batch studies and the dynamic environments of the miscible-displacement studies. Comprehensive and robust models were developed to describe the various non-equilibrium degradation and sorption processes of hormones and their metabolites in the batch studies. This model included the simultaneous transformation (i.e., chemical and biological) and mass exchange between the aqueous phase and solid phase (i.e., reversible and irreversible sorption sites). Due to the complexity, high nonlinearity, and large number of parameters of this model, the traditional local optimization methods were not suitable to seek the globally optimal parameters. A global optimization strategy, the stochastic ranking evolutionary strategy, was developed to uniquely estimate parameters. The independently estimated batch parameters were then incorporated into chemical non-equilibrium solute transport models and used to describe the undisturbed soil column experiments. Finally, the fate and transport of hormones were then uniquely identified by combining the simultaneous biological processes with the physical sorption and transport mechanisms. |
