2007 Annual Report 1a.Objectives (from AD-416) To develop a conceptual model of oxanions transformations and volatilization that can later be used to develop management strategies for reduced toxic ion discharge in drainage water. 1b.Approach (from AD-416) To conduct theotetical, laboratory, and field research as needed to describe the aspects of oxanion transformations, volatilization and transport for improved management of drainage water discharge from agricultural fields.Documents SCA with with UC- Riverside. Formerly 5310-61000-012-14S (FEB 07) 3.Progress Report This report serves to document research conducted under a Specific Cooperative Agreement between ARS and the University of California, Riverside. Additional details can be found in the report of the parent project 5310-61000-013-00D. We separately developed a large set of selenite (Se II) adsorption isotherms representative of arid land and mid Western soils. Utilizing pedotransfer functions a model was developed to predict the adsorption constants for the Constant Capacitance Model (CCM). The developed model was evaluated using the jack-knife technique allowing prediction of observations not used in the model. We inserted the generated soil specific constants into the CCM, and successfully predicted selenite adsorption as a function of pH. An earlier developed predictive model for molydate adsorption using the CCM provided only qualitative results above pH7. The model was modified by utilizing the Triple Layer Model instead of the CCM and again developing a pedotransfer model for the constants. These pedotransfer model, combined with the chemical adsorption models, allow for prediction of selenite and molybdate adsorption utilizing widely available soil properties, such as oxide content, organic matter content, inorganic matter content and surface area. Since we are on site at the UCR campus we participate in weekly meetings with the UCR employees. The research is mostly conducted at our facility and as cooperators we assist in the conduct of the experiments.