Project Number: 6206-13610-007-14
Project Type: General Cooperative Agreement

Start Date: Jan 01, 2012
End Date: May 31, 2013

Objective:
Update the existing pesticide theoretical mathematics sub-module in SWAT for application to emerging contaminants. Specifically, (1) update the soil surface model, and (2) establish the foundation for developing a dynamic "air box" compartment to connect soil-surface processes to the atmospheric boundary layer as appropriate for emerging contaminants.

Approach:
The Soil and Water Assessment Tool currently does not model the transport and fate of emerging contaminants, although it does model pesticides. Therefore, the Lavoisier mass balance (MB) approach for a single emerging contaminant will be used to provide the first principle approach. Each system to which the MB is applied will be carefully defined and will consider three phases in soil: solid particles, water, and soil gas. The three-layer soil structure presently in SWAT likely will be retained. Processes occurring within the individual micro-phases will reflect reaction, transport (diffusive and advection), and partitioning. Continuity of flux at interface concept will be used to connect transport between adjoining phases. Literature search on the latest mechanisms will be used to update process rate equations for reaction, transport, and partitioning.