Mass Balance

The processes described above can be combined into mass balance equations for the well-mixed reach segment and the well-mixed sediment layer: \$\Delta pst_{rchwtr}=pst_{in}-(pst_{sol,o}+pst_{sorb,o})-pst_{deg,wtr}-pst_{vol,wtr}-pst_{stl,wtr}+pst_{rsp,wtr}\pm pst_{dif}$​

7:4.3.1

$\Delta pst_{rchsed}=-pst_{deg,sed}+pst_{stl,wtr}-pst_{rsp,wtr}-pst_{bur}\pm pst_{dif}$ 7:4.3.2

where $\Delta pst_{rchwtr}$ is the change in pesticide mass in the water layer (mg pst), $\Delta pst_{rchsed}$ is the change in pesticide mass in the sediment layer (mg pst), $pst_{in}$ is the pesticide added to the reach segment via inflow (mg pst), $pst_{sol,o}$ is the amount of dissolved pesticide removed via outflow (mg pst), $pst_{sorb,o}$ is the amount of particulate pesticide removed via outflow (mg pst), $pst_{deg,wtr}$ is the amount of pesticide removed from the water via degradation (mg pst), $pst_{vol,wtr}$ is the amount of pesticide removed via volatilization (mg pst), is the amount of pesticide removed from the water due to settling (mg pst), is the amount of pesticide removed via resuspension (mg pst), is the amount of pesticide transferred between the water and sediment by diffusion (mg pst), is the amount of pesticide removed from the sediment via degradation (mg pst), is the amount of pesticide removed via burial (mg pst).