Mass Balance

The processes described above can be combined into mass balance equations for the well-mixed water body and the well-mixed sediment layer:

$\Delta pst_{lkwtr}=pst_{in}- (pst_{sol,o}+ p st_{sorb,o})-pst_{deg,wtr} -pst_{vol,wtr}- pst_{stl,wtr}+pst_{rsp,wt r}\pm pst_{dif}$

8:4.3.1

$\Delta pst_{lksed}=pst_{deg,sed}+pst_{stl,wtr}-pst_{rsp,wtr }-pst_{bur}\pm pst_{dif}$ 8:4.3.2

where $\Delta pst_{lkwtr}$ is the change in pesticide mass in the water layer (mg pst), $\Delta pst_{lksed}$ is the change in pesticide mass in the sediment layer (mg pst), $pst_{in}$ is the pesticide added to the water body via inflow (mg pst), $pst_{sol,o}$ is the amount of dissolved pesticide removed via outflow (mg pst), $p st_{sorb,o}$ 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), $pst_{stl,wtr}$ is the amount of pesticide removed from the water due to settling (mg pst), $pst_{rsp,wt r}$ is the amount of pesticide removed via resuspension (mg pst), $pst_{dif}$ is the amount of pesticide transferred between the water and sediment by diffusion (mg pst), $pst_{deg,sed}$ is the amount of pesticide removed from the sediment via degradation (mg pst), $pst_{bur}$ is the amount of pesticide removed via burial (mg pst)