~ ~ ~ PURPOSE ~ ~ ~
this subroutine computes the daily stream pesticide balance
(soluble and sorbed)
initialize depth of water for pesticide calculations
volume of water entering reach and stored in reach pesticide transported into reach during day calculate mass of pesticide in reach calculate mass of pesticide in bed sediment in-stream processes calculate sediment concentration set kd calculate fraction of soluble and sorbed pesticide ASSUME DENSITY=2.6E6; KD2=KD1 calculate flow duration calculate amount of pesticide that undergoes chemical or biological degradation on day in reach add decay to daughter pesticides calculate amount of pesticide that volatilizes from reach calculate amount of pesticide removed from reach by settling calculate resuspension of pesticide in reach calculate diffusion of pesticide between reach and sediment calculate removal of pesticide from active sediment layer by burial verify that water concentration is at or below solubility insignificant flow benthic processes calculate loss of pesticide from bed sediments by reaction add decay to daughter pesticides set new pesticide mass of (in + store) after processes calculate outflow and storage in water column