DDT_in_air(t) = DDT_in_air(t - dt) + (Application_rate_to_air
+ Evaporation_rate_from_soil - Precipitation_rate_into_ocean - Precipitation_rate_on_soil)
* dt
INIT DDT_in_air = 0
INFLOWS:
Application_rate_to_air = Application_rate_input*Airborne_fraction*10000
Evaporation_rate_from_soil = DDT_in_soil/(1.5*Evaporation_halflife_in_soil)
OUTFLOWS:
Precipitation_rate_into_ocean = DDT_in_air*(1-Soil_fraction)/(1.5*Precipitation_halflife)
Precipitation_rate_on_soil = DDT_in_air*Soil_fraction/(1.5*Precipitation_halflife)
DDT_in_fish(t) = DDT_in_fish(t - dt) + (Uptake_rate_in_fish - Dead_fish_remaining_in_ocean
- Toxic_excretion_rate - Fish_consumed - Harmless_excretion_rate) * dt
INIT DDT_in_fish = 0
INFLOWS:
Uptake_rate_in_fish = Concentration_in_plankton*Mass_of_fish*Body_weights_eaten_per_year
OUTFLOWS:
Dead_fish_remaining_in_ocean = Deaths_of_fish*(1-Consumed_fraction)
Toxic_excretion_rate = DDT_excretion_rate_from_fish*(1-Degraded_fraction)
Fish_consumed = Deaths_of_fish*Consumed_fraction
Harmless_excretion_rate = DDT_excretion_rate_from_fish*Degraded_fraction
DDT_in_ocean(t) = DDT_in_ocean(t - dt) + (Precipitation_rate_into_ocean
+ Dead_fish_remaining_in_ocean + Toxic_excretion_rate + Run-off_rate - Degradation_rate_in_ocean
- Uptake_rate_in_fish) * dt
INIT DDT_in_ocean = 0
INFLOWS:
Precipitation_rate_into_ocean = DDT_in_air*(1-Soil_fraction)/(1.5*Precipitation_halflife)
Dead_fish_remaining_in_ocean = Deaths_of_fish*(1-Consumed_fraction)
Toxic_excretion_rate = DDT_excretion_rate_from_fish*(1-Degraded_fraction)
Run-off_rate = DDT_in_rivers/(1.5*Run-off_halflife)
OUTFLOWS:
Degradation_rate_in_ocean = DDT_in_ocean/(1.5*Degradation_halflife_in_ocean)
Uptake_rate_in_fish = Concentration_in_plankton*Mass_of_fish*Body_weights_eaten_per_year
DDT_in_rivers(t) = DDT_in_rivers(t - dt) + (Solution_rate
- Run-off_rate) * dt
INIT DDT_in_rivers = 0
INFLOWS:
Solution_rate = DDT_in_soil/(1.5*Solution_halflife)
OUTFLOWS:
Run-off_rate = DDT_in_rivers/(1.5*Run-off_halflife)
DDT_in_soil(t) = DDT_in_soil(t - dt) + (Application_rate_to_soil + Precipitation_rate_on_soil
- Evaporation_rate_from_soil - Solution_rate - Degradation_rate_in_soil)
* dt
INIT DDT_in_soil = 0
INFLOWS:
Application_rate_to_soil = Application_rate_input*(1-Airborne_fraction)*10000
Precipitation_rate_on_soil = DDT_in_air*Soil_fraction/(1.5*Precipitation_halflife)
OUTFLOWS:
Evaporation_rate_from_soil = DDT_in_soil/(1.5*Evaporation_halflife_in_soil)
Solution_rate = DDT_in_soil/(1.5*Solution_halflife)
Degradation_rate_in_soil = DDT_in_soil/(1.5*Degradation_halflife_in_soil)
Airborne_fraction = 0.5
Body_weights_eaten_per_year = 10
Concentration_in_fish = DDT_in_fish/Mass_of_fish
Concentration_in_ocean = DDT_in_ocean/Mass_of_mixed_layer
Concentration_in_plankton = Ocean-plankton_concentration_factor*Concentration_in_ocean
Consumed_fraction = 0.5
DDT_excretion_rate_from_fish = DDT_in_fish/(1.5*Excretion_halflife_from_fish)
Deaths_of_fish = DDT_in_fish/(1.5*Halflife_of_fish)
Degradation_halflife_in_ocean = 15
Degradation_halflife_in_soil = 10
Degraded_fraction = 0.1
Evaporation_halflife_in_soil = 2
Excretion_halflife_from_fish = 0.3
Halflife_of_fish = 3
Mass_of_fish = 6*10^8
Mass_of_mixed_layer = 3*10^16
Ocean-plankton_concentration_factor = 2000
Precipitation_halflife = 0.05
Run-off_halflife = 0.1
Soil_fraction = 0.3
Solution_halflife = 500
Application_rate_input = GRAPH(TIME)
(1943, 0.00), (1948, 4.00), (1953, 9.00), (1958, 13.0), (1963, 16.0), (1968,
17.5), (1973, 17.5), (1978, 11.0), (1983, 7.00), (1988, 4.00), (1993, 1.00),
(1998, 0.00)
|