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G Case Study Solutions
Level III Environmental Fate Model
(a) The three equations are:
dm s
dt
= E s − m s × k s + t as × m a − t sa × m s + t ws × m w − t sw × m s
dm a
dt
= E a − m a × k a + t sa × m s − t as × m a + t wa × m w − t aw × m a
dm w
dt
= E w − m w × k w + t sw × m s − t ws × m w + t aw × m a − t wa × m w
(b) Using the information provided on ASM in Table 10.7, the continuous emission
rate of ASM into 1 ha of soil during the growing season can be calculated as the
total amount of ASM applied over the entire season of 120 days (assuming five
applications with 24 days between each application):
75 g Bion
ha
×
500 g ASM
1000 g Bion
×
5 applications
season
×
1 mol ASM
210 g ASM
×
1
2880 hr
=
3.1 × 10 −4 mol ASM
hr
(c) The resulting distributions for the level III solution from the small-region model
using a continuous emission rate of 3.1 × 10 −4 mol/hr are:
• For emission only to air: 54% air, 2% water, 44% soil, 0% sediment
• For emission only to water: 0% air, >99% water, 0% soil, <1% sediment
• For emission only to soil: 0% air, <1% water, >99% soil, 0% sediment
• For emission only to sediment: 0% air, <1% water, 0% soil, >99% sediment
(d) With the exception of the air compartment, the largest fraction (>99%) of
ASM remains in the compartment where it was emitted. This shows the low
propensity of ASM to be redistributed to other compartments after emission
into the environment. Of the four compartments, ASM is expected to have the
most mobility when emitted to air, particularly into the soil compartment.
(e) The level III model assumes a steady-state emission rate and is not able to
predict changes in the compartment inventory over time in response to changing
emission rates. It also does not consider other environmental compartments that
exist such as vegetation, the various types of soil, etc.
The assumption of steady-state emission also does not most accurately represent
the actual use of Bion ® (and other crop protection products). The corresponding
local environmental concentrations are better modeled with more complex, timeresolved models that give realistic peak concentrations in representative soils or
water bodies.
G Case Study Solutions
Level III Environmental Fate Model
(a) The three equations are:
dm s
dt
= E s − m s × k s + t as × m a − t sa × m s + t ws × m w − t sw × m s
dm a
dt
= E a − m a × k a + t sa × m s − t as × m a + t wa × m w − t aw × m a
dm w
dt
= E w − m w × k w + t sw × m s − t ws × m w + t aw × m a − t wa × m w
(b) Using the information provided on ASM in Table 10.7, the continuous emission
rate of ASM into 1 ha of soil during the growing season can be calculated as the
total amount of ASM applied over the entire season of 120 days (assuming five
applications with 24 days between each application):
75 g Bion
ha
×
500 g ASM
1000 g Bion
×
5 applications
season
×
1 mol ASM
210 g ASM
×
1
2880 hr
=
3.1 × 10 −4 mol ASM
hr
(c) The resulting distributions for the level III solution from the small-region model
using a continuous emission rate of 3.1 × 10 −4 mol/hr are:
• For emission only to air: 54% air, 2% water, 44% soil, 0% sediment
• For emission only to water: 0% air, >99% water, 0% soil, <1% sediment
• For emission only to soil: 0% air, <1% water, >99% soil, 0% sediment
• For emission only to sediment: 0% air, <1% water, 0% soil, >99% sediment
(d) With the exception of the air compartment, the largest fraction (>99%) of
ASM remains in the compartment where it was emitted. This shows the low
propensity of ASM to be redistributed to other compartments after emission
into the environment. Of the four compartments, ASM is expected to have the
most mobility when emitted to air, particularly into the soil compartment.
(e) The level III model assumes a steady-state emission rate and is not able to
predict changes in the compartment inventory over time in response to changing
emission rates. It also does not consider other environmental compartments that
exist such as vegetation, the various types of soil, etc.
The assumption of steady-state emission also does not most accurately represent
the actual use of Bion ® (and other crop protection products). The corresponding
local environmental concentrations are better modeled with more complex, timeresolved models that give realistic peak concentrations in representative soils or
water bodies.