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Environmental Fate Models
in surface area containing at least 300 m 3 water at a maximum depth of 2 m.
The design also prescribes the type and depth of the bottom sediment and
“representative” biota, including fsh. A minimum of 12 ponds is required
for statistical analysis. Recommended pesticide dosing levels are 0.1× and 10×
the intermediate level, which is determined based on modeling and experiential data. Another study looked at the possible effect of mesocosm pool size
on algal growth (especially the effect of change in surface area/volume ratio)
and found little, if any, effect. The conclusion was that study results using
relatively small mesocosms could be extrapolated to larger artifcial and natural systems (Spivak et al., 2011). By contrast, a study showed the diffculty
of extrapolating marine mesocosm results to the open ocean for computer
model validation (Watts and Bigg, 2001). A fnal example is a study using a
mesocosm to monitor the impact of a marine pathogen on a fsh (sharpsnout
seabream) raised in an aquaculture environment (Katharios et al., 2015). The
authors concluded: “These results demonstrate the advantage of mesocosm
studies for investigating the effect of environmental bacteria on susceptible
hosts and provide an important insight into the genome dynamics of a novel
fsh pathogen.”
5.4 Numeric Models (Computer)
Chamber models, such as those discussed above, are typically used in a
lab/greenhouse/feld plot setting. They allow control of some variables and,
in some cases, can incorporate radiolabeled compounds. They are good for
ranking chemicals in terms of such parameters as biodegradability and ecological magnifcation. They are also good for understanding how structures
and key physicochemical properties infuence behavior and fate. The data set
accumulated over the years from using these model systems has been converted into computer code for relatively rapid estimation of chemical environmental fate using numeric models. Although they are time-consuming
and labor-intensive, chamber models are still used as needed (e.g., to validate
a computer model).
Numeric models allow one to simulate environmental behavior using only
a computer. They give answers relatively quickly, which is important when a
real-life escape or spill of a chemical occurs. And if it becomes necessary to
implement evacuation plans or make other decisions requiring actions. They
also allow one to do “what if” assessments—what if the chemical had a nonpolar substituent added, or had its vapor pressure reduced, or the daytime
high temperature during a spray application was 35°C vs 15°C, etc.? There are
many types of models that we deal with in daily life: economic, weather, traffc
congestion, and fre danger. These all allow us to paint a realistic scenario for
the future—not necessarily exact, but close enough to base some decisions on.
Environmental Fate Models
in surface area containing at least 300 m 3 water at a maximum depth of 2 m.
The design also prescribes the type and depth of the bottom sediment and
“representative” biota, including fsh. A minimum of 12 ponds is required
for statistical analysis. Recommended pesticide dosing levels are 0.1× and 10×
the intermediate level, which is determined based on modeling and experiential data. Another study looked at the possible effect of mesocosm pool size
on algal growth (especially the effect of change in surface area/volume ratio)
and found little, if any, effect. The conclusion was that study results using
relatively small mesocosms could be extrapolated to larger artifcial and natural systems (Spivak et al., 2011). By contrast, a study showed the diffculty
of extrapolating marine mesocosm results to the open ocean for computer
model validation (Watts and Bigg, 2001). A fnal example is a study using a
mesocosm to monitor the impact of a marine pathogen on a fsh (sharpsnout
seabream) raised in an aquaculture environment (Katharios et al., 2015). The
authors concluded: “These results demonstrate the advantage of mesocosm
studies for investigating the effect of environmental bacteria on susceptible
hosts and provide an important insight into the genome dynamics of a novel
fsh pathogen.”
5.4 Numeric Models (Computer)
Chamber models, such as those discussed above, are typically used in a
lab/greenhouse/feld plot setting. They allow control of some variables and,
in some cases, can incorporate radiolabeled compounds. They are good for
ranking chemicals in terms of such parameters as biodegradability and ecological magnifcation. They are also good for understanding how structures
and key physicochemical properties infuence behavior and fate. The data set
accumulated over the years from using these model systems has been converted into computer code for relatively rapid estimation of chemical environmental fate using numeric models. Although they are time-consuming
and labor-intensive, chamber models are still used as needed (e.g., to validate
a computer model).
Numeric models allow one to simulate environmental behavior using only
a computer. They give answers relatively quickly, which is important when a
real-life escape or spill of a chemical occurs. And if it becomes necessary to
implement evacuation plans or make other decisions requiring actions. They
also allow one to do “what if” assessments—what if the chemical had a nonpolar substituent added, or had its vapor pressure reduced, or the daytime
high temperature during a spray application was 35°C vs 15°C, etc.? There are
many types of models that we deal with in daily life: economic, weather, traffc
congestion, and fre danger. These all allow us to paint a realistic scenario for
the future—not necessarily exact, but close enough to base some decisions on.