ComET™ Farfield Modelling ComET™ Farfield Modelling Dr. Dr. Don Mackay Don Mackay Mr. Jon Arnot Mr. Jon Arnot Canadian Environmental Modelling Centre Canadian Environmental Modelling Centre Trent University Trent University Peterborough, ON Peterborough, ON www.trentu.ca/cemc www.trentu.ca/cemc Slides and Materials Copyright Protected
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ComET™ Farfield Modelling Dr. Don Mackay Mr. Jon Arnot Canadian Environmental Modelling Centre Trent University Peterborough, ON Slides.
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Dr. Dr. Don MackayDon MackayMr. Jon ArnotMr. Jon Arnot
Canadian Environmental Modelling CentreCanadian Environmental Modelling CentreTrent UniversityTrent University
Peterborough, ONPeterborough, ON
www.trentu.ca/cemcwww.trentu.ca/cemc
Slides and Materials
Copyright Protected
Two Sources of Human Two Sources of Human ExposureExposure
Nearfield:Nearfield:– Indoor or direct product useIndoor or direct product use
e.g., cleaning agentse.g., cleaning agents
Farfield (focus of this Farfield (focus of this presentation):presentation):– Environmentally mediatedEnvironmentally mediated
e.g., outdoor inhalation, water e.g., outdoor inhalation, water ingestion, foodstuffs, etc…ingestion, foodstuffs, etc…
Estimates of both are desirableEstimates of both are desirable
Which one dominates?Which one dominates?
Varies from substance to substanceVaries from substance to substance
Depends on how the substance is Depends on how the substance is produced and used and its produced and used and its physical/chemical propertiesphysical/chemical properties
Two Sources of Human Two Sources of Human ExposureExposure
HumanPharmacokineticProcesses
Transformationor DestructionProcesses
Migration intoHuman Exposure
Media of Air, Water & Food
Transport & Transformation in Air, Soil,Sediment, Surface & Groundwater,
Key Similarities:Key Similarities:– Compartment based Compartment based
mass-balance mass-balance modelsmodels
– Level IIILevel III– Fate and exposure Fate and exposure
pathwayspathways– Generally similar, Generally similar,
diffusive and diffusive and advective inter-advective inter-media transfer media transfer processprocess
Key Differences:Key Differences:– Farfield model includes Farfield model includes
regions in Canada and regions in Canada and can be run in ‘batch can be run in ‘batch mode’mode’
– Farfield model includes Farfield model includes media specific half-livesmedia specific half-lives
– Farfield model includes Farfield model includes mechanistic mechanistic bioaccumulation modelsbioaccumulation models
– Fugacity vs. rate constant Fugacity vs. rate constant formulationformulation
Assumption (3):Assumption (3): Organisms selected as representative speciesOrganisms selected as representative species
– Use current “state of the science” bioaccumulationUse current “state of the science” bioaccumulation– Including reported respiration and feeding ratesIncluding reported respiration and feeding rates
– Environmental half-lives in air, water, Environmental half-lives in air, water, soil and sedimentsoil and sediment
Unit emission rate:Unit emission rate:– 100 kg/h100 kg/h– 3 modes of entry (air, water and soil)3 modes of entry (air, water and soil)
Assumption (5):Assumption (5):
Metabolic transformation rate constant Metabolic transformation rate constant is initially set to be zero in the is initially set to be zero in the bioaccumulation models for organisms bioaccumulation models for organisms of the food webof the food web– Reasonable assumption about metabolic Reasonable assumption about metabolic
transformation in organisms if no data transformation in organisms if no data availableavailable
– If reliable metabolic transformation rate If reliable metabolic transformation rate data are available they can be incorporateddata are available they can be incorporated
Model OutputModel Output Excel spreadsheet – transparent and Excel spreadsheet – transparent and
available to allavailable to all
Unit emission rate – 100 kg/h to air, water Unit emission rate – 100 kg/h to air, water and soiland soil
Aim is priority setting -- to set aside or Aim is priority setting -- to set aside or prioritize for additional considerationprioritize for additional consideration
Matrix Emission ApproachMatrix Emission Approach 100 kg/h to air:100 kg/h to air:
– CCAIR AIR = 100; C= 100; CWATERWATER = 30; C = 30; CFOODFOOD = 5000 = 5000
100 kg/h to water:100 kg/h to water:– CCAIR AIR = 15; C= 15; CWATERWATER = 150; C = 150; CFOODFOOD = 3000 = 3000
If If actualactual emission is emission is 200200 to air: to air:– CCAIR AIR = 200; C= 200; CWATERWATER = 60; C = 60; CFOODFOOD = 10,000 = 10,000
If If actualactual emission is emission is 200200 to air & to air & 300300 to to water:water:– CCAIR AIR = (200/100) = (200/100) 100 + (300/100) 100 + (300/100) 15 = 245 15 = 245– CCWATER WATER = (200/100) = (200/100) 30 + (300/100) 30 + (300/100) 150 = 510 150 = 510
No need to re-run model, just scale the resultsNo need to re-run model, just scale the results
Emission OptionsEmission Options
Ideally, we will use current reliable and real Ideally, we will use current reliable and real data on emissionsdata on emissions
Alternatively, there are a number of options Alternatively, there are a number of options under consideration which will be the subject under consideration which will be the subject of the next talk on emission estimationof the next talk on emission estimation
To Recap: To Recap: – CEMC will provide data on “unit emissions”CEMC will provide data on “unit emissions”– LLG and HC will estimate and apply emission LLG and HC will estimate and apply emission
estimatesestimates
SummarySummary Physical-chemical properties (CEMC)Physical-chemical properties (CEMC) Unit emissions (CEMC)Unit emissions (CEMC) Calculate all exposure concentrations from unit Calculate all exposure concentrations from unit
emissions (CEMC)emissions (CEMC) Scale to desired emission rate (LLG)Scale to desired emission rate (LLG) Recalculate concentrations (LLG)Recalculate concentrations (LLG) Calculate dosages for selected age classes using Calculate dosages for selected age classes using
exposure quantities (e.g., food intake rates) (LLG)exposure quantities (e.g., food intake rates) (LLG) Combine / compare with near field dosages (LLG)Combine / compare with near field dosages (LLG)