Pathway: a dynamic food-chain model to predict radionuclide ingestion after fallout deposition
This manuscript describes the structure and basis for parameter values of a computerized food-chain transport model for radionuclides. The model, called PATHWAY, estimates the time-integrated ingestion intake by humans of 20 radionuclides after a single deposition from the atmosphere to the landscape. The model solves a set of linear, coupled differential equations to estimate the inventories and concentrations of radionuclides in soil, vegetation, animal tissues and animal products as a function of time following deposition. Dynamic processes in the model include foliar interception, weathering and absorption; plant growth, uptake, harvest and senescence; soil resuspension, percolation, leaching and tillage; radioactive decay; and livestock ingestion, absorption and excretion. Human dietary data are included to permit calculation of time-dependent radionuclide ingestion rates, which are then numerically integrated. The model considers seasonal changes in the biomass of vegetation and animal diets, as well as specific plowing and crop-harvest dates; thus the integrated radionuclide intakes by humans are dependent on the seasonal timing of deposition. The agricultural data base represents the arid and semi-arid regions of the western United States. The foliar deposition parameters apply to regional fallout out to a few hundred miles from nuclear detonations at the Nevada Test Site. With modification, the model could be applied to chronic or other acute releases, providing the ground deposition in Bq m-2 could be estimated. The output of PATHWAY (Bq ingested per Bq m-2 deposited) may be multiplied by the deposition and a dose conversion factor (Gy Bq-1) to yield an organ-specific dose estimate. The model may be run deterministically to yield single estimates or stochastically (''Monte-Carlo'' mode) to provide distributional output that reflects uncertainty in the output due to uncertainty in parameters.
- Research Organization:
- Colorado State Univ., Fort Collins
- OSTI ID:
- 6272858
- Journal Information:
- Health Phys.; (United States), Vol. 6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FOOD CHAINS
CONTAMINATION
RADIOISOTOPES
INGESTION
RADIONUCLIDE KINETICS
MATHEMATICAL MODELS
COMPUTERIZED SIMULATION
DIFFERENTIAL EQUATIONS
DOSE-RESPONSE RELATIONSHIPS
ENVIRONMENTAL TRANSPORT
FALLOUT
PLANTS
SEASONAL VARIATIONS
TIME DEPENDENCE
EQUATIONS
INTAKE
ISOTOPES
MASS TRANSFER
SIMULATION
VARIATIONS
560161* - Radionuclide Effects
Kinetics
& Toxicology- Man