The TaPL3 model is intended as an evaluative tool to be used in the detailed assessment of chemicals for persistence and potential for long-range transport in a mobile medium, either air, or water, in a Level III (steady state environment). It is expected that chemicals will be compared. (Absolute values may be misleading due to the absence of advection.) The Level III model should be used for more general applications.
Chemical is continuously discharged at a constant rate and achieves a steady state condition in which input and output rates are equal. The loss processes are degrading reactions and advection. In general, each medium is at a different fugacity and a mass balance applies to each compartment, and the system as a whole. Rates of intermedia transport are calculated using D values which contain information on mass transfer coefficients, areas, deposition and resuspension rates, diffusion rates, and soil runoff rates.
Mass balances are calculated for the four bulk media of air (gas + aerosol), water (solution + suspended sediment + biota), soil, (solids + air + water), and sediment (solids + pore water). Equilibrium exists within, but not between media. For example, sediment solids and pore water are at equilbrium, but sediment is not necessarily at equilibrium with the overlying water.
Physical-chemical properties are used to quantify a chemical's behaviour in an evaluative environment. Three types of chemicals are treated in this model: chemicals that partition into all media (Type 1), involatile chemicals (Type 2), and chemicals with zero, or near-zero, solubility (Type 3). The model can not treat ionizing or speciating substances. The TaPL3 model assumes a simple, evaluative environment with user-defined volumes and densities for the following homogeneous environmental media (or compartments): air, water, soil, sediment, suspended sediment, fish and aerosols. The rates of intermedia transport are controlled by a series of 12 transport velocities. Reaction half-lives are requested for all 7 media.
Chemical is set to enter each of the mobile media (air and water) separately and at a fixed rate. Overall environmental persistence and potential for long-range transport in the mobile medium are calculated. There is no advective removal from the environment.
Features of the TaPL3 Model:
- Provides a database of chemicals and chemical properties.
- Permits temporary additions/changes of chemicals and their properties to a simulation.
- Permits permanent additions, changes and deletions of chemicals and their properties to the database.
- Provides a database of environments and environmental properties.
- Permits temporary additions/changes of environments and their properties to a simulation.
- Permits permanent additions, changes and deletions of environments and their properties to the database.
- Provides context-sensitive help.
- Displays and prints the TaPL3 model calculations, as performed by the program.
- Allows the printing of simulation tables and the summary diagram.
- Allows the program results to be saved as a comma separated value file viewable by most spreadsheet software packages.
This program was based on the following publication:
Beyer, A., Mackay, D., Matthies, M., Wania, F., Webster, E. 2000. Assessing Long-range Transport Potential of Persistent Organic Pollutants. Environ. Sci. Tech. 34: 699-703
The required input data are:
- Chemical name
- Molecular mass
- Data temperature
- Reaction half-life estimates for:
- Suspended sediment
- Aquatic biota
- For Type 1 chemicals:
- Water solubility
- Vapour pressure
- Log Kow
- Melting point
- For Type 2 and 3 chemicals:
- Partition coefficients
- Areas and depths for all bulk media
- Volume fractions for all subcompartments
- Densities for all subcompartments
- Organic carbon content (soil, sediment & suspended sediment only)
- Fish lipid content (Type I chemicals only)
- Transport velocities
- Air side air-water mass transfer coefficient
- Water side air-water mass transfer coefficient
- Rain rate
- Aerosol deposition velocity (wet and dry combined)
- Soil air phase diffusion mass transfer coefficient
- Soil water phase diffusion mass transfer coefficient
- Soil air boundary layer mass transfer coefficient
- Sediment-water mass transfer coefficient
- Sediment deposition velocity
- Sediment resuspension velocity
- Soil water runoff rate
- Soil solids runoff rate
Model output includes:
(for each of emission to air and emission to water)
- Overall environmental persistence
- Long-range transport potential
- Partition coefficients (Type 1)
- Z values
- Fugacity of each medium
- Intermedia transport rates and D values
- Reaction D values and loss rates
- Concentrations and amounts for each medium
- A summary diagram
This program is only available in compiled form. A "readme.txt" file with more detailed technical information is included in the zipped file.
Please read the software license before downloading the software. Use of the software constitutes your agreement to abide by the terms and conditions set out in the license agreement.