AirWater Model

The AirWater model simulates air-water exchange processes which may be useful for 1) estimating chemical loss from treatment lagoons, ponds, and lakes, 2) estimating deposition rates of atmospheric contaminants, and 3) interpreting observed air and water concentrations to establish the direction and rate of transfer.

The AirWater model is a Level III model that provides a non-equilibrium steady-state assessment of chemicals in an air-water environment. Three types of neutral organic chemicals are treated: chemicals that partition into all media (Type 1), involatile chemicals (Type 2), and chemicals with zero or near-zero solubility (Type 3).

The model treats the following processes: volatilization, dry deposition, absorption, and rainfall (both wet dissolution and wet particle deposition). Default environmental properties are present but can be modified.

Features of the AirWater 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 standard environment for chemical comparison.
Provides context-sensitive Help.
Displays and prints the model calculations, as performed by the program.
Allows the printing of simulation tables, summary diagrams, and a small selection of charts.
Allows the program results to be saved as a comma separated value (csv) file, readable by many spreadsheet programs such as Excel.

This program was based on the following publications:

Mackay, D., Paterson, S., Schroeder, W. “Model describing the rates of transfer processes of organic chemicals between atmosphere and water”. Environ. Sci. Technol. 20 No. 8, 810-816, 1986.
Parnis, J.M., Mackay, D. “Multimedia environmental models: the fugacity approach”. 3rd ed. CRC Press, Taylor & Francis Group. Boca Raton, FL. 2021.

The required input data are:

Chemical Properties

Molar mass
Data collection temperature
Melting point
Vapour pressure
Henry’s law constant
Log K_OW
K_OC

Environmental Properties

Chemical concentration in water
Chemical concentration in air

Model output includes:

Z and D values
Fugacities of each compartment
Concentrations and amounts in each compartment
Chemical residence times
Summary diagrams
Transfer rates for each process

The program is available as an Excel spreadsheet which is still in the "beta" test phase. Please report any problems to Prof. Mark Parnis.

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.