The Canadian

Centre for Environmental Modelling and Chemistry

Level I Model

Version 3.00 - September 2004

New in version 3.00!

A Level I simulation is of the equilibrium distribution of a fixed quantity of conserved (ie. non-reacting) chemical, in a closed environment at equilibrium, with no degrading reactions, no advective processes, and no intermedia transport processes (e.g. no wet deposition, or sedimentation). The medium receiving the emission is unimportant because the chemical is assumed to become instantaneously distributed to an equilibrium condition.

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 Level I Model assumes a simple, evaluative, closed environment with user-defined volumes and densities for the following homogeneous environmental media (or compartments): air, water, soil, sediment, suspended sediment, fish and aerosols.

This model is useful for establishing the general features of a new or existing chemical's behaviour. A Level I calculation gives the general impression of the likely media into which a chemical will tend to partition and an indication of relative concentrations in each medium. The results of changes in chemical and environmental properties may be explored.

Features of the Level I Program:
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 chemical database.
Supplies default values for all input fields which may be easily changed. These values are regarded as typical, as discussed in the text referred to earlier.
Provides context-sensitive Help.
Displays and prints the Level I 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 (csv) file.

This program was based on the following publication:

Mackay, D. 2001. "Multimedia Environmental Models: The Fugacity Approach - Second Edition", Lewis Publishers, Boca Raton, pp. 1-261.

Other related publications:

Mackay, D., Paterson, S., Kicsi, G., Di Guardo, A., Cowan, C.E. 1996. Assessing the Fate of New and Existing Chemicals: A Five Stage Process. Environ. Toxicol. Chem. 15: 1618-1626.

Mackay, D., Paterson, S., Di Guardo, A., Cowan, E.C. 1996. Evaluating the Environmental Fate of a Variety of Types of Chemicals Using the EQC Model. Environ. Toxicol. Chem. 15: 1627-1637.

Mackay, D., Paterson, S., Kicsi, G., Cowan, E.C., Di Guardo, A., Kane, D.M. 1996. Assessment of Chemical Fate in the Environment Using Evaluative, Regional and Local-Scale Models: Illustrative Application to Chlorobenzene and Linear Alkylbenzene Sulfonates. Environ. Toxicol. Chem. 15: 1638-1648.

The required input data are:
Chemical Properties:

  • chemical name
  • molecular mass
  • data temperature
  • Type 1 chemicals

  • - water solubility
    - vapour pressure
    - log Kow
    - melting point
  • Type 2 and 3 chemicals

  • - partition coefficients

    Environmental Properties:

  • volumes for all 7 media
  • densities for all 7 media
  • organic carbon content (soil, sediment & suspended sediment only)
  • fish lipid content (Type I chemicals only)
  • Emissions:

  • chemical amount
  • Model Output:

  • partition coefficients (Type 1)
  • Z values
  • fugacity of the system
  • concentrations and amounts for each compartment
  • 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.

    Minimum sytem requirements:
    Pentium-75MHz with 8 Mb of RAM running Windows 95, 98, or XP. On some systems it may be necessary to adjust your screen resolution.

    The Level I Model Version 2.11, released August 1999 continues to be available.

    For non-Windows users the BASIC, evaluative, Level I, II and III fugacity models are available.

    Please read the LEVEL I 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.


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    Last updated June 10, 2013.