The Sediment model simulates sediment-water exchange processes which may be useful for estimating 1) rates of accumulation or release from the sediment, 2) the concentration of chemicals in organisms living or feeding from the benthic region, 3) which transfer processes are most important in a given situation, and 4) the likely recovery times in the case of ‘in-place’ sediment contamination.
The Sediment model is a Level III model that provides a non-equilibrium steady-state assessment of chemicals in a sediment-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: sediment deposition and resuspension, diffusion, reaction, and sediment burial. Default environmental properties are present but can be modified.
Features of the Sediment 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 publication:
- Parnis, J.M., Mackay, D. “Multimedia environmental models: the fugacity approach”. 3rd ed. CRC Press, Taylor & Francis Group. Boca Raton, FL. pp 193-210, 2021.
- Publications that describe model exchange processes:
- Reuber, B., Mackay, D., Patersonm S., Stokes, P. “A discussion of chemical equilibria and transport at the sediment-water interface”. Environ. Toxicol. Chem. 6, pp 731-739, 1987.
- Eisenreich, S.L. “The chemical limnology of non-polar organic contaminants. PCBs in Lake Superior”. In: Sources and Fates of Aquatic Pollutants. Hites, R.A., Eisenrich, S.J., Eds., American Chemical Society, Advances in Chemistry Series 216, Washington DC, Ch 13, 1987.
- Diamond, M., Mackay, D., Cornett, R.J., Chant, L.A. “A model oof the exchange of inorganic chemicals between water and sediments”. Environ. Sci. Technol. 24, 713-722, 1990.
The required input data are:
Chemical Properties
- Molar mass
- Data collection temperature
- Henry’s law constant
- Log KOW
- KOC
- KMW
- Degradation half-life
Environmental Properties
- Chemical concentration in water
- Chemical concentration in sediment
Model output includes:
- Z and D values
- Fugacities of each compartment
- Concentrations and amounts in each compartment
- Half-times associated with each process
- Transfer rates for each process
- Summary diagrams
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.