Software Description
The Biosolids-Amended Soil: Level IV (BASL4) model calculates the fate of chemicals in soil. Chemical may be introduced to the soil by direct application or in association with contaminated biosolids. Application can be to the surface of the soil or injected into a deeper layer. Processes of chemical degradation, volatilization, leaching, erosion, diffusion and sorbed phase transport due to bioturbation are quantified. The degradation of the organic matter (OM) present in the soil and biosolids is also calculated. Applications of biosolids or neat chemical can occur at user-specified times during the simulation, as can ploughing events which result in the mixing of chemical and OM between the layers of soil.
BASL4 also contains six biota sub-models: two carrot models (equilibrium, simple dynamic), two soil invertebrate models (steady-state, dynamic) and two invertebrate-eating mammal models (steady-state, dynamic). These calculate concentrations in biota as a result of soil concentrations.
This model is useful for assessing the long-term, year-to-year fate and possible build-up of chemicals in biosolids-amended soils as well as for estimating risk of biotic uptake and bioaccumulation in soil-dwelling organisms.
Features of the BASL4 model:
- Provides a database for chemicals and chemical properties.
- Provides a database for soils and soil properties.
- Provides context-sensitive Help.
- Displays and prints the BASL4 model calculations, as performed by the program.
- Program results may be saved as a comma separated value (.csv) file viewable by standard spreadsheet software.
This program was based on the following publications:
- Hughes, L., Mackay, D. 2011. Model of the Fate of Chemicals in Sludge-Amended Soils with Uptake in Vegetation and Soil-Dwelling Organisms. Soil and Sediment Contamination 20, 938-961.
- Hughes, L., Webster, E., Mackay, D. 2008. An Evaluative Screening Level Model of the Fate of Organic Chemicals in Sludge-Amended Soils Including Organic Matter Degradation. Soil and Sediment Contamination 17, 564-585.
- Armitage, J., Gobas, F.A.P.C. 2007. A Terrestrial Food-Chain Bioaccumulation Model for POPs. Environmental Science and Technology 41, 4019-4025.
- Hughes, L., Mackay, D., Webster, E., Armitage, J., Gobas, F. 2005. Development and Application of Models of Chemical Fate in Canada: Modelling the Fate of Substances in Sludge-Amended Soils. Report to Environment Canada. CEMN Report No. 200502. Trent University, Peterborough, Ontario.
- Mackay, D. 2001. Multimedia Environmental Models: The Fugacity Approach, Second Edition, Lewis Publishers, Boca Raton, 194-199.
A guidance document is available for this model:
- Hughes, L., Mackay, D. 2011. Assessing the Exposure and Risk of Organic Contaminants in Soils: Using The Biosolids-Amended Soil Level 4 Model (BASL4). Report to Environment Canada.
The required input data are:
Chemical Properties
- Chemical name
- Molar mass (g/mol)
- Data temperature (oC)
- Degradation half-life in soil (d)
- Water solubility (mg/L or g/m2) and vapour pressure (Pa)
- Log (octanol - water partition coefficient), log Kow
- Mineral matter - water partition coefficient, Kmw (L/kg)
- Organic carbon - water partition coefficient, Koc (L/kg)
Soil Properties:
- Soil layer depth (m)
- Diffusion path distance (m)
- Volume fractions of air and water
- Mass fractions of slow- and fast-degrading organic carbon (OC)
- OC degradation half-lives for the fast- and slow-degrading (OC)
- Mass fraction of OC per unit mass of organic matter (OM)
- Density of organic matter and mineral matter (kg/m2)
- Air boundary layer thickness (mm)
- Molecular diffusivity in pore air and pore water (m2/h)
- Leaching rate (mm/day)
- Runoff rate rate (cm/year)
- Erosion rate (cm/year)
- Bioturbation rate (cm/year)
Chemical Application Events:
- initial concentrations in each soil layer
- number of chemical or biosolids applications
- For each application:
- Day applied or frequency (e.g., once a year) of applications
- Method of application (surface or injection)
- Type of addition (pure or biosolid)
- Biosolid composition (if applicable): fraction of fast- and slow-degrading OC, concentration of chemical in the biosolid
- For ploughing Events
- Number of events
- Day of event or frequency (e.g., once a year) of ploughing
Model output includes:
- All input data for the chemical
- All input data for the soil
- All input data for the biota
- Simulation time and event inputs
- Chemical fate in the soil
- Z and VZ values, fugacity
- Concentrations by phase and soil layer
- Amounts by phase and soil layer
- Chemical inventory for each layer
- Fluxes and D values
- Chemical fate in the biota
- Z values
- Diagrams (schematic only, no values) and charts of selected results
- Fugacity
- Concentrations
- Fluxes and D values (if non-equilibrium calculations are selected)
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.