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Model Report

Bioaccumulation and Aquatic System Simulator

Last Revision Date: 11/16/2009 View as PDF
General Information Back to Top
Model Abbreviated Name:

BASS
Model Extended Name:

Bioaccumulation and Aquatic System Simulator
Model Overview/Abstract:
BASS (Bioaccumulation and Aquatic )System Simulator) is a Fortran 95 simulation program that predicts the population and bioaccumulation dynamics of age-structured fish assemblages that are exposed to hydrophobic organic pollutants and class B and borderline metals that complex with sulfhydryl groups (e.g., cadmium, copper, lead, mercury, nickel, silver, and zinc). The model's bioaccumulation algorithms are based on diffusion kinetics and are coupled to a process-based model for the growth of individual fish. These algorithms consider both biological attributes of fishes and physico-chemical properties of the chemicals that determine diffusive exchange across gill membranes and intestinal mucosa. Biological characteristics used by the model include the fish's gill morphometry, feeding and growth rate, and proximate composition (i.e., its fractional aqueous, lipid, and structural organic content). Relevant physico-chemical properties are the chemical's aqueous diffusivity, n-octanol / water partition coefficient (Kow), and, for metals, binding coefficients to proteins and other organic matter. BASS simulates the growth of individual fish using a standard mass balance, bioenergetic model (i.e., growth = ingestion - egestion - respiration - specific dynamic action - excretion). A fish's realized ingestion is calculated from its maximum consumption rate adjusted for the availability of prey of the appropriate size and taxonomy. The community's food web is delineated by defining one or more foraging classes for each fish species based on its body weight, body length, or age. The dietary composition of each of these foraging classes is specified as a combination of benthos, incidental terrestrial insects, periphyton / attached algae, phytoplankton, zooplankton, and one or more fish species. Population dynamics are generated by predatory mortalities defined by community's food web and standing stocks, physiological mortality rates, the maximum longevity of species, toxicological responses to chemical exposures, and dispersal. The model's temporal and spatial scales are that of a day and of a hectare, respectively.
Keywords:
Model Technical Contact Information:
M. Craig Barber, Ph.D.
Ecosystems Research Division
U.S. Environmental Protection Agency
960 College Station Road
Athens, GA 30605-2700
Phone: 706-355-8110
FAX: 706-355-8104
e-mail: barber.craig@epa.gov
Model Homepage: http://www.epa.gov/athens/research/modeling/bass.html

User Information Back to Top
Technical Requirements
Compatible Operating Systems
Win98, Win2000, WinNT4.0, or WinXP
Other Software Required to Run the Model
Users running NT, 2000, or XP operating systems must have Administrator privileges on their systems in order to install the BASS v2.2 and BASSGUI software.
Download Information
BASS version 2.2 will be posted to the CEAM (Center for Exposure Assessment Modeling) website in August 2004.
Using the Model
Basic Model Inputs
BASS input data and commands are broadly classified into four categories: simulation control parameters, chemical parameters, fish parameters, and non-fish biotic parameters. Simulation control parameters provide information that is applicable to the simulation as a whole, e.g., length of the simulation, the ambient water temperature, water column depth, and any desired output options. Chemical parameters specify the chemical's physico-chemical properties (e.g., the chemical's molecular weight, molecular volume, n-octanol / water partition coefficient, etc.) and the chemical's exposure concentrations in various media. Fish parameters specify the fish's feeding and metabolic demands, dietary composition, predator-prey relationships, gill morphometrics, body composition, and initial conditions for the body weights, whole-body chemical concentra�tions, and population sizes of a fish's cohorts. Non-fish biotic parameters specify how benthos, terrestrial insects, periphyton, and plankton will be simulated.
Basic Model Outputs
BASS generates the following four types of output files:

1) an output file that summarizes the user's input parameters, any input errors detected by BASS, and any warnings / errors encountered during an actual simulation. This file has the same name of the executed project file with extension "MSG."

2) an output file that tabulates selected results of the simulation. Tabulated summaries include 1) annual bioenergetic fluxes and growth statistics (i.e., mean body weight, mean growth rate) of individual fish by species and age class, 2) annual bioaccumulation fluxes and statistics (i.e., mean whole-body concentrations, BAF, and BMF) of individual fish by species and age class, and 3) annual community fluxes and statistics (i.e., mean population densities and biomasses) of each fish species by age class. This file has the same name of the executed project file with extension "BSS."

3) a Post-script file that contains the plots that were requested by the user using the commands /ANNUAL_PLOTS and /SUMMARY_PLOTS. This file has the same name of the executed project file with extension "PLX."

4) a XML file that outputs daily values of community state variables as well as integrated annual flow summaries and annual means for selected state variables. Users can import this file into the BASS Output Analyzer to generate their own custom plots and tables.

User Support
User's Guide Available?
Barber MC. 2001. Bioaccumulation and Aquatic System Simulator (BASS) User's Manual Beta Test Version 2.1. EPA/600/R-01/035. U.S. Environmental Protection Agency, Office of Research and Development, Athens, GA, USA. Download the User's Manual here.

Model Science Back to Top
Summary of Model Structure and Methods
Fully described in the BASS version 2.1. User's Manual that can be download in PDF format.
Model Evaluation
Fully described in the BASS version 2.1.User's Manual that can be download in PDF format.
Case Studies
Barber, M.C. 2003. "A review and comparison of models for predicting dynamic chemical bioconcentration in fish." Environmental Toxicology and Chemistry 22: 1963-1992.

Barber, M.C., L.A. Su�rez, and R.R. Lassiter. 1987. "FGETS" (Food and Gill Exchange of Toxic Substances): A simulation model for predicting the bioaccumulation of nonpolar organic pollutants by fish. U.S. Environmental Protection Agency, Office of Research and Development, Athens, GA. EPA/600/3-87/038.

Barber, M.C., L.A. Su�rez, and R.R. Lassiter. 1988. "Modeling bioconcentration of nonpolar organic pollutants by fish." Environmental Toxicology and Chemistry 7: 545-558.

Barber, M.C., L.A. Su�rez, and R.R. Lassiter. 1991. "Modelling bioaccumulation of organic pollutants in fish with an application to PCBs in Lake Ontario salmonids." Canadian Journal of Fisheries and Aquatic Sciences 48: 318-337.


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