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Environmental Modeling



Last updated: June 23, 2017



AQUATOX is the only general ecological risk model that represents the combined environmental fate and effects of conventional pollutants, such as nutrients and sediments, and toxic chemicals in aquatic ecosystems. It considers several trophic levels, including attached and planktonic algae and submerged aquatic vegetation, invertebrates, and forage, bottom-feeding, and game fish; it also represents up to 20 associated organic toxicants. It has been implemented for streams, ponds, lakes, and reservoirs.


For questions and comments about AQUATOX please utilize the AQUATOX Email Listserver.

AQUATOX is currently available for download from EPA as "EPA RELEASE 3.1 PLUS"  

In 2014, EPA Release 3.1 plus was released with several additions to the model.  Most importantly, the option to model nutrient limitation in plants based on internal rather than external nutrients was added.  The internal concentration of P and N in each plant is tracked with a separate state variable (See Internal Nutrients in section 4.1 of this document).  This allows for luxury uptake of nutrients during high-nutrient periods and expenditure of nutrient stores during lower-nutrient periods.  Concentrations of internal nutrients and derivative rates may be output from these new state variables as well as the nutrient-to-organism ratio for each plant.  Internal-nutrient simulations maintain nutrient mass balance throughout




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