The conceptual model presents all the biotic and abiotic elements defining the ecosystem under study.

In TerraSys™, the conceptual model includes:

• A graphic representation of the elements of the ecosystem
• The interactions between these elements
• The values of the variables defining the elements and the interactions
• The concentrations of all the contaminants in each environmental medium (water, air, soil, biotic elements, etc.).
  

The TerraSys™ interface allows fast and easy creation of the conceptual model of the ecosystem under study. To include an element in the model, simply drag the appropriate icon from the ecological components palette onto the workspace. Then define the properties of the element, if necessary. These properties can be rapidly defined by using the default values included in the database on ecological receptors.

TerraSys™ also includes various tools that perform verifications of the model and reduce the possibility of errors or missing values when defining the model.

		The TerraSys™ interface allows the fast and easy definition of the properties of the conceptual model elements. These properties correspond to the values of variables that will be used to model multimedias concentrations and exposure levels of receptors, as well as to calculate the risk indices.
		TerraSys™ includes several interactive tools for the definition of the conceptual model. These tools facilitate the definition of the model, even for the new user who does not have an exhaustive expertise in ecological risk assessments In addition to the information available in the various TerraSys™ databases, default values are also available for several other variables. TerraSys™ can also calculate the values of numerous variables from other easily available data.