The GoldSim Contaminant Transport Module allows you to simulate the transport of mass through an environmental system by providing a number of specialized GoldSim elements. The most important of these is the transport pathway (of which there are several types).
Transport pathways represent physical components through which contaminant species can move and/or be stored, such as aquifers, lakes, sediments, surface soil compartments, and the atmosphere. You define the properties of the pathways, such as their geometry and which environmental media (e.g., water, soil, air) they contain. All pathways contain one or more environmental media. You define the general properties of each medium (e.g., its density) as well as the properties of each species in each medium (e.g., solubilities and partition coefficients).
You create an environmental system by defining a network of transport pathways, as shown below:
To create such a network, individual pathways are connected via mass flux links. A mass flux link defines the mechanisms by which species move between pathways. It represents a vector by species (i.e., it has one item for each species), since the flux will differ for each species being simulated, and has dimensions of mass/time.
Note: The Contaminant
Transport Module relies heavily on GoldSim's ability to create and manipulate
vectors. Therefore, in order to use the module, you must be comfortable
with using vectors in GoldSim.
Two major types of mass flux links and three special purpose mass flux links can be defined in GoldSim. In an advective mass flux link, a quantity of a medium is specified to flow from one pathway to another, carrying dissolved, sorbed, and/or suspended species with it. In a diffusive mass flux link, species diffuse between pathways according to a concentration gradient. Three special purpose mass flux links allow you to model processes that cannot be represented as using advection or diffusion. In a direct transfer mass flux link, species are moved from one pathway to another based on a user-specified transfer rate. In a precipitate removal mass flux link, species present as precipitated mass are moved from one pathway to another based on a specified transfer rate. In a treatment mass flux link, species are treated or filtered and are moved to from one pathway to another based on a specified treatment efficiency (a fraction).
Note: The Contaminant
Transport Module is a mass transport model, not a flow model. That is, it
does not directly solve for the movement of media through the environmental
system being modeled. Hence, you must directly enter the media flow rates
associated with an advective flux link (or provide GoldSim with the equations
for computing them).
Based on the properties of each pathway, the media in each pathway, the species, and the specified mass flux links, GoldSim computes the temporally varying concentrations in each pathway's media, as well as the mass fluxes between pathways. Hence, the fundamental output of a pathway element is a series of vectors:
•The mass (of each species) in the pathway;
•the concentration (of each species) within each environmental medium in the pathway; and
•the mass flux (of each species) to each of the pathways to which it is connected via mass flux links.
A typical pathway output is shown below:
Learn more about: