The Chemical Reaction package is used to model sorption, decay, and dual porosity mass transfer. The Chemical Reactions Package dialog contains the following options:
The Reset button deletes all of the data currently defined in the Chemical Reactions package and restores the package parameters to the default values.
Sorption and dual porosity mass transfer are enabled by selecting one of the options in the Sorption pull-down list. If sorption or dual porosity mass transfer is turned on, bulk density and sorption constants must be entered. The sorption and rate constants must be entered for each species. For the First order kinetic sorption (rate-limited sorption) option, the initial condition of the sorbed phase can be specified. For the Dual porosity mass transfer option, the initial condition of the immobile phase can be specified.
Decay is enabled by selecting the First order irreversible kinetic reaction option. If decay is enabled, the rate constants must be entered for each species.
By default, the bulk density, sorption constants, and rate constants are entered on a layer-by-layer basis. However, if the cell by cell input option is selected, an entire array of constants is entered for each layer.
In GMS, the data for the MT3DMS chemical reaction package can be entered on a layer-by-layer basis, but when you save an MT3DMS simulation from GMS, the data is saved as cell-by-cell arrays. Thus the IRCTOP variable in the chemical reaction package is always written as 2, meaning the data is written as cell-by-cell arrays always and not just one value per layer (even if all values in a layer are the same). With RT3D, IRCTOP can be 1 or 2 depending on how the user enters the data.
For more information on input values for this package consult the MT3DMS documentation.
Related Links:
Building an MT3DMS Simulation
Packages