BTEX Instant Aerobic Decay (RT3D module 1)
To simulate aerobic degradation of BTEX using an instantaneous reaction model. At each time step, within each grid cell, either hydrocarbon or oxygen (whichever is limiting) will be reduced to zero. This is implemented using the MT3D-USGS instant EA/ED reaction module (IREACTION=1) see below.Bedekar and others (2016), p. 16
Clement (1997), p. 19
BTEX Kinetic Decay using Multiple EAs (RT3D module 3)
To simulate kinetic-limited biodegradation of BTEX via five different degradation pathways: aerobic respiration, denitrification, iron reduction, sulfate reduction, and methanogenesis. This is implemented using the MT3D-USGS advanced reaction module (IREACTION=2).Clement (1997), p. 23-27
Bedekar and others (2016), p. 17-24
PCE Sequential Decay (RT3D module 6)
To simulate reactive transport coupled by a series of sequential degradation reactions (up to four components). The example considered here focuses on modeling dechlorination of PCE and its daughter products under anaerobic conditions. This is implemented using the MT3D-USGS Chain reaction module (IREACT=3).Clement (1997), p. 31-33
Bedekar and others (2016), p. 17
PCE/TCE Decay (aerobic/anaerobic) (RT3D module 7 without Cl)
To simulate degradation of PCE/TCE and their degradation products via both aerobic and anaerobic pathways. This is implemented using the MT3D-USGS Chain reaction module (IREACT=3) and the advanced reaction module (IREACTION=2). Note that in this implementation, sequential concentrations within each timestep are used to calculate anaerobic chain degredation, while oxygen and chloro-compound concentrations from the previous timestep are used to calculate aerobic degredation. While this implementation is similar to module 7 in RT3D, oxygen is added as a component and the chlorine produced during degredation is not simulated.Clement (1997), p. 33
Bedekar and others (2016), p. 17
Single Pair Instant EA/ED
To simulate the consumption of one species, an electron donor (ED), through the interaction with another species, an electron acceptor (EA), to the formation of a third (non-simulated) species. This can be used, for example, to simulate the injection of ethanol (the ED) to reduce toxic hexavalent chromium [Cr(VI)] (the EA) to its less toxic form [Cr(III)]. This option does not simulate the transport and fate of the species formed from the reaction—in this case, Cr(III). This reaction option is implemented, assuming that the reaction is instantaneous; kinetic processes are not accounted for. Furthermore, this option uses a simple mass balance approach to instantaneously deplete the mass of an ED on the basis of the mass of an EA and the mass ratio between them.Bedekar and others (2016), p. 16
IGW-NET does not yet support RT3D Module Equivalents
- BTEX Instant Decay using Multiple EAs (RT3D module 2 cannot be implemented in MT3D-USGS)
- Rate Limited Sorption (RT3D module 4 overlaps with a dual domain model)
- Double Monod (RT3D module 5 cannot be implemented in MT3D-USGS)
- User defined reaction modules with multiple EA/ED reactions.
External Links
- MT3D-USGSLanding page for MT3D-USGS
MT3D-USGS manual - Bedekar and others (2016)
Notes on implementation of RT3D - p.36
MT3D-USGS Input Information - USGS (2019)
- RT3D
Landing page for RT3D
RT3D manual - Clement (1997)
- MT3DMS (version 5.2 utilized implicitly when running variable density models with SEAWAT)
Documentation landing page - University of Alabama Hydrogeology Group
MT3DMS user manual - Zheng & Wang (1999)
MT3DMS v5 supplemental documentation - Zheng (2010)