8.
Valence of the compound.
SESOIL model. Extensive validations that work
9.
Neutral hydrolysis constant.
under different site specific scenarios must be
10.
Base catalyzed hydrolysis constant.
done to calibrate the model. The model is struc-
11.
Acid catalyzed hydrolysis constant.
tured to simulate chemical transport for more than
12.
Biodegradation rate in the liquid phase.
a month. SESOIL accommodates physical, chemi-
13.
Biodegradation rate in the solid phase.
cal and biological changes in the contaminant
14.
Stability constant of compoundligand com-
leaked into the soil system.
plex.
The sensitivity analyses were conducted on ad-
15. Number of moles of ligand per mole of com-
sorption and volatilization for different soil types
pound complexed.
and in different climates. SESOIL's hydrologic cy-
16. Molecular weight of ligand.
cle has been found to be a good long-term predic-
tor for groundwater and surface runoff, evapo-
Application data
transpiration and infiltration. Uncertainty analysis
1. Number of soil layers.
is introduced into the hydrological cycle with
2. Number of years of data included in the data
probability density functions, which produces
set.
probability distributions of water balance and
3. Surface area of the compartment.
yields long-term seasonal averages of the water
4. Depth of each layer.
balance.
5. pH of each layer.
6. Intrinsic permeability of each layer.
SESOIL's demerits
7. Layer ratios for biodegradation in the liquid
Application of the SESOIL model in the Alaskan
phase.
environment requires extensive calibration and
8. Layer ratios for biodegradation in the solid
modifications because it does not function at tem-
phase.
peratures below freezing (Calabrese and Kostecki
9. Layer ratios for organic carbon content.
1992). The present code for SESOIL uses a single
10. Layer ratios for cation exchange capacity.
homogeneous soil column for the hydrological cy-
11. Layer ratios for the Freundlich exponent.
cle. In the Alaskan environment, because soils usu-
12. Layer ratios for adsorption coefficient.
ally have discontinuous and fractured permafrost
13. Monthly pollutant load (mass/unit area)
underneath, the model will need modifications.
entering each zone.
SESOIL will not work at sites having large vertical
14. Monthly mass of pollutant transformed in
variations in soil properties.
each sublayer by some other process.
The use of SESOIL is limited because it requires
site-specific data for calibration. When input data
15. Monthly mass of pollutant removed from
are not available, the model user must use com-
each sublayer by some other process
plex calculations to generate an input file. The user
16. Monthly ligand mass input to each sublayer.
needs the expertise to select the appropriate equa-
17. Index of volatilizationdiffusion occurrence
tions required for developing input data. In a situ-
from each layer.
ation where site-specific data are not available, us-
18. Index of subsurface pollutant runoff.
RISKPRO contains a file management system that
ing data published in the literature or default
simplifies data input for SESOIL. Default climatic
values might simulate results that are inaccurate
data for a particular state can be purchased and ac-
by orders of magnitude.
cessed through the RISKPRO package.
The model does not address the free product
movement in the vadose zone, such as depth of
penetration of bulk hydrocarbons, spread and mi-
SESOIL's merits
Being a part of PCGEMS and now RISKPRO, SE-
gration rate of free product, effects of large con-
SOIL is popular among regulators for risk as-
centrations of other organics on adsorption and
sessment studies. The compartmental module lets
mobility, and emission rate for a pure bulk hydro-
carbon on a soil surface. Furthermore, the model
many users run the model for specific data sets or
accommodates the migration of a single solute in
site conditions. The model had continuous sup-
an aqueous phase rather than a nonaqueous
port from EPA-OTS. Periodically, SESOIL is im-
phase. The model's inability to distinguish be-
proved and modified by the Oak Ridge National
Laboratory.
tween the NAPL phase or the water phase (domi-
The scientific community engaged in chemical
nant transport carrier) can create significant errors
fate modeling has accepted and recognized the
in simulations.
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