vxEPA
United States
Environmental Protection
Agency
User Manual for EXPRESS, the
"EXAMS-PRZM Exposure
Simulation Shell"
RESEARCH AND DEVELOPMENT
-------
EPA/600/R-06/095
September 2006
User Manual for EXPRESS, the
"EXAMS-PRZM Exposure Simulation Shell"
Version 1.01.02, September 30, 2006
by
Lawrence A. Burns
National Exposure Research Laboratory
Ecosystems Research Division
Athens, GA
U.S. Environmental Protection Agency
Office of research and development
Washington D.C. 20460
-------
NOTICE
The information in this document has been funded by the Unites States Environmental
Protection Agency. It has been subject to the Agency's peer and administrative review, and it has
been approved for publication as an EPA document. Mention of trade names of commercial
products does not constitute endorsement or recommendation for use.
ABSTRACT
The Environmental Fate and Effects Division (EFED) of EPA's Office of Pesticide Programs
(OPP) uses a suite of ORD simulation models for the exposure analysis portion of regulatory risk
assessments. These models (PRZM, EXAMS, AgDisp) are complex, process-based simulation
codes that combine chemical and physical data required by EPA of industry with agronomic,
physiographic, and limnological descriptions of the environmental settings into which pesticides are
released. This complexity, while providing significant sophistication and specificity in analysis, has
posed difficulties in maintaining a transparent, reproducible process clearly devoid of arbitrariness
in parameterselections, exposure metrics, and interpretation of ecological and human health risks.
This project was undertaken to develop a Graphical User Interface (GUI) to combine
regulatory simulation models, their supporting databases, regulatory "scenarios" for major crops,
and data input screens for chemical properties into a user-friendly "simulation shell" lending itself
to consistent analytical practices and reproducible exposure and risk assessments. The resulting
computer software - Express (the EXAMS - PRZM E/posure Simulation Shell) - is a joint project
of EFED and ORD. EFED designed and funded an initial draft of the Express software, and retains
responsibility for developing and maintaining crop-specific modeling scenarios for regulatory
analyses. ORD is responsible for continuing development, quality control, maintenance, and public
availability of the software and its constituent models and analytical modules.
With the completion of Express, exposure metrics (peak, 4-day, 21-day, 60-day, annual)
for ecological and human health risk assessments can be easily and conveniently and, as
importantly, reproducibly, developed for any or all of the agronomic scenarios developed by EFED.
Probabilistic analyses (Weibull distribution) of these exposure metrics are derived by coupling 30-
year time-series of meteorological data to linked PRZM/EXAMS simulation studies. Express
significantly reduces the variability, lack of reproducibility by external analysts, and perceived
arbitrariness of EPA's regulatory processes for determining the safety and appropriate uses of
registered pesticides.
-------
Table of Contents
1.0 Introduction to EXPRESS 1
2.0 Acquiring and Installing EXPRESS 4
3.0 Starting EXPRESS 5
3.1 Project Directories and the Master Project File 7
3.2 Format of the Master Project File 9
3.3 Project Manager 11
4.0 Creating Input Files for PRZM-EXAMS Simulation 12
4.1 Project Design and Tier II Scenario Selection 13
4.2 PRZM Environmental Fate Parameters 15
4.3 EXAMS Environmental Fate Parameters 16
4.4 PRZM Application Data for Pesticide Use Patterns 20
4.5 PRZM-EXAMS Input File Creation 21
5.0 Starting and Running the PRZM-EXAMS Simulation 22
6.0 Evaluation of the PRZM-EXAMS Simulation 22
6.1 PRZM-EXAMS Grapher 23
7.0 PRZM Versions 24
8.0 Database and Scenario Management 25
9.0 Additional Capabilities Included in EXPRESS (Index Reservoir, PCA) 26
9.1 New Scenarios for Tiers I and II 27
9.2 Index Drinking Water Reservoir 27
9.3 Percent Crop Area (PCA) Adjustments 28
10.0 Using EXPRESS: Data Preparation and Input Example 29
Surface Water Exposure Inputs 29
EXPRESS Example Input Screens 31
11.0 Appendices 35
APPENDIX A: Format of Daily Value Meteorological Time-Series Files 35
APPENDIX B: Added Capabilities of ORD Mode 36
APPENDIX C: References 37
-------
REGIONAL TRANSPORT
DRY
DEPOSITION
PRECIPITATION
vn
EVAPORATION
SPRAY DRIFT
WIND EROSION
WITH-
DRAWAL
FROM
WELLS -
RUNOFF
J.
WATER
-RUNOFF
AGROUND-WATER
DISCHARGE
RECHARGE TO STREAMS
FROM
STREAMS
SEEPAGE
WITH-
DRAWAL
FROM
WELLS
ENTRY
THROUGH
WELLS
Transport Pathways of Pesticides
-------
1.0 Introduction to EXPRESS
The Office of Pesticide Programs (OPP) Environmental Fate and Effects Division (EFED)
has developed a tiered approach to determine the appropriate level of modeling needed to perform
a risk assessment for a pesticide. This tiered approach is designed to minimize the amount of
analysis required to evaluate any given chemical. Each of the tiers is designed to screen out
pesticides by requiring higher, more complex levels of investigation only for those compounds that
have not passed the previous tier. Each tier screens out a percentage of pesticides from having
to undergo a more rigorous review prior to registration or reregistration. "Passing" a given
assessment tier indicates that there is a low possibility of risk to the aquatic environment. "Failing"
an assessment tier does not, however, necessarily mean the chemical is likely to cause
environmental problems, merely that the assessment should continue on to the next higher
assessment tier. The intent of this tiered modeling system is to produce only as thorough an
analysis as is necessary for each pesticide, and thereby focus greatest resources and efforts
toward areas of greatest potential ecological threat. As a matter of policy, OPP does not take
significant regulatory action based solely upon the results of screening models.
"Tier I" models provide simplified, highly conservative initial screening risk assessments of
pesticides. For Tier I analyses, the Environmental Fate and Effects Division (EFED) of the U.S.
Environmental Protection Agency's Office of Pesticides Programs (OPP) uses, inter alia, two
"meta-models," GENEEC2 (Parker et al. 1995) and FIRST, developed by summarization of
standardized linked simulations using the EPA PRZM and EXAMS models. Dynamically (file
transfer-) linked Pesticide Root Zone Model (PRZM) and Exposure Analysis Modeling System
(EXAMS) simulations are used for a "refined" (Tier II) estimation of pesticide concentrations in
surface waters used as drinking water sources and for aquatic ecosystem exposure assessments.
PRZM is a one-dimensional, dynamic, compartmental model used to simulate chemical movement
in unsaturated soil systems within and immediately below the plant root zone (Carsel et al. 1984,
Carsel et al. 1985, Suarez 2005). EXAMS contains a set of process modules that link fundamental
chemical properties to the limnological parameters that control the kinetics of fate and transport of
chemicals in aquatic ecosystems (Burns et al. 1982, Burns and Cline 1985, Burns 2000). Multiple-
year pesticide concentrations in the water column and benthic sediments, generated by the PRZM-
EXAMS simulations, are analyzed to produce, for each year, the single-day peak concentration,
the maximum 24-hour, 96-hour, 21-day, 60-day, and 90-day mean concentrations, and the mean
annual concentration. From simulation results encompassing the period of record for the available
meteorological data, upper 10th percentile concentrations are made available in tabulations and
-------
graphics for comparison with ecotoxicological and human health levels of concern (LOG).
Documentation and access for these models can be found at:
• GENEEC2: http://www.epa.gov/oppEFED1/models/water/index.htm
• FIRST: http://www.epa.gov/oppEFED1/models/water/index.htm
• PRZM: http://www.epa.gov/ceampubl/gwater/PRZM3/index.htm
• EXAMS: http://www.epa.gov/ceampubl/swater/EXAMS/index.htm
The standard PRZM-EXAMS runoff modeling scenario captures the properties and
dimensions of an agricultural field draining into water bodies for subsequent drinking water safety
and aquatic exposure assessments. PRZM links two subordinate models (PRZM per se and
VADOFT), that combine differing root zone and vadose zone characteristics into a single simulation
to predict pesticide transport and transformation in the crop root and unsaturated zones, and edge-
of-field losses in runoff waters and eroded sediment. Each PRZM modeling scenario represents
a unique combination of climatic conditions, crop-specific management practices, specific soil
properties, site-specific hydrology, and pesticide-specific application and dissipation (fate and
transport) processes. Each PRZM simulation is conducted for multiple years (usually 30, spanning
the years 1961 -1990) using historical weather data (Burns 2001) to provide a probabilistic exposure
characterization for a single site. Daily edge-of-field loadings of pesticides dissolved in runoff
waters and sorbed to entrained sediment, as predicted by PRZM, are discharged into a standard
water body simulated by the EXAMS model. The EXAMS model accounts for subsequent
hydrologic transport, volatilization, sorption, hydrolysis, biodegradation, and photolysis of the
pesticide.
EXPRESS (the EXAMS - PRZM Exposure Simulation Shell) has been created to facilitate
a rapid and consistent Tier II assessment of aquatic pesticide exposure for multiple geographic and
agronomic settings. EXPRESS was a joint project of the U.S. Environmental Protection Agency's
Office of Pesticide Programs (OPP) and its Office of Research and Development (ORD). OPP
contracted with Waterborne Environmental, Inc., for initial development of the shell code, and
retains responsibility for development and maintenance of the crop-specific modeling scenarios.
ORD developed and maintains the constituent Tier II models (PRZM and EXAMS) and the
meteorological databases. Although EXPRESS provides access and output file management for
GENEEC2 and FIRST, EXPRESS does not provide a Graphical User Interface (GUI) to facilitate
use of these models for exposure assessment. Users wishing to run these Tier I models may wish
to download their respective user manuals from the http sites cited above; the EXAMS and PRZM
user manuals are provided with EXPRESS.
-------
EXPRESS, developed using the WinteracterGUI development system (version 7.1a)fromlSS Ltd.,
provides the following features:
User-friendly scenarios and parameters in a Microsoft Windows environment.
Simulation of an unlimited number of crop "scenarios" in a single run in less than 15
seconds per crop.
• Automatically runs both the ecological farm pond and the drinking water index reservoir
scenarios.
Provides options for simulating selected groupings of scenarios for special purposes (e.g.,
cumulative assessments).
• Provides flow/no-flow and steady/unsteady flow options for the farm pond and index
reservoir, respectively.
Simulates parent pesticide and degradates.
• Provides options for mixing types of applications, spray drift calculations, incorporation
depth, etc., in the same simulation.
Runs alternative versions of PRZM with the same initial setup to permit comparisons.
Provides graphical and tabular ranked summary results for all scenarios together.
• Provides graphical and tabular output for each individual scenario.
• Provides graphical and tabular output for water column and benthic sediment zones.
Provides a graphical and tabular PRZM water balance summary for each scenario run.
Each graph and table can easily be printed or exported to reporting software.
• Time-series files for transmission to OPP's Health Effects Division (HED) for analysis of
drinking water source contamination are automatically generated and inventoried. These
files are in comma-separated-value (csv) format suitable for direct import into, for example,
Excel for further analysis and plotting.
• New scenarios can be added or existing scenarios quickly and easily changed through a
password-protected facility.
Saves all run information in a single, email-able file from which the entire, multi-crop
simulation can be recreated. This master file can be shared among multiple modelers
working on the same problem set, or archived so that runs can be reproduced later or with
future versions of PRZM and/or EXAMS.
EXPRESS also includes the Tier I screening models FIRST and GENEEC2 (Section 9), but
does not facilitate their use beyond providing project results file management and access.
-------
2.0 Acquiring and Installing EXPRESS
The EXPRESS user interface software can be obtained (gratis) from the EXPRESS main
page at EPA's Center for Exposure Assessment Modeling (CEAM):
http://www.epa.gov/ceampubl/swater/EXPRESS/.
EXPRESS uses standardized files of weather data that must be downloaded separately and
installed in the "...\EXPRESS\stdmet\" directory. Thirty-year (1961-1990) data files of U.S.
meteorological data are available via the "Meteorological Data" link at the EXPRESS main page,
or go directly to
http://www.epa.gov/ceampubl/tools/metdata/index.htm, and download file DVF_ALL.EXE. The
format of these data files is provided in Appendix A.
EXPRESS runs on PCs under the Windows operating system (installation has been tested
on Windows 98, NT, 2000, and XP). To install, click on the downloaded files
(lnstall_EXPRESS.EXE and DVF_ALL.EXE) and follow the on-screen directions. All required files
will be installed automatically along the user-selected installation path ...\EXPRESS\. Download file
"lnstall_EXPRESS.EXE" is 40 MB; "DVF_ALL.EXE" is 65 MB. EXPRESS requires a screen area
setting of 1024x768 or higher, and will issue an error message if it is invoked from a lower
resolution display. The free Adobe Reader is required to access model User Guides and location
maps. EXPRESS is removed using the standard Windows uninstall procedure, i.e., via "Settings
- Control Panel -Add/Remove Programs", followed by deletion of the directory structure along with
any remaining user-modified project or meteorological data files.
To manually move the installation to a different directory or disk drive follow these steps:
1) Use Windows Explorer to either copy or move EXPRESS in its entirety to the
desired drive. The directory structure must remain exactly as installed, using
"EXPRESS" as its base.
2) Create a new (or modify the existing) Windows shortcut to point to the new drive (a
modifiable shortcut file is supplied in the ...\EXPRESS\EXPRESS\folder).
The latest PRZM release notes are available at
the latest EXAMS release notes are
available at
-------
3.0 Starting EXPRESS
Following installation, EXPRESS is started by double-clicking on EXPRESS.EXE or by
using any shortcut to the EXPRESS executable. The starting screen (Figure 1) appears, depicting
a stream flowing through an agricultural landscape, providing access to EXPRESS' main
functionalities.
Select/Create Project Directory i Project Management I I OPP ORD I
Help
GEOCEC
^i
1 USEPA
Current Project Directory:
Figure 2. EXPRESS opening display screen
The functions available from EXPRESS' initial screen are:
Navigate to a project folder, or start a new project:
Recall, annotate, or delete existing projects:
Pm\eci Directory
Check software and database version numbers and dates; access EXPRESS, EXAMS, and PRZM
User Guides: | Hefe
-------
Operate EXPRESS in regulatory mode for submission of studies to EPA's Office of Pesticide
Programs:
Operate EXPRESS in ORD (Office of Research and Development) mode with additional flexibility
and input data control (see Appendix B for details):
- access the FIRST Tier I model
- access the GENEEC2 Tier I model
- prepare chemical and agronomic input data
- start PRZM/EXAMS simulations
- analyze and display PRZM/EXAMS results
-------
3.7 Project Directories and the Master Project File
The first step in using EXPRESS is to select (or create) an active project directory. All
relevant input/output data of a simulation run is saved in this directory; EXPRESS requires full
read/write permission for the specified directory. New directories can be created on hard disks or
network drives using EXPRESS itself, Windows Explorer, or other tools. Long filenames are
supported. The default directory upon initiation of EXPRESS is undefined or "unset." When the
Select/Create Project Directory;
button is pushed, the input screen in Figure 2 is displayed.
The initial project directory display is always the default project folder
"...\express\PROJECTS." To select an existing directory, use the scroll bar to move to the desired
drive\directory (if it is not already visible in the selection window), and then double-click on it. The
selected folder (The terms "drive\directory" and "folder" are equivalent) will then replace the
"...\express\PROJECTS" text initially displayed (see Figure 2). Pressing the OK button at this time
will set the selected drive\directory to be the current project directory. To create a new project
directory, type a "\" followed by the new project directory name on the line in Figure 2 labeled
"create new directories here." For example, typing "\newchem1" at the end of the folder selection
window creates a new project directory called "...\express\projects\newchem1." Only one
C:\express\PROJECTS
express
:_Lj does
;__j examiner
:_J EXAMSEMV
Li] EXPRESS
: I met
:_D progs
: " I progsoth
± ' | new
+: —I trichlorochern
: ''\ STDEFED
Use scroll bar to
search for other
directories or drives
Cancel
Figure 2. Create or select the active project directory
-------
subdirectory can be created in a single step: entering, for example, "\newchem1\app1", is not
supported. To create dependent subdirectories (i.e. .folders within folders), first create \newchem1,
press the "OK" button, then reselect the Select/Createjproj&ctrjoictory_
button and enter "\app1." This will create the "...\express\projects\newchem1\app1" projects
directory.
This option also serves to switch between previously
created projects (which can contain multiple crop
scenarios). (Section 3.3 describes the "project
manager," a facility for cataloguing previously created
scenarios.) Each simulation scenario can be modified,
re-run, or re-analyzed by choosing a project directory
in which simulations have previously been executed.
A master project file (MPF), named "master.fpj," is
created within each active project directory. This file
contains all scenario-specific information necessary to
characterize the entire simulation project in the active
project directory. After an active project directory has
been chosen, EXPRESS checks to see whether an
MPF is present in this directory. If an MPF is present,
EXPRESS returns an output window (Figure 3) for
choosing the action to be taken. The available options
are: Copy, Edit, Browse, Reselect, EMail, Rerun,
and View. The function of each of these options is
further described in Figure 3. If no MPF is found,
EXPRESS starts the input generator program.
Figure 3. Options if Master Project File
exists in currently selected directory
The Master Project File contains all the
information needed to identify and replicate an EXPRESS analysis. The MPF enables convenient
exchange of EXPRESS simulation scenarios among EXPRESS users. Once an MPF received from
another user has been copied into a valid folder, it is available to the receiving analysts as an active
project directory. This (MPF) feature makes it possible to easily re-create each crop-use scenario,
pesticide chemistry, and the application-specific model inputs used to generate a particular
EXPRESS analysis. Because every master project file is named "MASTER.FPJ," only one MPF
can be stored in a project folder.
This directory a
;* Project Fil*
I Copy
Edit
Browse
Resetect
EMail
Ffenin
¥taw
Cspy the Master Project File to a
new directory
Eel the Master Propel Hie
Thil will ill
ind
Srswse/Print (he Matter Prated
Hie
Choo** « Create
directory
EmaiHhe Maitsr Project File to
EPA (or iiiititnci, or
SopUormly) 1st colleagues
Rerun
limulaltonW utftg Ihii Muter
Project He
Vlewrwyfe ot
simylationM
Caneal
-------
3.2 Format of the Master Project File
The definitions of the scenario, pesticide chemistry, and application-specific parameters are
compiled according to formats used in the PRZM input parameter file (*.inp) (Suarez 2005). A
typical example of a Master Project File is given in Figure 4. This sample Master Project File was
created for a parent compound, a single scenario, and a single application.
The information included in the Master Project File is complete, but omits EXPRESS default
settings to save space. The following information is coded in the individual lines of the Master
Project File:
Line 1: Date on which the file was created by the EXPRESS.
Line 2: Version and date of EXPRESS
Line 3: Name of the parent compound
Line 4: Identification of Group File, if any
Line 5: Scenario type (3 = Standard Tier II)
Line 6-9: Index of selected scenarios (1 = used; 0 = not used for this project)
Line 10: Chemical input data controls
Line 11: EXPRESS operational mode (OPP or ORD)
Line 12-24: Chemical properties (parent and metabolites)
Line 25: Number of specific application sequences
Line 26: Application input data controls
Line 27-34: Application parameters for each crop
Line 35: EXAMS chemistry and flow process controls
Line 36-47: EXAMS process parameters
This file must not be modified by hand in anyway. This description of the MPF is provided
solely for informational purposes. Attempts to modify this file will in all probability result
in loss of data and EXPRESS execution failure.
The MPF is not designed to provide a complete input summary of model parameters with
complete descriptions of all input values and their units. The MPF does, however, provide complete
documentation of EXPRESS input values used for a specific analysis.
-------
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Master Project File Created: 2006-08-28 at 13:02:43
EXPRESS v. 1.01.01 (2006-08-12)
Parent Compound: Chemical A
Scenario Group File: 0 No GroupFile
Scenario Type: 3
PRZM Crop Selector: 00000100000000000000000000000000000000000000000000
PRZM Crop Selector: 00000000000000000000000000000000000000000000000000
PRZM Crop Selector: 00000000000000000000000000000000000000000000000000
PRZM Crop Selector: 00000000000000000000000000000000000000000000000000
Chemical Input Data Controls: 11010
EXPRESS Operational Mode: OPP
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
Chemical Name(s): Chemical A
Molecular Weight:
Plant Uptake Factor:
Partition Coefficent Method:
Partition Coefficient Value:
Vapor Pressure:
Solubility :
Soil Degradation Half-Life:
% Degradate formed:
Foliar Half-Life:
Foliar Washoff Coefficient:
Air Diffusion Coefficient:
Enthalpy of Vaporization:
Application DataSets Number:
Application Parameters:
Days Relative/Absolute :
Month :
CAM :
Depi (cm) :
Rate :
Drift Farm Pond % :
Drift Index Reservoir % :
Efficiency % :
Product chem./hydr. status:
Aerobic Metabolism (days) :
Q10 Base Temperature :
Q10 Limnetic Bacteria:
Anaerobic Metabolism (days):
Q10 Base temperature:
Q10 Benthic Bacteria:
Photolysis Half-Life (days):
Number of Hydrolysis Obs.:
Hydrolysis Temperatures:
Hydrolysis Cl:
pH Hydrol. Cl:
I
30.00
0.1000E-05
100.0
30.00
0.000
0.000
0.5000
4300.
20.00
1
1 1
221
4.000
0.5000
5.000
16.00
95.00
111
20.00
25.00
2.000
100.0
25.00
2.000
10.00
3
25.00
3.000E+01 3.000E+01 3.000E+01
5.00 7.00 9.00
Melting Point: -99.00
10
-------
3.3 Project Manager
The "Project Manager" tracks and maintains EXPRESS simulation scenarios. Information
for each project created is stored in a database that includes the location of the project folder, the
date and time the project was created, the name of the primary chemical, and optional user-
supplied commentary/annotation (Figure 5). A record is added (or updated) in the Project Manager
database each time the Write option is executed in the input generator.
1
2
1
4
i
i
?
8
Gtemteal
Ma&sthiBn
Kfetehion
Trishta roslMMn
yaneoieb
MitwMsato
Maldi™
BASFOhemioal
OmmioaiA
Action
^BBp
Keep
-------
4.0 Creating Input Files for PRZM-EXAMS Simulation
The input generator (Figure 6) creates an exposure model input data set in five consecutive
steps. Start the input generator by pressing the inputs button on the main EXPRESS screen
(Figure 1). (Recall that the project directory must be selected prior to starting the input generator.)
The input data tabs (Figure 6) have the following functions.
torn
Design Project PRZM-Efate EXAMS-Efate Application Write Exit
'inn _
Database Manaqement
jfA
Figure 6. EXPRESS Input Generator
option:
Design Project:
PRZM-Efate:
EXAMS-Efate:
Application:
description:
Select one or more of the predefined (EFED Standard Tier II) scenarios
Define the physical-chemical and environmental fate ("Efate") pesticide
properties needed for PRZM.
Define physical-chemical and "Efate" properties needed for EXAMS.
Choose application date(s), method, rate(s)
12
-------
Write:
Write PRZM-EXAMS input files, create (or update) the Master Project File,
and add or update a record in the scenario manager data base
All five of these data creation steps should initially be completed in the suggested order (Design,
PRZM-Efate, EXAMS-Efate, Application, Write) to guarantee proper creation of the input file set.
Users of EXPRESS should be generally familiar with the use of simulation models for
environmental risk assessments. Further information for EXAMS, including detailed model
documentation, can be found and, for
PRZM, at For authorized Tier II
simulations, process implementations and parameter definitions should follow EFED
guidelines and reflect the intended uses of the compound. (These guidelines are available
on-line at http://www.epa.gov/oppEFED1/models/water/input 28 O2.htmj
4.1 Project Design and Tier II Scenario Selection
To begin scenario definition, click on the Project Design menu item (Figure 7). The "Project
Design" screen (Figure 7) then presents a pick-list of predefined scenarios. The scenarios are
defined by State, crop, soil properties,
meteorology, and Major Land Resource Area
(MLRA) (SCS 1981). There are approximately
85 EFED standard scenarios currently
included within EXPRESS. As additional
scenarios are created and certified by EFED,
they can be added to the set. This database
can only be altered by an authorized database
manager (see Chapter 8).
One, many, or all of the currently
available scenarios can be selected for
inclusion in a project. In addition to scenario
selection, the number and transformation
product chemistry of chemicals to be
simulated is chosen on this screen. Both
EXAMS, and PRZM from 3.12.2 onwards, can
N umber /Relationship of Modeled Pesticides :Qne Parent No Metabolite;
Select EFEO Tiei II Crop(;.)
Current Stoup: ia'JSad'OPP/fFED Scenario!
:MICherrv MLRA-96
iORChiislrna-Trees MLRA-2
:» Citrus MLRA-17
.FL Citrus MLRA-1S64
:pHCotfeeMLRA-2?0
ill Corn MLRA-108
: MS Com MLRA-134
:NCCorn-E MLRA-1534
: OH Com MLRA-111
: PA Com MLRA-148
:CA Cotton MLRA-17
i MS Cotton MLRA-134
iNC Cotton MLRA-133A
:Fl Cucumber MLFIA-156A
OR Filberts MLRA-2
• OR Grass Seed MLRA-2
: OR Hop? MLRA-2
:CA Lettuce MLRA-14
'• OR Mint MLRA-2
iCADniom MLRA-17
Select AiH)e;elect Alt:
PHZM Crop S
USA Crop Acr
Figure 7. Selecting scenarios
13
-------
model the creation and subsequent fate and transport of chemical metabolites and transformation
products of the pesticides or toxic chemicals under evaluation. EXPRESS allows for a choice
among four possible transformation product chemistries:
1) One Parent, No Metabolites
2) One Parent -> One Metabolite
3) One Parent -> Two Metabolites
4) One Parent -> First Metabolite -> Second Metabolite
The PRZM and EXAMS User Manuals include detailed discussions of metabolite simulation.
The EXPRESS input generator does not permit simulation of metabolites in PRZM 3.12 beta (see
Chapter 7 for a discussion of PRZM model versions). Because the current (3.12.2) version of
PRZM is restricted to three chemical entities, this limitation is also enforced in EXPRESS and
EXAMS. __^^^^^^^^_^^^_^^_^^__
A final option on this screen,
the "Scenario Group Functions," allows
for the creation or selection of scenario
groupings. Two examples of scenario
groupings are illustrated in Figure 8,
"OP" (organophosphate pesticide)
1STDEFEDJ3RP Standard EFEFJ See
?_GP.6RP [oigaiia-PhBaphates
scenarios and "Standard EFED"
scenarios. The "Standard EFED" -
"~ do not use a group Hie
Currently setaited group f iff
scenarios (Group 1) are selected by
default. To create a new scenario
group, first select the desired
scenarios (from the screen shown in
Figure 7), and then press (mouse-
click) the "Scenario Group
Functions" button. The scenario
group manager then opens (Figure
Figure 8. Scenario Group Manager
Figure 9. Defining a scenario group
8). Next, push (click) the "Save the
currently selected scenarios to a Group File" button. The "Save Group File" panel (Figure 9) then
opens, with space for a file name (required) and for descriptive text and annotation comments for
the new group file (strongly recommended).
14
-------
4.2 PRZM Environmental Fate Parameters
Chemical 1 i j j
|- PRZM 3.12 Tier II Standard Analysis-
Chemical Name jForchfoflenuron
Molecular Weight
Solubility (mg/L)
Partition Coefficient Method
Partition Coefficient Value
Aerobic Soil Half-life (days)
248 00
1763.000
S" Enter Chemical-Specific Foliar Process Data
Plant Uptake Factor j 6.0000
Foliar Half-life (days) ! 6.000E+00
Foliar Washoff Coefficient I 6.50000
Volatilization from Soil
Vapor Pressure
Units of Vapor Pressure
3.50E-10
jTorr (mmHg) »•
jEnter Chernical-Specific Data
Air Diffusion Coeff. (cm2/daji) ! 4300.0
Enthalpji of Vaporization (kcal/mole) j 20.000
Cancel
Figure 10. PRZM Chemical Parameters
The PRZM Chemical Parameters screens include data entry fields for the following
chemical properties: molecular weight, solubility, Koc/Kd, vapor pressure, degradation half-life
(applied equally to dissolved and sorbed phases), plant uptake factor, foliar half-life, foliar washoff
coefficient, air diffusion coefficient, and enthalpy of vaporization (Figure 10). When simulating
transformation products or metabolites, enter a parameter set for each chemical. Vapor pressure
units are specified at the Chemical 1 input pane; vapor pressures for other chemicals must be
entered in the units so selected. Enter the percent transformed from the parent to the
transformation product or metabolite as 100 * (mole of product)/(mole of parent); EXPRESS
15
-------
applies the ratio of compound molecular weights prior to entry in the PRZM input files. Chemical
dissolved in the soil solution and that sorbed with the soil particulates are parameterized with the
same product yield in EXPRESS Tier II simulations. The product yield parameter can be entered
as a zero (0) for those cases in which transformation processes are only relevant for the aquatic
ecosystems (aquatic product yields are entered on the EXAMS data entry screen).
All compound-specific parameters (parent and metabolites) can be saved in a chemical
database provided with EXPRESS. The same chemistry can then be used for additional
simulations with alternative soil, crop, and application scenarios. Database maintenance functions
include a facility for deleting a single entry (Chapter 8).
4.3 EXAMS Environmental Fate Parameters
The EXAMS Efate Input screen provides data entry fields for transformation process half-
lives; these are converted to chemical dynamics parameters (rate constants) by EXAMS (Figure
11).
Solubility, Koc, and vapor pressure are transferred to EXAMS from the PRZM Chemical
Parameters data entries (Figure 10). As with PRZM, when simulating transformation products and
metabolites the product half-lives must be entered on a separate tab for each secondary chemical.
(Although EXAMS can accommodate an arbitrary number of chemicals in a single simulation, the
current version of PRZM, and perforce EXPRESS, is limited to three chemicals.) A 0.0 (zero) entry
for a half-life is used to indicate that the transformation process is inactive (i.e., not, as a literal
interpretation might suggest, that it is immeasurably rapid). Particular care is required with the
hydrolysis inputs: at least three non-zero half-lives at three different pH values must be entered
(conforming with EPA guidelines), or hydrolysis will not be simulated. (EXPRESS will accept up to
10 pH-half-life observations.) In Figure 11, were the example chemical reacting by a neutral
hydrolysis pathway only, the same half-life (e.g., 10 days) would have to be entered for pH 5, 7,
and 9: EXPRESS requires entry of all three values for correct calculation of rate constants.
Aerobic and anaerobic metabolism half-lives should be corrected for the contribution due to abiotic
hydrolysis prior to entry on these data screens.
In addition to product chemistries, the pathways of formation must also be defined.
Transformation product information is communicated to EXAMS by setting an identifying number
for each parent and daughter chemical, for each process generating a product, for the reactive
form of the parent molecule, and for the process yield. The EXPRESS input parameters are:
16
-------
CHPAR, the chemical parent number; TPROD, the transformation product number; NPROC, the
identifying number of the transformation process generating the TPROD; RFORM, to identify the
reactive form of the parent molecule, and YIELD, the (Mole/Mole) transformation process yield from
this pathway.
V Farm Pond (no How)
V Index Reservoir (steady reservoir flow, m3/hr)
I Chemical 1 !! ! •
Half-Lives ("metabolism" must be manually corrected for interferences by hydrolysis etc. prior to entry]
Bacterial Biolysis in Water Column Bacterial Biolysis in Benthic Sediment
Aerobic Metabolism (days) j 1.156E+03 Anaerobic Metabolism (days) I 2.2161+02
Hydrolysis
Test Temperature (C) I 25.0
Number of Different pH (3 or more] 13 ~"w I
Test pH
Half-life (days)
1
2
3
5.00
7.00
9.00
O.OOOE+00
O.OOOE+00
O.OOOE+00
Aquatic Direct Photolysis (days)
1.430E+02
Cancel
Figure 11. EXAMS Efate Input Screen
The generating transformation process is specified using the following numerical codes for
NPROC:
1 = specific acid hydrolysis
2 = neutral hydrolysis
3 = specific base hydrolysis
4 = direct photolysis
5 = singlet oxygen
17
-------
6 = free radical oxidation (e.g., hydroxyl radical)
7 = water column bacterial biolysis
8 = benthic sediment bacterial biolysis
9 = reduction
Twenty-eight reactive form numerical codes are available for specifying RFORM, in addition to
which total dissolved etc. can be specified using an RFORM code of
29 = all dissolved species
30 = all sediment-sorbed species
31 = all doc-complexed species
32 = all biosorbed species
(The complete list of RFORM specifications is given in Table 1.) In EXPRESS, the process yield
must be entered as the simple mole of product per mole reacted (i.e., EXAMS temperature-
dependent product yields are not currently supported).
Table 1. Product Chemistry "Reactive Forms" for EXAMS
Ionic species
Valence
Forms:
Dissolved
Solids-sorbed
doc-complexed
Biosorbed
Neutral
0
1
2
3
4
Cations
1 +
5
6
7
8
2+
9
10
11
12
3+
13
14
15
16
Anions
1-
17
18
19
20
2-
21
22
23
24
3-
25
26
27
28
Total
(all)
29
30
31
32
For example, if the CHPAR parent compound (e.g., parathion) is chemical 1, and the
TPROD product (e.g., paraoxon) is chemical 2, then a reaction scheme in which direct photolysis
of DOC-complexed parathion yields a 50% generation of paraoxon by pathway 1, and hydroxyl
radical oxidation of dissolved parathion produces paraoxon in mole-for-mole formation by pathway
2, would be specified in EXPRESS as illustrated in Figure 12.
18
-------
||J:^^
Farm Pond (no flow)
Index Reservoir (steady reservoir flow.. m3/hr]
Chemical 1 j Chemical 2 ;
Number of ; •}
Different ^
Transfer- 13
rnation ; 4
Reaction ; 5
Pathways: j 6
Pathways
CHPAR
TPROD
NPROC
RFORM
YIELD
Pathl
Path 2
1
1
2
2
4
6
3
1
0.500
1.000
113
CHPAR = Parent Number
TPROD = Metabolite Number
NPROC = Transformation process
RFORM = Reactive form (dissolved, etc.)
YIELD = Mole of producti^mole of reactant
Cancel
Figure 12. Example of transformation product data entry for EXAMS
Section 2.4.1 ("Product Chemistry") of the EXAMS manual (Burns 2000) (also available
through the primary EXPRESS screen's "HELP" button) should be consulted for further explanation
on entering pathway data.
In addition to product chemistry parameters, the user can also select whether a static pond
and/or a steady reservoir flow rate scenario will be simulated. The current default is set for both of
these options to be in effect. The static pond does not change volume, nor does it allow for
hydrologic export of chemical. Turning the static pond option off (un-checking the box) lets the
pond detention time vary (monthly) based on an EXAMS analysis of evaporation and rainfall from
the Crop Scenario meteorological file and daily PRZM runoff volumes. The steady flow reservoir
scenario uses a period-of-record average daily runoff from the PRZM scenario to calculate the flow.
Turning the steady flow reservoir option off will, as with the farm pond scenario, allow EXAMS to
calculate a monthly detention time for the reservoir based on meteorology and daily PRZM runoff.
19
-------
4.4 PRZM Application Data for Pesticide Use Patterns
The Pesticide Application Data screen contains data entry fields for the number of
applications, application timing, application method, application rate, depth of incorporation, and
chemical application method (Figure 13). The same values can be applied to all selected scenarios,
•' " Select/specifj' She same application parame ett for all ere
•'» Sebct/: pacify diffe ent applied on parameters for each c
: Current Crop and Status;
! 3 MSToion"""MLRA-T3l7Unmod^led"
: Inde* Reservoir PCA >%} [""""" 2000
jps {PCA, daies, rates, liming, etc.!
rap
Select Crap :
First Previous Ne$ Last i
_*»j jtj [H »• I
Tofal Number of Crops: : 5 :
Toial Unmodrfied Crops ; 5 :
: Number of Application;. :25 •*• : :
: Application Timing • On Specific Date(s) ^j
: Application Units : ." kg/ha 5 8j/acre
: ; Applica ion 1
: : Applic a ion 2
: : Applica ion 3
: ; Applica ion 4
: : Applrca ion 5
: : Applica ion 8
: ; Applica ion 1
\ '. Applica ton 8
: ; Applica ion 9
! i Applica bn 10
\ '. Applica ton 1 1
: ; Applica ion \ 2
: ; Applrca ion 1 3
| : Applica ton 1 4
Applicatron Method
DaysReL : Day : Month : O^M Sncorp. (cm)
j_
1
4
7
10
13
16
19
22
25
28
1
4
7
10
6
6
6
6
6
6
6
6
6
6
7
7
7
7
2
2
2
2
Z
2
2
2
2
2
2
2
2
2
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
4.00
jAerral v :
Rate Drift Pond % \ Dfift Res. X :. Efficiency % '• I
2.5000
2.5000
2.5000
2.5000
2.5000
2.5000
2.5000
2.5000
2.5000
2.5000
2.5000
2.5000
2.5000
2.5000
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
16.00
1600
16.00
16.00
16.00
16.00
16.00
16.00
16.00
16.00
16.00
16.00
16.00
16.00
95.00 ;
95.00 :
9500 i
95.00 :
95.00 :
9500 i
95.00 :
95.00 :
9500 i
95.00 :
95.00 :
9500 ;
95.00 :
9500 -•• :
c • u jc . • HP Help (CAM Definitions] !
Finished Entering Data ..............„..;.....................................:....;
Figure 13. Pesticide Application Data Entry Screen
or, as here, specific values can be entered for each of the selected scenarios. To minimize the
amount of data entry required, first enter any values that are common among crops, and only then
select the option to enter specific values for each crop. At that juncture, the first-entered values will
be copied to all additional scenarios, reducing the labor required to enter identical values across
the selected scenario set.
For Tier II, the aerial application default drift values have been set at 5% and 16% for the
pond and reservoir, respectively. For aerial applications, the default efficiency is 95%. The ground
sprayer application default drift values are 1% and 6.4% for pond and reservoir simulations,
respectively. The default efficiency value for ground applications is 99%.
20
-------
Pesticide application dates can either be set absolutely (by calendar date), or relative to
crop planting, emergence, maturity, or harvest dates. This feature facilitates rapid configuration of
application scenarios for multiple crops. For example, when the pesticide is intended for application
7 days pre-planting, the user can enter-7 days relative to planting and the correct application date
for each crop will be calculated from the crop phenology embedded in the crop scenario file.
4.5 PRZM-EXAMS Input File Creation
Finally, selecting the Write menu option creates all input files needed by PRZM and
EXAMS. The current release of EXPRESS includes two PRZM versions when run in OPP mode:
PRZM 3.12 beta, and PRZM 3.12.2. In ORD Mode, the latest version of PRZM (3.12.3) is also
available. PRZM 3.12.2, the current regulatory model, is the default selection. Earlier versions of
PRZM contain known bugs and limited features (See PRZM release notes at
Multiple PRZM versions are included
within EXPRESS to facilitate comparisons of exposure analysis results across successive versions;
PRZM 3.12.3 adds a mass balance reporting function to the suite of Express output graphics.
Once the version of PRZM has been selected, the model input files are created. The
information necessary to run PRZM-EXAMS is contained in several input data files:
PRZM
annotated parameter file incorporating the scenario definition, *.inp
climate file providing the weather data used, *.dvf
file with definition of the PRZM run options, *.run
EXAMS
parameter file including the scenario selection, *.exa
multiple PRZM to EXAMS transfer files, *.dyr (yr represents year of run)
Each standard scenario is assigned an unique six character name that identifies the USA
State and crop. An R or P is added to this file name to specify whether the input file is a reservoir
run or pond run, respectively. All scenario-, chemical-, and application-specific information is also
stored in the Master Project File master.fpj. In addition, a file of type *.scn is created to support
data analysis and data visualization in EXPRESS.
21
-------
The scenario and parameter definitions combine input data specified by the user in
EXPRESS with internal EXPRESS-defined data and parameters (as developed by the OPP/EFED
Water Quality Technical Team). The parameter definitions and values specified by EPA (e.g., in
PRZM crop scenarios) and stored internally within EXPRESS cannot be altered by EXPRESS
users. EXPRESS also generates some of its input data from user choices within fixed menus of
EPA-approved alternatives. All predefined and menu-selected data within model input files
produced by EXPRESS can be edited manually to create special scenario definitions. Under no
circumstances, however, should data files created by EXPRESS be modified when producing EPA
"Standard Tier II" simulations.
With the input file set written, the data preparation phase is now complete. Select the Exit
menu option to return to the main EXPRESS program screen.
5.0 Starting and Running the PRZM-EXAMS Simulation
With the input files created, simulations are started by pressing the lightning bolt icon
(Figure 1). Current versions of PRZM run in a DOS console window. Each successive requested
PRZM-EXAMS simulation scrolls in this window. Once simulation runs have been completed, the
display screen reverts back to the opening menu (Figure 1), and the graphing options described
in Section 6 become available.
6.0 Evaluation of the PRZM-EXAMS Simulation
After a completed simulation run, the relevant scenario output data is provided in three
PRZM ASCII files (*.hyd, *.cnc, and *.out), and three EXAMS ASCII files (*.xms, *.yms, and *.zms).
These files are analyzed automatically by EXPRESS to generate tables and graphics of the results
obtained. For Tier II runs, there is no need to analyze the output files in a different format. The
EXPRESS grapher can also, however, export results for each simulated scenario in an ASCII file
with an extension of ".tab." These files are created in the current project directory whenever the
"Display ... as Text File" option is selected. These files can be used for further data analysis; they
include all output data required for Tier II calculations.
EXPRESS generates daily time-series files for each combination of a surface drinking-water
reservoir scenario and chemical simulated. These files are deposited in the project folder; they are
comma-separated-value (*.csv) formatted files suitable for direct importation into risk assessment
models (e.g., dietary exposure models in use by EPA- DEEM/CALENDEX, CARES, and a Lifeline
22
-------
Excel template). An inventory of the produced files is stored in the project directory in file
"HED_Files.txt (the name derives from the nominal target audience for these csv files, OPP's
"HED" (Health Effects Division).
PRZM Output
*.out = summary of PRZM output. Contains all PRZM output
*.cnc = mean annual soil concentration at depths of 1 meterfrom the soil surface and at the bottom
of the soil column
*.hyd = annual hydrology summary (total precipitation, runoff, erosion, and evapotranspiration)
*.msb = annual chemical mass balance at depths of 1 meter from the soil surface and at the
bottom of the soil column (total application, runoff flux, decay flux, erosion flux, mass
remaining in soil column, etc.) (ORD mode with PRZM 3.12.3 only)
Note: PRZM 3.12 beta does not create .cnc and .hyd files.
EXAMS Output
*.xms = EXAMS standard tabular report file
*.yms = EXAMS EcoRisk output file containing "instantaneous" and mean 24-hour, 96-hour,
21-day, 60-day, 90-day, and annual average aquatic concentrations of parent and
transformation product chemicals
*.zms = EXAMS EcoTox output files (daily concentrations of parent and product chemicals)
EXPRESS Output
*.csv = Comma-separated-value time-series files of dates (as MM/DD/YYY) and associated
exposure concentrations (mg/L), each chemical/scenario in a separate file
HED_Files.txt Inventory of .csv files generated by an exposure analysis
6.1 PRZM-EXAMS Grapher
Start the PRZM-EXAMS grapher by selecting the graph icon on the main EXPRESS screen
(Figure 1) and then selecting the Standard Tier2 menu item. All EXPRESS graphing functions are
available from the next screen display (Figure 14). Graphical or tabular output is generated by
selecting either the Display graphs or Display tables radio buttons respectively. Selecting the
Farm Pond or Index Reservoir radio buttons switches between the pond and reservoir results.
Each created graphic can be printed to any installed printer or exported to a windows metafile by
pressing the Print or Export buttons located at the bottom of the screen. The Display... as Text
23
-------
File buttons create ASCII flat files (*.tab) within the project folder; these can be imported into other
software for additional analyses.
Upper 10th Percentile Limnetic EECs in Farm Pond
Chemical - Maiathion
o
1
o
o
Q
35.00 -
25.00 -
20.00 -
15.00 -
10.011 -
Scenarios
kte Peak | Max. 96-Hour 1 Max. 21-Day 1 Max. 0 Max. 30-Day Q Mat.Amual
Display graphs
Display tables
IFarm Pond •" Index Reservoir
10th Percenlile Limnetic, All
10th Percenlile Benlhic, All
PR2M Hydrology Report
Limnetic Concentrations
Benthic Pore Water Cone.
Display Current : Display Results
Results as Text j (or 10th Xtiles
File i as Test File
Print : Export
OK I Cancel
Figure 14. EXPRESS graphic display
7.0 PRZM Versions
EXPRESS includes the obsolete PRZM 3.12 beta, and the current (3.12.2) regulatory
release, and the most recent ORD maintenance release (3.12.3 as of 2006-09-30). This facilitates
comparisons of results between PRZM versions. In many cases, versions are backwards
compatible (i.e., if the input sequences are set up the same, the results will be the same),
especially when new model versions are in the main providing new options and simulation
capabilities. This is not, however, always the case; e.g., when errors in the code have been
discovered and corrected, exact results may not recur unless the corrections have been applied
to all versions. In general, EFED prefers that the older codes be maintained in an uncorrected state
to provide a baseline for revisions to regulatory analyses. The current version of all codes accessed
24
-------
by EXPRESS are available (Figure 15) by selecting the Help button on the main EXPRESS screen
(Figure 1). For regulatory submissions, two versions of PRZM 3.12 are included in the shell at
present. PRZM 3.12 beta was released for testing in February, 1998. PRZM 3.12.2 repairs errors
and completes implementation of peer-review suggestions received regarding PRZM 3.12 beta,
and adds several enhancements as well. A complete description of the several PRZM versions, and
the modifications underpinning each, can be found on the CEAM web site at
http://www.epa.gov/ceampubl/gwater/PRZM3/index.htm and
respectively.
a
Software and Data Versions
Express Version
Eaqaress v. 1. SI. 01
Software Components
V. 1.00 00
(2086-08-12)
GEKEEC
WPIC
PEZS!
(2001-
(2001-
(200C-
V. 2.00.00
V. 1.02.00
v. 3.12. beta (2004
PEZM V. 3.12.21:48] (2085
Exams r. 2.9«.04.8« (2085
GrapM.ce r. 1.B0.2S (ZOOS
KED Report r. 1.00.14 (ZOOS
OPJ/EEEB Regulatory Studies Ver,
-17)
-17)
-23)
-13)
-12)
-87)
-23)
-23)
Data
Two important changes between the
primary (3.12 beta and 3.12.2) PRZM versions in
EXPRESS lie in the new ability to enter up to 32
curve numbers in 3.12.2, and correction in
3.12.2 of errors in the parent/metabolite
degradation kinetics coded in the older PRZM
3.12 beta. Use of the complete set of available
curve numbers in version 3.12.2 sometimes
results in small differences in the results
obtained. When simulating degradates, versions
after PRZM 3.12 beta must be used; these input
data are not accessible to version 3.12 beta.
8.0 Database and Scenario Management
One of the primary motivations
underlying the development of EXPRESS has
been realized by creation of the "scenario
database": The scenario database contains all F'9ure 15 EXPRESS Software Versions (This
Figure may not present latest versions or dates)
the data needed to create PRZM input files, in a
fixed form that cannot be cavalierly altered by the analyst community. This ensures that all analysts
are using the same base data set, and helps to standardize regulatory analyses and facilitate
archiving, public access, and peer review of exposure analysis results. Only an authorized
"scenario manager" can change current scenarios and add or delete scenarios; the database is
password-protected. The database as currently constructed can hold up to 200 PRZM scenarios.
r. 1.S2.00
(2086-01-18)
•Meteorology v. 1.00.00 (2082-05-19)
View EXPRESS User's Manual
Manual
s Manual
25
-------
In addition, chemical parameters can be entered and stored in a separate database specific
to each user. This database includes information used in both PRZM and EXAMS.
9.0 Additional Capabilities Included in EXPRESS (Index Reservoir, PCA)
In addition to the PRZM and EXAMS Tier II models, EXPRESS includes two Tier I OPP
screening models, GENEEC2 and FIRST. GENEEC2 uses the "standard agricultural field-farm
pond" scenario that EFED selected for all aquatic exposure assessments. This "standard pond"
scenario assumes that ten centimeters of rain fall on a treated, 10-hectare agricultural field,
causing pesticide-laden runoff into a one-hectare body of water of 20,000 cubic meters volume,
2.00 meters deep. Although this "standard scenario" was designed to predict pesticide
concentrations in a "standard farm pond," it has been shown to be a good predictor of upper level
pesticide concentrations in small, but ecologically important, upland streams (Effland et al. 1999;
additional detail available on-line at http://www.epa.gov/scipoly/sap/1999/may/pca sap.pdf).
For Tier I estimations of pesticide
concentrations in drinking water, OPP uses a
surface water model called FIRST. FIRST is
based on an "Index Reservoir" watershed and
includes Percent Cropped Area (PCA) factors
which account for the percentage of a
watershed that is planted with specific crops.
The Index Reservoir scenario and the PCA
have been built into standard EXPRESS Tier
II analyses.
Index reservoir: Shipman City Lake
The Index Reservoir is based on a
drinking water reservoir in Illinois, Shipman City Lake. This reservoir was selected because it is
representative of a number of reservoirs in the central Midwest that are known to be vulnerable to
pesticide contamination. It is used similarly to the OPP "standard farm pond," except that flow rates
through the reservoir are set to reflect site-specific long-term average runoff. Like the standard
pond, pesticide loadings to the water body are modeled using local soils and weather data to reflect
crop-specific scenarios around the country. These scenarios are intended by OPP to represent
sites at roughly the upper 90th percentile of runoff vulnerability for pesticide transport to surface
waters.
26
-------
9.1 New Scenarios for Tiers I and II
Following passage of the Food Quality Protection Act (FQPA) by Congress in August of
1996, EFED developed a source water modeling approach (the Tier I FIRST model, and modified
agricultural use scenarios for EXPRESS) to supplement that already in place for ecological risk
assessment. Recognizing that few people drink water derived from small farm ponds or from small,
upland streams, EFED developed an "index agricultural watershed-drinking water [source]
reservoir" or "index reservoir" scenario to supplement the "standard field-pond" ecological scenario.
In addition, it was noted that most watersheds large enough to support a community drinking water
system (CWS) are not entirely planted in only one crop. FIRST and EXPRESS therefore
incorporate a method to consider a maximum percent cropped area (PCA) factor to account for this
fact.
9.2 Index Drinking Water Reservoir
In July, 1998, OPP presented to the FIFRA Science Advisory Panel (SAP) a proposed
"index reservoir" scenario to estimate pesticide concentrations in drinking water derived from
surface water, supplementing the "field pond" scenario used in its ecological screening models. The
concept behind use of a model of an "index" reservoir to screen pesticides was that the chosen
reservoir - and its associated characteristics - would become the standard set of conditions by
which EPA would judge the potential of a pesticide to contaminate drinking water derived from
surface water. The "index" reservoir was selected from a group of actual reservoirs that are the
source of drinking water for communities throughout the country. EPA picked from that group a
particular reservoir having watershed characteristics associated with a higher potential for pesticide
contamination of surface water, and uses those real-world characteristics in its mathematical
screening model. Because the "index" reservoir model uses a set of real-world characteristics, it
is thought likely to produce more realistic estimates of pesticide concentrations in surface drinking
water sources than could a simple assemblage of average watershed properties. Because the
"index" reservoir model has characteristics that are associated with a higher potential for pesticide
contamination of surface water, the model is also likely to be protective of other drinking water
sources less vulnerable to contamination.
The actual reservoir chosen for simulation is a small drinking water reservoir located in
Shipman, Illinois. Shipman City Lake is 13 acres in area, 9 feet deep, and has an input drainage
watershed area of 427 acres. Its ratio of drainage area to capacity (volume of water in the lake) is
approximately 12 m"1. As a comparison, the "standard farm pond" currently used has a ratio of 5
27
-------
m"1. Shipman City Lake is one of a number of mid-western potable source water reservoirs that
tend to be small and shallow with small input drainage area watersheds, and that frequently have
Safe Drinking Water Act (SOWA) compliance problems with atrazine, a herbicide widely used on
corn grown in these watersheds. The Index Drinking Water Reservoir scenario characteristics have
been incorporated into the dynamically linked PRZM-EXAMS and FIRST models, and are
implemented in conjunction with the percent cropped area adjustment (Effland et al. 1999, available
on-line at http://www.epa.goV/scipoly/sap/1999/may/pca sap.pdf). Although estimates of pesticide
concentrations in drinking water based on a Midwestern "index drinking water reservoir" may not
be wholly representative of residue levels in drinking water sources in other parts of the country,
the scenario provides an effective screening tool to determine the need for more refined
assessments. The modeling scenarios currently account for region-specific rainfall, soil, and
hydro logic/run off factors. Steps to develop additional scenarios to describe regional reservoirs for
more advanced Tiers of modeling have been hampered by the lack of reservoir monitoring data
outside of the Midwest that is of sufficient quality and extent to develop such scenarios.
9.3 Percent Crop Area (PCA) Adjustments
The PCA is a generic adjustment representing the maximum percent of any watershed that
is planted to the crop or crops being modeled and, thus, may potentially be treated with the
pesticide in question. PCA factors, generated from Geographic Information System (GIS) overlays
of cropping area and watershed delineations, are applied directly to estimates of index reservoir
surface water pesticide concentration values from the PRZM-EXAMS and FIRST models. The
output concentration estimates generated by these models are multiplied by the maximum decimal
fraction of cropped area in any watershed associated with the crop or crops of interest. To be
effective as an adjustment to screening model estimates, the PCA should also result in estimated
concentrations that are closer to, but not less than, actual observed pesticide concentrations in
vulnerable (prone to pesticide-laden runoff) surface drinking water sources. While relaxing the
assumption that the entire watershed would be treated at the same time with the pesticide under
study, the use of the PCA concept is still regarded as a screening tool because it represents the
highest percentage of crop cover of any large watershed in the U.S., and still assumes that the
entire crop is being treated. Current PCA values and a description of how the values were derived
and applied can be found at http://www.epa.gov/oppEFED1/models/water/regional pea.htm.
28
-------
10.0 Using EXPRESS: Data Preparation and Input Example
Chapter 10 is a worked Tier II example of preparing data and entering them into EXPRESS
for Forchlorfenuron. Table 10-1 presents the Efate parameters for Forchlorfenuron and indicates
the EXPRESS input generator screen where the values are entered. (An "MRID" (Master Record
Identification) Number is a unique cataloging number assigned to an individual pesticide study at
the time of its submission to the Agency.) (Input parameters based on OPP 2002-02-28 Input
Parameter Guidance (http://www.epa.gov/oppEFED1/modeIs/water/input_guidance2_28_02.htm))
Table 10-1. Surface Water Exposure Inputs for Forchlorfenuron
MODEL INPUT VARIABLE
Scenario Selection
Application Rate (kg/ha)
CA Grape (irrig), MLRA 17
NY Grape, MLRA 100
Molecular Weight
Vapor pressure
Koc(ml/g)
Aerobic Soil Metabolic Half-life
(days)
parent
Solubility (mg/L)
Aerobic Aquatic Metabolic
Half-life (days)
INPUT
VALUE
CA Grape
NY Grape
0.025
0.025
248
3.5x10-10
1763
578
39
1156
COMMENTS/EXPRESS SCREEN
Source: Label; EXPRESS Screen: Project Design
California grapes (raisin, wine, and fresh market)
NY grapes (wine and fresh market)
Source: Label
EXPRESS Screen: Pesticide Application Data
g/mole
EXPRESS Screen: PRZM-Efate
Torr
EXPRESS Screen: PRZM-Efate
Average Koc from 4 soils range of 852-3320.
MRIDs 44359516, 45840121
EXPRESS Screen: PRZM-Efate
Only aerobic soil metabolism study. Half-life not
multiplied by 3 because very long. Based on
extractable residues in MRIDs 44359515,
45840119. Half-life based on extractable+ bound
was 1,659 days
EXPRESS Screen: PRZM-Efate
9-7-00 EUP memo
EXPRESS Screen: PRZM-Efate
2X aerobic soil metabolism half-life (578 days)
EXPRESS Screen: EXAMS-Efate
29
-------
MODEL INPUT VARIABLE
Anaerobic Aquatic Metabolism
half-life (days)
Aquatic Photolysis Half-life
(days)
Maximum No. of Applications
All outdoor uses
Interval between appl.
Application Date(s)
Method of application
Ground (all uses)
Incorporation depth
All outdoor uses
Application Efficiency
Ground Sprayer
Spray Drift (Farm Pond)
Ground Sprayer
Spray Drift (Drinking Water)
Ground Sprayer
INPUT
VALUE
226
143
1
N/A
May 15
June 15
Ground
Sprayer
Default
0.99
0.01
0.064
COMMENTS/EXPRESS SCREEN
Anaerobic soil metabolism half-life (MRIDs
44359514,45840118)
EXPRESS Screen: EXAMS-Efate
MRID 44394605
EXPRESS Screen: EXAMS-Efate
Label, p. 4
EXPRESS Screen: Pesticide Application Data
For a single application
All California Grapes
NY Grapes (Concord)
Based on 2003-12-9 Email from Bernie Schneider of
HED to Jim Breithaupt of EFED
EXPRESS Screen: Pesticide Application Data
CAM 2 - application to foliage
EXPRESS Screen: Pesticide Application Data
Can be modified for broadcast applications.
EXPRESS Screen: Pesticide Application Data
Per 2000-1 1-7 Input Parameter Guidance
EXPRESS Fixed parameter
EXPRESS Screen: Pesticide Application Data
Per 2000-1 1-7 Input Parameter Guidance
EXPRESS Fixed parameter
EXPRESS Screen: Pesticide Application Data
Per 2000-1 1-7 Input Parameter Guidance
EXPRESS Fixed parameter
EXPRESS Screen: Pesticide Application Data
30
-------
EXPRESS Example Input Screens
1. EXPRESS Screen: Project Design
Number/Relationship of Modeled Pesticides jOne Parent No Metabolites
Select EFED Tier II Crop[s)
Current Group: ^Standard OPP/EFED Scenarios
| Ml Cherry MLRA-96
: OR Christmas Trees MLRA-2
;CA Citrus MLRA-17
!FL Citrus MLRA-156A
:PRCoffeeMLRA-270
III Corn MLRA-108
i MS Corn MLRA-134
!NCCorn-E MLRA-153A
! OH Corn MLRA-111
i PA Com MLRA-148
!CA Cotton MLRA-17
IMS Cotton MLRA-134
:NC Cotton MLRA-133A
;FL Cucumber MLRA-156A
I OR Filberts MLRA-2
: OR Grass Seed MLRA-2
I OR Hops MLRA-2
ICA Lettuce MLRA-14
I OR Mint MLRA-2
!CA Onions MLRA-17
S elect AII/D eselect All i S cenario D etails
PRZM Crop Scenario Group Functions
USA Crop Acreages 2002
Cancel
31
-------
2: EXPRESS Screen: PRZM Efate
Chemical 1 !j 1 1
r PRZM 3.12 Tier II Standard Analysis
Chemical Name |ForchIorienuron
Molecular Weight j 24800
Solubility (mg/L) j 39X100
Partition Coefficient Method ISoilKoc •»• j
Partition Coefficient Value j 1763.000
Aerobic Soil Half-life (days) j' 5780E+K
i Enter Chemical-Specific Foliar Process Data
Plant Uptake Factor j
Foliar Half-life (days) j
Foliar Washoff Coefficient j
Volatilization from Soil
Vapor Pressure j 3.50E-10
Units of Vapor Pressure ;Torr (mmHg) j»j
Enter Chemical-Specific Data
Air Diffusion Coeff. (cm2/day) j
Enthalpy of Vaporization (kcal/mole) j
Cancel
32
-------
3: EXPRESS Screen: EXAMS Efate
y Farm Pond (no flow)
y Index Reservoir (steady resetvoir How, mS/hr)
[ Chemical 1 II I j
HaB-lives
Bacterial Biolysis in Water Column
Aerobic M etabolism (days) i 1.156E +03
Hydrolysis
Test Temperature (C) i 25.0
Number of Different pH (3 or more) 13 T ;
Aquatic D irect Photolysis (days) j 1.430E +02
Bacterial Biolysis in Benthic Sediment
Anaerobic M etabolism (days) 12.260E +02
Test pH
Half-life (days)
5.00
7.00
9.00
O.OOOE+00
O.OOOE+00
O.OOOE+00
Cancel '••
33
-------
4: EXPRESS screen(s): Pesticide Application Data
! " Select/specif the canre application parameters tor a8 crop? (PCA. dales, rates, timing, ete.j
!'» Select/specify different appfcation parameter? for each crop
Curienr Crop and Status: Select tfop :
i 1 »l»pelirrB"""Mr»-T?7D"rii«>5Sd ?"* Pmvuut Hem Last :
Index Reserve* PCA K\ : S?J£ =• =i =^~ =^~ ;
ToW Number of Crops' :" 2 :
Total UnnotfiedCiops. : 2 :
Number oi Applications :1
Application Tirrang : On Specific Datefs) j^
Application Units ; •* kg/ha ./ |b/acfe
App^cation HeHiod | Ground Spsa^es
JDaysRd. : Day Mmth ; CAM : Incorp. (cm) Rate : DoHPondt ': Drift Res. %.
15
400 | 025000E-01 | 1.00 | 640 | 9900
Entering Palo
Select/specily the same app&caiion patarnelers loi all ciop^ [PCA, date?, fate?, ttrrang etc.)
Seied/speei^j different application parameteis for each asp
': 2 .MY Grape MLRA-100 Unmodified
indes. Reservoir PCA (%j : 87.00
Number of Appfcationc 1
Total Nufrtber of Crops:
Tofai Unmodified Qops:
: Da5*sFlel- : Day : McsiSh
Finished Entering Data
34
-------
11.0 Appendices
APPENDIX A: Format of Daily Value Meteorological Time-Series Files
Field
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Columns
1
38389
38580
18-27
28-37
38-47
48-57
58-63
64-73
74-77
78-80
81-90
91-96
97 -102
103-106
Description
blank
Date
Precipitation
Pan Evaporation
Temperature (mean)
Wind Speed @ 10 meter
Solar Radiation
FAO Short Grass Et0
Daylight Station Pressure
Daylight Relative Humidity
Daylight Opaque Sky Cover
Daylight Temperature
Daylight Broadband
Aerosol
Daylight Prevailing Wind
Speed at 10 meter height
Daylight Prevailing Wind
Direction
Units
N/A
mmddyy
cm/day
cm/day
Degrees
Centigrade
cm/second
Langleys/day
mm/day
kiloPascal
Percent
Tenths of Sky
Covered
Degrees
Centigrade
Optical Depth
meter/second
degrees (N=0,
E=90, ...)
Type
Character
Integer
Real
Real
Real
Real
Real
Real
Real
Integer
Integer
Real
Real
Real
Integer
Format
1x
3i2
f10.2
f10.2
f10.1
f10.1
f10.1
f6.1
f10.1
14
13
f10.1
f6.3
f6.1
i4
Daily values file format:
(1x, 3i2, t8,f10.2, t18,f10.2, t28,f10.1, t38,f10.1, &
t48,f10.1, t58,f6.1, t64,f10.1, t74,i4, t78,i3, &
t81,f10.1, t91,f6.3, t97,f6.1, t103,i4)
Fields 03 - 08 represent daily totals or mean values (Wind Speed and Temperature)
Fields 03 - 07 units preserved from earlier PRZM met files for compatibility
Fields 09-15 represent mean values for daylight hours only.
35
-------
APPENDIX B: Added Capabilities of ORD Mode
In ORD mode, several additional capabilities are available to the analyst:
1. Sorption parameters include the octanol-water partition coefficient, Kow. Kow is passed through
directly to EXAMS. For use in PRZM, the soil Koc is calculated as 0.175 Kow and applied to the soil
organic carbon content in each soil horizon, as in the following code fragment:
do M=1,SSNHORIZ
select case (KDTYP(J))
case (1) ! entered soil Koc
KD(J,M,Zone)=(KDSP(J)*SSOC(M))/100.0
case (2) ! direct Kd
KD(J,M,Zone)=KDSP(J)
case (3) ! Kow (see p. 13 of EXAMS manual (EPA/600/R-00/081))
KD(J,M,Zone)=(0.175*KDSP(J)*SSOC(M))/100.0
end select
end do
2. The initial default parameters for foliar processes correspond to the ORD-recommended values
(Suarez2005: foliar washoff coefficient FEXTRC=0.10 (p 5.12), plant uptake factor UPTKF=1.0,
representing passive movement in the transpiration stream (p. 5-22)). As in OPP mode, these can
be altered at the user's discretion.
3. For aquatic chemistry, additional parameters are made available: Q10 for aerobic and anaerobic
aquatic biolysis, the temperature of the biolysis experiments, and melting point of the chemicals.
4. For a more detailed view of spray drift, AgDrift program outputs tailored to the standard farm
pond and index reservoir are displayed. These include several droplet size categorizations for aerial
applications and ground sprayers, and orchard/vineyard airblast applications. The protective impact
of spray buffers of various widths, separately for the farm pond and the index reservoir, can be
evaluated in ORD mode.
5. Available versions of PRZM include 3.12.3, which also provides a mass balance analysis and
display by EXPRESS.
36
-------
APPENDIX C: References
Burns, L. A. 2000. Exposure Analysis Modeling System (EXAMS): User Manual and System
Documentation. EPA/600/R-00/081, U.S. Environmental Protection Agency, National
Exposure Research Laboratory, Athens, Georgia.
Burns, L. A. 2001. Probabilistic Aquatic Exposure Assessment for Pesticides. I: Foundations.
EPA/600/R-01/071, U.S. Environmental Protection Agency, National Exposure Research
Laboratory, Athens, Georgia.
Burns, L. A., and D. M. Cline. 1985. Exposure Analysis Modeling System: Reference Manual for
EXAMS II. EPA/600/3-85/038, U.S. Environmental Protection Agency, Athens, Georgia.
Burns, L. A., D. M. Cline, and R. R. Lassiter. 1982. Exposure Analysis Modeling System (EXAMS):
User Manual and System Documentation. EPA-600/3-82-023, U.S. Environmental
Protection Agency, Athens, Georgia.
Carsel, R. F., L. A. Mulkey, M. N. Lorber, and L. B. Baskin. 1985. The Pesticide Root Zone Model
(PRZM): A procedure for evaluating pesticide leaching threats to ground water. Ecological
Modeling 30:49-69.
Carsel, R. F., A. E. Smith, L. A. Mulkey, J. D. Dean, and P. Jowise. 1984. User's Manual for the
Pesticide Root Zone Model (PRZM): Release 1. U.S. Environmental Protection Agency,
Athens, Georgia.
Effland, W. R., N. C. Thurman, and I. Kennedy. 1999. Proposed Methods For Determining
Watershed-Derived Percent Cropped Areas and Considerations for Applying Crop Area
Adjustments To Surface Water Screening Models. USEPA Office of Pesticide Programs,
Presentation to FIFRA Science Advisory Panel, May 27, 1999, Washington, D.C., USA.
Parker, R. D., R. D. Jones, and H. P. Nelson. 1995. GENEEC: A Screening Model for Pesticide
Environmental Exposure Assessment. Pages 485-490 in International Exposure
Symposium on Water Quality Modeling. Proceedings of the American Society of
Agricultural Engineers, Orlando, Florida, USA.
SCS. 1981. Land Resource Regions and Major Land Resource Areas of the United States.
Agriculture Handbook 296, United States Department of Agriculture Soil Conservation
Service, Washington, D.C.
Suarez, L. A. 2005. PRZM-3, A Model for Predicting Pesticide and Nitrogen Fate in the Crop Root
and Unsaturated Soil Zones: Users Manual for Release 3.12.2. EPA/600/R-05/111. U.S.
Environmental Protection Agency, National Exposure Research Laboratory, Athens,
Georgia.
37
------- |