PRZM_SW

 

About PRZM_SW

 General Information
PRZM (Pesticide Root Zone Model) is a one-dimensional non-deterministic compartmental model for the prediction of chemical movement in unsaturated soils by vertical chromatographic leaching. The original PRZM version developed by Carsel, Smith, Mulkey, Dean and Jowise (1984) has been continuously improved. The actual PRZM3 is a standard model to be used in environmental risk and exposure assessments by the the United States Environmental Protection Agency (U.S. EPA) and is included in the FIFRA list of recommended regulatory models for USA Pesticide Registration.

FOCUS_SW PRZM Development Team : Gerald Reinken (Bayer CropScience Aktiengesellschaft), Mark Cheplick (Waterborne Environmental, Inc.)

Short Model Description

The first official release of PRZM was published in 1984 by the U.S. EPA although beta versions were available beginning in 1982. The German PELMO model was developed based on this PRZM1. An upgraded version PRZM2 was issued as part of the RUSTIC package (Dean et al., 1989a & 1989b) and later released as a stand-alone model by the Center for Exposure Assessment Modeling (CEAM) of the U.S. EPA (October 1994). In the mid-1990’s the runoff routines were upgraded as part of the work of the FIFRA Exposure Modeling Work Group and the FIFRA Environmental Model Validation Task Force (FEMVTF) to produce version 3.12. This version also included more flexibility with application techniques, the ability to make degradation a function of soil temperature, and output which is more user friendly. Version 3.12 is also the version that has been used by the FIFRA Environmental Model Validation Task Force in its program to compare model predictions with actual data from runoff and leaching field studies. The actual PRZM version 3.12 beta was released officially in March 1998 by CEAM. For use in the FOCUS ground water and surface water scenarios an enhanced PRZM3 (version 3.20, FOCUS release) was developed. In addition to the capabilities of version 3.12 it has the option of using the normalised Freundlich isotherm, the ability to make the degradation rate a function of soil moisture, and the capability to consider increasing sorption with time. The new PRZM 3.20 executable is a truly Windows based, 32bit PRZM3 code. The program coding was conducted by Waterborne Environmental.

Description of the PRZM Model concept :

PRZM is based on a one-dimensional finite-difference code. The model consists of hydrologic (flow) and chemical transport components to simulate runoff, erosion, plant uptake, leaching, decay, foliar washoff, and volatilisation. Pesticide transport and fate processes include advection, dispersion, molecular diffusion, and soil sorption. The model includes soil temperature effects, volatilisation and vapour phase transport in soils, irrigation simulation and a method of characteristics algorithm to eliminate numerical dispersion. Predictions can be made for daily, monthly or annual output. PRZM allows the user to perform dynamic simulations considering pulse loads, predicting peak events, and estimating time-varying emission or concentration profiles in layered soils.

PRZM2 (release Oct 94) links two subordinate models in order to predict pesticide fate and transport through the crop root zone, and the unsaturated zone: PRZM and VADOFT. PRZM, VADOFT and SAFTMOD are part of RUSTIC. RUSTIC links these models in order to predict the fate and transport of chemicals to drinking water wells. The codes are linked together with the aid of a flexible execution supervisor (software user interface) that allows the user to build models that fit site-specific situations. PRZM2 incorporates several features in addition to those simulated in the original PRZM code: specifically, soil temperature simulation, volatilisation and vapour phase transport in soils, irrigation simulation, microbial transformation, and a method of characteristics (MOC) algorithm to eliminate numerical dispersion. PRZM is capable of simulating fate and transport of the parent compound and as many as two daughter species.

VADOFT is a one-dimensional finite-element code which solves the Richard's equation for flow in the unsaturated zone. The user may make use of the constitutive relationships between pressure, water content, and hydraulic conductivity to solve the flow equations. VADOFT may also simulate the fate and transport of two parent and two daughter products. The PRZM and VADOFT codes are linked together with the aid of a flexible execution supervisor that allows the user to build loading models which are tailored to site-specific situations. In order to perform exposure assessments, the code is equipped with a Monte Carlo pre- and post-processor.

PRZM3 (v. 3.12 Beta, release Mar 98) is the actual DOS PRZM version that links the two subordinate models (PRZM and VADOFT) in order to predict pesticide transport and transformation down through the crop root and unsaturated zone. Enhancements to Release 3.0 include algorithms that enable modelling of nitrogen cycle soil kinetic processes with the ability to track nitrogen discharges from a septic tank into the soil environment and movement to groundwater. Additional enhancements enable better simulation of physicochemical processes, increased flexibility in representing agronomic practices, and improved post-processing and data interpretation aids. The ability to describe pesticide degradation as a function of soil temperature was introduced. The most recent PRZM3 Release Notes including a detail listing of all changes between release versions is available from CEAM DOS-Software WebPage. The PRZM3 model system with documentation is for microcomputer (DOS) also available from the CEAM WebPage (http://www.epa.gov/ceampubl/DOS/PRZM3/INSTALP3.EXE).

WINPRZM (PRZM v. 3.20 Beta, FOCUS release, August 2000) is a truly Windows based, 32bit PRZM3 code and therefore independent from any DOS limitations. Major parts of the program code have been re-coded to achieve this. Several new process descriptions have been implemented (see Table below). In addition to the capabilities of PRZM version 3.12 it has the option of using the Freundlich isotherm, the ability to make the degradation rate a function of soil moisture, and the capability to consider increasing sorption with time. The implementation of the first order degradation routines has been modified for both, parent and daughter compounds, from an approximation to an exact implementation of first order kinetics. More user friendly output options have been also introduced according to the requirements of FOCUS. Input and output files are not compatible to those from older PRZM versions.

Summary of the processes in PRZM_SW (FOCUS release) :

 

Process

Approach

water movement

capacity-based water flow (tipping bucket approach) using a daily time step for all hydrological processes, option for Richard’s equation below the root zone. *Preferential flow, capillary rise and drainage are not considered

substance movement

convection dispersion equation based on a daily time step solved by an simplifying backward difference method which can produce artificially high numerical dispersion

crop simulation

changing root zone during growing season, changing foliage (both height and areal extent) during growing season, crop interception of water, crop interception of substances, foliar washoff, foliar degradation

degradation in soil

first order degradation rate with option for bi-phasic degradation, option for effects of soil temperature and moisture on degradation

substance sorption to soil

Kd, Koc, or normalised Freundlich equation for sorption; option for increasing sorption with time

substance volatilisation (from soil)

approach is a combination of results from previous research

runoff

Soil Conservation Service curve number technique

soil erosion

Universal Soil Loss Equation

soil temperature

Approach is based on previous work by a number of researchers including Van Bavel and Hillel, Thibodeaux, Hanks, Gupta, and Wagenet and Hutson

plant uptake

simple model based on soil concentrations

substance applications

applications may be foliar sprays, applied to the soil surface, or incorporated into the soil; for soil incorporated applications a variety of soil distributions can be specified

metabolism

up to two metabolites may be simulated simultaneously with the parent

 

 

Role and Place in FOCUS scenarios calculation

The major objective of the FOCUS Surface Water Scenarios Working Group was to implement a harmonised approach for performing aquatic risk assessments in Europe according to Council Directive 91/414/EEC. To provide simulation of runoff and erosion, the FOCUS_PRZM_SW model was devloped and integrated into the overall suite of Step 3 FOCUS surface water models. The FOCUS_PRZM_SW model runs quickly with a typical execution time of less than a minute on a standard PC (e.g. Pentium III, 750 MHz, 128 MB). FOCUS_PRZM_SW allows efficient and user friendly calculations for compounds with no more than two metabolites.

 

Current use outside FOCUS

PRZM3 is a standard model used in environmental risk and exposure assessments by the the United States Environmental Protection Agency (U.S. EPA) and is included in the FIFRA list of recommended regulatory models for USA Pesticide Registration. The U.S. EPA will sustain the FOCUS_PRZM_SW release as a basis for further PRZM development.

Excerpt of existing model documentation

Model documentation :

  • Carsel, R.F., C.N. Smith, L.A. Mulkey, J.D. Dean, and P. Jowise (1984): User's manual for the pesticide root zone model (PRZM): Release 1. EPA/600/3-84/109. U.S. EPA, Athens, GA.
  • Dean, J. D., P. S. Huyakorn, A. S. Donigian, K. A. Voos, R. W. Schanz, Y. J. Meeks, and R. F. Carsel (1989a): Risk of Unsaturated/Saturated Transport and Transformation of Chemical Concentrations (RUSTIC). Volume 1: Theory and Code Verification, EPA/600/3-89/048a. U.S. EPA, Environmental Research Laboratory, Athens, GA.
  • Dean, J. D., P. S. Huyakorn, A. S. Donigian, K. A. Voos, R. W. Schanz, and R. F. Carsel (1989b): Risk of Unsaturated/Saturated Transport and Transformation of Chemical Concentrations (RUSTIC). Volume 2: User's Guide, EPA/600/3-89/048b. U.S. EPA, Environmental Research Laboratory, Athens, GA.
  • Mullins, J.A., R.F. Carsel, J.E. Scarbrough, A.M. Ivery. (1993): PRZM-2, A Model for Predicting Pesticide Fate in the Crop Root and Unsaturated Soil Zones: Users Manual for Release 2.0. EPA/600/6-93/046. U.S. EPA, Environmental Research Laboratory, Athens, GA. (last release in October 1994).
  • R.F. Carsel, J.C. Imhoff, P.R. Hummel, J.M. Cheplick, and A.S. Donigian, Jr. (1998): PRZM-3, A Model for Predicting Pesticide and Nitrogen Fate in the Crop Root and Unsaturated Soil Zones: Users Manual for Release 3.0. (last release in March 1998).
  • FOCUS groundwater scenarios in the EU plant protection product review process. The report of the work of the Groundwater Scenarios Workgroup of FOCUS (FOrum for the Co-ordination of pesticide fate models and their USe), final version April 2000.
  • FGRAT User Manual provided with the installation files (version 1.4, October, 2000).
  • FOCUS PRZM Parameterisation Document. Updated version, October 2000.
  • Information available from the Centre for Exposure Assessment Modeling (CEAM) Home Page (http://www.epa.gov/ceampubl/).

References for PRZM applications :

  • Cogger, C.G.; Bristow, P.R.; Stark, J.D.; Getzin, L.W.; Montgomery, M. (1998): Transport and persistence of pesticides in alluvial soils: I. Simazine. Journal-of-Environmental-Quality.1998, 27: 3, 543-550.
  • Dean, J.D.: Atwood, D.F. (1985): Exposure Assessment Modeling for Aldicarb in Florida. U.S. Environmental Protection Agency, Athens, GA. EPA/600/3-85/051.
  • Donigian, A.S. Jr.; Carsel, R.F. (1992): Developing computer simulation models for estimating risks of pesticide use: research vs. user needs. Weed-Technology. 1992, 6: 3, 677-682; Proceedings of a symposium of the Weed Science Society of America held on 4 Feb., 1991, at Louisville, Kentucky, USA.
  • Ma, Q.L.; Wauchope, R.D.; Hook, J.E.; Johnson, A.W.; Truman, C.C.; Dowler, C.C.; Gascho, G.J.; Davis, J.G.; Sumner, H.R.; Chandler, L.D. (1998): GLEAMS, Opus, and PRZM-2 model predicted versus measured runoff from a coastal plain loamy sand. Transactions of the ASAE.1998, 41: 1, 77-88.
  • Mueller, T.C. (1994): Comparison of PRZM computer model predictions with field lysimeter data for dichlorprop and bentazon leaching. Journal of Environmental Science and Health. Part A, Environmental Science and Engineering. 1994, 29: 6, 1183-1195.
  • Nicholls, P.H. (1995): Simulation of the movement of bentazon in soils using the CALF and PRZM models. Journal of Environmental Science and Health. Part A, Environmental Science and Engineering.1994, 29: 6, 1157-1166.
  • Parrish, R.S.; Smith, C.N.; Fong, F.K. (1992): Tests of the pesticide root zone model and the aggregate model for transport and transformation of aldicarb, metolachlor, and bromide. Journal of Environmental Quality. 1992, 21: 4, 685-697.
  • Sadeghi, A.M.; Isensee, A.R.; Shirmohammadi, A. (1995): Atrazine movement in soil: comparison of field observations and PRZM simulations. Journal of Soil Contamination.1995, 4: 2, 151-161.
  • Sanders, P.F. (1995): Calculation of soil cleanup criteria for volatile organic compounds as controlled by the soil-to-groundwater pathway:comparison of four unsaturated soil zone leaching models. Journal of Soil Contamination.1995, 4: 1, 1-24.
  • Strek, H.J . (1998): Fate of chlorsulfuron in the environment. 2. Field evaluations. Pesticide Science.1998, 53: 1, 52-70.
  • Trevisan M.; Capri, E.; Re, A.A.M. del; Vischetti, C.; Marini, M.; Businelli, M.; Donnarumma, L.; Conte, E.; Imbroglini, G.; Walker, A. (ed.); Allen, R. (ed.); Bailey, S.W. (ed.); Blair, A.M. (ed.); Brown, C.D. (ed.); Gunther, P. (ed.); Leake, C.R. (ed.); Nicholls, P.H. (1995): Evaluation of pesticide leaching models using three Italian data-sets. Pesticide movement to water. Proceedings of a symposium held at the University of Warwick, Coventry, UK, on 3-5 April 1995. 1995, 269-274; BCPC Monograph No. 62.
  • Trevisan, M.; Capri, E.; del Re, A.A.M. (1993): Pesticide soil transport models: model comparisons and field evaluation. Toxicological and Environmental Chemistry.1993, 40: 1-4, 71-81.
  • Zacharias, S.; Heatwole, C.D. (1994): Evaluation of GLEAMS and PRZM for predicting pesticide leaching under field conditions. Transactions of the ASAE.1994, 37: 2, 439-451.   
 

Download PRZM_SW

Download PRZM_SW

Latest version: FOCUS_PRZM_SW_4.3.1

Package FOCUS_PRZM_SW_4.3.1.exe (29/May/2015, 1 file)
Getting Started You need to install SWASH before PRZM. The default directory for PRZM is C:\SWASH\PRZM. In case you selected  another drive than C for SWASH,
                                 the PRZM application should also be installed on that drive on subdirectory of the SWASH directory. For example if you have installed SWASH on
                                 D:\SWASH then PRZM should be installed at:
  -    D:\SWASH\PRZM
TestResults  
Comments 22/May/2015:  It is essential to de-install any previous version of PRZM for surface water before installing FOCUS_PRZM_SW_ 4.3.1 to ensure correct installation and operation.

Previous version : FOCUS_PRZM_SW_3.1.1

Package FOCUS_PRZM_SW_3.1.1.exe (04/June/2012, 1 file, 6 MB)
Getting Started
Comments 1) It is essential to de-install any previous version of PRZM for surface water before installing FOCUS_PRZM_SW_ 3.1.1 to ensure correct installation and operation.

Warning (19/February/2013) If CAM 8 is selected PRZM will not simulate the specified application rate, erroneously a zero soil loading will be simulated. To workaround this problem choose a different CAM (if suitable for the given application pattern) or to use the older PRZM 1.5.6 (only for when CAM 8 needs to be selected), until a new version is released.


 

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