## Implementation of Vegetative Buffer Strip Effectiveness in Removing Pesticides in Regulatory Assessments

Bjoern Roepke, Russell L. Jones and George Sabbagh

Presentation to the EMPM March 19, 20132 

# Outline

 

## Introduction

 

## Chronology of Industry Research

 

## Implementation in Europe

 

## Current activities in the U.S.

March 19, 20133 

# Introduction

 

## Vegetative buffer strips are a mitigation practice commonly used to reduce the effects of pesticide
runoff

 

### Used for many years to prevent soil erosion

 

### Also provide other benefits, such as reduction of runoff and nutrients, wildlife habitat improvement, and streambank protection

March 19, 20134 

# Introduction

 

## Industry scientists in Europe and the United States for many years have been interested in vegetative buffer strips for removal of pesticides in runoff

water

 

### Also interested in quantifying the effectiveness of this mitigation practice

 

## Ultimate goal is to implement a successful risk mitigation practice and to have this reflected in regulatory risk assessments

March 19, 20135 

# Early Industry Collaboration in the U.S.

 

## Collaboration with USDA on guidance

document issued in

2000

March 19, 20136 

# Early Industry Collaboration in the U.S.

 

### Early 2000s

- Industry funded the compilation and analysis of available published data on vegetative buffer strip efficiency compiled and analyzed at Iowa State (eventually published as Arora, 2010)

 

### This work was of considerable use in later projects in both the U.S. and Europe

March 19, 20137 

# Early Industry Collaboration in Europe

 

## Product specific runoff studies conducted in 1991

- 1992 in collaboration with the University of Karlsruhr in the Weiherbach region of Germany

 

## Joint collaboration on runoff studies in France and Germany beginning in early to mid

- 1990s

 

## Work by national industry association in Germany to quantify effectiveness of buffer strips as part of assessments for national registrations

March 19, 20138 

# Early Industry Collaboration in Europe

 

## Participation of industry in FOCUS groups dealing

with surface water assessments

 

### Surface Water Scenarios (2003)

 

### Landscape and Mitigation (2005)

 

### The information from the literature compilation from the Iowa State project was included in the final report

March 19, 20139 

# Industry Activities

 

## Two developments led to an increased need for industry to have quantitative assessments of the efficacy of buffer strips for removing pesticides

 

### The work at Iowa state was unsuccessful in developing a quantitative model for estimating the efficacy of vegetative buffer strips for removing pesticides

 

### The simple estimates proposed by the FOCUS Landscape and Mitigation Group were rejected as being unsuitable for regulatory assessments

March 19, 201310 

# Industry Research Chronology

 

## In late 2007, scientists in the CropLife America
Environmental Risk Assessment Committee requested scientists in member companies to explore ways to characterize the effectiveness of buffer strips

 

### George Sabbagh of Bayer working together with Garey Fox and A. Kamanzi, supported by Bayer scientists, developed an equation predicting pesticide removal as a function of the infiltration of

water in the buffer and the amount of sediment removal using the Iowa State data base

March 19, 201311 

# Pesticide Trapping Equation

March 19, 2013 

### Predicted vs . measured reductions in pesticide transfer across vegetated filter strips ( Sabbagh et al., 2009):

- development (n=47; left

- hand figure)

- evaluation (n=120; right

- hand figure) datasets12 

# Industry Research Chronology

 

## The equation of Sabbagh et al. did a good job of predicting pesticide removal but infiltration and sediment reduction are a function of the specific event runoff event and buffer design

 

## In 2008 Sabbagh and Fox worked with Munoz

Carpena (University of Florida) to incorporate the pesticide trapping equation into Munoz

- Carpena’s buffer strip model VSFMOD

March 19, 201313 

# Other Buffer Strip Modeling Research

 

## Other organizations also started to develop buffer strip models or expand nutrient models to pesticides. Some examples

 

### APEX: USDA

- ARS

 

### REMM: Texas Blacklands Research and Extension

 

### PRZM

- BUFF: Waterborne Environmental

 

### SWAT: USDA

- ARS

 

## CropLife America (CLA) funded a comparison of these models along with VSFMOD (presented at the EMPM in 2008)

- did not include a comparison

on common data sets

March 19, 201314 

# Industry Research

 

## The European Crop Protection Association (ECPA) wanted to consider buffer strip models in their program on Advancing Intelligent Mitigation (AIM)

 

### Wanted to determine which buffer strip model seemed to be providing the most realistic conditions

 

## ECPA and several U.S. companies sponsored a comparison on three U.S. and European data sets

 

### Results presented at an EMPM meeting in 2010

 

### ECPA chose VSFMOD for their work in Europe

March 19, 201315 

# Model Comparison Study Results Summary

March 19, 2013 Model APEX PRZM

BUFF REMM VSFMOD

Pesticide 

### 15.6 (10) 16.3 (14) 31.2 (31) 8.5 (8)

Runoff 

### 30.4 (20) 36.9 (28) 34.5 (32) 12.3 (9)

Sediment 

### 19.4 (17) 31.0 (31) 30.3 (24) 12.2 (17)



### Number in parentheses is the standard deviation Ranking by Mean Absolute Error (%)16 

# Implementation into EU Assessments

 

## Needs regulatory acceptance

 

### FOCUS Landscape and Mitigation

 

### PPR opinion on FOCUS LM

 

## Clear principles for implementation

 

### Mitigation measures must be effective and practical

 

### Needs to be an accepted approach to be incorporated into the estimate of exposure

March 19, 201317 

# Implementation Procedure

 

## Conduct sensitivity analysis to determine important parameters

 

## Define runoff buffer scenarios for each of the four
FOCUS runoff scenarios

 

## Incorporate scenarios into modeling software

 

## An effort involving a number of organizations

 

### ECPA

 

### University of York and FERA

 

### Università Cattolica del Sacro Cuore

 

### University of Florida

March 19, 201318 

# Sensitivity Analysis

 

## Analysis based on field experiments reported in

the literature

 

## Two soil types and six pesticides with a range of different properties

March 19, 2013 Sensitive Parameters Insensitive Parameters

Soil Vegetation

- saturated hydraulic conductivity

- spacing of stems

- saturated water content

- height

Sediment

- hydraulic resistance

- average diameter of particles

- organic carbon content

- clay content Muñoz

- Carpena et al. (2010). JEQ 39:630

- 64119 

# Parameter Definition

 

## Insensitive parameters

 

### Assess likely range across the EU

 

### Propose default values

 

### Appropriate level of conservatism

 

### Documentation to justify selection from literature

 

## Sensitive parameters

 

### GIS analysis within each scenario

 

### Generate distributions for each parameter

 

### Support selection of conservative values

 

### Facilitate higher

- tier modelling (e.g. Probabilistic)

March 19, 201320 

# Probability Distributions for Ksat

March 19, 2013 R1 R3 R2

R4

 N for each R scenario small

 Hydraulic parameters strongly

correlated 

### scenario n mean st.dev.

R1 348 23.1 20.3

R2 69 98.6 77.5

R3 171 49.5 59.5

R4 222 53.9 56.3
Lognormal distribution

k

s 

### as variable and area as density21 

# Deriving Conservative Values for Ksat & θ sat

 

## Separate simulations for :

 

### The four FOCUS R scenarios (n = 69

– 348)

 

### Storm events with 30 mm rain over 1 hour or 8 hours

 

### Pesticides with Koc of 100 L/kg or 10,000 L/kg

 

## Each run reads Ksat

, θ sat and θ fc for one soil

unit

 

### θ fc used as fixed (and correlated) input for initial water

content

 

## All other parameters held at constant values

relevant to the FOCUS R scenario

March 19, 201322 

# Deriving Conservative Values for Ksat & θ sat

March 19, 2013 0 10 20 30 40 50 60 70 80 90 100

40 50 60 70 80 90 100Percentile of the frequency distribution

% pesticide removal 8 hour event,

Koc=10,000

8 hour event,

Koc = 100

1 hour event,

Koc = 10,000

1 hour event,

Koc = 100 

## R323 

# Note

March 19, 2013 

## The efficiency in removing pesticide varies with properties of soil, pesticide and runoff event

The relative vulnerability of different soils is independent of pesticide and event properties but24 

# 90 th 

# Percentile Worst

- Case Values in the VFS

March 19, 2013 Parameter R1 R2 R3 R4

K

s (m s - 1 ) 7.04 x 10

- 7 2.79 x 10

- 6 9.25 x 10

- 7 1.52 x 10

- 6

θ

s (cm 3 cm - 3 ) 0.447 0.403 0.472 0.420

θ fc (cm 3 cm - 3 ) 0.395 0.312 0.385 0.37225 

# Changes to Ksat and θ sat in the VFS

 

## Data from SEISMIC (LandIS data, NSRI) for soil series in England and Wales

 

## SEISMIC reports Ksat and θ sat for each soil series and distinguishes between permanent grassland and arable land

 

## Use information to estimate Ksat and θ sat for grassed buffer strips from the field Ksat and θ sat

March 19, 201326 

# Ksat and θ sat in the VFS

March 19, 2013 y = 1.1058x
R2 = 0.2344

35 40 45 50 55 60 65 70

35 40 45 50 55 60 65 70Theta sat (cm/day) Permanent grassland

Theta sat (cm/day) Arable land Theta sat

- 15 - 10

- 5 0 5 10 15

40 45 50 55 60 65Residuals (Pred-Obs)

Theta sat (cm/day)



### Worst

- case assumption as default: Hydraulic properties equal to those in arable field27 

# Determination of Sediment Particle Size

March 19, 2013 0 100 200 300 400 500 600

0 50 100 150 200 250 300d50 sediment (μm)

d50 parent soil (μm) Elliot

Chisci & Martinez

Slattery & Burt

0 5 10 15 20 25 300-2020-4040-6060-8080-100100-120120-140140-160160-180180-200200-220220-240240-260260-280280-300300-320320-340340-360360-380380-400400-420420-440440-460460-480480-500500-520520-540% of samples

d50 range (μm)



## Mean particle size of

eroded sediment:

Worst

- case value as default (30 μm)28 

# Software Development

March 19, 2013 

## FOCUS

PRZM VFSMOD

- W FOCUS
TOXSWA

SWAN

Edge

- of

- field

runoff Interception in
VFS Fate in
surface water29 

# Example Result

March 19, 2013 

### 66% reduction

80% reduction Red = no mitigation Blue = 5m buffer
Green = 10m buffer30 

# European Status

 

## Scenario Development report available at: www.york.ac.uk/environment/pesticide

 

## SWAN software including vegetative buffer strip modeling as a mitigation measure now available

 

## Training conducted for European regulators in

Paris on October 10, 2012

March 19, 201331 

# Conclusions

 

## Develop of the mitigation practice of removal of pesticides by vegetative buffer strips and quantifying its effectiveness has been a multi

- step process involving many scientists over a period of about 25 years

 

### Built on previous work for use in removing sediment

 

## Current a procedure for quantifying the effectiveness of vegetative buffer strips is being adopted in European regulatory risk assessments

March 19, 201332 

# Conclusions

 

## The process for potential implementation in regulatory assessments in the U.S. continues

 

### Next step is a workshop sponsored by the Soil and Water Conservation Society on April 17

 

### Participants will include scientists from USDA, EPA, universities, and industry

March 19, 2013