Document ID: EPA-HQ-OPP-2005-0128-0146
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-02-13T05:00Z

Post-harvest

	Tuesday, October 30, 2007	8:00 – 10:00 AM

EPA Determination of Structural Fumigation Emission Profiles	Moderator

	Jeff Dawson/

Steven Weiss

8:00 - 8:10 am	EPA Overview: Jeff Dawson/Steven Weiss

8:10 - 9:00 am	Research Panel Presentations: Eric Winegar, Richard
Reiss, Suresh Prabhakaran, Dirk Maier, Michael  Kaae

9:00 - 10:00 am	Open Discussion 

Goal:	The U.S. EPA recently evaluated the potential risks associated
with the post-harvest uses of methyl bromide as well as other
post-harvest fumigant chemicals.  In its effort to develop risk
management decisions for these materials, it has become increasingly
clear that quantitative data of sufficient quality would allow for a
more rigorous determination of how basic factors such as building
design, sealing methods, changing weather conditions, absorptive
properties of treated commodities, and aeration techniques influence
emissions from treated structures during holding times and active
aeration.  Given the regulatory challenges that exist, the development
of emission reduction factors which better reflect modern practices and
conditions are required.  It is envisioned that these factors can be
used to potentially alleviate the regulatory burdens for users who
utilize such approaches as part of their practices.  Examples of such
factors may include:  (1) placement of active aeration outflows; (2)
numbers of active aeration outflows and associated performance criteria;
and (3) influence of building location and design on emissions relative
to surrounding terrain and typical weather conditions during treatments.
 The goal of this session is to begin to summarize available research on
this issue, use this research to identify the critical factors that
should be considered related to emissions reduction, and to begin to
define factors for these parameters.

Questions:

Individual factors that impact fumigant emissions from structures
include aeration methods, building design, climate, and location
relative to topography. What are the most important factors which impact
emissions from treated structures?  Are they independent or do they
impact emission rates in a synergistic manner?  How much impact do
differences in building design and aeration methods have on these
results?

Can parameters be manipulated in a typical commercial production system,
to reduce emissions yet still retain an effective, economically viable
production system?  If so, what techniques can be used to manipulate
emissions from treated structures (e.g., high barrier films, emission
stacks, recovery systems)?

Do data exist that can be used to demonstrate, in a reliable manner,
responses to questions 1 and 2?

Modeling approaches have been suggested as a means for using laboratory
and field-scale data for predicting emissions under varied conditions
based on changes in sealing methods and aeration parameters.   What
model systems can be used for this purpose, if any? What data are
required for the reliable use of such models?  

The intent of this session is to provide a public forum where research
and initiatives related to the above goal and questions are presented.  
EPA is not asking participants for recommendations to make regulatory
decisions.

Slides for this and other MBAO conference sessions can be viewed at  
HYPERLINK "http://mbao.org/"  http://mbao.org/ Pre-plant

	Tuesday, October 30, 2007	3:30 – 5:30 pm

Determination of Soil Fumigant Emission Reduction Factors	Moderator

	Jeff Dawson/

Charles Smith

3:30 - 3:40 pm	EPA Overview: Jeff Dawson/Charles Smith

3:40 - 4:30 pm	Research Panel Presentations: Dan Chellemi,  Dong Wang,
Husein Ajwa, Scott Yates, Steven Cryer

4:30 - 5:30 pm	Open Discussion 

Goal:	The U.S. EPA is currently evaluating the potential risks
associated with the pre-plant uses of a variety of soil fumigant
chemicals.  In its effort to develop risk management decisions for these
materials, it has become increasingly clear that quantitative data of
sufficient quality would allow for a more rigorous determination of how
basic factors such as soil moisture, soil temperature, mulch types, or
the percent of organic matter influence emissions at the field level. 
Given the regulatory challenges that exist, the development of emission
reduction factors which better reflect modern cultural practices and
conditions are required.  It is envisioned that these factors can be
used to potentially alleviate the regulatory burdens for users who
utilize such approaches as part of their practices.  Examples of such
factors may include:  (1) emission reduction based on high barrier film
use; (2) influence of soil moisture levels; and (3) influence of organic
matter on emissions.  The goal of this session is to begin to summarize
available research on this issue, use this research to identify the
critical factors that should be considered related to emissions
reduction, and to begin to define factors for these parameters.

Questions:

Individual factors that impact fumigant emissions from treated fields
such as soil characterization, depth/type of delivery system, moisture
levels, soil temperature, and soil surface laminar air flows can be
generally referred to as first-principles factors.  What are the most
important first-principles factors which impact emissions from treated
fields?  Are they independent or do they impact emission rates in a
synergistic manner?  How much impact do regional and cultural practice
differences have on these results?

Can first-principles parameters be manipulated by producers, in a
typical commercial production system, to reduce emissions yet still
retain an effective, economically viable production system?  If so, what
techniques can be used to manipulate field conditions (e.g., high
barrier films, irrigation, soil adjuvants)?

Do data exist that can be used to demonstrate, in a reliable manner,
responses to questions 1 and 2?

Modeling approaches have been suggested as a means for using laboratory,
micro-field, and field-scale data for predicting emissions under varied
field conditions based on changes in first-principle parameters.  One
such suggested system is Chain 2D that was developed by USDA ( 
HYPERLINK "http://www.ars.usda.gov/Services/docs.htm?docid=8914" 
http://www.ars.usda.gov/Services/docs.htm?docid=8914 ).  What data are
required for the reliable use of such models?  Do other viable model
options exist that can be used to predict emission rates based on
first-principles parameters?

The intent of this session is to provide a public forum where research
and initiatives related to the above goal and questions are presented.  
EPA is not asking participants for recommendations to make regulatory
decisions.

Slides for this and other MBAO conference sessions can be viewed at  
HYPERLINK "http://mbao.org/"  http://mbao.org/ 

	Wednesday, October 31, 2007	3:45 – 5:30 pm

EPA Determination of Field-Scale Soil Fumigant Emission Profiles
Moderator

	Jeff Dawson/

Charles Smith

3:45 - 3:55 pm	EPA Overview: Jeff Dawson/Charles Smith

3:55 - 4:30 pm	Research Panel Presentations: David Sullivan, Richard
Reiss,  Randy Segawa, Stanley Culpepper

4:30 - 5:30 pm	Open Discussion 

Goal: The U.S. EPA is currently evaluating the potential risks
associated with the pre-plant uses of a variety of soil fumigant
chemicals. In its effort to develop risk management decisions for these
materials, it has become increasingly clear that quantitative data of
sufficient quality would allow for a more rigorous determination of
emission profiles that would be expected due to regional differences in
major fumigant use areas of the country as well as the cultural
practices employed in those regions to produce major crops.  Given the
regulatory challenges that exist, the development of emission profiles
which better reflect modern cultural practices and conditions are
required.  It is envisioned that such measurements can be used to
potentially alleviate the regulatory burdens for users who use practices
that are intended to reduce emissions.  Examples of such factors may
include:  (1) high barrier film use; (2) regions with higher percent
organic matter in their soils; and (3) cooler climates.  The goal of
this session is to begin to summarize available research on field-scale
emissions, use this research to identify the critical factors that
should be considered related to how emissions vary from region to region
based on chemicals used and cultural practices, and to begin to define
factors for these parameters including approaches for more economical,
yet reliable, monitoring methods.

Questions: 

Fumigant emissions from treated agricultural fields can be impacted by
many factors and understanding how they vary for different cultural
systems is critical.  This is important both for the mitigation
strategies that might be employed for individual chemicals or within
limits defined by a cultural system or geographic region.  It follows
that there is a desire to obtain as much field-scale emissions data as
possible in order to evaluate trends in the data and also to be able to
provide more definitive risk estimates for the wide ranges of cultural
practices in use in agriculture today.  In an effort to solicit this
information, the Agency seeks any additional emissions data that may not
have been considered in our current process.  Do additional data exist? 
What cultural systems were evaluated?  Are they representative of
current cultural practice and for what crops? 

What are the most viable techniques for determining emission profiles
(e.g., indirect or aerodynamic flux)?  Are these techniques
systematically biased with regard to the results provided?

Is it possible to capture the necessary information to develop emission
profiles from field-scale treatments in a manner that is less expensive
and complex than the currently available monitoring methods?  If so,
what are these techniques?  What are the attributes of each and are they
inherently biased to the more commonly used methods?

Do data exist that can be used to demonstrate, in a reliable manner,
responses to question 3? 

The intent of this session is to provide a public forum where research
and initiatives related to the above goal and questions are presented.  
EPA is not asking participants for recommendations to make regulatory
decisions.

Slides for this and other MBAO conference sessions can be viewed at  
HYPERLINK "http://mbao.org/"  http://mbao.org/