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<title>Development and Selection of Ammonia Emission Factors</title>
<type>single page tiff</type>
<keyword>nh3 emission factors research emissions literature sources recent emis project inventory united inventories european sion battye potws agricultural majority fac</keyword>

                United States
                Environmental Protection
 Atmospheric Research and
 Exposure Assessment Laboratory
 Research Triangle Park, NC 27711
                Research and Development
EPA/600/SR-94/190  November 1994
EPA       Project  Summary
                Development  and  Selection  of
                Ammonia Emission  Factors
                Rebecca Battye, William Battye, Calvin Overcash, and Stephen Fudge
                 This project compiles recent litera-
               ture on ammonia  (NH3) emission fac-
               tors for application in the United States.
               Most of the recent research supports
               acid deposition studies in the Euro-
               pean community (specifically, the Neth-
               erlands, Great Britain, and Scandinavia),
               but some research has been conducted
               in Australia. The majority of NH3 emis-
               sions in current inventories, (up to 90
               percent or more of anthropogenic emis-
               sions) originates from livestock wastes
               with fertilizer  applications  providing a
               significant proportion.  Some  invento-
               ries exclude industrial emissions en-
               tirely because they are  insignificant
               relative to agricultural sources. Global
               climate change research indicates that
               undisturbed soils  and  biomass burn-
               ing may also  have significant emis-
               sions,  up to  half of the  global NH3
               budget. The recommended NH3 emis-
               sion factors  are the following: Euro-
               pean factors for agricultural sources;
               the Pollutant  Emission Factors—Vol-
               ume I  (AP-42) for industrial sources;
               and National Acid Precipitation Assess-
               ment Program factors for combustion
               sources,  human breath and perspira-
               tion, and  publicly owned treatment
               works (POTWs). New factors are devel-
               oped for beet sugar production, froth
               flotation in mineral processing, mineral
               wool (fiberglass) production, refrigera-
               tion,  and selective  catalytic  and
               noncatalytic reduction for control of ni-
               trogen oxide emissions. Additional dis-
               creet industrial sources of NH3 are
               identified through  the  Toxic  Release
               Inventory. Five future research  projects
               are  recommended:  investigate global
               climate literature on NH3 from undis-
               turbed soils and biomass burning; use
               animal  husbandry  primary references
               to provide better linkage with United
               States  Department of Agriculture sta-
               tistics;  develop temporal profiles  for
               agricultural emissions; and conduct
 additional research into emissions from
 refrigeration, POTWs, and selective
 catalytic and noncatalytic reduction.
   This Project Summary was developed
 by EPA's Atmospheric Research and
 Exposure Assessment Laboratory, Re-
 search Triangle Park, NC, to announce
 key findings of the research project that
 is fully documented in a separate report
 of the same  title (see Project Report
 ordering information at back).

   Ammonia (NH3)  emissions are impor-
 tant in air quality models because NH3 is
 the most important alkaline constituent in
 the atmospheric boundary layer. The fate
 of NH3 released from the ground into the
 atmosphere is complex and varied, but
 NH3 can have  a significant effect on oxi-
 dation rates, particularly in clouds, and
 hence on deposition rates of acidic spe-
 cies. The effect is predicted not only by
 models for the heterogeneous chemistry
 of cloud  droplets but has also been con-
 firmed by observation and experimenta-
 tion.  The  long  range transport of
 atmospheric sulfur  dioxide and nitrogen
 oxide and the products of their reactions
 have long been studied in relation to at-
 mospheric deposition. However, much less
 research has been done on the effects of
 atmospheric NH3, although it is well known
 that over large areas of Europe, acid pre-
 cipitation is falling in which  up to 70 per-
 cent of the original  acid is neutralized by
  The importance of  NH3  in the  atmo-
 spheric chemistry  of air quality requires
 that accurate emission source inventory
 data be available for chemical and trans-
 port air quality modeling. Relatively little
 NH3 emission data have been gathered
 and little effort expended in developing
 source-category specific NH3 emission fac-
tors because NH3 is generally not a regu-
 lated air  pollutant.  Also, it is not feasible
to speciate NH3 from volatile organic com-
                                                                  Printed on Recycled Paper

pound (VOC) emission or particulate mat-
ter (PM) emission inventories because as
an inorganic gaseous chemical NH3 is not
included  in  VOC emission  estimates or
PM emission estimates.  Consequently,
estimated inventories of NH3  emissions
provide very crude first-order information
at this time.
  This project compiled  and reviewed  re-
cent (after 1985) literature on sources of
NH3 emissions and emission factors. The
compilation  contains the most recent  re-
search in the field of NH3 emission fac-
tors. The primary focus of the  project is
on  emission factors  as  opposed to esti-
mates of total NH3 emissions.  Emission
estimates are, however, made  for some
categories to determine the relative im-
portance of the source category to overall
NH3 emissions and to assist  in developing
priorities for the NH3 emission  factor  re-
  The project compiled and critically evalu-
ated  NH3 emission information from  re-
cent  literature with the objectives  of 1)
evaluating the quality of available emis-
sion factors, 2)  recommending adoption
of the factors where appropriate, 3) devel-
oping emission  factors  from data in the
literature where possible, 4) recommending
assignments of  emission  factors to spe-
cific U.S. Environmental Protection Agency
(U.S. EPA) source category codes, and 5)
arriving at a set of recommendations for
future research likely to provide the great-
est gain  in knowledge  of NH3 emission
  The scope of the literature search in-
cluded peer-reviewed books and journals
and published and unpublished private and
governmental laboratory reports. The
search used computer-based library cata-
logs and personal contacts. The majority
of available  relevant literature  was from
North America and Europe. When the lit-
erature contained process activity data and
information  on the content of NH3 in  the
emissions, an emission factor was com-
puted and the scope of application (source
category codes) determined.
   Emission factors from or derived from
the literature were assigned quality rating
factors that depend  on the quantity and
rigor  of underlying data and testing. The
quality rating system is that used by U.S.
EPA's Office  of  Air Quality  Planning and
Results and  Discussion
   Recent research on NH3 emissions as it
relates to acid deposition, is concentrated
in the European community (specifically,
in  the Netherlands, Great  Britain, and
Scandinavia). In addition, there has been
some research in Australia. The majority
of  the NH3 emissions included in current
inventories  originate from  agricultural
sources.  These agricultural  sources  are
mainly livestock wastes, with fertilizer ap-
plications also providing a significant pro-
portion. NH3 emission estimate numbers
vary widely between different studies, but
the authors of  recent European  invento-
ries all consider animal wastes and fertil-
izers to be responsible for 90 percent or
more of the anthropogenic NH3 emissions.
Some of the more recent inventories in
Europe even exclude contributions for in-
dustrial facilities entirely, noting that they
are insignificant relative to the agricultural
  Although the European"inventories cur-
rently focus on agricultural sources, there
is  evidence that  additional, significant
sources of NH3 may exist. Studies  in the
United Kingdom suggest that current esti-
mates of NH3  emissions are too small to
explain the concentrations of ammonium
in  precipitation and that there  may be other
sources of NH3 that have not been con-
sidered in budget studies. Other research,
principally  in  support  of global climate
change research, suggests that there may
be significant  NH3 emissions from undis-
turbed soils and biomass burning.
   Much of the research obtained and re-
viewed by this project concerns the mea-
surement of NH3  in which  results were
generally reported as experimental rather
than as emission factors. The, majority of
NH3 emission  factors available in the lit-
erature are discussed  relative to the de-
velopment of  an  emission  inventory. In
the  development of an  emission inven-
tory, emission factors are often either de-
veloped for the experimental measurement
literature or are  borrowed  directly from
other bodies of work. The primary source
for the emission factors reviewed by this
project was the body of recent  emission
inventory literature. The experimental mea-
surement literature was also reviewed to
provide detail  on how the measurements
were made. This review contributes to un-
derstanding the uncertainty  of the emis-
sion factors, addresses the extent to which
the factors presented incorporate the most
recent research, and identifies data gaps
for future emission factor development.
   The most recent NH3 inventory prepared
in the United  States is the Emissions In-
ventory for the National Particulate Matter
Study, which  used  Bureau  of Economic
Activity data to project the 1985 NAPAP
inventory to the 1990 study year.  There
are  several recent NH3 emission invento-
ries for specific European  countries, in-
cluding Great  Britain,  the Netherlands,
Denmark, and Germany. The most recent
European inventory was published in 1992.
Another NH3 inventory was published for
Australia in 1990.
  Rough estimates of anthropogenic NH3
emissions in the United States  indicate
that animal husbandry and fertilizer appli-
cation dominate emissions (approximately
80 percent)  as  they do in Europe. Indus-
trial emissions of NH3 and NH3 emissions
from combustion are relatively insignifi-
cant (about 1 percent). NH3 emissions from
refrigeration  and POTWs may be signifi-
cant (perhaps 7 percent).
  Estimates of NH3  emissions for biom-
ass burning and undisturbed soils were
not made because of the unavailability of
an  emission factor for  biomass burning
and activity data for undisturbed soils. Re-
cent research indicates that these two cat-
egories may contribute significantly (up to
half) of the  global budget of NH3 emis-
Conclusions and
  The NH3 emission factors recommended
for  use in future U.S. inventories include
the following: European factors for agri-
cultural sources (animal husbandry and
fertilizer application); the  Compilation of
Air Pollutant Emission Factors—Volume I
(AP-42) for  the majority of the stationary
industrial sources; and the NAPAP factors
for the majority of the combustion sources
(including coal, oil, natural gas, and mo-
bile sources), human breath and perspira-
tion, and POTWs. New emission factors
are developed  for beet  sugar production,
froth flotation in mineral processing, min-
eral wool (fiberglass)  production, refrig-
eration,  and  selective  catalytic and
noncatalytic reduction for control of nitro-
gen oxide  emissions.  Specific industrial
sources of  NH3 with  no corresponding
emission factors are identified through the
Toxic Release  Inventory.
  Five research areas  are recommended
to enhance  the quality  of NH3 factors ad-
dressed by  this project.  The five research
areas  include completion of the following:
  1.   Investigate the recent global climate
       change  literature on NH3 from un-
       disturbed soils. Merge the literature
       on emission fluxes with new land
       use and land cover data categories
       to develop emission factors for bio-
       genie and mobile sources  catego-
  2.   Investigate recent literature on NH3
       emissions for biomass burning.  In-
       tegrate the data  results with infor-

mation in the United States on natu-
rally occurring fires to develop emis-
sion factors for the United States.      4.
Also, investigate all information on
NH3 emissions  for  the  chemical
agents used to fight these naturally
occurring fires.
Research the primary references for
the animal husbandry emission fac-      5.
tors to provide more accurate link-
ages with the U.S. Department of
Agriculture statistics.  In addition, in-
vestigate  the  discrepancy  in the
emission factors for sheep in the
Develop temporal  profiles for the
larger  NH3  emission categories.
Specifically, investigate  the  sea-
sonal nature of the animal  hus-
bandry  and fertilizer application
Conduct additional research on the
NH3 emission  factors reported for
refrigeration, POTWs, and selective
catalytic and noncatalytic reduction
(for control of  NOX emissions) to
improve confidence in their validity.
Refrigeration contributes a signifi-
cant portion of the NH3 inventory
(about 5 percent); however, this fac-
tor was developed  based on a ma-
terial  balance.  POTWs  also
contribute a significant  amount of
NH3 (about 2 percent); additional
research is  ongoing  in the United
Kingdom and  California that may
improve the accuracy of the emis-
sion factor.

   R Battye, W. Battye, C. Overcash, and S. Fudge are with EC/R Incorporated,
     Durham, NO 27707.
   William G. Benjeyis the EPA Project Officer (see below).
   The complete report, entitled "Development and Selection of Ammonia Emis-
     sion Factors, "(Order No. PB95-123915; Cost: $27.00, subject to change) will
     be available only from
           National Technical Information Service
           5285 Port Royal Road
           Springfield, VA22161
           Telephone: 703-487-4650
   The EPA Project Officer can be contacted at
           Atmospheric Research and Exposure Assessment Laboratory
           U.S. Environmental Protection Agency
           Research Triangle Park, NC 27711
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268

Official Business
Penalty for Private Use
   PERMIT No. G-35

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