THE URBAN PERSPECTIVES OF ACID RAIN
WORKSHOP SUMMARY
Bruce E. Tonn
Oak Ridge National Laboratory
June 4, 1993
Sponsored by the Office of the Director,
National Acid Precipitation Assessment Program
Funded by the U.S. Department of Energy
Prepared by the
Oak Ridge National Laboratory
Oak Ridge, Tennessee 37831-6285
managed by
Martin Marietta Energy Systems, Inc.
for the
U.S. Department of Energy
under
Contract No. DE-AC05-84OR21400
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EXECUTIVE SUMMARY
This report documents discussions held during the workshop entitled "The Urban Perspective of Acid
Rain." The workshop was sponsored by the Office of the Director (OD), National Acid Precipitation
Assessment Program (NAPAP), funded by the U.S. Department of Energy, and organized by Oak
Ridge National Laboratory. The workshop was held in Raleigh, North Carolina, September 23-24,
1992.
NAPAP/OD anticipates giving increased emphasis to the benefits in urban areas of emissions
reductions under Title IV of the 1990 Clean Air Act Amendments. The goal of this informal,
exploratory workshop was to serve as a first step towards identifying pollutant monitoring and
research and assessment needs to help answer, from an urban perspective, the two key questions
posed to NAPAP by Congress: 1) what are the costs, benefits, and effectiveness of the acid rain
control program, and 2) what reductions in deposition rates are needed in order to prevent adverse
ecological effects?
f
The workshop addressed research and monitoring activities needed to respond to these questions. The
discussions focused, sequentially, on data needs, data and model availability, and data and modeling
gaps. The discussions concentrated on four areas of effects: human health, materials, urban forests,
and visibility.
The workshop participants identified numerous research needs associated with monitoring, modeling,
methodological considerations, and computing. Issues related to monitoring entail: data collection
(emissions, air quality, deposition, exposure, and effects data); monitor network design; extrapolation
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methods; and instrument design. Several air quality models exist (e.g., Regional Acid Deposition
Model), but they need further testing on finer resolutions appropriate for studies of urban issues.
Improved model descriptions are needed to bridge the interfaces between air quality and deposition,
deposition and exposure, and exposure and effects.
Methodological considerations include: determining how many urban areas to select for case study
analysis; specifying criteria for selecting the most efficient set of urban areas for analysis; and
apportioning attribution of acid deposition to appropriate sources. Computing issues include: making
available computing resources to handle large scale acid deposition modeling; and developing a
central database system for storing and sharing NAPAP research results.
The workshop participants did not attempt to place priorities on the research needs nor were
budgetary issues discussed. The workshop achieved its aims of raising concerned interest in urban
issues and in initiating dialogue across disciplinary boundaries. Follow-up discussions are needed to
lay out a strategy for refining and implementing the recommendations. It was suggested that a
f
separate workshop address the question of how to assess the benefits of Title IV with respect to urban
areas.
IV
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TABLE OF CONTENTS
EXECUTIVE SUMMARY iii
1.0 INTRODUCTION 1
2.0 OBJECTIVES OF URBAN ACID PRECIPITATION ASSESSMENT 2
2.1 General Goals 4
2.2 Effects of Concern 4
3.0 DATA NEEDS AND STRATEGY 9
3.1 General Methodological Approach 9
3.2 Selection Criteria for Urban Areas 11
4.0 EXISTING MONITORING DATA AND MODELS 13
4.1 Existing Monitoring Data 13
4.2 Existing Models '. 18
5.0 RESEARCH ISSUES AND DATA NEEDS 21
5.1 Monitoring 21
5.2 Modeling 24
5.3 Methodological Considerations 26
5.4 Computing 27
6.0 COST/BENEFIT CONSIDERATIONS 28
7.0 SUMMARY 30
8.0 REFERENCES '. 32
ACKNOWLEDGEMENTS 32
APPENDIX A. WORKSHOP AGENDA A - 1
APPENDIX B. LIST OF WORKSHOP PARTICIPANTS B - 1
APPENDIX C. VIEWGRAPHS OF SELECTED WORKSHOP PRESENTATIONS C - 1
Urban Forests C - 1
Visual Air Quality C-3
Linking Urban and Regional Models C-8
Urban Environmental Characterization for Estimating the Economic Benefits
Associated with Materials Effects C - 12
Acid Deposition Monitoring in the United Kingdom C-14
Wet Deposition C - 35
Formulating Dry Deposition in Urban Areas C - 55
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1.0 INTRODUCTION
The Workshop on Urban Perspectives of Acid Rain was held in Raleigh, North Carolina, September
23-24, 1992. The Workshop was sponsored by the Office of the Director (OD), National Acid
Precipitation Assessment Program (NAPAP), funded by the U.S. Department of Energy (DOE), and
organized by Oak Ridge National Laboratory (ORNL), with considerable help from NAPAP and the
National Park Service.
Title IV of the Clean Air Act Amendments (CAAA), Public Law 101-549, Nov. 15, 1990, directs
NAPAP/OD to continue its work of assessing the impacts of certain provisions of the CAAA on acid
deposition and resulting effects in the United States. NAPAP/OD anticipates giving increased
emphasis to the benefits (i.e., reduced damage) of Title IV experienced by urban areas due to
emissions reductions. Reasons for this emphasis are numerous. Over 70% of the population of the
United States resides in urban areas. Similarly, a large proportion of the nation's economic wealth is
also located in urban areas in the form of buildings, vehicles, factories, and cultural artifacts. Lastly,
t
one can argue that to best address equity concerns related to environmental protection and Title IV,
many of the nation's core urban areas need to be incorporated into the NAPAP research design.
f
The general goal of this informal, exploratory workshop was to act as a first step towards identifying
pollutant monitoring, research, and assessment needs to help answer, from an urban perspective, the
two key questions posed to NAPAP by Congress. One, what are the costs, benefits, and effectiveness
of the acid rain control program? Two, what reductions in deposition rates are needed in order to
prevent adverse ecological effects?
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To accomplish this goal, an interdisciplinary group of participants was assembled to engage in cross-
cutting discussions for efficiently integrating NAPAP activities from the urban perspective and as
points of consideration by the formal NAPAP Working Groups', the NAPAP member agencies2, and
the Office of the Director of NAPAP. The participants were drawn from member agencies,
universities and national laboratories. A list of attendees can be found in Appendix B.
The dialogue at the workshop helped those with different areas of expertise, such as modeling or
monitoring, to understand each others' research needs. It was useful to observe where various data
needs intersect and can be synthesized into an integrated approach. The discussion at the workshop
was able to tap into knowledge about on-going data collection and modeling activities in various urban
areas and plans for data collection and modeling efforts.
This report summarizes the discussions and recommendations of the workshop. Section 2.0 discusses
the general objectives of an urban acid precipitation research program. Section 3.0 outlines a strategy
for developing such a program. Section 4.0 summarizes existing monitoring data and models related
/
to urban acid precipitation. Section 5.0 presents research needs associated with monitoring,
modeling, methodological considerations, and computing. Section 6.0 briefly addresses the issue of
assessing the costs and benefits of Title IV.
2.0 OBJECTIVES OF URBAN ACID PRECIPITATION ASSESSMENT
This section reports on three initial tasks tackled by the workshop participants. First, some general
agreement was needed on the main workshop discussion points. The NAPAP Director presented a
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cogent discussion which suggested several points (see viewgraphs in Appendix C). These points
encompassed: pursuing a case study-based strategy versus a broad brush approach; developing
defensible criteria for selecting case study sites; establishing an integrated pollutant monitoring
network; and establishing credible methods for attributing pollutant concentrations and deposition to
the proper sources. The workshop participants endorsed these points of discussion.
Second, consensus was needed on the approach to be taken at the workshop to organize discussions
on research needs. It was agreed that the workshop should be organized into four parts: (1)
presentations by experts in the four major effects areas - human health, materials, urban forests, and
visibility; (2) discussions to identify data needed by researchers working in each of the four specific
effect areas (Sect. 2.2 summarizes these discussions); (3) discussions to recognize data already being
collected or soon to be collected and models already in existence that can be applied to assessing
effects of Title IV in urban areas (see Sect. 4.0); and (4) discussions to identify gaps between the
data needs and data being collected and modeling needs and existing models that could provide the
basis for the NAPAP urban research program (see Sect. 5.0). Appendix A presents the agenda that
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was followed at the workshop.
Third, workshop participants addressed goals needed to guide research focusing on the urban
perspective of acid deposition. These goals are presented next, in Sect. 2.1. Sect. 2.2 presents issues
associated with the four major effects of concern.
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2.1 General Goals
As stated above, the general goals of NAPAP are to assess reductions of acid deposition due to the
CAAA and to assess the costs and benefits of these reductions. These two general objectives were
fashioned into four guiding questions with respect to the urban perspective of acid rain. One, what
will be the urban air quality changes attributable to the CAAA? Due to the positioning of NAPAP
within the complex national environmental programmatic structure, the focus of urban air quality
assessments will be on changes in atmospheric concentrations of sulfur and nitrogen species and their
deposition.
Two, how do air quality changes relate to different land uses within urban areas (e.g., central city,
residential, parkland)? It was recognized by the workshop participants that urban areas have mixed
and complex land use patterns that will significantly complicate assessment activities. Three, what are
the relationships between NAPAP and Title IV of the CAAA and the other titles? It is possible that
efficiencies in data collection, modeling, and assessment activities can be gained if research activities
under all the Titles of the CAAA are thoughtfully coordinated.
f
Four, how will changes in air quality impact the four major effects of concern of acid deposition in
urban areas? This is a very important question because a multi-disciplinary approach will be needed
to link emissions to air quality, to deposition, to exposure, and finally to effects.
2.2 Effects of Concern
The urban issues associated with acid deposition are quite complex, challenging, and potentially
significant. Urban areas are subjected to numerous types of airborne pollutants, in addition to those
attributable to the fossil power plants covered by Title IV (see Figure 1). Multifarious and
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complicated urban land use patterns make establishing linkages from the various emission sources to
their ultimate effects a very challenging endeavor. For example, urban land use patterns can produce
very idiosyncratic urban microclimates, which can significantly influence deposition rates and thereby
affect exposures to acid aerosols and acid-based chemicals. The combination of urban land use
patterns, microclimates, and population behavior also makes it very challenging to evaluate the role
that emissions from the fossil power plants play in serious health problems.
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Location of 110 Power Plants Affected Under Phase I of Title IV
of the 1990 Clean Air Act Amendments (ASL & Associates)
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September 1992
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To focus workshop participants' attention on initial steps toward confronting these complexities, four
specific effect areas were targeted during the workshop: human health, materials, urban forests, and
visibility. This subsection briefly summarizes presentations about these areas of concern. Appendix C
contains viewgraphs used by workshop participants who made presentations in these areas.
Human health concerns relate to individuals being exposed to acid aerosols, SCX, and S042", which in
turn may cause respiratory problems such as shortness of breath, chronic bronchitis, and other serious
health problems. It is suspected that these pollutants are responsible for a significant amount of
respiratory problems, but there have been few scientific studies to quantify this suspicion. Current
research is attempting to discern whether it is the particles per se, as opposed to their chemistry,
which causes the health-related problems. One difficulty associated with research in this area is that
air quality in urban areas, which has been widely studied, is not the same as exposure. This is
because people's time allocations between indoor and outdoor activities and infra-urban concentration
gradients combine to complicate exposure estimates to outdoor airborne pollutants. The workshop
participants recommended that NAPAP address the need to collect better exposure data.
f
Materials in urban areas are subject to damage from both the wet and dry deposition of acidic
pollutants. The workshop focused for the most pan on stationary structures. The primary pollutants
of concern for materials include S02, SO^ and HNO3. Quantitative evaluation of the effects of these
pollutants is difficult in urban areas because there are numerous construction types (e.g., engineering
structures, sculptures, office buildings, residences) and numerous construction materials (e.g., brick,
stone, concrete, painted steel and wood, copper, etc.). Estimating the deposition of pollutants to
structures requires understanding urban variations in meteorology and pollutant concentrations,
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structure geometry (e.g., materials surfaces may be exposed or sheltered from rain), and materials use
patterns on urban and regional scales.
There is concern that acid deposition could adversely effect tree health and productivity. For
example, acid deposition could affect a tree's appearance, its susceptibility to insects and diseases, and
predispose a tree to early decline and mortality. In addition, acid deposition could decrease tree leaf
area and transpiration, and alter species composition, regeneration, and nutrient cycling of more
natural stand areas. This potential damage to urban forests could therefore affect the urban trees'
ability to modify the urban physical environment (e.g., reduce air temperatures), reduce urban energy
consumption, improve urban air quality, and improve the overall quality of life for urban inhabitants.
Evaluating the effect of acid deposition on urban trees is difficult as there are many other
environmental stresses that can also influence urban tree health and functions. In addition, the
response to these stresses can vary by tree species, which are generally diverse in urban areas. The
key pollutants to address are S02, H2S04, N0xand HN03.
/
Visibility became an important aspect of the original NAPAP research program (i.e., NAPAP I).
Visibility Air Quality (VA) is the effect of atmosphere on our outdoor visual experience, as directly
judged by humans or as indirectly assessed by analysis of atmospheric properties. VA degradation is
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caused by small particles and gases in the air that absorb and/or scatter sunlight. SO, and NO,
emissions adversely effect VA, and consequently, human perceptions of air quality and enjoyment of
the physical environment. Photographs presented during the workshop vividly illustrated the
potentially significant degradation of visibility air quality that can be caused by these pollutants.
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With these introductions to the four areas of concern, the workshop participants moved on to
discussing data needs, data and model availability, and data and modeling gaps associated with
measuring the effects of Title IV in these areas.
3.0 DATA NEEDS AND STRATEGY
Data needs are intimately tied to the overall strategy for assessing the impacts of Title IV on the four
effects areas. This section discusses the strategy recommended by workshop participants. The
strategy has two parts. The first part contains an outline of general points on research methodology
(e.g., over what time periods to collect data from where). The second part provides guidance on
selecting urban areas to be the subject of intensive case studies.
3.1 General Methodological Approach
Several methodological issues were raised and discussed at the workshop. This subsection
*
summarizes the seven most important points.
One, as.mentioned above, the workshop participants agreed at the beginning to adopt a case-based
research strategy rather than a broad-brush approach.
Two, NAPAP should collect data over long periods of time to best estimate relationships between
changes in air quality and effects and to separate changes in emissions from the effects of
meterological changes.
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Three, data collection efforts should mainly address air quality, although data also needs to be
collected to establish links between air quality and the four effects areas and between the effects
areas ar.u estimates of costs and benefits.
Four, the initial geographic area of interest should be the Title IV Phase I control area, which is
depicted in Figure 1. However, the workshop participants agreed that it might be beneficial to
include at least one urban area outside the impact area to act as a baseline (i.e., control area in
the jargon of experimental design).
Five, a pilot study should be initiated as soon as possible in one urban area to test key aspects of
the approach, such as monitoring technology, number and placement of monitors, capability for
extrapolation, etc.
Six, monitoring activities should be integrated wherever possible (e.g., share monitoring sites,
monitor pollutants that have the widest possible effects) to reduce costs and data management
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challenges.
Seven, the development of a rigorous and defensible detection strategy for attributing air quality
changes to Title IV should be emphasized, and the needs of the detection strategy should be
synthesized with monitoring and modeling plans.3
These strategic issues influenced discussions on selection criteria for urban areas, next section, and on
defining research needs, Sect. 5.0.
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3.2 Selection Criteria for Urban Areas
It was important for workshop participants to consider criteria for selecting urban areas for the case
studies. First, at this stage in the development of NAPAP's urban research program, it is vital to
know, at a fundamental level, whether there are many, some, a few, or no urban areas that match the
preferred criteria. Second, the dialogue at the workshop helped those with different areas of
expertise, such as modeling or monitoring, to understand each others' research needs. Third, it was
useful to observe where various data needs intersect and can be synthesized into an integrated
approach. Fourth, the discussion at the workshop was able to tap into knowledge about on-going data
collection activities in various urban areas and plans for data collection efforts. With these thoughts
in mind, seven recommendations were presented.
One, the selected urban areas should be representative of certain metropolitan types (i.e.,
large/small; industrial/commercial; dense/dispersed; etc.) so that results can be generalized.
Unique urban areas (e.g., Los Angeles)"should be avoided.
Two, it would be extraordinarily useful if the selected areas already had existing data (e.g., on
emissions, air quality, wet and dry deposition, exposures, and effects).
Three, the selected urban areas should represent a range of regional climates within the Title IV
control area.
Four, it should be certain that the selected urban areas be downwind of emissions sources that are
covered by Title IV. Of course, the baseline (i.e., experimental control) areas, if any are
selected, should not meet this criterion.
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Five, selection of urban areas for detailed studies should try to eliminate complicating terrain
factors if possible. '
Six, the set of selected urban areas should represent a diversity of human populations, materials,
urban forests, and visual air quality situations. It was not decided whether each urban area should
manifest this diversity, or whether to simply ensure that the set of selected urban areas manifests
this diversity.
Seven, the number of selected urban areas should be consistent with budget constraints and with
the ability of the scientific community to design, test, and implement rigorous data collection and
experimental programs within the time constraints. The first NAPAP analysis of costs and
benefits and report on reduction in deposition rates needed to prevent adverse ecological effects
is due to Congress in 1996.
No urban areas were chosen or firmly eliminated from consideration during the workshop. It was
f
suggested that EPA's Regional Acid Deposition Model (RADM) be used to assist in identifying cities
which would theoretically enjoy the largest reductions in acid deposition due to implementation of
Title IV. An action item resulting from the workshop is that these criteria be defined more
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specifically and given weights, so that the selection process proceeds in a timely fashion.4
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4.0 EXISTING MONITORING DATA AND MODELS
The second discussion point of the workshop related to identifying existing monitoring data and
models. This section summarizes these discussions.
4.1 Existing Monitoring Data
Discussions considered data that were collected as part of special case studies and as part of previous
and on-going Title IV activities. The following brief summaries are organized around each of the
four effects areas.
HUMAN HEALTH
It was the consensus of the workshop participants that not many data exist that are related to urban
acid deposition and health effects. There are numerous reasons for this. One is that few researchers
have asked this specific question. Another reason is that it is a difficult question to tackle. This is
/
because it is very difficult to statistically relate observed health problems in urban populations to
specific exposures to outdoor exposures to acid aerosols. An interesting observation is that data do
exist that des.cribe human health in urban areas and that represent past levels of air pollution. These
data could provide the basis for future NAPAP urban effects research. Numerous national data bases
exist that could support acid rain and health effects studies. These include the 1990 Decennial
Census, mortality data on the causes of death, University of Michigan individual time use data, and
various urban and regional transportation data bases.
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MATERIALS
Several case studies on acid rain and materials have been performed. These include the Philadelphia
Merchants Exchange Building Study, the Mesa Verde Study, a study of the Gettysburg National
Battlefield, the Research Triangle Park Configuration Study, and the Pittsburgh Building Soiling
Project. General Motors has also conducted an automobile paint study. Studies such as these will
help inform the development of more comprehensive studies of the effects of acid deposition on urban
materials.
On a national scale, numerous data bases can be used to study acid rain and materials. These include
National Climatic Data Center data on humidity, rainfall, etc. SO,, N02, and paniculate matter (PM)
emissions inventories are available from the federal government. Also, useful data may be found in
EPA's Toxic Release Inventory (TRI) data base.
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URBAN FORESTS
Comprehensive databases and analyses of urban forests are very limited, although numerous databases
exist for street and park tree populations in various cities. Comprehensive databases on urban
vegetation (based on field sampling) exist for Oakland and Los Angeles, California, and Chicago,
Illinois. In addition, the Chicago database contains information on artificial surfaces. The vegetation
data generally include information on the type, amount, sizes, condition, and location of vegetation by
land use type within the city. The databases from Oakland and Chicago are available. The
availability of Los Angeles data is unknown at this time.
Less detailed analyses of urban forest cover (i.e., the amount of area when viewed from above that is
occupied by trees, grass, buildings, roads, etc.) currently exist for 45 cities in the United States. This
cover information ranges from city-wide detailed analyses by land use type within geographic subunits
of the city (e.g., census tracts) to sampling of portions of the city. These cover data are generally
available or can be easily obtained for new cities air photo sampling and interpretation. Satellite
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imagery is also available for cities, but provides little detailed information on urban vegetation.
Satellite imagery can provide broad vegetation, structure, and land use information. Also, various
city organizations often have land use maps.
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VISIBILITY
Special studies have been completed and reported for several cities, including Denver, Detroit, Los
Angeles, and Houston. These studies collected data on aerosols and optical properties and, to varying
degrees, human perceptions of the decline in of visual ranges. In addition, visibility data have been
and are being collected at airports around the country. Visibility as measured by light extinction is
being routinely monitored only in a few urban areas.
DEPOSITION DATA BASES
The workshop was treated to a very comprehensive discussion of data sets available on the wet
deposition of acidic materials in urban areas (see "Wet Deposition: Available Databases" in Appendix
C). A number of databases are identified for cities not only in North America but in various parts of
the world, as reported in the peer reviewed literature. North American cities where wet-deposition
measurements have been made include St. Louis, Washington, DC, Chicago, and Philadelphia.
t
Numerous chemicals were measured overall, but the species measured differ among cities. Most
databases include H+, S042', and NH/.
Unfortunately, there are numerous problems related to using these existing data sets for NAPAP
research associated with urban areas. For example, problems associated with samplers include:
sampler siting criteria; diversity of sampler type (both bulk and wet samplers were used); sampler
size, configuration, and material; and collector material and cleaning method as well as storage bottle
material cleaning method. The databases also differ with respect to sample duration, averaging
period, sample preservation method, field procedures, laboratory sample handling methods, and
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analysis methods. It was concluded that useful data do exist, but the data are difficult to compare. A
coordinated urban wet deposition network using consistent methods is needed.
Discussions addressing dry deposition focused on methodologies (see "Formulating Dry Deposition in
Urban Areas in Appendix C). Specifically, it was pointed out that it is important to collect data about
deposition to specific types of surfaces (i.e., galvanized iron) and this should be a goal of NAPAP II.
Distinctions between wet and dry deposition science were also discussed. For example, the surface
chemistry of the sampler receptor materials is often a dominant factor in determining the reliability of
dry deposition data. Theoretical models relating to deposition to surfaces and from the atmosphere
were presented. Field testing of these methodologies and various sampler designs and constructions is
needed.
GREATER MANCHESTER ACID DEPOSITION SURVEY (GMADS)
The workshop was fortunate to have a representative of the GMADs program provide a presentation.
*
GMADS is the only urban acid rain monitoring system in existence. GMADS data are taken from an
area of some 1300 km2 in the North-West of England. The area has a population in excess of 2.5
million in the ten boroughs which make up the Metropolitan County of Greater Manchester.
The GMADS monitoring network consists of 19 bulk precipitation collectors. Passive diffusion tube
samplers for the determination of ambient nitrogen dioxide and ammonia gas concentrations are also
located at each site. The following criteria were used to site the monitors: sources of contamination,
obstructions, land use, topography, accessibility, and security.
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The GMADS network has been in place long enough to yield some interesting results. The data
indicate significant spatial variability in concentrations and depositions of non-marine sulphate, nitrate,
ammonium, calcium, hydrogen, nitrogen dioxide, and ammonia, among other chemicals. Specifically,
sulfate, nitrate, calcium, and ammonium concentrations were higher in the central city, whereas
hydrogen concentrations were lower. Seasonal variations were also observed.
It was the general consensus of the workshop participants that NAPAP could learn a great deal from
the experiences in Manchester, England, and that efforts should be made to establish close ties
between the two programs. Additional information on GMADS is found in Conlan et al. 1992 (also
see "Acid Deposition Monitoring in the United Kingdom" in Appendix C).
4.2 Existing Models
These discussions focused on EPA's RADM and other models that have evolved from this core
system. Since the conclusion of the NAPAP model development effort, a "family" of RADM-based
regional air quality models has been developed. The research group that developed RADM, now the
t
Atmospheric Modeling Section of the Atmospheric Sciences Research Center, State University of
New York at Albany (SUNYA), is encouraging and contributing to work with RADM-based models
that is being done by EPA and groups in Germany and Taiwan. The interrelationships among these
models and the working groups could be used to provide valuable contributions to future NAPAP II
programs.
The ongoing operational modeling work on RADM at EPA involves RADM 2.6, HR-RADM, and
associated variations. The current version of EPA's RADM, version 2.6, is operational. This
version makes predictions of S and N deposition over the eastern U.S., with a grid cell size of 80
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km! RADM 2.6 is designed to simulate regional transport of acid rain deposition. For application to
urban regions, it is necessary to reduce the grid size of RADM. EPA has prototyped a new version
of RADM, called High Resolution RADM or HR-RADM, which has a 20 km resolution. There is
ongoing discussion about whether this level of resolution is still too large for use in most urban
regions. It was predicted that HR-RADM will not be out of the research mode before 1996, given
current budget and manpower resources.
Associated with RADM 2.6 are several other models. One is a visibility post-processing model
which calculates the sulfate-associated aspects of visibility. Another is an engineering model that
estimates regional materials damage to zinc coatings related to sulfur deposition. EPA staff at the
workshop indicated that these models require more testing.
Several new versions of RADM have been developed and are being applied to study visibility and
related issues. A few highlights are noted here.
/
The Denver Air Quality Model (DAQM) was derived from AQM (the SUNYA research version of
RADM, renamed in recognition of the fact that RADM is in reality an air quality model) for studying
the visibility problem in the region that extends north and south from Denver along the eastern foot of
the Front Range of the Colorado Rockies. Currently, DAQM operates on an 8 km grid scale.
Among the new generation of urban- and regional-scale air quality models, DAQM is unique in that
complex aerosol as well as gas-phase processes are treated within the comprehensive three-
dimensional Eulerian framework. A variety of visibility parameters are determined from three-
dimensional hourly aerosol and gas concentrations calculated by DAQM and assumed aerosol light
extinction efficiency factors based on Mie theory analysis of observational data as well as factors
The Urban Perspectives of Acid Rain 19 September 1992
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derived from other studies. The light extinction calculations are then related to the Colorado visibility
standards, to provide a measure of acceptability of the visual air quality.
The Regional Paniculate Model (RPM) is the EPA's developmental aerosol complementary
counterpart to DAQM. DAQM treats sulfate, nitrate, organic, and dust aerosols in fine and coarse
particle sizes. RPM focuses on sulfate but characterizes multiple particle sizes.
Other RADM-related efforts are making advances in a variety of modeling areas important for future
urban-regional scale studies. For example, the SARMAP Air Quality Model (SAQM) is being
developed by SUNYA for a consortium led by the California Air Resources Board to study air
pollution in the Central Valley of California. All dynamical and transport equations in both models
are recast without the hydrostatic assumption, allowing better description of the dynamical and
microphysical interactions over complex terrain. The Taiwan Air Quality Model (TAQM) is a
version of AQM developed as a joint project of SUNYA and the National Taiwan University,
Taiwan. It focuses on two-way nested AQM and variable grid systems. One product of this research
*
is the development of a telescoping grid system for nesting several levels to achieve increased
resolution. A direct result of this is the telescoping grid system for SAQM for better description of
subgrid plumes.
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5.0 RESEARCH ISSUES AND DATA NEEDS
This section addresses research issues and data needs in four areas. The two major areas of concern
are monitoring and modeling (i.e., areas concerned with scientific research). The third and fourth
areas are methodological considerations and computing, respectively. Although these last two areas
were not a major focus of the workshop, both are indispensable in their own ways to a successful
NAPAP research program.
In some ways, this section raises more questions than it answers. There are numerous research issues
that need to be addressed; the workshop accomplished its goal of bringing many issues to light. The
purpose of this section, then, is to highlight issues that NAPAP participants should consider building
into their research programs, coordinated through discussions within the NAPAP community such as
those that occurred at this workshop. As a last point, this section focused on issues of science and
topics related to supporting scientific activity. Section 6.0 addresses issues associated with using
scientific results for policy purposes.
t
5.1 Monitoring
The most important monitoring challenge relates to developing the overall data collection design. As
discussed in Sect. 3.2, criteria must be developed to assist in the selection of urban areas for case
study analysis. However, there are broader questions that must also be addressed. One relates to
how many urban areas should be selected. It is possible that a sophisticated optimization algorithm
could be applied to maximize the satisfaction of selection criteria while also optimizing the number of
urban areas selected. If this approach is developed, the broader question shifts from how many urban
areas to select, to defining very specifically the parameters for selecting an optimal set of urban areas.
The Urban Perspectives of Acid Rain 21 . September 1992
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Once the set of urban areas is decided upon, then a number of monitoring questions arise. How
many monitors are needed in each urban area? What data should be collected? In the near-term,
consideration should be given to surveying the literature on sensor placement, to determine whether
existing algorithms can be transferred to this application. If the literature cannot provide a suitable
answer, then consideration must be given to developing a suitable algorithm. Also, once urban areas
have been selected, an inventory of existing receptors should be made to feed into the monitor
requirement algorithm.
How sensitive must the monitoring network be? In other words, what level of change in pollutant
concentrations needs to be measured? Experts in each effect area need to provide some input to help
answer this question on a pollutant-specific basis. It should be recognized that detecting a 10%
change in the deposition of a pollutant will entailless effort than detecting much smaller changes.
Not even considering budget and manpower constraints, it is impossible to monitor air quality and
acid deposition in as many areas as would be desirable. Thus, extrapolation methodologies are
/
needed to calculate the sphere of influence for each of the monitors. Consideration should be given
to reviewing the available extrapolation methodologies and determining their applicability to the urban
context.
Attention must also focus on monitoring instruments. With respect to wet deposition, it should be
emphasized that better collectors, such as wet-only samplers versus bulk samplers, will provide better
data. Designing dry deposition samplers is challenging because both their configuration and their
surface chemistry determine their effectiveness. In fact, these factors interact in complex ways to
influence the effectiveness of samplers. Carefully designed field experiments are needed to optimize
The Urban Perspectives of Acid Rain 22 September 1992
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sampler designs with respect to theoretical models that explain the deposition of materials from the
atmosphere to the samplers. A workshop presentation contained in Appendix C - Formulating Dry
Deposition in Urban Areas - explains these concepts in more detail.
The adequacy of current monitoring instrumentation was not discussed in-depth during the workshop.
However, it is certain that instrumentation used for collecting data on wet and dry deposition could be
improved in numerous ways. New microsensors, artificial intelligence, real-time microprocessors,
and, maybe before the decade is out, even nanotechnology, should be considered for application in
new instrumentation technology. Monitoring surface wetness, and microspaces around buildings for
humidity, temperature, wind speed and direction might be especially amenable to new instrumentation
technology.
The last area of monitoring concern relates to exactly what data need to be collected. As indicated in
Sect. 2.2, the bottom line is that researchers in: health effects are interested in acid aerosols, S02 and
SO4; materials are interested in SO-, and HNO, wet and dry deposition; urban forests are interested in
*
tree exposure to S0;, H,S04, and NOX and HN03; and visibility are interested in aerosols, optical
properties, and human perception. The monitoring networks must collect appropriate data at a scale
(time and space) and with the necessary reliability to support these researchers needs. For example,
for visibility, it is perhaps adequate to monitor the concentrations and optical properties of pollutants
in the air and retain a photographic record of visual air quality. For materials, wet and dry
depositions of pollutants need to be monitored. For urban forests, air quality and wet and dry
depositions would seem to be required. For human health, air quality and exposure to pollutants need
to be monitored, with the latter presenting formidable research challenges. It should be noted that all
The Urban Perspectives of Acid Rain 23 September 1992
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of the above need fairly detailed information on local meterological conditions within the urban
region.
Lastly, the effects themselves - be they human mortality and morbidity, structural decay, tree decline
and death, perceived visibility - also must be monitored because these data will be needed for
cost/benefit analyses.
5.2 Modeling
There are numerous research opportunities associated with developing the modeling component
needed to assess the impacts of acid rain in urban areas. Much workshop attention focused on
improvements, evaluations, and resources needed by the RADM family. As mentioned in Sect. 4.2,
EPA is working on a high resolution version of RADM. This version will have a grid cell size of 20
km, which some workshop participants agreed was a minimum grid cell size to make RADM
particularly useful for urban-based research while others argued that resolutions of 1 km or less are
needed to resolve known intra-urban variability. There was a great deal of concern expressed over
f
the 1996 delivery date for the HR-RADM. There was also concern expressed over the computing
resources available to run HR-RADM. On EPA's single-processor CRAY-YMP, it takes a month to
develop and a month to run each scenario.
/'
Other developmental successors of RADM, in particular DAQM and RPM, which include aerosol
processes and are operating on higher resolutions (8km for DAQM) also are candidate models for
addressing these assessment issues. As with other versions of RADM, computer resources are an
issue. In addition to the suggestions made for RADM 2.6, the use of workstations is being explored
the Urban Perspectives of Acid Rain 24 September 1992
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by the SUNYA team, and could provide a cost-effective alternative to the computer resource
problems.
With respect to RADM, there are several research needs. One, consideration needs to be given to
increasing resources devoted to further development and testing of high resolution versions of
RADM. Two, consideration needs to be given to providing RADM developers more powerful
computational resources, providing resources to have RADM redesigned for a parallel processing
environment, and/or exploring workstation applications. Three, consideration needs to be given to
incorporating a meteorology pre-processing model to drive the estimation of annual rainfall averages.
Four, consideration needs to be given to further development of versions of RADM which include
treatment of aerosol processes and descriptions of optical properties. Aerosol outputs are very
important inputs to assessing the visibility and human health effects of acid rain. Five, a rigorous
testing and evaluation protocol needs to be developed for the RADM-family of models.
Another focus of the discussions was modeling emissions. Improvements are needed in modeling
t
emissions of NH3, organic aerosols, elemental carbon, crustal material, Ca, Zn, Na, K, Mg, and
VOCs. The inventories of these emissions should be done at a very fine scale (e.g., 1 km resolution)
for the regions of concern. Coordination with States and cities is important, as urban emission
inventories are being revised in the next several years as part of the 1990 Clean Air Act and other
modeling efforts.
Workshop participants indicated that models need to be improved to better handle N budgets,
secondary organic aerosol processes, aqueous phases, H;0 budgets, and meteorology at fine levels of
The Urban Perspectives of Acid Rain 25 September 1992
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resolution. Also, attention is needed on developing transfer process models that handle the boundary
between the air concentration models, and deposition/exposure to resources and populations at risk.
Transfer process (or deposition/exposure) models need to have extremely fine resolution levels, at the
neighborhood level for urban forests, at the individual structure level for materials, and at the
individual level for human health effects.5 The deposition models for materials need to incorporate
key parameters, such as surface moisture, surface temperature, turbulent characteristics, and
roughness. Exposure models for human health need to include inputs related to inhalation rates and
other factors.
Protocols must be established to link monitoring and modeling activities. Specifically, monitoring
activities should be designed to provide models with the necessary data at the required resolution.
On the other hand, monitored data should also be able to greatly assist in the testing and validation of
the various models. Lastly, data collecting activities and model enhancements should be done in
concert to allow data and models to be generalized to urban areas not included in the set of case
/
studies.
As a final point, a process should be established to transfer lessons learned about model development
within the modeling community. For example, analyses of RADM exercises could be used to
improve simpler models that are often more amenable to use in a large-scale, long-term assessment.
53 Methodological Considerations
There are research needs relating to general methodology development diat do not neatly fit into the
monitoring or modeling rubrics. One such issue pertains to source apportionment techniques. For
The Urban Perspectives of Acid Rain 26 September 1992
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example, methods are needed to apportion emissions due to natural versus anthropogenic sources, and
even by natural anthropogenic sources versus man-made sources. Methods are also needed to
apportion emissions by scale, from local to regional, with resolutions appropriate for urban analysis
(e.g., 1 km). Undoubtly, other methodological considerations will be raised as time progresses.
5.4 Computing
This topic was only marginally addressed during the workshop, but it should not be neglected in any
discussion about future research needs. This is because advanced computing methods can be used for
data analysis, data management, research program management, and policy analysis. For example, .
one potentially valuable computing project would be to develop a database containing all scientific
results pertaining to urban acid rain. This database could be accessible over INTERNET for all
NAPAP-associated researchers and staff. Users could peruse the database for specific research
results, and could also extract data deposited in the database for use in models. The database would
provide an integration function for managing NAPAP-related research and communicating results
among researchers.
f
Second, at least with respect to RADM activities, high performance computing resources, such as
massively parallel processors and networked workstations could lead to great improvements in
/
developing and exercising models. Such resources could reduce time needed by modelers to make
enhancements to models and reduce the time needed to exercise models to explore various modeling.
scenarios. Such resources could save many months of time, thereby allowing NAPAP-associated
researchers to accomplish more within the tight time-frames. Costs are potentially much lower than
traditional mainframe time, too.
The Urban Perspectives of Acid Rain 27 September 1992
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It must be pointed out that the federal government has actively supported and is planning on
increasing its support for high performance computing and telecommunications research. The
Computing Grand Challenges Program supports applications of high performance computing related
to complex models, such as models associated with global climate change and groundwater flows. It
is possible that such research funding could be accessible to NAPAP researchers, which would be
over and above funding accessible to NAPAP researchers through traditional avenues.
Third, consideration should also be given to other advanced computing technologies. As mentioned
above, new monitoring instruments could be designed with embedded artificial intelligence methods.
Also, to assist with cost/benefit analysis, artificial intelligence-based, object-oriented urban simulation
models could be developed to model economic processes and individual preferences, values, and
beliefs. In the long-term, practically anything is possible in the computing world, even the creation
of the virtual worlds to study emission, deposition, exposure, and effect processes. Computing holds
such significant potential to continue to revolutionize science and how science is conducted and
communicated to the public, that it must be included as an important point in any discussion of long-
*
term research needs.
6.0 COST AND BENEFIT CONSIDERATIONS
The workshop did not explicitly address how to assess the benefits and costs of Title IV with respect
to urban areas. It is just too early in the process of formulating an urban acid rain assessment
strategy to be able to tackle this issue in such detail. On the other hand, the issue was not ignored
because it is clear that cost and benefit estimates will need to be made, and that scientific results will
The Urban Perspectives of Acid Rain 28 September 1992
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ultimately contribute to the cost and benefit mosaic. With these thoughts in mind, two presentations
addressed the cost and benefit issue. One was a briefing on EPA's retrospective cost and benefit
analysis. The other presented the goals of NAPAP's Economic and Social Effects Working Group.
Due out in 1993 are the results of EPA's retrospective analysis of the costs and benefits of all titles of
the Clean Air Act, from 1970 to 1990. Macroeconomic models (e.g., the JorgensenAVilcoxen
Model) are being used to estimate economic costs with and without the Act. Work on the cost side is
progressing; analysis of benefits is being initiated. After the completion of the retrospective study,
prospective studies will be due every two years. The message communicated to workshop
participants is that it is very important to assess costs and benefits, but at this time it is premature for
EPA to be able to provide advice on data and modeling gaps that the NAPAP urban acid rain
program should be aware of.
NAPAP's Economic and Social Effects Working Group has four major objectives that will include the
urban perspective. These objectives are to: monitor the development of the SO, emissions trading
f
system; identify the net costs of compliance with Title IV of the 1990 CAAA ; identify methods for
estimating economic benefits of reductions of 10 millions tons of SO2; and develop methodology for
assessing performance of free market mechanisms established under Title IV. With respect to the
/
urban perspective of acid rain, particularly important research needs are associated with estimating the
benefits of Title IV on human health, urban materials, urban forests, and urban visibility and on
collecting data on people's preferences, values, and risk perceptions about air pollution. The entire
monitoring and modeling structure described in this report will be needed to provide the foundation
for these estimates. How to use this foundation to produce the benefits estimates is arguably an open
research question that warrants further discussion.
The Urban Perspectives of Acid Rain 29 September 1992
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As a step toward continuing the integration of cost and benefit concerns with the activities of those
involved in acid deposition monitoring and modeling, consideration should be given to holding a
second workshop whose focus would be the linkages between these activities and cost and benefit
analyses. This second workshop would continue the accomplishments of the first workshop in
opening up interdisciplinary communication, and could also focus on explicit data needs and
cost/benefit methods.
7.0 SUMMARY
In summary, the workshop met its goal of discussing data needs, existing data and models, and
research issues and needs associated with assessing the urban consequences of Title IV. The
workshop participants were enthusiastic about NAPAP's emphasis on the urban perspective. The
monitoring and modeling research issues and needs are challenging. Criteria for selecting urban areas
for study need to be defined. Monitoring systems for each area of concern need to be designed.
*
RADM and other models need to be enhanced to handle finer spatial resolutions, among other
improvements. Links between air quality and exposure to acid deposition by people, materials, and
urban forests need a great deal of attention. Links between exposure and effects also need more
study.
The workshop did not consider prioritizing the various research needs. Nor did it consider budget
questions. Research prioritization and budgeting undergo rigorous assessment within each NAPAP
member agency; it was not within the scope of the workshop to take these issues under consideration.
The Urban Perspectives of Acid Rain 30 September 1992
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On the other hand, the workshop succeeded at initiating attention on the urban perspective of acid
rain. The participants came to a better understanding of the state of science and what needs to be
done. In their work and within their agencies, the urban perspective will receive an enhanced
emphasis.
Notes
1. The six formal NAPAP working groups are: emissions and controls; atmospheric effects;
ecological effects; materials effects; human health effects; and economic and social effects.
2. The seven NAPAP member agencies are: Environmental Protection Agency, Department of
Energy, Department of Interior, National Aeronautic and Space Administration, National Oceanic and
Atmospheric Administration, Council on Environmental Quality, and Department of Agriculture.
/
3. Models and monitoring data complement each other in complex ways. For example, model
outputs, by themselves, cannot be used as proof of any effects of Title IV. Only rigorously collected
monitoring data can be used as decisive evidence. Unfortunately, data cannot be collected
everywhere. Thus, models are needed to make estimates for areas not covered by data collection
efforts. Also, models can,to some extent, be used to indicate where to collect data. And, lastly, data
are needed to initialize, calibrate and evaluate the models. Therefore, the data collection plans must
be synthesized with the modeling plans in order to achieve the ultimate goal of assessing the impacts
of Title IV on urban areas.
The Urban Perspectives of Acid Rain 31 September 1992
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4. In order to select one or more urban areas upon which to focus NAPAP attention, some guidelines
(i.e., criteria) are needed for the selection process. For example, the urban area must have
population of at least X, have Y acres of urban forests, must be within Z miles of Q emission
sources, must have R type of land use patterns, should have monitoring data available for A, B, C,,,
etc. These issues need to be discussed in a rigorous and systematic fashion. The process of defining
the urban area selection criteria is intertwined with setting up the entire experimental design.
5. References to individual structures and people is meant to convey the point that research designs
will need to make estimates of effects on populations of structures and humans, probably broken into
representative classes, not that specifically identifiable structures and people need to be considered.
8.0 REFERENCES
Conlan, D.E., Longhurst, J.W.S., and Gee., D.R. 1992. "Urban Acid Deposition: Results from
/
the GMADS Network, 1991" Atmospheric Research & Information Centre, Manchester Polytechnic,
Manchester Ml 5GD, England.
ACKNOWLEDGEMENTS
Several individuals contributed their time and attention to the preparation of this report. Paulette
Middleton of the Atmospheric Sciences Research Center, State University of New York at Albany,
Dave Nowak of the U.S. Forest Service, and Susan Sherwood of the National Park Service provided
The Urban Perspectives of Acid Rain 32 September 1992
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materials to help fill out the report's descriptions of existing data and models and provided
constructive comments. Noreen Clancy of NAPAP reviewed several versions of the report both for
content and style. Dave Nowak, Jim Kahn of Oak Ridge National Laboratory, Jack Shannon of
Argonne National Laboratory, Ray Hosker of NOAA, and Fred Lipfert of Brookhaven National
Laboratory provided comments on the draft report. Thanks are due to the workshop participants,
whose work and interests are presented herein.
The Urban Perspectives of Acid Rain 33 September 1992
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The Urban Perspectives of Add Rain 34 September 1992
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APPENDIX A. WORKSHOP AGENDA
Agenda for Workshop on
"The Urban Perspective of Acid Rain"
September 23 and 24, 1992
Sheraton at Crabtree Valley
Raleigh, North Carolina
Sponsored by the Office of the Director, National Acid Precipitation Assessment Program
Funded by the U.S. Department of Energy
Workshop Purpose
NAPAP Office of the Director anticipates giving increased emphasis to the benefits in urban areas of
emissions reductions. This informal, exploratory workshop is an important first step towards
identifying pollutant monitoring and research and assessment needs to help answer, from an urban
perspective, the two key questions posed to NAPAP by Congress: 1) what are the costs, benefits and
effectiveness of the acid rain control program; and 2) what reductions in deposition rates are needed
in order to prevent adverse effects? The results of the cross-cutting discussions will be valuable for
efficiently integrating NAPAP activities on the urban perspective and as points of consideration by the
formal NAPAP Working Groups, the NAPAP member agencies, and the Office of the Director.
The Urban Perspectives of Acid Rain A - 1 September 1992
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DAY 1 SEPTEMBER 23, 1992
8:30am OPENING REMARKS: Derek Winstanley, NAPAP Director
NAPAP mission vis a vis urban areas - How can we determine the changes in
concentrations and deposition in urban areas that are due to SO2 and NOx emissions
reductions under the acid rain control program?
Purpose of workshop - PRODUCE A DRAFT PLAN TO OUTLINE HOW NAPAP
COULD ADDRESS THE URBAN ASPECTS OF ITS MISSION. THE PLAN
SHOULD EFFECTIVELY COMBINE MONITORING WITH METHODOLOGIES
AND ANALYTICAL TOOLS.
A. What concentration and deposition information/estimates does NAPAP need in
urban areas to help evaluate the benefits of emissions reductions?
OBJECTIVE: Develop a statement of information needs that can be plausibly met.
9:00am Retrospective Analysis of Control Benefits - J. Demacher
Implications for information needs for a prospective analysis.
Overview of Urban Effects
Health Risk Assessment - J. Graham ,
Urban Visibility - P. Middleton
Urban Forests - D. Nowak
Materials - S. Sherwood
10:00am BREAK
10:15am Group discussions
Group A - Health and Visibility Effects
Group B - Materials and Urban Forest Effects
11:45am Plenary Session
Develop joint statement of information needs
12:15pm LUNCH
The Urban Perspectives of Add Rain A - 2 September 1992
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DAY 1 (CONTINUED)
B. What data, models, and analytical tools can be expected to be provided from existing
and planned programs?
OBJECTIVE: Develop a statement of expected information availability.
l:30pm EPA Air quality Standards in Urban Areas - J. Pearson
Wet deposition in Urban Areas - D. Gatz
Urban Monitoring in the UK - B. Conlan
Formulating Dry Deposition in Urban Areas - B. Hicks
Estimating Human Health Exposure - W. Wilson
3:10pm BREAK
3:25pm Group Discussions
Group A - Monitoring
Group B - Modelling
5:00 Plenary session on information availability
The Urban Perspectives of Acid Rain A - 3 September 1992
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DAY 2 SEPTEMBER 24, 1992
G. What are the important data and information gaps and; how can ;they be filled?
OBJECTIVE: Develop a list of significant gaps with recommendations on how they can be
filled.
8:30am Opening Remarks - D. Winstanley
8:45am Linking Urban and Regional Models - R. Dennis
9:00am Group discussions on data and modelling gaps for effected areas
Group A - Monitoring
Group B - Modelling
10:15am BREAK
10:30am Group discussions on how to fill information gaps
Group A - Monitoring
Group B - Modelling
ll:30am Plenary Session
Develop statement of gaps and recommendations
12:15pm LUNCH
/
l:30pm Summary Plenary Session
How can we determine the changes in concentrations and deposition in urban areas
that are due to SO2 and NOx emissions reductions under the acid rain control
program?
Develop revised, summary statement of
Information Needs
Data/Tool Availability
Significant Information Gaps
3:00pm BREAK
3:15pm Summary Plenary Session
Feasibility of filling gaps
5:00 Adjourn
The Urban Perspectives of Acid Rain A - 4 September 1992
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DAY 2 SEPTEMBER 24, 1992
0. What are the important data and information gaps and how can they be Tilled?
OBJECTIVE: Develop a list of significant gaps with recommendations on how they can be
Tilled.
8:30am Opening Remarks - D. Winstanley
8:45am Linking Urban and Regional Models - R. Dennis
9:00am Group discussions on data and modelling gaps for effected areas
Group A - Monitoring
Group B - Modelling
10:15am BREAK
10:30am Group discussions on how to fill information gaps
Group A - Monitoring
Group B - Modelling
ll:30am Plenary Session
Develop statement of gaps and recommendations
12:15pm LUNCH
l:30pm Summary Plenary Session
How can we determine the changes in concentrations and deposition in urban areas
that are due to SO2 and NOx emissions reductions under the acid rain control
program?
Develop revised, summary statement of
Information Needs
Data/Tool Availability
Significant Information Gaps
3:00pm BREAK
3:15pm Summary Plenary Session
Feasibility of filling gaps
5:00 Adjourn
The Urban Perspectives of Acid Rain A - 5 September 1992
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APPENDIX B. LIST OF WORKSHOP PARTICIPANTS
Alan Van Arsdale
NESCAUM
129 Portland Street
Boston, MA 02114
617-367-8540
617-742-9162 (Fax)
C. Bruce Baker
National Climatic Data Center
Federal Building
37 Battery Park Avenue
Asheville, NC 28801-2696
919-966-7553 (Fax)
Francis Binkowski
EPA
MD - 80
Research Triangle Park, NC 27711
919-541-4541
919-541-1379 (Fax)
Robert Burton
EPA/AREAL
MD-56
Research Triangle Park, NC 277.11
919-541-3077
919-541-1486 (Fax)
Jason Ching
EPA MD-80
Research Triangle Park, NC 27711
919-541-4541
919-541-1379 (Fax)
Noreen Clancy
NAPAP
1110 Vermont Ave., NW
Washington, DC 20005
202-296-1002
202-296-1009 (Fax)
Beth Conlan
United Kingdom
Atmospheric Research and Information Center
Department of Environmental
and Geographical Studies
Manchester Polytechnic
011-44-612471590
011-44-612476318 (Fax)
Jim DeMocker
EPA
Office of Policy Analysis and Review
Room 925, West Tower
ANR-443
401 M Street, SW
Washington, DC 20460
202-260-8980
202-260-9766 (Fax)
Robin Dennis
EPA
MD-80
Meterology Division
Research Triangle Park, NC 27711
919-541-2870
919-541-1379 (Fax)
Gary Eaton
RTI
P.O. Box 12194
Research Triangle Park, NC 27709-2194
919-541-6720
919-541-5929 (Fax)
The Urban Perspectives of Acid Rain
B- 1
September 1992
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Gardner Evans
EPA
MD-56
Research Triangle Park, NC 27711
919-541-3887
919-541-4609 (Fax)
Peter Finklestein
ASMD/AREAL
MD-80
Research Triangle Park, NC 27711
919-541-4553
919-541-7588 (Fax)
Donald Gatz
Illinois State Water Survey
2204 Griffith Drive
Room 651A
Champaign, IL 61820
217-333-2512
271-333-6540 (Fax)
Judy Graham
EPA - Environmental Assessment
US EPA MD-52
Research Triangle Park. NC 27711
919-541-4173, 919-541-2266
919-541-5078 (0254) (Fax)
Tom Graham
Department of Energy
FE-20
1000 Independence Avenue, SW
Forrestal Building
Washington, DC 20585
202-586-7149
202-586-7085 (Fax)
Sue Grimmond
Climate and Meterology Program
Geography Department
120 Student Building
Indiana University
Bloomington, IN 47405
812-855-7971
812-855-1661 (Fax)
Bruce Hicks
NOAA/ARL
SSMCII-Room3152
1315 East West Highway
Silver Springs, MD 20910
301-713-0684
301-713-0119 (Fax)
Ray Hosker
NOAA/ATDD
P.O. Box 2456
456 Illinois Avenue
Oak Ridge, TN 37831-2456
615-576-1248
615-576-1327 (Fax)
John Huckabee
EPRI
3412 Hillview Avenue
P.O. Box 10412
Palo Alto, CA 94303
415-855-2589
415-855-1069 (Fax)
James Kahn
ORNL/UT
P.O. Box 2008
Building 4500N, MS 6205
Oak Ridge, TN 37831-6205
615-576-5585
615-574-3895 (Fax)
The Urban Perspectives of Acid Rain
B-2
September 1992
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Paul Kapinos
USGS
415 National Center, Room 5A-409
12201 Sunrise Valley Drive
Reston, VA 22092
703-643-6875
703-648-5295 (Fax)
Dennis Leaf
EPA
401 M Street, SW
MC - 6204 - J
Washington, DC 20460
202-233-9129
202-233-9585 (Fax)
Sharon LeDuc
EPA
Research Triangle Park, NC 27711
919-541-1335
919-541-7588 (Fax)
Fred Lipfert
BNL
Building 475
12 South Avenue
Upton, NY 11973
516-282-7824
516-282-7867 (Fax)
Paulette Middleton
NCAR
P.O. Box 3000
Boulder, CO 80307
303-497-8620
303-443-2038 (Fax)
Tilden Myers
NOAA/ATDD
456 S. Illinois Ave.
P.O. Box 2456
Oak Ridge, TN 37831-2456
615-576-1245
615-576-1327 (Fax)
Tihomir Novakov
Lawrence Berkeley Laboratory
Building 73
1 Cyclotron Road
Berkeley, CA 94720
510-486-5319
510-486-5172 (Fax)
Dave Nowak
U.S. Forest Service
5801 North Pulaski Road
Chicago, IL 60646
312-539-1363
312-539-0882 (Fax)
Dick Olsen
ORNL
Building 1505, MS 6038
P.O. Box 2008
Oak Ridge, TN 37831-6038
615-574-7819
Johnnie Pearson
EPA
EERDAREAL MD - 56
Research Triangle Park, NC 27711
919-541-0572
919-541-1486 (Fax)
The Urban Perspectives of Acid Rain
B-3
September 1992
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Ruth Reck
Argonne National Laboratory
Environmental Research Division
Global Climate Change Program
Building 203
9700 South Cass Avenue
Argonne, IL 60439
708- 252-9202
708-252-4793 (Fax)
Susan Shenvood
NFS
P.O. Box 37137, Room 6111
800 North Capitol Street, Suite 200 (zip
20001)
Washington, DC 20013-7127
202-343-1055
202-343-6004 (Fax)
John Spence
EPA
MD-84
Research Triangle Park, NC 27711
919-541-2649
919-541-7588 (Fax)
Elliot Spiker
U.S. Geological Service
4th Floor
National Center
Reston, VA 22090
703-648-5330
703-648-6684 (Fax)
Kenneth Stolte
U.S. Forest Service
P.O. Box 12254
Research Triangle Park, NC 27709
919-549-4020
919-549-4047 (Fax)
Bruce Tonn
ORNL
Building 4500N, MS 6207
P.O. Box 2008
Oak Ridge, TN 37831
615-574-4041
615-574-3895 (Fax)
Rodney Weiher
NOAA
1825 Connecticut Avenue
Universal Building
Washington, DC 20235
202-606-4360
202-606-4355 (Fax)
William Wilson
EPA/AREAL
MD-75
Research Triangle Park, NC 27711
919-541-2551
919-541-7588 (Fax)
Derek Winstanley
NAPAP
1110 Vermont Ave., NW
Washington, DC 20005
202-296-1002
202-296-1009 (Fax)
The Urban Perspectives of Acid Rain
B-4
September 1992
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APPENDIX C. VIEWGRAPHS OF SELECTED WORKSHOP PRESENTATIONS
Urban Forests as presented by Dave Nowak.
The Urban Perspective of Acid Rain
Urban Forests
Air Quality Issues Regarding Urban Forests
I. Monitor-dose relationship
II. Tree Health
Visual
Fertilization
Predisposition to decline
Mortality
Insects and Diseases
IQ. Productivity
Stomates - gas exchange (transpiration)
Leaf area / crown density
Pollen production
Tree regeneration
Soil nutrient cycling
IV. Species Differences
The Urban Perspectives of Acid Rain C - 1 September 1992
-------
The Urban Perspective of Acid Rain
Urban Forests
Altered Structure and Function: Costs and Benefits
I. Energy Conservation / Physical Environment
Air temperature
Wind
Shading
Water cycling
Erosion
H. Air Quality
Power plant emissions (including
Ozone
Volatile organic compounds
Deposition rate
ffl. Urban Inhabitants
Health (mental and physical)
Real estate value
Aesthetics
Species composition / wildlife
Management alternatives and costs
The Urban Perspectives of Acid Rain C - 2 September 1992
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Visual Air Quality as presented by Paulette Middleton.
VISUAL AIR QUALITY
(VAQ)
VAQ is the effect of atmosphere on our outdoor visual experience.
Degradation of our visual experience has economic reprocussions.
Judgments of VAQ are based on our
Borders betwi
Clear and Colored
VAQ Can Be
Directly by human judgments of scenes
(or judgments of photographs)
Indirectly by analysis of atmospheric properties
VAQ Degradation _is causfidtty
small parudesana rases in the air
VA( _.
small particles and gases in the air
that absorb and/or scatter sunlight
These chemicals also have other
adverse impacts on the environment.
We need to_
Monitor VAQ directly
Develop appropriate strategies
The Urban Perspectives of Acid Rain
C-3
September 1992
-------
n .121
r --0.802
y --0.9X + 3.47
-5
Relationship between average overall visual air quality index, as
perceived by a group of observers, and the natural logarithm of
the aerosol light scattering coefficient during the Winter 1982
Denver Brown Cloud Study.
The Urban Perspectives of Acid Rain
C-4
September 1992
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VISIBILITY
Visibility is the major indicator of air quality on urban and regional scales.
Regional visibility became an important part of NAPAP I.
Visibility improvements established as part of acid rain control
benefits.
Visibility characterization, provided for west and east, is now being
used for developing visibility programs.
Urban visibility has been a growing concern especially in the west.
Standards are being set ( e.g., Colorado).
Connections with other issues are being addressed ( esp, PM,0).
National visibility program is needed. Urban-regional scope important in these
developments, (e.g., DOE visibility program, Grand Canyon Commission,
Western states efforts).
Urban sources effect National parks. Also cause local visibility
degradation (e.g., Los Angeles).
Broader perspectius needed ( e.g., NAS report).
The Urban Perspectives of Acid Rain C - 5 September 1992
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MAJOR FACTORS TO CONSIDER
Big Picture
Same chemicals and same sources are implicated in visibility, acid,
rain, oxidant and climate concerns.
These connections have important positive implications for model
building, measurement program development and policy
formulation.
Technical concerns
Characterization of visibility requires measurement of human
responses to gauge optical measures.
Emission inventories for aerosols are essential. (PM10 is helping).
Long term monitoring of optical properties is needed ( Historical
records important too).
Better characterization of aerosol and optical processes are essential.
The Urban Perspectives of Add Rain C - 6 September 1992
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ASSESSMENT GUIDELINES
Integration of issues - possible & important
Maximum use of resources - possible & essential
"Active" Issues
visibility
oxidants,
acid rain,
climate.
Resources
ongoing modeling efforts ( e.g., comprehensive modeling family
developed from RADM),
recent major field efforts [visibility focus], (e.g., Grand Canyon,
California, Eastern cities, Western cities) + other efforts/other
foci,
program development efforts ( e.g., DOE visibility, Grand Canyon
Commission, local/state efforts).
Integration Techniques
multiple model approach - complex to simple scoping,
communication strategies - east concepts based on hard facts.
The Urban Perspectives of Acid Rain C - 7 September 1992
-------
Linking Urban and Regional Models as presented by Robin Dennis.
NAPAP/Urban 9/23/92
NAPAP Planning Meeting
URBAN ASPECTS OF ITS MISSION
September 23-24, 1992
Raleigh, NC
Linking Urban and Regional Models
Robin Dennis
The Urban Perspectives of Acid Rain C - 8 September 1992
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NAPAP/Urban 9/23/92
Linking Urban and Regional Models
Seems Pretty Clear That Urban Model Estimates Must be
Linked to Regional Model Results to Account for Long-
Range Transport. The Acid Rain Controls Are Regional
Controls.
If We Are Going to Perform Assessments, Models Are
Probably Going to be Needed. Then We Must Have the
Urban Modeling Tools to Link to the Regional Models.
Where Do We Stand? What Modeling Base Do We Have?
Bottom Line
RADM has been evolving/improving
Evaluation results demonstrate that 80 km RADM is
too coarse to use to support urban assessments
For other reasons, a High Resolution RADM is being
developed. A research version of HR-RADM running
at 20 km resolution exists.
A 20 km HR-RADM could probably support urban
assessment studies. Thus, a possibility exists.
The reality is that HR-RADM will not be out of
research mode before 1996. Issue: Resources.
The Urban Perspectives of Add Rain C - 9 September 1992
-------
NAPAP/Urban 9/23/92
RADM Has Been Evolving
RADM2.6 is now the operational version.
RADM2.6's predictions of S and N are improved
over RADM2.1's (used in NAPAP Assessment)
Major sulfate underprediction has been
corrected
External Peer Review panel has stated they
believe RADM can be used for S and N
deposition assessment studies
We better understand RADM2.6's predictions and
can demonstrate that it is too coarse to represent
urban exposures of primary pollutants.
We have developed a visibility post-processing model
to calculate the sulfate-associated aspects of visibility
(visual range and b^). Needs more testing.
We have developed an engineering model to estimate
regional materials damage for zinc coatings, related
to sulfur. Needs more testing.
We have developed the HR-RADM.
We Would Like The System to Continue to Evolve
(Question of Resources)
Operational capability at 54-km coarse/18-km nest.
N-Tracking capability (engineering approximation)
77!* Urban Perspectives of Acid Rain C - 10 September 1992
-------
NAPAP/Urban 9/23/92
The Possibility
There Will Be a RADM-Based Model That Could
Support Urban-Oriented Assessment Activities, At A
Relatively Coarse Resolution.
The Reality
A HR-RADM Modeling System Will Not be Available
Prior to 1996. Key Issues:
Lack of evaluation and testing
Lack of meteorology to drive the system
for estimation of annual averages
Aggregation methodology that is designed
for regional deposition, not urban studies
On current single-processor CRAY-YMP,
will take a month to develop and a month
to run each scenario.
20 cpu hours/case
30-40 cases for aggregation method
What Is Still Missing?
Aerosols still won't be in the model.
The Urban Perspectives of Acid Rain C - 11 September 1992
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Urban Environmental Characterization for Estimating the Economic Benefits Associated with
Materials Effects as presented by Susan Sherwood.
SISherwood, 9/23/92 presentation notes
URBAN ENVIRONMENTAL CHARACTERIZATION FOR ESTIMATING THE
ECONOMIC BENEFITS ASSOCIATED WITH MATERIALS EFFECTS
How does decreasing S02 emissions change economics of rnaf^riaic? The primary issue
is the optimum spatial ««»ip of analysis
SO2 emissions H^tn are most available at the regional ifc^lf w SO2 <*-npf*mttn«iniiy jj jjjp
urban ««»ip (1 or marc measurements per city). In contrast, sub-building is the *& challenge to deposition ^grmmtp^ j$ urban areas, which are
geometrically more «mpier man rural areas. But complexity need not be a deterrent;
fa»h«»r it J5 a OMBS**"*1 qf ^Pt^rnrininp « fyatftiltt gimplffirafirtn Brrg^pgy and going after it
In determining an appropriate spatial yite for analysis, some simplifying assumptions
with respect to the great degree of variabOiry in structural form axe in orden
a) treat structures not as individuals, but with a «fari«t««ai description of the class
(e.g., within an area of homogeneous land use)
b) dftfinc two types of structures vis a vis aerodynamics,
fibrous (engineering structures, sculptures) and
bluff bodies (buildings, neighborhoods of buildings)
c) rlfifinr two types of surfaces, rain-washed and sheltered, to relate to the two
modes of ffat»riaiq decay
The Urban Perspectives of Acid Rain
. jo September 1992
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For wet deposition, define interception areas by class of structure (a relatively tractable
geometric question that requires attention) and measure/model the rain volume and
chemistry at the urban scale.
For dry deposition, the optimal/feasible temporal scale of the analysis is more
to resolve because S02 deposition to materials is so strongly dependent on the presence
of surface moisture. Further, diurnal cycles of pollutant gas concentration and
to generate a short-term high fl'ff in the morning 'which may exceed
the deposition throughout the remainder of the day. Therefore, some cut between
imfo'ciu concentrations uin^r 'condensing* situations versus concentrations during "dry
surface* conditions is
A possible approach is to seek a convergance between urban scale dispersion models
(such as EPA guideline models) anrl energy balance models (to provide material surface
wetness predictions). Models of regional emissions as input to the urban scale models
are nggdcd to link Title IV controls with changes in urban concentrations.
The Urban Perspectives of Acid Rain C - 13 September 1992
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Acid Deposition Monitoring in the United Kingdom as presented by Beth Conlan.
Acid Deposition Monitoring in the United Kingdom - A case study of the Greater Manchester
Acid Deposition Survey.
by
Dr D.E. Conlan & Dr J.W.S. Longhurst.
Atmospheric Research &. Information Centre (ARIQ,
Manchester Metropolitan University,
Chester Street.
Manchester Ml 5GD. U.K.
1.0 Introduction
Within the United Kingdom acid deposition is regulary monitored through the operation of
the national network. This includes 32 sites in the rural environment, and the programme
is co-ordinated by Warren Spring Laboratory on behalf of the Department of Environment.
The data are reported on an annual basis for the nation (Fig. 1) (RGAR. 1990). However.
in the urban environment in the United Kingdom the only long term continuous monitoring
of acid deposition is carried out within the Greater Manchester Acid Deposition Survey
(GMADS). This survey was established in 1986 by the Atmospheric Research & Information
Centre (ARIC) at the Manchester Metropolitan University for and on behalf of the local
government in this region. The only other surveys in the U.K. into urban acid deposition
include a study in Leeds in the north of England for an annual period, one rain collector
beside .Lincoln cathedral in the Midlands for one year. Limited monitoring has been
undertaken in London but this has also ceased.
Manchester is a city in the north west of England (Fig. 2) and is the 'capital' of the county
of Greater Manchester. Historically, it has suffered high concentrations of air pollutants
since the Industrial Revolution (Fig. 3). Indeed. Manchester was where the "Industrial
Revolution" began and in 1852 Robert Angus Smith first coined the term "Acid Rain" when
working in Manchester where he gave the following description of air quality:
"When the air has so much acid that 2 or 3 grains are found in a gallon or 40 parts in a
million there is no hope for vegetation in a climate such as we have in the northern pans of
the country [U.K.]" (Smith, 1872).
Today, however, the area is dominated by commercial and light industry and air quality has
substantially improved.
GMADS includes 19 sites in the urban or near urban environment (Fig. 4). These are
located in the county of Greater Manchester and in the adjacent boroughs of Warrington in
the south west, Rossendale in the north and High Peak in the south east (Fig. 5). The
conurbation covers some 1500 km2 and has a population in excess of 2.8 million. It is
adjacent to Merseyside in the west which supports a population of over 2 million. Across
the Pennines in the east over 3 million people live in both south and west Yorkshire.
Although there are certainly green belts in between these urban locations, this whole region
in the north of England is undoubtedly highly populated and highly industrial. To the north
and south of Greater Manchester are the of counties Lancashire and Cheshire, respectively.
both of which are predominantly agricultural.
The Urban Perspectives of Acid Rain C - 14 September 1992
-------
Hills surrounding the GMADS area form the boundary of the county to the north, east, north
west and south east. Consequently, the monitoring area has great altitudinal variation
ranging from about 30 m (asl) in the west to more than 300 m in the north east. The long
term mean annual rainfall measured at Manchester airport in the south east is 820 mm.
2.0 Operation of Survey
The main objective of GMADS is to provide regional measurements of the patterns of ion
concentrations in rainfall, and deposition rates. It was, therefore, necessary to locate sites
to characterise the regional precipitation chemistry as influenced by the urban area. The
fundamental, and difficult, requirement was to provide a site in an urban/near urban
environment which was not unduly influenced by local sources of pollution.
The siting criteria were developed to allow comparison with data from the national network
by using similar siting criteria as those used for the national rural network. The following
criteria were used, based upon Devenish (1986).
Sources of contamination
- very local sources must be avoided
- small point sources eg domestic chimney
- mobile point sources eg. vehicle exhaust
- wind mediated contaminants eg. dust from roads/fields
- large surface works eg. sewage works
- large point sources eg. power stations, industrial complexes
- major roads eg. motorways, major class roads
As a general guideline, there was to be a horizontal separation of 100 m between the
collector and any small or mobile source. 1 km between major roads and the collector and
10 km between the collector and a large point surce.
Obstructions
In order to avoid wind shadow, the horizontal separation between the collector and the
obstruction must be at least three times the height of the obstruction.
Land Use
The most desirable site was one where no change in land use. construction activity or
substrate disturbance was anticipated.
Topography
The following situations were to be avoided:
- Extremes of altitude eg. valley bottom, hill tops
- Zones of strong vertical air currents
- Eddy zones
- Roof tops
The Urban Perspectives of Acid Rain C - 15
September 1992
-------
Accessibility
The target data capture rate was at least 90% (which has been reached in the vast majority
of sites). Consequently the sites had to be accessible under ail weather conditions.
Security
In any urban area site security is of great importance and inevitably at some of the sites it
was given preference over other site criteria.
GMADS is operated in conjunction with other agencies. These include local authorities and
one regional authority. The local government Environmental Health officers collect the
precipitation samples from bulk collectors (Fig. 6) on a weekly basis. It is a collector
designed for use in the UK national rural network of acid deposition monitoring. Samples
are submitted to a central laboratory, the Greater Manchester Scientific Services. Quality
control/quality assurance procedures are carried out in conjunction with other national
laboratories. The following ions are measured:
hydrogen magnesium
sulphate sodium
nitrate potassium
ammonium zinc
calcium hydrogen carbonate
chloride
3.0 Concentration and Deposition data for 1991
The spatial variability of the data are investigated on an annual basis and concentration and
deposition maps are produced using a kriging mapping procedure. The mean annual
concentration for non-marine sulphate for the network in 1991 was 123 fieq f (Fig. 7)
(Conlan. Longhurst & Gee, 1992). Generally, concentrations in the city centre of
Manchester are about 2.5 times that suggested by regional patterns derived from the national
rural network. The highest mean concentrations were recorded in the city centre of
Manchester with concentrations generally decreasing towards the urban fringes. However,
a secondary peak of nm sulphate in the south of Warrington is also evident. The industrial
base within Warrington itself is not extensive, but approximately 30 km to the west there are
large chemical industrial plants and approximately 12 km west is a coal tired power station
called Fiddlers' Ferry. This is the largest coal fired power station in the north west of
England. It is a 2000 MW station and burns coal with 1.4% sulphur. Fiddlers' Ferry has
been estimated to emit 143 kt of sulphur per year which constitutes about 50% of the total
emissions of sulphur dioxide in the north west of England (Fig. 8) (Lee & Longhurst. in
press). Other coal fired power stations in the region are much smaller than Fiddlers' Ferry.
Agecrort. about 10 km from the city centre, emits approximately 15.7 kt.
The Urban Perspectives of Acid Rain C - 16 September 1992
-------
As with sulphate the spatial variability of nitrate concentrations was statistically significant
across the conurbation (Fig. 9). A peak occurs in the city centre of Manchester and
concentrations decrease towards the less urbanised parts of the conurbation in the north and
south east. This spatial distribution follows that for nitrogen dioxide and. indeed, nitrate
concentrations are significantly correlated with ambient nitrogen dioxide concentratations
suggesting efficient scavenging of NO: in urban areas. This correlation has. however, only
been significant in the last two of the five full years of the survey to date (Conlan, et al.,
1992).
The highest mean annual concentration of nitrate is in the south of Warrington. Fiddlers'
Ferry has been retrofitted with low NO, burners, which have been estimated to have reduced
emissions by 30% on its 4 burners, but it still is the source of approximately 19% of
emissions in the north west of England (Lee & Longhurst. in press).
Concentrations of nitrate in the conurbation interpolated from the national rural network were
30 - 40 \j.eq I'1 in the east of the Greater Manchester conurbation and 20 - 30 fieq I'1 in the
west. Concentrations measured in the east were similar to interpolated values but in the west
measured data were higher than interpolated data.
Highest concentrations of ammonium in the GMADS network were observed in the south of
Warrington (Fig. 10). Concentrations were also high in the High Peak area. The Cheshire
Plain lies to the south of Warrington where the most intensive livestock farming in England
takes place. The dominant source of ammonia in Cheshire is from agricultural sources
(RGAR. 1990). Also, in the hills of the High Peak sheep farming is extensively practiced.
Concentrations of ammonium in precipitaion were also high in the city centre of Manchester.
A review of the potential emissions from the human population resulted in an estimate of
approximately 3.3 kt per year from this source in the Greater Manchester area (Lee &
Longhurst. in press). Consequently, humans were estimated to be the largest source of
ammonia emissions within the conurbation and the second largest in the north west of
England.
The regional pattern of ammonium concentrations in precipitation from the national rural
network suggest that concentrations should be in the class 30 - 40 neq I'1. This was exceeded
at those GMADS sites closest to intense agricultural activity. In Warrington concentrations
were twice those interpolated from the national rural network.
The pattern of hydrogen concentrations in the conurbation is quite complex (Fig. 11). It
relates very closely to concentrations of calcium (Conlan Si Longhurst, 1992). In every year
of the survey to date hydrogen concentrations were lowest in the city centre, with an increase
towards the urban fringes. The concentrations interpolated from the national rural network
data for the GMADS area was 30-40 tieq f. Concentrations in the city centre were below
this, but in the north and south west of the conurbation concentrations were up to 20% higher
than those predicted.
Elevated concentrations of calcium were found in the city centre of Manchester which is
assumed to be derived from urban dust (Fig. 12). Only 5 - 15 % of the calcium has been
estimated to be from marine origin (Lee &. Longhurst. 1990). Comparisons of data in
previous years of the survey between bulk and wet only collectors indicated that the majority
The Urban Perspectives of Acid Rain C - 17 September 1992
-------
of the calcium in urban precipitation samples arises from below cloud scavenging of locally
generated panicles rather than dry deposition or long range transport (Lee &. Longhurst,
1990)
Precipitation amounts show a gradation across the conurbation, which, however, is not
significant (Fig. 15). There is more rainfall in the north and east of the study area where
altitude is increasing in the foothills of the Pennines. This, of course, has an effect on the
deposition rates over the conurbation. Highest depostion rates of. for example, sulphate were
in the north and east (Fig. 16).
The spatial variability of hydrogen deposition rates is shown in figure 15. Low deposition
rates of hydrogen were observed in the city centre and this increases in the east and the north
of the conurbation. Lowest deposition rates of hydrogen were, however, observed in the
west of the region where precipitation amounts were relatively low.
4.0 Conclusion
The influence of the urban environment on acid deposition in Greater Manchester is such that
concentrations of the major species are higher in the urban area than that suggested by the
UK national rural network of acid deposition monitoring. As a consequence of the numerous
point sources of emission in the urban environment the spatial pattern of acid deposition is
complex. GMADS data suggest that site selection is highly important and in order to achieve
an overall representation numerous urban monitoring sites are necessary.
5.0 References
Conlan. D.E. & Longhurst. J.W.S. (1992) Spatial variability in urban acid deposition. 1990:
results from the Greater Manchester acid deposition survey (GMADS) network in the UK.
Science of the Total Environment, in press.
Conlan, D.E., Longhurst. J.W.S. & Gee, D.R. (1992) Urban Acid Deposition: Results from
the GMADS network. 1991. Report for the Association of Greater Manchester Authorities.
June 1992. ARIC. Manchester Polytechnic.
Devenish. M. (1986) The United Kingdom precipitation monitroing networks. Report nr.
LR 584(AP)M. Warren Spring Laboratory, Stevenage.
The Urban Perspectives of Acid Rain C - 18 September 1992
-------
Smith, R. A. (1872) Air and Rain. The beginnings of a chemical climatology. Longmans.
Green & Co, London.
Lee. D.S. &. Longhurst, J.W.S. (1990) Extended monitoring of wet-only precipitation in
Greater Manchester. Final report to National Power. ARIC. Manchester Polytechnic.
Lee. D.S. & Longhurst. J.W.S. (in press) Estimates of emissions of SO,. NO,, HC1 and NH,
from a densely populated region of the U.K. Environmental Pollution, in press.
RGAR (1990) Acid Deposition in the United Kingdom 1986-1988. Third report of the
'United Kingdom Review Group on Acid Rain. Department of Environment publication sales
unit. London.
Ike Urban Perspectives of Acid Rain C - 19 September 1992
-------
e
.-> *
r-~y
ABOVE 60
4060
20 *0
BELOW 20
Figure 1. Seasonal mean non-manne sulphate concentration. 1986 to 1988 (\j.eq I'), (a) Apnl
to June and (b) October to December from the national acid deposition monitoring network
(RGAR, 1990).
The Urban Perspectives of Acid Rain
C-20
September 1992
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Figure 2. Map of Manchester in relation to the U.K.
The Urban Perspectives of Acid Rain
C-21
September 1992
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Figure 3. Air Quality during Ihe Industrial Revolution. Photograph courtesy of the Mansall
Collection, London.
The Urban Perspectives of Add Rain
C-22
September 1992
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19
01 Hal 1 ith Wood
02 Horwich
03 Tottington
04 Thurston Hall Farm
05 Llttleborough
06 Ashworth Moor
07 Csstleshsw
08 Heyrod
09 Werneth Low
10 Manchester City Centre
11 Stye I
12 Dunham Forest
13 Pertlngton .
14 Agecroft
15 Green Acres
16 Crowden
17 Rlsley Moss
18 Hlllcllffe Reservoir
19 RewtenstalI
Figure 4 The GMADS network in relation to urban areas of the North west of England.
The Urban Perspectives of Acid Rain
C-23
September 1992
-------
GREATER MAN
Figure 5 The GMADS network in relation to local boundaries.
The Urban Perspective* of Acid Rain
C-24
September 1992
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Bird guard loosely strung with
0-64 mm diameter black
Dotyprooyiene line.
HScrm
25cm
1-75m
6cm-
Rstyethylene funnel.
Bird guaro mounting and
funnel retainer.
Stomtess steel oannsiB'
(9(U9Xii' highly polished
interor: blacked
contains 31 volume polypropylene
collecting vesei.
/yurnnium stand painted with
potyurethane to resist corrosion.
Figure 6 Diagram of bulk deposition collector.
The Urban Perspectives of Acid Rain
C-25
September 1992
-------
p'rSpiJuon
The Urban Perspectives of Acid Rain
C-26
September 1992
-------
1 I
20 30 Km
142.6 Kt .
Fiddler's Petty
Fossil fuel
power station
Incinerator
Figure 8 Estimated emissions of SO, from power stations in the north west of England.
The Urban Perspectives of Acid Rain
C-27
September 1992
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Figure 9 Spatial variability of the mean annual concentration of nitrate in precipitation in
1991
The Urban Perspective* of Add Rain
C-28
September 1992
-------
Figure 10 Spatial variability of the mean annual concentration of
in 1991 (neq I'1).
ammonium in precipitation
The Urban Perspectives of Acid Rain
C-29
September 1992
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Figure 11 Spatial variability of the mean annual concentration of hydrogen in precipitation
in 1991 (neq I'1).
The Urban Perspectives of Acid Rain
C-30
September 1992
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Figure 12 Spatial variability of the mean annual concentration of calcium in precipitation in
1991 (neq I'1).
The Urban Perspectives of Acid Rain
C-31
September 1992
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Figure 13 Spatial variability of total precipitation amount for 1991 (mm).
The Urban Perspectives of Acid Rain
C-32
September 1992
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Figure 14 Spatial variability of non-marine sulphate deposition in 1991 (g m2 yr'}.
The Urban Perspectives of Acid Rain
C-33
September 1992
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Figure 15 Spatial variability of hydrogen deposition in 1991
(g m-1 yr').
The Urban Perspectives of Acid Rain
C-34
September 1992
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Wet Deposition as presented by Don Gatz.
WET DEPOSITION:
AVAILABLE DATABASES
Donald F. Gatz
Illinois State Water Survey
Champaign, Illinois 61820
The Urban Perspectives of Acid Rain C - 35 September 1992
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OUTLINE
INTRODUCTION
WORLD CITIES WHERE MEASUREMENTS
HAVE BEEN MADE
NORTH AMERICAN CITIES WHERE
MEASUREMENTS HAVE BEEN MADE
MISCELLANEOUS DATA SOURCES
PROBLEMS IN USING EXISTING DATA
TJie Urban Perspectives of Acid Rain C - 36
September 1992
-------
HOW MANY DATA SETS ARE AVAILABLE
ON URBAN WET DEPOSITION?
NOT A HECK OF A LOT!
The Urban Perspectives of Acid Rain C - 37 September 1992
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SAMPLE TYPES
WET-ONLY; SAMPLER OPEN ONLY DURING
PRECIPITATION. LID OPENS AND
CLOSES AUTOMATICALLY.
BULK; SAMPLER OPEN CONTINUOUSLY.
The Urban Perspectives of Acid Rain C - 38 September 1992
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WORLD CITIES WHERE PRECIPITATION CHEMISTRY
MEASUREMENTS HAVE BEEN MADE
(EXCLUDING NORTH AMERICA)
(BASED ON PEER-REVIEWED LITERATURE)
CITY/REFERENCE
SAMPLE NO. OF
PERIOD SITES
SAMPLE
TYPE DURATION
UPPSALA, SW. 1962
(Andersson, 1969)
SHEFFIELD, U.K. 1969-70
(Davies, 1976)
UPPSALA, SW. 1972-73
(Hogstrom, 1974)
GLASGOW, U.K. 1978-80
(Fowler et al., 1982)
SYDNEY, AUS. 1980-81
(Ayers & Gillett, 1984)
SANTANDER, SP. 1984-85
(Diaz-Caneja et al., 1989)
TORRELAVEGA, SP. 1984-85
(Diaz-Caneja et al., 1989)
PALLANZA, IT. 1984-86
(Mosello et al., 1988)
PUNE, INDIA 1984-88
(Prakasa Rao et al.. 1992)
24
1
100
1
12
1
1
2
1
BULK
WET
BULK
BULK
BULK
BULK
BULK
1 BULK
1 WET
WET
MONTHLY
HOURLY
EVENT
MONTHLY
EVENT
DAILY
DAILY
EVENT
EVENT
DAILY,
WEEKLY
VENICE, IT. 1985-87 2
(Argese & Bianchini, 1989)
LEEDS, U.K. 1986-87 12
(Clark & Lambert, 1987)
MANCHESTER, U.K. 1986-87 11
(Leeetal., 1988)
ATHENS, GR. 1986-87 2
(Dikaiakos et al., 1990)
1 BULK EVENT
1 WET EVENT
10 BULK DAILY
2 WET DAILY
BULK WEEKLY
Q-WET EVENT
The Urban Perspectives of Acid Rain
C-39
September 1992
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NORTH AMERICAN CITIES WHERE PRECIPITATION
CHEMISTRY MEASUREMENTS HAVE BEEN MADE
(BASED ON PEER-REVIEWED UTERATURE)
CITY/REFERENCE
SAMPLE NO. OF
PERIOD SITES'
SAMPLE
TYPE DURATION
ST. LOUIS 1972-73"
(Hales & Dana. 1979)
ST. LOUIS 1972,74
(Semonin, 1976)
ST. LOUIS 1972-75"
(Gatz, 1980a,b)
NEW YORK CITY 1974
(Jacobson et al., 1976)
HAMILTON, ONT. 1974
(Vermette et al., 1988)
ST. LOUIS 1972-75"
(Bridgman, 1984)
OTTAWA, ONT. 1974-77"
WINNIPEG, MAN.
(Allan & Jonasson. 1978)
NEW YORK CITY 1 975-77
(Wolff et al., 1979)
WASHINGTON, D.C. 1975-81
(Miller et al., 1983)
HAMPTON, VA 1977-80
(Pellett et al.. 1984)
LOS ANGELES 1978-79
(LJIjestrand & Morgan. 1981)
WORCESTER, MA 1978-86
(Vidulich et al., 1987)
120-140
80
80-85
1
11
80-85
Varied
8
10
1
9
1
BULK
BULK
BULK
BULK
BULK
BULK
SNOW-
CORE
BULK
BULK
Q-WET
Q-WET.
BULK
EVENT
EVENT
EVENT
EVENT
EVENT
EVENT
EVENT,
SEASON
EVENT
DAILY
SUB-EVENT
EVENT
EVENT,
SUB-EVENT
Some samplers may be non-urban.
Summers only.
Winters only.
The Urban Pertpecaves of Add Rain
C-40
September 1992
-------
CITY/REFERENCE
SAMPLE NO. OF
PERIOD SITES'
SAMPLE
TYPE DURATION
MONTREAL, QUE. 1979"
(Landsberger et al., 1983)
LOS ANGELES 1979-83
(Zeldin & Ellis. 1984)
MONTREAL 1980"
(Lewis et al., 1983)
CHICAGO 1981-82
(Sisterson & Shannon, 1989)
DETROIT 1981-83
(Dasch & Cadle, 1985)
NEW YORK CITY 1 981 -84
(Dupuis, 1985)
SEATTLE 1982-83
(Vongetal.. 1985)
PHILADELPHIA 1983
(Patrinos & Brawn. 1984)
PHILADELPHIA 1983-84
(Patrinos. 1985)
WILMINGTON, NC 1983-87
(Willey et al., 1988)
DENVER 1985"
(Schroder et al., 1987)
WASHINGTON, D.C. 1986-87
34
6
10
2
2
8
4
40
40
5
2
31
BULK
Q-WET
BULK
WET
WET
WET
WET
BULK
24 WET
16 BULK
BULK 2yr
WET3yr
WET
16Q-W
EVENT
EVENT
EVENT
EVENT,
WEEKLY
EVENT
EVENT
WEEKLY
EVENT
EVENT
EVENT
EVENT,
SUB-EVENT
EVENT,
(Patrinos et al., 1989)
16 WET SUB-EVENT
16+ BULK
20+ SEQ
^ Some samplers may be non-urban.
Winters only.
~" Summer only.
The Urban Perspectives of Acid Rain
C-41
September 1992
-------
SUMMARY OF SPECIES MEASURED
AND AVERAGING PERIOD
NORTH AMERICAN MEASUREMENTS
CITY/REFERENCE SPECIES MEASURED
AVERAGING
PERIOD OF
REPORTED
DATA (#)
ST. LOUIS H% NH/, SO42', SOa, NO,', NO2
(Hales & Dana. 1979)
ST. LOUIS
(Semonin, 1976)
ST. LOUIS
(Gatz, 1980a)
ST. LOUIS
(Gatz. 1980b)
S042', LI*, Mg2*, K*, Ca2*, Fe,
Cd, Pb (soluble and insoluble)
SO,2", LT, Mg2*, K*. Ca2*, Fe,
Cd, Pb (soluble and insoluble)
NEW YORK CITY Free H*. Total H*. SO,*, NO,',
(Jacobson et al., 1976) CC, F, total dissolved ions
HAMILTON, ONT. H% Na% Mg2t, Al, CP, Ca2*, V,
(Vermette et al., 1988) Mn, Cu, Br", I'
ST. LOUIS SO4*
(Bridgman, 1984)
EVENT (9)
(SITE AND
NETWORK
MEANS)
pH CONTOUR
MAPS ONLY
DEPOSITION
CONTOUR
MAPS ONLY
EVENT (10)
(NETWORK
MEANS)
MEANS OF 1
OR 15 EVENTS
AT 11 SITES
DAILY (4) SO,2"
CONCENTR
CONTOURS
ONLY
The Urban Perspectives of Add Rain
C-42
September 1992
-------
SUMMARY OF SPECIES MEASURED
AND AVERAGING PERIOD
NORTH AMERICAN MEASUREMENTS
CITY/REFERENCE SPECIES MEASURED
AVERAGING
PERIOD OF
REPORTED
DATA (#)
H', NH4*. Ca2*, Mg2*, Zn, Pb
OTTAWA, ONT.
WINNIPEG, MAN.
(Allan & Jonasson, 1978)
NEW YORK CITY \
(Wolff etal., 1979)
WASHINGTON, D.C. H*, Na% K*, Ca2*, Mg2*, NH/,
(Miller et al., 1983) CP, NO2'f NO3", SO,2'
HAMPTON, VA
(Pellett et al., 1984)
LOS ANGELES
(Liljestrand
& Morgan, 1981)
H*, Na*, K*. Ca2*, Mg2t, NH/,
cr, r, NO,-, NO/, so,2-, po4"
H*, Na% K*, Ca2*, Mg2% NH4*.
cr, er, NO,-, so4*,
strong and weak acid
DAILY (1)
WINTER (2)
(Ca2*, pH ONLY)
3-YR SEASON,
ANNUAL MEAN
PH
DAILY pH AT
10 SITES;
DAILY IONS AT
1 SITE;
MONTHLY,
SEASONAL, &
ANNUAL MEAN
pH & [H*],
MNTHLY IONS
SEASONAL,
ANNUAL, 3-YR
pH
ANNUAL
(approx)
MEANS
The Urban Perspectives of Acid Rain
C-43
September 1992
-------
SUMMARY OF SPECIES MEASURED
AND AVERAGING PERIOD
NORTH AMERICAN MEASUREMENTS
CITY/REFERENCE SPECIES MEASURED
AVERAGING
PERIOD OF
REPORTED
DATA (#)
WORCESTER, MA H*, NH4*, Na*, K*, Ca2*
(Vidulich et a)., 1987)
MONTREAL, QUE. 25 TRACE ELEMENTS
(Landsberger et al.. 1983) (soluble, insoluble)
LOS ANGELES H*, Na*, K*, Ca2*, Mg2*, NH4*.
(Zeldin & Ellis, 1984) Cl', NO,', S042'
MONTREAL H*, Na*, K*, Ca2*, Mg2*, NH4*.
(Lewis et al.. 1983) Cl', NO,', SO42'
CHICAGO
(Sisterson &
Shannon. 1989)
H', Na*, Ca2*, Mg2*, NH4*.
Cl'f NO,', S042'
DETROIT H*, Na*, K*. Ca2*, Mg2*, NH4*.
(Dasch & Cadle, 1985) CI', NO,', SO42'
ANNUAL MEAN
pH(9)
GRAPHS ONLY
ANN'L MEANS
AT 6 SITES
FOR 5 YEARS
NETWORK
MEANS FOR 6
EVENTS; CON-
CENTRATIONS
AT 10 SITES
FOR EACH OF
6 EVENTS
ANN'L MEANS
(1 YR) FOR
1 URBAN SITE
ANNUAL, SEAS
ONAL CONCEN
MEANS AT 1
URBAN SITE
The Urban Perspectives of Add Rain
C-44
September 1992
-------
SUMMARY OF SPECIES MEASURED
AND AVERAGING PERIOD
NORTH AMERICAN MEASUREMENTS
CITY/REFERENCE SPECIES MEASURED
AVERAGING
PERIOD OF
REPORTED
DATA (#)
NEW YORK CITY H*, Na*, Ca2*, Mg2*, NH4*.
(Dupuis, 1985) Cr, NO,', SO,2'
SEATTLE H*. Na% K*, Ca2*, Mg2*, NH/,
(Vong et al.. 1985) CP, NO,', SO42', PO*,
As, Pb, Cu, Cd, Zn
PHILADELPHIA H*, NH4*. SO42', NO3' + NO/, CP
(Patrinos & Brown, 1984)
PHILADELPHIA H*, Na% Ca2*, NH4% SO42', NO,'
(Patrinos, 1985)
3-YR ANNUAL
& SEASONAL
MEANS AT 2
URBAN SITES
ANNUAL (1)
MEAN CONCEN
AT 2 URBAN
SITES
SITE MEAN
DEPOSITION,
UPWIND,
DOWNWIND
NETWORK
MEAN DEPOS
FOR 2 EVENTS
UPWIND,
DOWNWIND
NETWORK
MEAN DEPOS
FOR 11
EVENTS
The Urban Perspectives of Acid Rain
C-45
September 1992
-------
SUMMARY OF SPECIES MEASURED
AND AVERAGING PERIOD
NORTH AMERICAN MEASUREMENTS
CITY/REFERENCE SPECIES MEASURED
AVERAGING
PERIOD OF
REPORTED
DATA (#)
WILMINGTON, NC H*. Na*, K*, Ca2*, Mg2*, NH4*,
(Willey et al.. 1988) CK, NO3', SO42'
DENVER
H*. Na*, Ca2*, Mg2*, NH4*.
(Schroder et al., 1987) Cl", NO,*, SO4'
WASHINGTON, D.C. H*, Na*, Ca2*, NH4*. CP, NO3
(Patrinos et al., 1989) SO42', H2O2
WINTER,
SUMMER, &
ANN'L MEANS
FOR SOME
SPECIES
MEAN CONCS
OVER SUMMER
(1) AT 1 SITE
UPWIND,
DOWNWIND
MEAN DEPOS
FOR 4 EVENTS,
INDIV SITE
DEPOS FOR
SOME IONS IN
ALL 4 EVENTS
The Urban Perspective* of Acid Rain
C-46
September 1992
-------
MISCELLANEOUS URBAN DATA SOURCES
CITY/REFERENCE
SAMPLE NO. OF
PERIOD SITES*
SAMPLE
TYPE DURATION
GREAT LAKES ATMOSPHERIC
DEPOSITION (GLAD) NETWORK
(U.S. EPA GREAT LAKES NATIONAL PROGRAM OFFICE,
CHICAGO)
MAJOR IONS + METALS
[DATA MAY BE USEFUL, BUT USE CAUTION]
DULUTH
GREEN BAY
MILWAUKEE
CHICAGO
BENTON HAR
MUSKEGON
BAY CITY
MT.CLEMENS
TOLEDO
LORAIN
ERIE
GRAND IS.
ROCHESTER
1982-85
1982-
1982-
1982-
1982-
1982-85
1982-85
1982-
1982-85
1982-85
1982-
1982-
1982-85
1
1
1
3
1
1
1
1
1
1
1
1
1
WET
WET
WET
WET
WET
WET
WET
WET
WET
WET
WET
WET
WET
WEEKLY*
WEEKLY*
WEEKLY*
WEEKLY*
WEEKLY*
WEEKLY*
WEEKLY*
WEEKLY*
WEEKLY*
WEEKLY*
WEEKLY*
WEEKLY*
WEEKLY*
The Urban Perspectives of Acid Rain
C-47
September 1992
-------
MISCELLANEOUS URBAN DATA SOURCES
SAMPLE NO. OF
CITY/REFERENCE PERIOD SITES'
SAMPLE
TYPE DURATION
DOI BUREAU OF MINES
MATERIALS EXPOSURE SITES
(DOI, Bureau of Mines, Albany, OR)
MAJOR IONS
WASHINGTON, D.C. 1982-
STUEBENVILLE, OH 1982-
WET
WET
MONTHLY
MONTHLY
PHILADELPHIA 1989-92 1 Q-WET
(DOLSKE, UNPUBLISHED) (MAJOR IONS)
EVENT
PHILADELPHIA 1979-91 1 BULK EVENT
(DUGAN, UNPUBLISHED) (pH, MAJOR IONS ON SUBSET)
The Urban Perspective* of Add Rain
C-48
September 1992
-------
PROBLEMS IN USING AVAILABLE DATA SETS
DATA DIFFER WITH RESPECT TO:
SAMPLER SITING CRITERIA
SAMPLE TYPE (bulk, wet)
SAMPLER SIZE, CONFIGURATION, MATERIAL
COLLECTOR MATERIAL, CLEANING METHOD
STORAGE BOTTLE MATERIAL, CLEANING METHOD
SAMPLE DURATION
AVERAGING PERIOD
- Annual
- Seasonal
- Monthly
- Weekly
. Dally
- Event
- Sub-event
SAMPLE PRESERVATION METHOD (Including none)
HELD PROCEDURES (gloves, moon suit, bagging used or
not, etc.)
LAB SAMPLE HANDLING METHOD (filter or not)
SPECIES MEASURED
ANALYTICAL METHOD
The Urban Perspectives of Acid Rain C - 49 September 1992
-------
CONCLUSIONS
RESULTS ON URBAN PRECIPITATION
CHEMISTRY MEASUREMENTS HAVE BEEN
PUBLISHED FOR MANY NORTH AMERICAN
AND WORLD CITIES
SOME OF THESE PAPERS CONTAIN USEFUL
DATA
DATA AND RESULTS ARE DIFFICULT TO
COMPARE BECAUSE OF A DIVERSITY OF
METHODS, USES AND APPROACHES
ADDITIONAL DATA SOURCES EXIST, BUT
MUST BE USED WITH GREAT CARE
A COORDINATED URBAN NETWORK USING
CONSISTENT METHODS IS NEEDED
The Vrt>an Perspective* of Acid Rain C - 50 September 1992
-------
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Atmos. Environ. 12:1169-1173.
Andeisson, T. 1969. Small-scale variations of the contamination of rain caused by washout
from the low layers of the atmosphere. Tellus. 21:685-692.
Argese, E, and A.G. Bianchini. 1989. Chemical and physical characteristics of rainfall in
Venice: influence of the sampling method on the reliability of the data. The Science of the
Total Environment, 83:287-298.
Ayers, G.P., and R.W. Gillett. 1984. Some observations on the acidity and composition of
rainwater in Sydney, Australia, during the summer of 1980-81. J. Atmos. Chem. 2:25-46.
Bigelow, D.S. 1984. Instruction manual: NADP/NTN site selection and installation. Report.
Program Coordinator's Office, National Atmospheric Deposition Program, Natural Resource
Ecology Program, Colorado State University, Fort Collins, CO 80523. 39 pp.
Bonet, A., N. Diaz-Caneja, I. Guttierrez, A. Martinez, and E. Villar. 1988. A comparative
study of the precipitation acidity in two cities in Cantabria (Spain) with different degrees of
industrialization. Wat. Air, Soil Pollut. 38:181-188.
Bowersox, V.C. 1980. Acid precipitation at a rural central Pennsylvania site. M.S. Thesis,
Department of Meteorology, Pennsylvania State University. 123 pp.
Bowersox, V.C, and R.G. DePena. 1980. Analysis of precipitation chemistry at a central
Pennsylvania site. J. Geophys. Res. 85(C1):5614-5620.
Bowersox, V.C., and GJ. Stensland. 1981. Seasonal patterns of sulfate and nitrate in
precipitation in the United States. Paper 81-6.1. In: Proceedings of the Annual Meeting. Air
Pollution Control Association. Pittsburgh PA
Bridgman, HA. 1984. Mesoscale spatial variability of sulfate in air and rainwater at St
Louis. Wat., Air, Soil Pollut 22:153-172.
Gty of Philadelphia. 1987. Emissions inventory and air quality data report to the Air
Pollution Control Board. Dept of Public Health, Air Management Services.
Clark, A.G., and D.R. Lambert. 1987. Local factors affecting the chemistry of precipitation.
In: Acid Rain: Scientific and Technical Advances. Selper. London, pp 252-259.
Dasch, J.M., and S.H. Cadle. 1985. Wet and dry deposition monitoring in southeastern
Michigan. Atmos. Environ. 19:789-796.
Davies, T.D. 1976. Precipitation scavenging of sulphur dioxide in an industrial area. Atmos.
Environ. 10:879-890.
The Urban Perspectives of Acid Rain C - 51 September 1992
-------
Diaz-Caneja, N., A. Bonet, I. Gutierrez, A. Martinez, and E Villar. Wat., Air, Soil Pollut.
43:277-291.
Dikaiakos, J.G., CG. Tsitouris, PA. Siskos, DA. Melissos, and P. Nastos. 1990. Rainwater
composition in Athens, Greece. Atmos. Environ. 248:171-176.
Dupuis, L. 1985. Unpublished manuscript Analysis of precipitation chemistry data in the
New York City and surrounding region. Brookhaven National Laboratory. Upton, NY. April.
17pp.
Endlich, R.M., B.P. Eynon, RJ. Ferek, A.D. Valdes, and C Maxwell. 1988. Statistical
analysis of precipitation chemistry measurements over the eastern United States. Pan I:
Seasonal and regional patterns and correlations. J. Appl. Meteorol., 27(12), 1322-1333.
Fowler, D., J.N. Cape, I.D. Leith, IS. Paterson, J.W. Kinnaird, and IA. Nicholson. 1982.
Rainfall acidity in northern Britain. Nature. 297:383-386.
Galloway, J.N., and G.E Likens. 1978. The collection of precipitation for chemical analysis.
Tellus 30:71-82.
Gatz, D.F. 1980a. An urban influence on deposition of sulfate and soluble metals in summer
rains. In: Shriner, D.S., C.R. Richmond, and S.E. Lindberg, Editors, Atmospheric Sulfur
Deposition: Environmental Impact and Health Effects. Ann Arbor Science Publishers, Ann
Arbor, Michigan, pp 245-261.
Gatz, D.F. 1980b. Associations and mesoscale spatial relationships among rainwater
constituents. J. Geophys. Res. 85:5588-5598.
Hales, J.M., and M.T. Dana. 1979. Precipitation scavenging of urban pollutants by
convective storm systems. J. Appl. Meteorol. 18:294-316.
Hfigstrom, U. 1974. Wet fallout of sulfurous pollutants emitted from a city during rain or
snow. Atmos. Environ. 8:1291-1303.
Jacobson, J.S., LI. Heller, and P. van Leuken. 1976. Acidic precipitation at a site within the
northeastern conurbation. Wat., Air, Soil Pollut. 6:339-349.
Landsberger, S., R.E. Jervis, G. Kajrys, and S. Monaro. 1983. Characterization of trace
elemental pollutants in urban snow using proton induced X-ray emission and instrumental
neutron activation analysis. Intern. J. Environ. Anal. Chem-, 16:95-130.
Lee, D.S., J.W.S. Longhurst, D.R. Gee, and S.E. Green. 1988. Urban acid deposition; results
from the GMADS network, June 1986-June 1987. Report for the Association of Greater
Manchester Authorities, Acid Rain Information Centre, Department of Environmental and
Geographical Studies, Manchester Polytechnic, John Dalton Extension, Chester Street,
Manchester U.K. Ml 5GD.
The Urban Perspective* of Add Rain C - 52 September 1992
-------
Lewis, J.E., T.R. Moore, and N J. Enright. 1983. Spatial-temporal variations in snowfall
chemistry in the Montreal region. Wat., Air, Soil Pollut. 20:7-22.
Liljestrand, H.M. and JJ. Morgan. 1981. Spatial variations of acid precipitation in southern
California. Environ. Sci. & Techno). 15:333-339.
Martin, A. 1979. A survey of the acidity of rainwater over large areas of Great Britain.
Science of the Total Environment, 13:119-130.
Maxwell, C. B.P. Eynon, and R.M. Endlich. 1988. Statistical analysis of precipitation
chemistry measurements over the eastern United States.- Part-IV: the influences of
meteorological factors. J. Appl. Meteorol. 27:1352-1358.
Miller, J.M., D.H. Pack, and K. Telegadas. 1983. The pH of precipitation in the
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Resources Laboratory, Rockville, Maryland.
Mosello, R., A. Marchetto, and GA. Tartan. 1988. Bulk and wet atmospheric deposition
chemistry at Pallanza (N. Italy). Wat., Air, and Soil Pollut., 42:137-151.
National Academy of Sciences. 1986. Acid Deposition: LonE-Term Trends. National
Academy Press, Washington, D.C.
Patrinos, AA.N. 1985. The impact of urban and industrial emissions on mesoscale
precipitation quality. J. Air Pollut. Control Assoc. 35:719-727.
Patrinos, AA.N., and R.M. Brown. 1984. Mesoscale wetfall chemistry around Philadelphia
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rain study in the Washington, D.C. area. J. Applied Meteorol. 28:948-968.
Pellett, GI_ R. Bustin, and R.C Harriss. 1984. Sequential sampling and variability of acid
precipitation in Hampton, Virginia. Wat., Air, Soil Pollut. 21:33-49.
Prakasa Rao, P.S., L.T. Khemani, G.A. Momin, P.D. Safai, and A.G. Pillai. 1992.
Measurements of wet and dry deposition at an urban location in India. Atmospheric
Environment, 26B(l):73-78.
Raynor, G.S., and J.V. Hayes. 1981. Acidity and conductivity of precipitation on central
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15:229-245.
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The Urban Perspectives of Acid Rain C - 53 September 1992
-------
Sisterson, D.L., and J.D. Shannon. Submitted. A comparison of urban and suburban
precipitation chemistry. Environmental Research Division, Argonne National Laboratory.
Argonne, IL 60439.
Summers, P.W., V.C. Bowersox, and GJ. Stensland. 1986. The geographical distribution
and temporal variations of acidic deposition in eastern North America. Wat., Air, Soil Pollut.
31:523-535.
Vennette, SJ., JJ. Drake, and S. Landsberger. 1988. Intra-urban precipitation quality:
Hamilton, Canada. Wat, Air, Soil Pollut. 38:37-53.
Vidulich, GA^ DA. Mackoul, and EM. Cohen. Chemical composition of precipitation in
central Massachusetts and its relationship to meteorological factors: a ten year study. In: Acid
Rain: Scientific and Technical Advances. Selper, Ltd., London, pp 183-190.
Vong, RJ., T.V. Larson, D.S. Coven, and A.P. Waggoner. 1985. Measurement and
modeling of western Washington precipitation chemistry. Wat, Air, Soil Pollut. 26:71-84.
Whitehead, H.C, and J.H. Feth. 1964. Chemical composition of rain, dry fallout, and bulk
precipitation at Menlo Park, California, 1957-1959. J. Geophys. Res. 69:3319-3333.
Willey, J.D., R.I. Bennett, JM. Williams, R.K. Denne, C.R. Kornegay, M.S. Periotto, and
B.M. Moore. 1988. Effect of storm type on rainwater composition in southeastern North
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Wilson, J., V. Mohnen, and J. Kadlecek. 1980. Wet deposition in the northeastern United
States. Report. Publication 796. Atmospheric Sciences Research Center. State University of
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Wolff, G.T., PJ. Lioy, H. Golub, and LS. Hawkins. 1979. Acid precipitation in the New
York metropolitan area: its relationship to meteorological factors. Environ. Sci. & Technol.
13:209-21Z
Zeldin, M.D., and E.C. Ellis. 1984. Trends in precipitation chemistry in southern California.
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The Urban Perspectives of Acid Rain C - 54 September 1992
-------
Formulating Dry Deposition in Urban Areas as presented by Bruce Hicks.
23 September 1992
BBH Page 1
Formulating Dry Deposition in Urban Areas
Bruce B. Hicks
NOAA, Air Resources Laboratory
1325 East West Highway
Silver Spring, MD 20910
The Vrban Perspectives of Acid Rain C - 55 September 1992
-------
23 September 1992
BBH Page 2
The problem.
Effects researchers are interested in the flux to receptors deemed to be of interest
marble columns
galvanized iron
painted surfaces
etc.
Atmospheric scientists tend to be more interested in the flux of pollutants leaving the
atmosphere, since this influences concentrations in the air and deposition downwind.
Hence, atmospheric scientists typically focus on deposition across areas,
usually defined either by some method of measurement (e.g. on towers, - 1
km scale) or by some model (if Eulerian, then - 20 to 100 km scale).
The Urban Perspectives of Acid Rain C - 56 September 1992
-------
23 September 1992
BBH Page 3
Wind Speed (m s'1)
024
400 -
300 -
JO)
01
X
Gravitational
Settling
200 -
100 -
The Urban Perspectives of Acid Rain
C-57
September 1992
-------
23 September 1992
BBH Page 4
A well-verified atmospheric model may yield excellent estimates of the wet and dry
deposition across a grid cell, but what effects researchers want to know is the
characteristic deposition to (say) galvanized iron surfaces contained within that grid
area.
Both communities differentiate between WET and DRY deposition, but the
estimates of these variables produced by existing Eulerian models are not
necessarily what effects researchers really need.
If it were easy to step from areal averages to receptor-specific estimates, then we
would not need to be gathered here. The fact that we are still asking questions of such
a kind after ten years of NAPAP indicates either that (a) the question is very difficult to
answer, (b) there has been inadequate attention given to it, (c) we are stupid, or (d) any
combination of the above.
The Urban Perspective* of Acid Rain C - 58 September 1992
-------
23 September 1992
BBH Page 5
The question of wet deposition can be addressed by collection of samples. In essence,
wet deposition is not affected by the chemistry of the receptor, but it is affected by its
physical characteristics (e.g. its shape, exposure, dimensions).
Dry deposition is also affected by the physical characteristics of specific receptors, but
differs from wet deposition in that the chemistry of the surface is often a dominant
factor.
Hence -- for both wet and dry deposition to specific receptors,
CONFIGURATION is an issue.
Here, we will focus on the DRY deposition issue, because its complexity is even greater
due to the role of surface chemistry.
The Urban Perspectives of Acid Rain C - 59 September 1992
-------
23 September 1992
BBH Page 6
Deposition to a surface element.
Consider a simple flat surface, large enough so that edge effects can be neglected. The
surface defines a parallel wind flow across it, with local gradients that depend on the
micro-scale roughness of the individual surface. To understand the scales involved,
recall that researchers are comfortable discussing such roughness in terms of analogy
to sand grains. This is the kind of surface investigated in classical laboratory studies.
Transfer from the air to such a surface can be expressed as a resistance analog, with
individual terms associated with atmospheric turbulence (the aerodynamic resistance,
ra), chemical uptake upon contact with the surface (the surface contact or "capture"
resistance, rc), and an intermediate quasi-laminar resistance (the boundary-layer
resistance, rb). We express the flux (Fe) to some single element of the surface as
Fe = C0/(ra + rb + rc), (1)
where C0 is the air concentration at the height to which the aerodynamic resistance
refers.
The UHxm Perspectives of Acid Rain C - 60
September 1992
-------
23 September 1992
BBH Page 7
The aerodynamic resistance ra depends on atmospheric turbulence; it is lowest in
high winds, under strong sunshine, and/or when the surface is complex and
rough.
The quasi-boundary layer resistance rb depends on the surface drag, and varies
with the molecular (or Brownian) diffusivity of the pollutant. It is lowest for rough
surfaces and low molecular weight trace gases.
The capture resistance rc depends on the affinity of the surface for the species
being deposited.
In an urban area, the concentration of relevance in (1) is that which influences the
individual surface element being considered. In the downtown area, it is the
concentration within the street canyons. In this case, the aerodynamic resistance of
relevance could be that appropriate for transfer from the street canyon to its walls.
No trace gas deposition can be assumed to always be dominated by any single one of
ra, rb, or rc. instead, these resistances need to be considered in concert.
The Urban Perspectives of Acid Rain C - 61 September 1992
-------
23 September 1992
BBH Page 8
Deposition from the atmosphere.
Once again, the Ohm's Law analogy is conventionally used, with the flux Fa being
related to the concentration in air above the height of surface elements (Ca) via
Fa = Ca/(Ra + Rb + Rc). (2)
Note that the upper case Ra, Rb, and Rc are completely different from the lower case
values used in describing the flux to single surface elements. In (2),
Ra is a vertically-diffusive quantity between some convenient level in the lower
atmosphere and the height of the effective sink.
Rb is the spatially-averaged consequence of the quasi-laminar transfers described
by the element-specific rb values.
Rc is the spatially-averaged capture resistance, made up of contributions from all
active surface elements.
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BBH Page 9
Wind-tunnel and laboratory modellers tend to talk about ra, rb, and rc.
Meteorologists and atmospheric chemists tend to refer to Ra, Rb, and Rc. A
major step is to ensure that all parties involved in the communication agree
on the terminology. It is partially as a mechanisms to achieve this goal that
the use of the present upper-case and lower-case symbolism is being
promoted.
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BBH Page 10
0 te
10'
10'
10'
10C
Re.
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BBH Page 11
Linkages.
In simple concept, we could measure the flux from the atmosphere Fa using eddy
correlation. Ra could be determined from the fluxes of momentum and heat. Ca
can be measured directly in such an experiment.
Such an experiment would quantify the flux from the atmosphere, Fa, which large-scale
numerical models attempt to predict. The work would also lead to determinations
of Fa, Ca, and Ra; hence there would be the opportunity to compute
Rb + Rc = (Fa/Ca) - Ra. (3)
The concentration C0 which influences individual surface elements is then
C0 = Fa- (Rc + Rb) (4)
It is at this stage that a linkage with the "view from below" is feasible, since it is this
concentration C0 that appears in (1).
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BBH Page 12
Modelling.
If it is desired to assess the deposition to some specific form of surface receptor,
having characteristic rb and rc, then we could follow the steps outlined above.
A regional model predicts values of Ca and Fa, and of other variables from which ra and
rb can be estimated. C0 can then be computed. If C0 is computed as in (4), then
application to specific surface elements (exposed aluminum, galvanized iron, etc.)
would then involve computation of the receptor-specific deposition rates
F0 = C0/(ra + rb + rc). (5)
In concept, and without data to allow a choice to be made, an alternative methodology
might be to compute C0 as
C0 = Fa- Rc (4a)
and then
F0 = C0/(rb + rc) (5a)
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BBH Page 13
Obviously, field testing is feasible. If test surfaces were distributed so that deposition
rates to them could be determined, then these individual samplings could be used
to assess the adequacy of these arguments (or of others like them). However,
the testing needs to be carefully constructed, and conducted using modern
technologies in conjunction with modern models. A key component of any field
test would be the determination of Rb. This would require attention to the
transfer of sensible heat and direct measurements of the radiative temperature of
the surface. Both are feasible, but require care and skill.
This is a problem that will not be solved by throwing large amounts of money at it. A
small amount, well directed, would be far more worthwhile.
The Urban Perspectives of Acid Rain C - 67 September 1992
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BBH Page 14
Envoi.
All of the above is hypothetical, bordering on heuristic. None of it is new. For any
such set of relationships to be developed requires the same field studies that were
advocated repeatedly during the era of NAPAP-I. At that time, the necessary
experimental capabilities were not as well developed as they are in this era of
NAPAP-II.
Today, however, it could easily be that the methodologies are willing but the budgets
are too weak.
The Urban Perspectives of Acid Rain C - 68
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1990 CLEAN AIR ACT AMENDMENTS
TITLE IV
ACID DEPOSITION CONTROL
Purpose: Reduce the adverse effects of acid deposition
Method: Reduce SOz emissions by 10 million tons
Reduce NOx emissions by 2 million tons
The Urban Perspectives of Acid Rain C - 69 September 1992
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Location of 110 Power Plants Affected Under Phase I of Title IV
of the 1990 Clean Air Act Amendments
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Senator Moynihan
Congressional Record, November 12,1991
Volume 137, No. 166, 81647-1648.
"In the Clean Air Act Amendments of 1990, we agreed to try an
experiment" [i.e., emissions trading].
"We will reduce sulfur dioxide emissions by 240 million tons
over the next four decades. We had better know how much it
really costs. And we had better know what we have to show
for it."
The Urban Perspectives of Acid Rain p -j i
September 1992
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KEY QUESTIONS
What is the cost, benefit, and
effectiveness of implementing TITLE
IV of the 199 DC AM?
What reductions in deposition rates
are needed to prevent adverse
effects?
The Urban Perspectives of Add Rain C - 72 September 1992
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NOx Emissions Projected Reductions
25
20-
15-
10-J
5-
Clean Air Act
NAAQS
Acid Rain & Ozone Controls (?)
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2010
Annual Emissions of Nitrogen Oxides in the United States: Historical
Data and Future Scenarios, (historical data source: U.S. EPA)
35
S02 Emissions
Possible Reductions
30-
25-
20-
15-
10-
5-
NAAQS- Nafl Ambient Air Quality Standards
Title IV - Acid Rain Controls
1900 1910 1920 1930 1940 1950 1980 1970 1980 1990 2010 2030 2050 2070
Annual Emissions of Sulfur Dioxide in the United States: Historical Data
and Future Scenarios, (historical data source: U.S. EPA)
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1
0.81
0.6
0.4
0.2-
0
r
ANC praMnt-day pra-1850
atagory (Cumuirtvt pMcantap)
<0 22 16
<2S 48 38
-------
t
5
8
7.0
6.0
5.0
4.0
50
0
-50
210
180
'150
120
160
120
80
75
50
25
0
15
10
5
0
600
450
300
Constable Pond
stope-2.1 tieq/L/ye&r (p>.05)
_J t B 1 I
I I
I I
I I
Jan 83 Jan 84 Jan 85 Jan 86 Jan 87 Jan 88 Jan 89 Jan 90 Jan 91
DATE
Charles T. Driscoll and Richard Van Dreason, 1992.
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Net societal \
benefit /
waste generation
and disposal
Improved
air quality
Secondary
costs and benefits
improved
visibility
Reduced
atmospheric
concentrations
Reduced
radiative forcing
Reduced human
health effects
Reduced
environmental
damage & risks
Deposition
Dose
Reduced
materials damage
Reduced
ecosystem damage
INTEGRATED ASSESSMENT FRAMEWORK
Key Components and Linkages in an Integrated Assessment: Determining the Costs, Benefits, and Effectiveness of Implementation
of Title IV of the 1990 Clean Air Act Amendments: source Max Henrion of Lumina Inc.,.
The Urban Perspectives of Acid Rain
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September 1992
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NAPAP ORGANIZATIONAL CHART
OVERSIGHT
REVIEW
BOARD
AGIO PRECIPITATION
TASK FORCE
INTERAGENCY
COMMITTEE
OmCE OF THE DIRECTOR
| WORKING GROUPS
T
Emissions
&
Controls
Atmospheric
Effects
\ 7
Economic
&
Social Effects
Assessment
Working
Group
L- ^
Ecological
Effects
Human
Health
Effects
Materials
Effects
SCIENTIFIC COMMUNITY STAKEHOLDERS
AND THE PUBLIC
The Urban Perspectives of Acid Rain
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September 1992
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