NNUAL
EPORT
1982
to the
President
and
Congress
National Acid Precipitation Assessment Program
Washington, D.C.
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DEPARTMENT
OF
AGRICULTURE
NATIONAL
OCEANIC AND
ATMOSPHERIC
ADMINISTRATION
ENVIRONMENTAL
PROTECTION
AGENCY
TVA
*D*°
Department of the Interior
Department of Health and Human Services
Department of Commerce
Department of Energy
Department of State
National Aeronautics and Space Administration
Council on Environmental Quality
National Science Foundation
Tennessee Valley Authority
Annual Report, 1982
prepared by
Interagency Task Force
on Acid Precipitation
Washington, D.C.
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CONTENTS
Page
Executive Summary 1
State of the Science 1
Research Progress and Outlook 2
Organization and Management Activities 5
History 5
Task Force 5
Technical Task Groups 5
Research Coordination Council 6
Program Coordination Office 6
National Laboratory Consortium 6
Major FY 1982 Program Development Activities 6
Research Progress and Outlook 8
Major Research Questions 8
A. Natural Sources 9
B. Man-made Sources 13
C. Atmospheric Processes 17
D. Deposition Monitoring 21
E. Aquatic Effects 27
F. Terrestrial Effects 33
G. Effects on Materials 39
H. Control Technologies 43
I. Assessments and Policy Analysis 47
J. International Activities 51
Appendices 53
I. FY 1982 Budget 53
II. List of Task Force FY 1982 Activities 54
III. Glossary 55
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Executive Summary
This statutory Annual Report to the President and the
Congress by the Interagency Task Force on Acid
Precipitation marks the end of the first full year of an
integrated research effort by the Federal agencies. The
National Acid Precipitation Assessment Program is
coordinated by the Task Force and focuses federally-
funded research on the timely development of a firmer
scientific basis for policy decisions.
This report summarizes the major research findings
and accomplishments of the National Program's first
year, with particular emphasis on their bearing on acid
precipitation policy questions. It provides a brief over-
view of the available scientific information relevant to
policy formulation. As the National Program progresses,
future annual reports will provide updates and increas-
ingly better information to assist decisionmakers and
the public in continuing to resolve the "acid rain" issue.
The program will integrate findings from diverse
research areas in order to arrive at successively better
answers to key questions, such as:
• What are the current and potential effects of acid
deposition within each region, and to what extent could
these be ameliorated by lower deposition levels or other
mitigation methods?
• What is the quantitative relationship between the
release of certain pollutants into the atmosphere and
the amount of acidic materials that are deposited?
• What are the costs and environmental impacts of
these effects, as well as the costs and benefits of con-
trolling pollutant releases?
In accordance with the Acid Precipitation Act of 1980
(P.L 96-294), the Task Force is vigorously implemen-
ting a comprehensive research program. Federally-
funded acid deposition research has doubled, from
about $11 million in FY 1980 to $22.3 million for FY
1983. The National Program is producing results at an
increasing rate, disseminating them as soon as they
become available. However, as recognized in the Act,
it will take a systematic effort over a number of years
to adequately address all the major uncertainties about
the causes, effects, and management of acid
deposition.
STATE OF THE SCIENCE
This overview on the current state of the science is
based on information from all available sources, in-
cluding research supported by Federal agencies, States,
environmental organizations, private sector groups, and
other nations.
Causes
Man-made atmospheric pollutants are probably the ma-
jor contributors to acid deposition in northeastern North
America. The approximate coincidence of the region
of highest precipitation acidity with the areas of greatest
sulfur dioxide and nitrogen oxides emissions provides
circumstantial evidence to support this assertion. This
conclusion is also supported by preliminary
meteorological studies tracking the physical movement
of one pollutant (sulfur dioxide) from sources of emis-
sion to suspected areas of deposition.
The National Program is also studying another con-
tributory pollutant (oxides of nitrogen) and chemical
substances suspected of being factors in controlling
acid deposition. Current data and available methods,
however, are not sufficient to quantify relationships be-
tween pollutant emissions and acid deposition on a
regional scale, or under varying conditions. Nor is it yet
possible to identify the specific change in acid deposi-
tion patterns that would result from a given change in
precursor emissions.
In addition to man-made sources, natural sources of
acid precursors are known to exist. On a global scale,
it is roughly estimated that half the sulfur in the at-
mosphere is from natural emissions. Regionally,
preliminary findings suggest that natural sources might
contribute significantly to the acidity of precipitation in
some areas, such as the southeastern United States.
In the northeastern United States natural sources are
believed to be minor contributors to acid deposition.
The National Program includes research to increase our
meager knowledge of the strengths, character, and
distribution of natural sources of sulfur and nitrogen that
can contribute to acidity as well as alkaline dusts that
neutralize acids in precipitation. This information will
be used to assess the potential significance of these
sources in contributing to acid deposition in sensitive
areas.
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Source/Receptor Relationships
To formulate scientifically based control strategies, the
relationship between emission of precursor pollutants and
deposition of acidic material at sensitive receptors should
be reliably established.
The ability of current generation models to predict
source/receptor relationships with adequate resolution and
accuracy is an unresolved issue. A study on the ability
of eight models to predict the deposition of sulfur emis-
sions in eastern North America found only a few suitable
monitoring data points. While a method is now available
to properly evaluate model performance, more data (quali-
ty assured and available as a time series) is needed to
quantify the uncertainties in model predictions. In addi-
tion there are widely differing views of the relative im-
portance of local sources (acid deposition from nearby
sources of pollution) and long-range transport (acid deposi-
tion from far-removed sources of pollution) on the recep-
tors in the local region.
Because of the urgent need to improve our ability to
make predictions that reasonably estimate the change in
amounts of acid deposition expected from decreases in
pollution levels, the National Program includes several
simultaneous approaches:
1. For near-term assessments, modifying current-
generation models to refine their accommodation of
chemical and physical factors over shorter periods of time;
2. Constructing a new generation of models to more
effectively treat the physical movement of pollutants in
the atmosphere, as well as the mechanisms for their con-
version to acids and deposition;
3. Designing a series of field experiments to provide
empirical, quantitative evidence of the relationship of
pollution source to acid deposition; and
4. Upgrading and evaluating a suitable local/mesoscale
model to quantify the relative contribution of local ver-
sus long-range transport on receptors.
Intensive efforts underway in the National Program and
elsewhere should enhance our ability to project the con-
sequences of changes in emission patterns.
Impacts
Among the possible effects of acid deposition, aquatic
impacts are currently of greatest concern because of the
sensitivity of certain surface waters to acidification and
the known potential for damage to fish and other
organisms. Initial surveys indicate that a small number
of lakes concentrated in the sensitive regions of north-
eastern North America have been acidified, and their biota
have changed.
In the Adirondacks, one of the most sensitive regions
in North America, the State of New York has c’assified
3.6 percent of lake area as in “critical” condition (7,466
acres of 246,388 acres total) and 14 percent endangered;
84 percent were surveyed. Acid deposition is probably
the major contributor to this acidification, but the rates
of change and the factors controlling it are still poorly
understood.
Many of the reported cases that suggest acid deposi-
tion is the cause of some observed change in an aquatic
ecosystem are based on circumstantial evidence and lack
documentation of the mechanisms linking cause and ef-
fect. At present, the extent of actual aquatic damages
is not well established. The question of long-term trends
in freshwater acidification also remains uncertain.
The National Program produced maps in FY 1982
depicting the regions where surface waters could be most
susceptible to acidification. Studies underway will better
define the factors that control acidification, and im-
proved regional monitoring and testing programs will pro-
duce more detailed and reliable inventories of the extent
of damages and the location and value of resources at
risk.
Beyond the alteration of the chemistry and biology of
certain sensitive surface waters, the other effects of acid
deposition in North America are undetermined. There is
concern about possible effects on crops, forests,
wetlands, soils, building materials, and indirect effects on
human health (through drinking water or food). Although
mechanisms for such effects are known, evidence has
not yet demonstrated that they are widely occur-
ring under ambient acid deposition in North America. For
instance, although experimental studies with simulated
acid rain have shown both positive and negative effects
on crop species, effects on crops growing under actual
field conditions have not been determined.
Similarly, although a dieback of spruce trees on moun-
tain sites in New England is observable, the relative con-
tribution of potential causes—acid deposition, drought,
disease, and other pollutants—is still undetermined. In
contrast to acid deposition, the effects of ozone and other
air pollutants on crops and forests are well documented.
The National Program is speeding up investigations and
analyses to determine the actual effects of acid deposition.
RESEARCH PROGRESS AND
OUTLOOK
In addition to the preceding synopsis of the state of
knowledge about acid deposition, the “Research Progress
and Outlook” part of this report describes in more detail
current findings in each subject area. It also outlines many
of the major research accomplishments of the National
Program.
National Program FY 1982
Accomplishments
Some selected highlights of progress in FY 1982 for each
research area follow.
A. Natural Sources:
• Developed and tested instruments for reliable
field measurement of sulfur and nitrogen emissions from
natural sources.
• Obtained preliminary measurements of natural
sulfur compounds in the ocean that suggest emissions
from marine sources may contribute significantly to at-
mospheric acidity in some areas.
B. Man-made Sources:
• Completed preliminary study on emission
sources that suggested that nearby petroleum combus-
tion and local and distant coal combustion could
significantly affect local acid deposition.
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• Continued development of models to predict the
cost and emissions changes from utilities and industries
based on various possible control strategies.
• Developed specifications for emissions inven-
tories with improved spatial, temporal, and source-type
resolution, and initiated studies to better characterize the
man-made sources of acid precursor pollutants.
C. Atmospheric Processes:
• Obtained initial observations that confirm the im-
portance of clouds in transforming sulfur dioxide to acidic
sulfates.
• Initiated field studies that suggest the importance
of man-made aerosols in cloud formation.
• Completed planning and initial testing for a ma-
jor field experiment to be performed in FY 1983 that will
track the movement of tracer gases over hundreds of
miles after their release in the Midwest.
• Improved atmospheric models and used them to
gain a better understanding of the movement and con-
version of pollutants and the deposition of acidic material.
D. Deposition Monitoring:
• Produced the first comprehensive maps describ-
ing the distribution of major chemical substances over
North America.
• Completed design for the National Trends Net-
work, which will be established in FY 1983 building on
existing National Atmospheric Deposition Program
(NADP) sites and others that meet specific criteria.
• Established four research sites to test improved
methods of monitoring wet and dry deposition.
• Compared field measurements of dry deposition
obtained from different prototype methods and continued
efforts to develop reliable techniques for routine measure-
ment of dry deposition.
E. Aquatic Effects:
• Produced a nationwide map indicating regions
where surface waters are likely to be most sensitive to
acidification.
• Began long-term monitoring of aquatic resources
(chemistry and biota) in key sensitive regions.
• Completed preliminary survey of drinking water
in the Northeast that indicates some reservoirs and their
watersheds have limited ability to buffer acid deposition.
• Developed better understanding of factors con-
trolling the susceptibility of surface waters to acidifica-
tion and evaluated models for predicting acidification.
• Evaluated existing information on rriitigation
strategies (liming), and initiated field and laboratory studies
to examine their effectiveness and limitations.
• Began studies of acid deposition effects in the
southeastern United States.
F. Terrestrial Effects:
• Initiated extensive long-term studies to determine
whether acid rain has caused changes in rate of growth
and species composition in forests.
• Completed a study evaluating whether acid rain
predisposes pine seedlings to succumb to stress factors.
It did not show increased susceptibility to insect or disease
attack; some seedlings showed increased resistance to
disease.
• Conducted agricultural experiments using
simulated acid rain that did not indicate injury to potato
plants or two forage plants, but decreased the yield in
soybeans and corn under some conditions and had no
effect under others.
• Performed soil studies in the Southeast, mid-
Atlantic coast, and Northeast that showed response to
acid rain varied according to mobilization of toxic metals
and leaching of nutrients.
• Conducted studies indicating that southeastern
watersheds are accumulating sulfur. The importance of
this change on the chemical and biological characteristics
of surface waters is not clearly understood.
• Completed several studies showing that forest
ecosystems alter the acidity of rain traveling through
them.
G. Effects on Materials and Cultural Resources:
• Began work to determine possible damage to
historical monuments that is related to acid deposition.
• Established several field sites for testing materials
and estimating the relationship of deterioration rates to
acid deposition.
• Began analyzing available materials deterioration
data and documenting the performance of possible pro-
tective treatments for masonry.
• Tested a simplified deposition monitor for ap-
plication to materials damage research.
H. Control Technologies: (FY 1982 developments
outside the National Acid Precipitation Assessment Pro-
gram under preexisting agency pollution control hardware
programs relevant to acid deposition)
• Successfully tested developmental prototype of
low-cost, retrofitable technology (LIMB) that can
simultaneously decrease sulfur dioxide and nitrogen ox-
ides emissions from utilities by 50 percent. (EPA)
• Developed burner systems to decrease nitrogen
oxides emissions by 75 percent in large coal-fired boilers.
(EPA)
• Assembled data on the characteristics of U.S.
coals to aid in determining their emission control poten-
tial. (EPA, DOE)
• Evaluated improved wet and dry sulfur dioxide
scrubbing (removal) processes. (DOE, TVA, EPA)
I. Assessments and Policy Analysis:
• Prepared the “Critical Assessment Document:
The Acidic Deposition Phenomenon and Its Effects” re-
quested by the Clean Air Science Advisory Committee
prior to formation of the National Program. Several
chapters review acid deposition and its impacts. Con-
tributors include 54 scientists from many institutions in
this country and abroad. The document is now undergo-
ing public review and final revision.
• Initiated work on developing methodologies for
conducting integrated assessments of the significance of
various scientific and economic information.
• Developed the preliminary version of a model for
assessing sulfur dioxide emissions from the utility sector.
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• Began investigation of estimating uncertainty in
models and the implications for formulating management
strategies.
J. International Activities:
• Established basis and mechanisms for increas-
ed cooperation between the United States and Canada
on research and monitoring activities.
• Began developing specific proposals for joint
research efforts with other nations.
• Published International Directory of Acid Rain
Researchers, listing 1,600 scientists in 32 countries.
This annual report contains more details of the ac-
complishments in the various research categories in
Sections A through J of the “Research Progress and
Outlook” chapter. The Task Force also has made signifi-
cant progress in FY 1982 in integrating and focusing
Federal activities and coordinating them more effective-
ly with private sector, State, and international acid
deposition research efforts. In FY 1982 the Task Force
met with representatives of these key groups to in-
crease coordination. These accomplishments are
described in the “Organization and Management Ac-
tivities” chapters.
Outlook
In the next several years the research under the National
Program will produce a number of important results.
From FY 1983 to FY 1985 the Task Force agencies ex-
pect to accomplish several goals:
• Produce a report estimating how effective control
of sulfur oxides, nitrogen oxides, and/or volatile organic
compounds would be in reducing acid deposition for
different regions.
• Complete assessments of the potential
significance of alkaline dusts and natural sulfur and
nitrogen emissions in influencing precipitation acidity
over sensitive regions.
• Begin applying advanced models to predict utility
emissions and develop a preliminary model to estimate
industrial combustion emissions.
• Complete a major transport experiment (CAPTEX)
to help determine long-range pollutant transport pat-
terns and facilitate evaluation of atmospheric models.
• Develop a model capable of estimating
local/mesoscale atmospheric deposition.
• Complete the National Trends Network, to provide
adequate coverage to produce reliable annual maps of
acid deposition for North America.
• Develop and begin applying improved techniques
for monitoring dry deposition.
• Complete inventories and detailed regional maps
of the extent of sensitive and currently acidified sur-
face water.
• Prepare a comprehensive report on the status of
drinking water supplies.
• Finish a broad assessment of the potential effects
of acid deposition on soils.
• Establish dose-response information on corn and
soybeans in eastern and midwestern regions of the
United States.
• Complete initial determination of the effect of acid
deposition on the susceptibility of forests to drought
and other stresses.
• Prepare a report on historical rates of deterioration
of building material and complete inventory of materials
at risk in the Northeast.
• Complete initial assessment of the scope of
material damages caused by acid deposition.
• Finish report on historical trends in emissions,
deposition, and effects.
• Develop and apply advanced integrated assess-
ment methods to evaluate the optimal strategies for
managing acid deposition and its effects.
These and the many other achievements of the National
Program will significantly improve our understanding
of acid deposition and help develop sound policies to
address the problem.
The National Acid Precipitation Assessment Program
made an ambitious start and broad progress during its
first year. The groundwork has been laid for continued
progress in answering the scientific questions
associated with acid deposition. A framework has been
established to organize and integrate research results
to address policy questions. The National Program’s
recurring assessments will provide a successively re-
fined scientific basis for decisionmaking as well as op-
portunities to reexamine research directions.
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Organization and
Management Activities
HISTORY
The Interagency Task Force on Acid Precipitation was
established by the Acid Precipitation Act of 1980 (P.L.
96-294) to plan and manage the National Acid Precipita-
tion Assessment Program. Planning for the National Pro-
gram began in October 1980, when the Task Force was
first organized. In accordance with the Act, the Task Force
drafted a National Acid Precipitation Assessment Plan,
outlining the proposed research effort. That plan under-
went extensive public review and the final version was
submitted to Congress in June 1982.
The Task Force developed its first interagency budget
for the Program in January 1981 and submitted it to Con-
gress as part of the President’s FY 1982 budget request.
In January 1982, the Task Force issued its first annual
report, outlining initial progress in the organization and
planning of the National Program. The National Program’s
integrated research effort began in October 1981 with the
beginning of FY 1982.
TASK FORCE
The Task Force oversees the planning and implementa-
tion of the National Acid Precipitation Assessment Pro-
gram. The 20 members include one high-level represen-
tative from each of the 12 Federal entities in the Program,
the directors of Argonne, Brookhaven, Oak Ridge, and
Pacific Northwest National Laboratories, and four
Presidential appointees. The Task Force is jointly chaired
by the National Oceanic and Atmospheric Administration
(NOAA), the Department of Agriculture (DOA), and the
Environmental Protection Agency (EPA). Other par-
ticipating Federal entities include the Departments of In-
terior IDOl), Health and Human Services (HHS), Com-
merce (DOC), Energy (DOE), and State (DOS); the Na-
tional Aeronautics and Space Administration (NASA); the
Council on Environmental Quality (CEQ); the National
Science Foundation (NSF); and the Tennessee Valley
Authority (T’JA).
The primary responsibilities of the Task Force are:
• Plan and manage the National Acid Precipitation
Assessment Program.
• Provide annual reports on the National Program’s
progress.
• Produce an annual interagency budget for the Na-
tional Program.
• Coordinate the National Program with the research
and monitoring activities of the private sector groups, en-
vironmental organizations, States, and other nations.
• Maintain an inventory of federally-funded acid
precipitation research projects.
• Disseminate research results and assessments of
their implications.
The role of the Task Force in planning the interagency
budget for the National Program is a highly effective and
unique aspect of the Federal effort. By working together
through the Task Force, the agencies have established
a research program that addresses national needs while
building on the research expertise of the individual agen-
cies. This strong interagency planning process avoids un-
necessary duplication and eliminates crucial omissions in
the National Program.
The Task Force sets the research goals for the National
Acid Precipftation Assessment Program, identifies the pro-
jects needed to meet these goals, and decides which
agencies are best suited to conduct the necessary work.
The result is a comprehensive program of interlocking pro-
jects, with each agency contributing to specific aspects
of the overall national effort.
During FY 1982 the Task Force met six times to review
and approve the final National Acid Precipitation Assess-
ment Plan, develop and approve the FY 1984 budget re-
quest, review and approve plans for the First Annual
Review Meeting, and begin developing a detailed
technical Operating Research Plan for the National Pro-
gram. Appendix II lists all major Task Force activities with
their dates and purposes.
TECHNICAL TASK GROUPS
The Task Force has 10 working-level Task Groups, one
for each of the National Program’s nine research
categories and one for international activities. These
technical groups include program managers and experts
from all the participating Federal agencies and National
Laboratories. They are responsible for detailed planning
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and work in their assigned areas. A Coordinating Agen-
cy serves as the contact point within each Task Group.
The Task Groups and their Coordinating Agencies are:
Coordinating Agency
A. Natural Sources NOAA
B. Man-made Sources DOE
C. Atmospheric Processes NOAA
D. Deposition Monitoring DOI
E. Aquatic Effects EPA
F. Terrestrial Effects DOA
G. Effects on Materials and
Cultural Resources DOI
H. Control Technologies EPA
I. Assessments and Policy
Analysis EPA
J. International Activities DOS
These Task Groups met numerous times throughout
FY 1982 and provided the material used in developing
this report.
with non-Federal groups in organizing the Acid Precipita-
tion Research Coordination Workshop (held in November
1982). The Program Coordination Office actively
distributed thousands of copies of Task Force documents
and responded to hundreds of requests for information
on the National Program.
NATIONAL LABORATORY
CONSORTIUM
The four National Laboratories on the Task Force form
the Consortium required by law to integrate their acid
precipitation research efforts and assist the Task Force
in planning and conducting research and assessment ac-
tivities. Each year the Consortium elects a chairperson to
serve on the Research Coordination Council.
During FY 1982 members of the National Laboratories
participated in the activities of all the Task Groups and
assisted the Task Force in drafting the Operating Research
Ran. The National Laboratory Consortium is studying data
management needs for the National Program and inven-
torying Federal and State acid rain research.
RESEARCH COORDINATION
COUNCIL
The Research Coordination Council (RCC) oversees and
integrates the efforts of the various Task Groups and
develops draft reports, program plans, budgets, and other
recommendations for consideration by the full Task Force.
The joint chairs designated the Task Force’s executive
director to oversee its efforts. The RCC includes the
leaders of all the task groups, the chairperson of the Na-
tional Laboratory Consortium, and other appropriate agen-
cy representatives.
The Research Coordination Council met 10 times in
1982 and tackled many different tasks, including:
• Revising the National Acid Precipitation Assessment
Plan;
• Drafting the Operating Research Plan;
• Planning the First Annual Review Meeting;
• Designing an inventory of Federal and State acid
deposition research;
• Developing the FY 1984 interagency budget request;
• Drafting the 1982 Annual Report to the President
and Congress.
The RCC will address many important management
issues during the coming year, including plans for inten-
sifying program review activities.
PROGRAM COORDINATION
OFFICE
The Program Coordination Office staffs the Task Force
and coordinates interagency activities. The office also
disseminates information on the Program and is the
primary liaison with States, private groups, the public, and
other countries. The office is housed at CEO and is fund-
ed by NOAA, EPA, DOA, DOl, and DOE.
During FY 1982, the Program Coordination Office
supervised planning for the Task Force’s First Annual
Review Meeting (held in September 1982), and worked
MAJOR FY 1982 PROGRAM
DEVELOPMENT ACTIVITIES
In addition to regular meeting and planning activities, the
Task Force has undertaken several major efforts to im-
prove the management and coordination of the National
Program, including:
1. Improving Coordination with Non-Federal Ac-
tivities. The Task Force is committed to conducting a
National Program that coordinates Federal efforts with the
research and monitoring activities of State and local
governments, the private sector, environmental organiza-
tions, and other countries. Several specific steps have
been taken to develop and encourage such cooperation
and more extensive joint planning activities are an-
ticipated. Besides reviewing the draft National Plan, the
Task Force’s April 1981 workshop of non-Federal experts
began a dialogue with State and private groups. The
v rkshop report describes the participants’ ideas concern-
ing how coordination and cooperation can best be ac-
complished. The Task Force is implementing many of
these suggestions and is actively pursuing continued ex-
changes of information with non-Federal groups.
At the First Annual Review Meeting of the Task Force
(September 1982), approximately 30 non-Federal par-
ticipants provided valuable ideas to discussions of inter-
relationships among research areas, using the draft
Operating Research Plan as background. Substantial
research on acid deposition is sponsored by the private
sector, certain States, and Canada; Task Force represen-
tatives have met with these non-Federal groups. These
meetings have focused on reviewing programs and
establishing a basis for better understanding and closer
coordination. During the last year, the two most signifi-
cant such events were:
• Task Force-Canadian Research Program Coopera-
tion. In April 1982, Task Force representatives met with
the Canadian Federal/Provincial Research and Monitor-
Task Group
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ing Coordinating Committee (RMCC) to discuss bilateral
scientific cooperation. Leaders of both the U.S. and
Canadian research efforts emphasized the mutual val-
ue of greater cooperation and coordination of activities.
• Task Force-State-Private Sector Coordination. The
Task Force initiated and encouraged joint sponsorship
of an Acid Deposition Research Coordination Work-
shop in November 1982. The non-Federal sponsors in-
cluded the Electric Power Research Institute, the American
Petroleum Institute, the Gas Research Institute, the Coordi-
nating Research Council, the National Council of the
Paper Industry for Air and Stream Improvement, and
the Keystone Center. The States, private sector, and
the Federal Task Force were represented about equally.
Environmental groups were also invited to participate.
The purpose of the workshop was to bring together
key Federal and non-Federal managers of acid deposition
research to review and discuss the management and
coordination of their research planning efforts. Specifically,
the two goals of the meeting were (1) to assess the scope
of the nationwide acid deposition research effort, and (2)
to initiate a continuing process for joint planning and coor-
dination of Federal and non-Federal acid deposition
research efforts.
In addition to developing joint statements on research
needs and disseminating information, the State represen-
tatives agreed to organize by regions and to define their
specific areas of expertise. The Task Force agreed to in-
vestigate ways to increase opportunities for State and
private sector participation in the National Program plan-
fling and review groups. Followup activities include fur-
ther discussion between the Task Force and the private
sector and State representatives to work out the details.
2. Developing a Detailed Operating Research
Plan. To ensure that diverse scientific findings are
systematically organized to address the relevant policy
questions, the Task Force is developing an Operating
Research Plan. This detailed document supplements the
more general National Acid Precipitation Assessment Plan
(June 1982) and describes each project and how it relates
to other activities and specific program outputs. This plan
gives the technical and programmatic details on how the
National Program’s objectives will be met. The completed
plan will be a dynamic document that will evolve with
the Program and be updated annually to track the Na-
tional Program and project plans for future years.
3. Developing an Inventory of All Federal and
State-Sponsored Acid Deposition Research. The in-
itial tabulation was completed this spring and the inven-
tory will be maintained and updated for use by the Task
Force and all interested parties. This inventory includes
information on all ongoing projects with the performer(s),
duration, funding, study area, research goals, meth-
odologies, and expected outputs. The private sector has
conducted a similar inventory of its activities; together
with the Task Force’s effort, this should provide a com-
plete catalog of all acid deposition research and monitor-
ing activities in the United States.
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GResearch Progress
and Outlook
MAJOR RESEARCH QUESTIONS
The National Program includes research, monitoring, and
assessment activities to develop answers to major
research questions. In addition to identifying and reduc-
ing scientific uncertainties, the National Program is
organizing the scientific information to address policy
questions. The Task Force is establishing a systematic
framework for evaluating the costs and benefits of alter-
native policy options for controlling man-made sources
of acidity or mitigating adverse effects.
Some of the overall research questions the National
Program is specifically addressing are given here with
some indication of the type of work underway to answer
the questions.
1 Does acid deposition significantly affect
aquatic resources, crops, soils, forests, materials, or
human health? Except for poorly buffered lakes,
evidence on other actual impacts is inconclusive. The Na-
tional Program included intensive laboratory and field
studies to develop a more definitive understanding of the
potential for damage to sensitive resources.
2. Where are the sensitive resources? How much
damage has occurred, or how long will it take for
damage to occur? Concern about acid deposition
centers around its potential and known effects. The Na-
tional Program is developing inventories of the aquatic,
terrestrial, and cultural resources at risk and is surveying
the resources that have already been affected by acid
deposition.
3. What is the relative contribution of wet versus
dry deposition acids? Dry deposition may constitute up
to 60 percent or more of acidifying substances, but reliable
methods for its routine collection and measurement do
not yet exist. Vigorous efforts are underway in the Na-
tional Program to develop appropriate techniques for ade-
quately monitoring dry deposition on a routine basis. In
the meantime, interim methods for collecting dry deposi-
tion will be used to provide the best currently attainable
data.
4. What is the relative importance of local versus
distant pollution sources in controlling the acidity
of deposition at a given location? Neither models nor
measurements currently address this question with a
reasonable degree of confidence. The National Program
includes a broad atmospheric sciences effort with models,
experiments, and measurements in the field and labora-
tory designed to improve our understanding of
source/receptor relationships as rapidly as possible. Infor-
mation on the characteristics and magnitude of local and
regional sources of man-made emissions is being re-
fineded as well.
5. What is the relative contribution of man-made
versus natural sources of acid-forming material?
Significant natural sources exist, but their role is uncer-
tain. The amount of natural acid precursors arising from
sources such as oceans and marshes is being deter-
mined by the National Program to assess their contribu-
tion to acidity over North America. The magnitude,
distribution, and character of man-made emissions are
also being inventoried to more accurately identify their
contribution to acid deposition.
6. What is the temporal and spatial distribution
of acid deposition? Monitoring efforts before 1977 were
fragmented and generally inadequate for determining
trends. A National Trends Network with standardization
and quality control has been established to answer these
questions. Using a variety of information sources, research
is also underway to improve monitoring techniques and
to decipher any past trends.
7. What changes in deposition would result from
a given change in sulfur dioxide, nitrogen oxides,
organics, and/or primary sulfate emissions? Scientists
cannot precisely calculate the amount of emission reduc-
tions that would be required to reduce acid deposition
below a particular level within a given area. We need to
know more about atmospheric processes to accurately
quantify source/receptor relationships. The National Pro-
gram’s assessment activities integrate information on
sources and atmospheric processes to address this
question.
8
-------
. Natural Sources
BACKGROUND*
The sources of acid precipitation
precursors are both natural and man-
made. Natural sources will continue
to contribute to precipitation
chemistry despite any foreseeable
abatement procedures that might
control man-made sources. Emission
control strategies and alternative
energy options, therefore, require an
accurate assessment of the relative
importance of the two types of
sources.
To make that assessment, the Na-
tional Program's natural sources
research focuses on answering two
key questions: —
• What natural emissions can in-
fluence precipitation chemistry? ___«___
• What are their strengths locally, regionally, na-
tionally, and globally?
This research seeks answers to these questions in the
context of current knowledge of natural emissions, which
is summarized as follows.
The present understanding recognizes both biogenic
and nonbiogenic natural sources. Some estimates place
biogenic sources—vegetation and microbial activities in
upland terrestrial sites, tidal/intertidal areas, and nutrient-
rich oceanic regions—at 80 percent of the total natural
source strength. The nonbiogenic sources include
geothermal activities, natural combustion, light-
ning, and airborne soil and water aerosols. Sulfur- and
nitrogen-containing gases are currently suspected to be
the principal emissions from natural sources that influence
precipitation chemistry, but natural alkaline materials such
as ammonia and wind-generated aerosols and other acidi-
fying components such as chlorine compounds could also
play significant roles.
Various researchers have estimated numerous global
budgets for sulfur compounds and have put natural emis-
sions from 35 to 85 percent of the total global sulfur
budget. On regional scales, the few existing estimates
place natural sulfur emissions at a much smaller fraction,
only a few percent in one study of the northeastern United
States. However, these estimates are derived largely from
a few measurement series. Furthermore, it is not clear
whether differences among the data arise from natural
variation within the environment or from problems with
the instruments and techniques used in measuring natural
sulfur emissions.
A recently completed assessment of nitrogen oxide
emissions found that industrial and agricultural emissions
together are approximately twice natural emissions on a
global scale, while in North America fossil fuel combus-
tion was found to produce 3 to 13 times more nitrogen
oxide than natural sources. Systematic studies are re-
quired to accurately determine natural nitrogen oxide
emissions with higher accuracy and geographical resolu-
tion than is currently available.
RESEARCH GOALS AND
ACTIVITIES
To resolve these uncertainties, the National Program's
research on natural sources has set the following specific
objectives for FY 1982 to FY 1985:
1. Establish the reliabilities of the current state-of-the-
art sulfur flux-measurement instruments and techniques.
2. Identify via field measurements, modeling, and
laboratory studies the major potential sources of natural
sulfur emissions that could contribute to precipitation
chemistry.
3. Determine the strength of acid-forming natural sulfur
emissions from land and ocean sources by using existing
data and supplementary studies.
4. Develop accurate techniques for identifying and
quantifying natural nitrogen emissions that could con-
tribute to precipitation chemistry.
5. Estimate the strengths of acid-forming nitrogen
emissions using survey measurements.
6. Provide an initial assessment, measurement tech-
nique development, and survey measurements of the
natural alkaline emissions that can contribute to precipita-
tion chemistry.
Reaching these goals will lead to a significant ac-
complishment by the National Program: an experimental
data base that adequately characterizes the source
strengths of the natural sulfur, nitrogen, chlorine, and
alkaline emissions that influence precipitation chemistry
on regional and national spatial scales.
• T>iese background aecDons are based on scientific information avaiabte from a variety of sources,
including research sponsored by Federal and Stare agenoes: environmental, private sector, and
international organizations; and other countries.
-------
These findings, together with analogous ones from
man-made sources research, will feed into the atmos-
pheric transport/transformation, source/receptor mod-
els used to study atmospheric processes. The models will
then be able to assess the impact of natural emissions
relative to man-made emissions.
PROGRAM ACCOMPLISHMENTS—
FY 1982
The research projects on natural sources began in FY
1982. Because of delays in budget allocations, funds
became available midway through the fiscal year; hence,
the results summarized here represent only the start of
the program.
Instrument Development. The initial research
thrust in FY 1982 was to develop and test analytical
techniques for sulfur- and nitrogen-containing species.
One of the major problems in reliably measuring low sulfur
concentrations, water vapor in the sample, has been
satisfactorily solved by developing a membrane that selec-
tively removes water without altering most other concen-
trations. A sensitive technique for measuring concentra-
tions expected for natural nitrogen emissions has also
been developed. Both of these instrumentation advances
should greatly improve the quality of future field
measurements required by the National Program’s
research in natural sources and atmospheric processes.
• Modeling. Studies are beginning to partition the
likely sources of natural nitrogen compounds. Using
measurements obtained in remote oceanic areas,
photochemical models have shown that most of the
nitrogen produced over the oceans arises from lightning,
with about a 10 percent contribution from the
stratosphere. In FY 1983, these studies will be extended
to other areas to improve estimates of the contribution
of lightning over continents.
• Field Measurements. Preliminary oceanic field
measurements have found reduced sulfur compounds in
biologically productive seawater in the Gulf of Mexico and
the North Pacific Ocean. Crude estimates of release rates
of these compounds to the atmosphere from the ocean
suggest they could be a significant source of atmospheric
sulfur. These data will guide the FY 1983 oceanic
measurements described here.
FUTURE ACTIVITIES
used to estimate sulfur gas emissions from natural
sources. The information gained not only will permit a
better assessment of the existing data base, but will help
plan how to improve it: both efforts will take place dur-
ing FY 1983 and FY 1984.
Also in FY 1983, the Natural Sources Task Group will
comprehensively review the existing land-based sulfur
emission data base, emphasizing the acid precipitation
problem. This inventory, categorized by soil types, will
yield a “first-look” at the magnitude of the natural sulfur
source budget, and it will be used to identify existing
needs. Field measurements will occur in the following year
as needed, drawing on the previous instrument
development.
Parallel to these studies, a detailed field and laboratory
investigation will examine the characteristics of specific
major sulfur emitters. These latter data will provide by
the middle of FY 1984 a much needed prognostic
understanding of sulfur sources and their importance to
the acid deposition problem.
Research cruises from FY 1983 to FY 1985 will further
explore oceanic emissions of sulfur. Emphasis will be
placed on quantifying the factors that influence the rate
of fixation of inorganic sulfur by marine organisms, their
release of reduced sulfur compounds and the vertical
distribution of these compounds within the upper oceanic
layer, and the transport of reduced sulfur compounds
across the sea/atmosphere interface. Additionally, the cor-
relation between the areal distribution of reduced sulfur
compounds in productive seawaters with biological
parameters that are amenable to remote sensing will be
determined.
Laboratory kinetic studies will investigate the paths by
which natural emissions are converted to acids. These
rates and mechanisms are necessary in atmospheric
models that will assess the acidification of precipitation
by natural emissions. Initial estimates of sulfur compounds
will begin in FY 1984 and continue through FY 1985.
In FY 1983 distributions and deposition fluxes of nitrate,
sulfate, and ammonium will be modeled over remote
oceanic stations, where the understanding of natural pro-
cesses can best be tested. It is anticipated that these
studies will point out previously unsuspected sources, if
they exist. An initial assessment of the global budget of
atmospheric nitrate precursors will be made in FY 1985.
The study of natural alkaline materials will be com-
pleted in FY 1983. This research will gather existing data
on airborne alkaline materials; assess amounts and iden-
tities by region, seasonal variation, influence of me-
teorological conditions, and solubilities; and thereby
estimate their potential neutralizing effect on precipitation.
A major element in the natural sources research program
is determining the confidence levels of various techniques
10
-------
FY83 FY84
Comparison of Sulfur
Measurement Techniques
FY85 FY86 FY87 FY88 FY89
Revised
Sulfur
Emissions
Figure Al. Proposed program implementation strategy, Natural Sources.
Extant Sulfur
Data Emissions
Review —Land
Biogenic Sulfur Ernisston j__.___
Sulfur Emissions —
Ocean Survey
Budget
Assess-
ment
I Natural
Sources Q
Key:
Other
Task Group
Interaction
11
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. Man-Made Sources
BACKGROUND
Research on acid deposition has iden-
tified several substances be-
lieved to be precursors to the for-
mation of acid compounds in the at-
mosphere. As more knowledge of the
acid formation process is gained, the
list may change.
A current list of pollutants likely to
be important includes sulfur dioxide,
oxides of nitrogen, volatile organic
compounds, primary sulfates, am-
monia, hydrochloric and hydrofluoric
acids, and alkaline dusts. Of these,
sulfur dioxide and oxides of nitrogen
have long been recognized as impor-
tant; studies of the potential in-
fluences of other pollutants, including
trace metals, are continuing.
Experimental work is developing emissions fac-
tors; its purpose is to increase the accuracy of existing
factors and to develop new factors for pollutants recent-
ly identified as potential precursors of acid deposition.
Typically these factors are expressed as pounds of pollu-
tant emitted for a unit produced or unit of fuel con-
sumed. The quality of any emissions inventory depends
on the accuracy of these factors. Work to develop new
emissions factors is focusing on nitrogen oxides, primary
sulfates, hydrocarbons, hydrochloric acid, and trace metals
such as vanadium and manganese. Emissions factors for
sulfur oxides are being refined.
Total emissions of sulfur dioxide (S02) and oxides of
nitrogen (NOX) for the United States and Canada in 1980
were calculated as part of the work done for the
U.S./Canadian Memorandum of Intent. These calculations
are (in million tonnes per year):
United States (%) Canada (%) Total
so.
24.1
19.3
(55.5)
(44.5)
(100.0)
4.8
1.8
(72.7)
(27.3)
(100.0!
28.9
21.1
Canadian emissions of nitrogen oxides make up a smaller
percentage of that country's total emissions than do
domestic NOX emissions in the U.S. total. A large por-
tion of the Canadian sulfur dioxide emissions is generated
by primary metal smelting, which contributes relatively
few nitrogen oxides.
Over the past 60 years U.S. sulfur dioxide emissions
have fluctuated between about 16 and 28 million tonnes
per year, primarily following the rate of coal use in the
country. The low point in total emissions was during the
1930's, the high point during World War II-closely
followed by the early 1970's, before the 1970 Clean Air
Act had an impact. The bulk of these emissions in the
United States occurs east of the Mississippi River.
In contrast, nitrogen oxide emissions have increased
more evenly over the years in response to increasing fuel
use. The shift in coal use from domestic and industrial
grade combustion to utility pulverized coal combustion
has also increased average emissions because of higher
combustion temperatures.
Future projections of sulfur dioxide and nitrogen oxide
emissions depend on assumptions about future economic
activity and regulatory changes. With no changes in
regulation, the U.S./Canadian Work Group projects a 7.8
percent increase in sulfur dioxide emissions (a 5 percent
drop in Canada offsetting a 10 percent increase in the
United States). The Work Group expects nitrogen oxide
emissions to increase a total of about 25 percent. Different
retirement rates of older industrial facilities in the United
States and replacement by new facilities subject to the
existing emissions limitations for new sources could make
these preliminary estimates highly uncertain.
RESEARCH GOALS
AND ACTIVITIES
The fundamental purpose of the National Program's man-
made sources research is to provide the other Task
Groups with information on man-made pollutants need-
ed for the overall assessment program. This research in-
volves developing estimates of past, present, and future
emissions of pollutants from man-made sources and then
devising quantitative methods to estimate the effects and
costs of possible government regulation of these emis-
sions. The overall purpose of this research effort can be
summarized in the following objectives:
1. Provide, with adequate geographic, temporal, and
economic sector .resolution, an accurate and complete in-
ventory of emissions from man-made sources believed
to be important in acid deposition processes.
13
-------
2. Provide models that (a) predict how these emissions
may be altered by such factors as economic growth, fuel
supply, emissions regulations, and control techniques; and
(b) calculate the cost of alternative control strategies.
A series of projects is being conducted to attain these
research objectives. In 1985 an interim version of the em is-
sions data required to achieve these objectives will be
completed, and in 1986, an interim group of models. The
Man-made Sources Task Group plans to submit final ver-
sions of the emissions data base and the required models
in 1988.
PROGRAM ACCOMPLISHMENTS—
FY 1982
One major accomplishment in FY 1982 was to adopt an
organizational structure to compile and analyze research
results. In addition, continuing technical projects have pro-
vided valuable information on meeting National Program
objectives and on conducting future projects. Major ac-
complishments are summarized.
Preliminary General Specification for the Man-
made Emissions Inventory Data Base. Current work
is delineating the pollutants to be included in the inven-
tory’s data base, specifying the geographic resolution, the
time frame (annual, weekly, daily), and the sources of
pollutants for which emissions data will be provided. This
will set a uniform standard for emissions data to be used
by the National Program in examining atmospheric pro-
cesses related to acid deposition. All man-made sources
research projects will be evaluated in terms of their abili-
ty to supply necessary data, and, if needed, will be
redirected to satisfy National Program needs.
• Preliminary General Specification for the Man-
made Sources Models. These models wll provide a tool
to help analysts develop and assess various regulatory
strategies. The National Program requires specific data
to be generated by man-made sources models, given
general descriptions of various projected emissions levels.
The models will help determine potential decreases in
emissions from a set of policy options and their costs.
The Man-made Sources Task Group will review the
specifications for the models, then transmit them to the
scientific community for review and comment. The final
specification will be used to evaluate existing and planned
projects and make appropriate adjustments.
• Initial Plan for Acid Deposition Inventory. This
document proposes a plan for creating a data base for
the emissions inventory, which will provide a single source
of emissions data within the National Program. The in-
ventory is designed to meet the information needs of Na-
tional Program researchers and other interested persons
in the scientific community who are explaining and model-
ing atmospheric processes related to acid deposition and
developing and evaluating pollution reduction techniques.
• Acid Precipitation Precursor Study. The com-
pleted Acid Precipitation Precursor Study presented find-
ings on the general relationship between fossil fuel use
and the location and degree of acid precipitation. This
study points out the potential importance of petroleum
combustion in addition to coal combustion in forming acid
deposition. The National Program will use this document
to help plan its emissions inventory activities, including
the potential expansion of the emissions examined and
the definition of required resolution. As a result of this
study, the National Program will also examine emissions
from transportation activities more closely.
• Studies Characterizing the Sources of Acid
Precipitation. Studies begun in the latter part of FY 1982
and continuing through FY 1984 include (1) investigation
of boron as a tracer of aerosol from the combustion of
fossil fuels; (2) sulfur isotope analysis; (3) receptor model-
ing, precision, accuracy, and data requirements; and (4)
source characterization for receptor model source appor-
tionment of acid rain precursor species. Because these
studies have begun recently, they have not yet produc-
ed results for publication. Eventually, they will lead to im-
proved characterization of sources of acid deposition
precursors.
All these accomplishments reflect the emphasis in the
latter half of 1982 to better define the products to be pro-
vided by the Man-made Sources Task Group to other
research groups, and to formulate effective and economic
plans for meeting these needs. This effort will provide
more accurate and timely results with a minimum of
expenditure.
• Advanced Utility Simulation Model (AUSM).
When completed, this model will allow the National Pro-
gram to evaluate the costs and changes in emissions that
would result from a wide range of control strategies for
utilities. In FY 1982 a prototype, single-State version of
the AUSM was developed and successfully operated for
several States. A data base was developed that will allow
operating the model for each State. The AUSM can be
used with other models to compare costs and emission
changes for strategies involving different combinations
of sectors, pollutants, and regions. This modeling effort
used in conjunction with the other emissions models will
show how emission patterns might be altered by a
number of control scenarios and the cost of each scenario.
These emission pattern data coupled with transforma-
tionftransport models and acid deposition/damage models
will help determine the cost/benefit relationship for the
control scenarios that might be considered.
• Industrial Combustion Emissions Model. Work
was begun on this model, which, when completed, will
be able to evaluate the costs and emissions reduction
potential of alternative regulatory strategies for industrial
combustion sources. The model will focus initially on the
industrial boiler sector.
FUTURE ACTIVITIES
The National Program’s Man-made Sources Task Group’s
major goal in FY 1983-84 is to review and modify
specifications for the Man-made Emissions Data Base and
Model Set. After completing this in early FY 1983, the
group will review its own projects against the specifica-
tions to ensure they satisfy National Program needs.
Besides working to establish the Man-made Emissions
Data Base, the group will continue work on the utility and
industrial emissions models during FY 1983-84. Under the
National Program, man-made sources research will
develop a comprehensive emissions inventory for a 1980
base year. This inventory will separate information on
14
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sulfur dioxide, nitrogen oxides, sulfates, and volatile
organic compounds on a seasonal basis for the United
States and southeastern Canada, covering both point and
area sources. Research will develop emissions factors for
ammonia, chlorides, fluorides, and alkaline dusts.
Planning will continue for compiling an improved emis-
sions inventory for a 1984 base year. Finally, the group
will develop an historical inventory of sulfur dioxide and
nitrogen oxides.
Advanced Utility Simulation Model. In FY 1983-84
a fully documented State level version of the AUSM and
associated data bases will be transferred to government
computer systems and tested. In addition, work will begin
on developing the remaining components required to
operate the model for either national or regional analyses.
Industrial Combustion Emissions Model. The ef-
fort to develop the Industrial Combustion Emissions
Model will intensify, with delivery scheduled for early in
FY 1984. FY 1983 activities will focus on modifying the
fuel choice decision module. Process heaters may be ad&
ed to the model’s capabilities. The Technical Advisory
Committee will continue to guide the project’s activities
and evaluate its products.
Industrial Process Emissions Model. The En-
vironmental Protection Agency will begin to develop an
Industrial Processes Emissions Model in FY 1983, ac-
celerating these activities through FY 1984. Initial em-
phasis will be on identifying the most significant pollutants
and the industries emitting them, along with determin-
ing the best mechanism to model emissions from in-
dustrial processes. The model will be able to evaluate the
cost and effectiveness of alternative control strategies im-
posed on industrial processes. This model will be com-
patible with the Industrial Combustion Emissions Model,
thereby aiding analyses of the entire industrial sector.
The refinement process for these models will be under-
taken in FY 1985 and continue through FY 1988.
WORK ELEMENT
• CREATE/ADOPT “DATA BASE SPECIFICATION”
• CONSTRUCT SKELETON DATA BASE
FROM “NEDS” AND “NERDS”
• DEVELOP EMISSIONS DATA
IFUEL, EMISSION FACTORS, SPECIATION FACTORS)
• REVIEW/RECONCILE DATA BASE
— RELEASE “INTERIM DATA BASE”
• OPERATE/MAINTAIN “INTERIM DATA BASE”
— CHANGE CONTROL-
• EMISSION AND SPECIATION FACTOR DEVELOP.
— FIELD/LAB SUPPORT
• ASSEMBLY OF SKELETON “1988 DATA BASE”
• REVIEW/RECONCILE “1988 DATA BASE”
— RELEASE 1988 DATA/RETIRE INTERIM
• OPERATE/MAINTAIN 1988 DATA BASE
— CHANGE CONTROL —
EPA
MGMT.
Figure B-I - — Proposed schedule — em ss ons data base, Man- made Sources.
YEAR
87 88
• FUEL/FEED STOCK AND OPERATIONS SURVEYS
DOE
DOE
NLC
EPA
MGMT.
MGMT.
15
-------
WORK ELEMENT
BY 83
8 87
• CREATE/ADOPT “MODEL SET SPECIFICATION” MGMT.
• CONSTRUCT HISTORICAL EMISSIONS MODEL EPA
• CONSTRUCT FUEL/COST SUPPLY SUB MODEL EPA
(USING EIA DATA BASE)
• CONSTRUCT ASSESSMENT SCENARIO SUB MODEL EPA
• CONSTRUCT CONTROL COST SUB MODEL EPA
• CONSTRUCT UTIUTY SIMULATION MODEL EPA
• CONSTRUCT INDUSTRIAL COMBUSTION MODEL EPA
• REVIEW/RECONCILE “INTERIM MODEL SET” MGMT.
— RELEASE ‘INTERIM MODEL SET” MGMT.
• OPERATE/MAINTAIN “INTERIM MODEL SET” EPA
— CHANGE CONTROL — MGMT.
• CONSTRUCT “INDUSTRIAL PROCESSES MODEL” EPA
• CONSTRUCT “TRANSPORTATION MODEL” EPA
• CONSTRUCT “RESIDENTIAL/COMM. MODEL” EPA
• PREPARE “AS BUILT” DESCRIPTIONS OF MODEL EPA
SET/ASSUMPTiONS
• REVIEW/RECONCILE “MODEL SET” MGMT.
— RELEASE “MODEL SET” MGMT.
• OPERATE/MAINTAIN “MODEL SET” EPA
— CHANGE CONTROL — MGMT.
E
I —EPA—
-U-
Figure B-2.—-Proposed schedule—mod& set data base, Man- made Sources.
16
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(^.Atmospheric Processes
BACKGROUND
One of the basic observations about
acid rain is the approximate coin-
cidence of the region of highest
precipitation acidity with the areas of
greatest sulfur dioxide and nitrogen
oxides emissions. Further, we know
that these two pollutants are the
primary precursors to acid materials,
and are transformed in the at-
mosphere, at least partially, to sulfuric
and nitric acid. To date, however, no
one has been able to reliably assess
the contribution of a specific source
or set of areal sources to the acidity
of deposition in a given distant region.
To establish this source/receptor rela-
tionship, which is needed to evaluate
the effectiveness of different pro-
posed control strategies, the relationship between
emissions and deposition must be reliably quantified.
Research on atmospheric processes is subdivided in-
to three major categories:
Transport. The speed and direction of the winds at
the level of ejection are the major influences on the move-
ment of the pollutants. How far they are moved depends
upon whether the given pollutants are gases or particles,
at what level they enter the atmosphere, and how they
are transported vertically during their lifetime. For exam-
ple, gases emitted at or transported to levels well above
the earth's surface will travel farther than large particles
ejected at the surface. Such factors are important in
understanding local versus long-range transport.
Transformation. While the material is being moved
by the air currents, chemical changes can take place. For
example, smog may form in the presence of sunlight, or
sulfur dioxide may be incorporated in a cloud droplet, for-
ming sulfuric acid. These complex interactions, especial-
ly those in clouds, are not yet well understood and pro-
bably hold an important key to explaining acid deposi-
tion patterns.
Deposition. After the pollutant material is transported
and possibly chemically transformed, it is finally deposited
either by contacting a surface directly (dry deposition) or
by being incorporated into precipitation and brought
down to the earth's surface in rain or snow (wet deposi-
tion). The relative importance of wet and dry deposition
is one of the major questions still unanswered.
Because transport, transformation, and deposition form
such a complex system, scientists have tried to sort out
their relative importance by using mathematical models.
At present, the models cannot account for every step but
have been designed to cover the gross features of the
atmospheric processes. The major emphasis to date has
been on transport studies, with very rough approxima-
tions of the transformation and deposition processes.
Plans are being made to incorporate more realistic con-
ditions into future, more sophisticated models. A major
goal of the National Program's atmospheric processes
research is to develop reliable models that can be used
in a predictive and interpretive mode to explain
source/receptor relationships.
Because the development of reliable models is com-
plex, alternative approaches to determining source recep-
tor relationships are being developed. One way would
be to conduct a series of field experiments in which inert
tracers or isotopically tagged man-made pollutants re-
leased into the atmosphere are measured and then
tracked while they are transported and diluted, transform-
ed physically and chemically, and eventually deposited
on the earth's surface. Such studies provide empirical in-
formation on the processing of these pollutants between
sources and receptors.
RESEARCH GOALS
AND ACTIVITIES
The National Program's research on atmospheric pro-
cesses is designed to provide an understanding of the
atmospheric link between the emission of pollutants and
acid deposition. Understanding this link requires research
that addresses the following key questions:
1. What are the important chemical species and pro-
cesses governing the formation of acidic substances in
the atmosphere and how do they operate?
2. What are the most important meteorological pro-
cesses governing the transport of acidic substances and
their precursors?
3. How do the processes of wet and dry removal
operate and how does their relative importance change
as distance from the source increases?
17
-------
4. How can the processes of transport, transformation,
and removal be modeled so that we can understand cur-
rent and predict future deposition patterns?
The answers to question 1 will tell us which at-
mospheric pollutants will have to be controlled to reduce
acid deposition. The answers to questions 2 and 3 will
indicate which source regions are most likely to affect
a given receptor region. However, the models developed
in response to question 4 will be the primary policy
development tools. These models will provide quantitative
estimates of the effects that changes in existing pollu-
tion sources will have on existing patterns of acid deposi-
tion. In other words, the models will tell us what the pollu-
tion sources have affected, what changes (if any) must
be made, and in what quantities.
To answer these questions, the atmospheric processes
research focuses on the following specific objectives:
• Improve understanding of the vertical and horizon-
tal transport of acidic substances and their precursors.
• Improve understanding of the major chemical
transformations that produce acidic substances in the
atmosphere.
• Improve understanding of precipitation scavenging
processes in the atmosphere.
• Improve treatment of dry deposition in numerical
models of source/receptor relationships.
• Improve and develop predictive and interpretive
models that explain source/receptor relationships in the
atmosphere.
• Perform field studies that are necessary to provide
a data base for developing and testing source/receptor
models. Such studies will also provide an independent
way of evaluating the source/receptor relationship on an
empirical basis.
PROGRAM ACCOMPLISHMENTS—
FY 1982
Transport
• Air trajectories were calculated from the recep-
tor of acid deposition backwards in time for
numerous sites in the United States. This technique
allows a chemical climatology to be established for various
areas in the United States. Initial results have been
published, and the work continues on a routine basis. The
importance of connecting the deposition chemistry with
the transport meteorology is one of the necessary ac-
tivities in understanding patterns of acid deposition and
their impact on sensitive ecological areas.
• Data from the sites in the Global Background
Research Program are being used to evaluate the
long-range transport on a hemispheric scale. Results
show that acidity of sites in remote areas is higher than
would be expected if carbon dioxide were the only fac-
tor influencing pH at “clean air” sites. Weak and strong
acids found in the samples show that the total acidity
may be related to a mixture of natural and man-made
sources. These results will be used in subsequent model
calculations.
• Initial observations confirm the importance of
clouds in the transformation process of precipita-
tion chemistry. Research results support the hypothesis
that fair weather cumulus clouds play a major role in
transforming sulfur dioxide to sulfate during the late
spring, summer, and early fall. Aircraft measurements of
air pollutants above and below fair weather cumulus
clouds indicated that these clouds transported pollution
out of the sub-cloud boundary layer and into the air above.
Moreover, the air pollutants processed through the clouds
underwent significant chemical transformation.
• A large cooperative program was started to
study the eastern North American chemical budget.
Since August 1982 numerous private and government
organizations including NOAA, NASA, General Motors,
and others have cooperated in a study that consists of
intensive measurements of aerosols both on the ground
and by aircraft, precipitation collection and analysis, and
meteorological flow studies. The results of this project
will help define one portion of the sulfur and nitrogen
budget of eastern North America, that is, what percen-
tage of these substances are transported off the East
Coast.
• Planning and initial testing of field equipment
began for Cross Appalachian Tracer Experiment
(CAPTEX). This long-range tracer experiment, which will
begin in 1983, consists of releasing an inert tracer under
specific meteorological conditions and measuring the
transport of the tracer over hundreds of miles. The results
of such experiments will be used to help verify meteoro-
logical models.
Transformation
• Preliminary results were obtained from a study
of the influence of man-made materials on the cloud-
forming process. Measurements made of clouds and
aerosols in polluted and nonpolluted air in the Northeast
identified man-made aerosols hundreds of kilometers
downwind from the source. This study is a part of the
effort to understand the chemistry and scavenging pro-
cesses in the atmosphere, and will provide necessary in-
put for model development.
• Preliminary results were obtained from a
laboratory study investigating the kinetics and
photochemistry of nitrate radicals. A laboratory ex-
perimental apparatus has been designed and assembled
to study the chemistry of the nitrate radical. This radical
is an important member of the nitrogen oxide family and
is involved in both gas-phase and heterogeneous reac-
tions leading to nitric acid formation. This experiment will
provide critical data needed to model the chemistry of
nitrogen oxides, particularly in urban environments, and
will provide direct input to the more sophisticated models
planned for FY 1985. In a separate experiment, kinetic
data have been obtained on the self reaction of
hydroperoxyl radicals. This reaction is very important
because it produces hydrogen peroxide, thought to be
the major oxidizer of sulfur dioxide to sulfuric acid.
• The atmospheric transformation of nitric oxide,
nitrogen dioxide, and nitric acid in the clean marine
atmosphere is being investigated to increase our
understanding of the chemistry that produces nitric
acid. The atmospheric photochemistry of the oxides of
18
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nitrogen has been modeled for clean marine air. The ox-
idation of nitrogen dioxide to nitric acid by the hydroxyl
radical in the gas phase is probably a major mechanism
in converting nonacidic oxides of nitrogen to nitric acid
in rural environments. The research results will be useful
in evaluating the oxidation rate of nitrogen oxides in the
relatively unpolluted regions of the atmosphere.
Deposition
Reanalysis of the past precipitation chemistry
data suggests the recent trend toward increased
precipitation acidity in the midwestern United States
is more a consequence of less alkaline dust in the
precipitation than greater concentrations of acidi-
fying agents. The complexity of interpreting past
precipitation chemistry data to establish trends of acid
deposition has been a topic of controversy mainly
because of the unknown quality of the data. Recent in-
formation from federally-funded research emphasized the
necessity for total chemistry interpretation, not just focus-
ing on the isolated acidic components. A rational inter-
pretation of the chemistry network data of the mid 1950’s
suggested that drought-induced increases in alkaline
crustal dust decreased precipitation acidity.
• The first comprehensive descriptive maps of
the distribution of major chemical species over
North America have been produced. The maps,
prepared from the MAP3S, NADP, and CANSAP data
bases, display seasonal concentrations and depositions
of calcium, ammonium, nitrate, sulfate, and hydrogen ion.
In general, the maps show relatively high concentrations
of acidic species over the upper northeastern States and
lower Canadian Provinces, but the greatest acid deposi-
tion is wholly confined to the United States over eastern
Ohio, western Pennsylvania, and northern West Virginia.
• Research on deposition of trace elements in
forests indicates that atmospheric deposition
dominates the landscape cycle of lead and has a
measurable influence on the cycles of cadmium and
zinc, but a minimal influence on the manganese cy-
cle in a deciduous forest in the eastern United
States. Rain event deposition rates are orders of
magnitude greater than the intervening dry deposition
rates; however, dry deposition supplies 20 to 90 percent
of the total annual input to the forest. This research direct-
ly links atmospheric deposition, both wet and dry, and
the effects research on terrestrial ecosystems. The Na-
tional Program recognizes that the study and sampling
of atmospheric deposition of metals should not be
overlooked, and that dry deposition must be included in
future network sampling strategies.
Models
• A new wet scavenging model has been used
to analyze precipitation data from the recently com-
pleted Oxidation and Scavenging Characteristics of
April Rains study (OSCAR). The model includes an im-
proved treatment of the physical process of scavenging
and an improved, nonlinear chemistry module that ac-
counts for aqueous phase reactions of sulfur and nitrogen
compounds. In an application to one of the OSCAR
storms, the model was able to explain the chemical com-
position of a sequence of precipitation samples. The
model strongly indicates that scavenging rates for that
particular storm were governed by the concentrations of
oxidants such as hydrogen peroxide and ozone and not
by the ambient concentrations of sulfur and nitrogen ox-
ides. Understanding the physical and chemical processes
governing wet deposition is important in developing im-
proved source/receptor models and determining the emis-
sions that may have to be controlled in any action to
mitigate acid deposition. The results from the OSCAR
model will be integrated into the overall atmospheric pro-
cesses modeling effort.
The Advanced Statistical Trajectory Regional
Air Pollution Model (ASTRAP) was used along with
seven other linear source/receptor models to analyze
wet deposition measurements in the eastern United
States and Canada for the year 1978. A procedure was
developed for using deposition monitoring data to
evaluate source/receptor models; however, the actual
evaluation showed that there was an insufficient data base
for determining whether or not existing source/receptor
models are capable of explaining current deposition pat-
terns. Since 1978, the monitoring effort has expanded,
especially in the Northeast. From 1980 to the present, an
excellent data base exists that the models can be tested
against.
FUTURE ACTIVITIES
Research under the National Program will continue to
improve our understanding of atmospheric processes; par-
ticular emphasis will be on improving the ability to deter-
mine source/receptor relationships so that the conse-
quences of changes in emission can be reliably predicted.
Highlights of the expected accomplishments for FY
1983 to 1985 include:
A comprehensive plan for developing an advanced
nonlinear source/receptor model will be produced and im-
plemented. Further advancement in modeling through
such nonlinear models will be critical in planning
regulatory options.
Work will begin on a detailed experimental and
management plan for conducting a major field experiment
to provide data for developing and evaluating
source/receptor models. The planning for field activities
will begin in P11983 with possible implementation in FY
1985.
The Cross Appalachian Tracer Experiment will be con-
ducted, providing the first sizeable data set for evaluating
long-range trajectory models. To do this, inert tracers will
be released in the Midwest and in Canada, and their con-
centrations measured over 800 miles away on the East
Coast. How well the models’ predictions compare to the
actual measurements will help put limits on the usefulness
of the models. The first major CAPTEX will be in
September to November, 1983. Based on the results of
that experiment, CAPTEX II will be planned for FY 1985.
In FY 1983 research to investigate the source/receptor
relationships of long-term precipitation chemistry data
bases at Hubbard Brook and from the MAP3S network
will be completed. These studies will demonstrate the
feasibility and limitations of the trajectory analysis ap-
19
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proach defining source/receptor relationships, and will be
used to evaluate the more complex models.
The North American sulfur and nitrogen study will, by
the end of FY 1983, produce preliminary results on
amounts of materials transported out to sea. These in-
itial estimates of the sulfur and nitrogen transport will be
used in the National Program’s work on assessments and
policy analysis.
The atmospheric trajectory models will be used in
various parts of the world for precipitation chemistry
evaluation. By the end of FY 1984, the Southern
Hemisphere data will be added so that trajectory calcula-
TRANSPORT
TRANSFORUAT (ON
V E1 SCAVFNGING
DRY DEPOS(TION
OSLO SXPER (P,TENTS
MOOS 09 5
FY94
tions can be made there also. This will allow scientists
to evaluate the global transport of acid-forming materials.
The key reactions that control the atmospheric produc-
tion and loss of hydrogen oxides and ozone will be iden-
tified and measured. Thus, the gas phase oxidation of
sulfur dioxide and oxides of nitrogen can be quantitatively
estimated. A review of the current acid deposition models
and the draft plan for developing a Eulerian acid deposi-
tion model will be completed to determine how informa-
tion on the critical reactions can be incorporated in these
models. This study will be finished in FY 1983. The
recommendations will be used to direct and focus this
modeling effort in FY 1984 and 1985.
FY87
Figure C-i - — Proposed program implementation strategy, Deposition Monitoring.
FY85 FY86
TASK GROUP C: PROGRAM LINKAGE
20
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JJ. Deposition Monitoring
BACKGROUND
Precipitation chemistry in the United
States has been measured on an er-
ratic basis since the early 1920's.
These early data were gathered most-
ly for agricultural research. Since the
early 1970's careful attention has
turned to the design and operation of
collectors and networks, and to pro-
cedures that will improve the data
quality.
Monitoring of dry deposition is in
its infancy. Although collectors trap
wet and dry materials separately, lit-
tle credence is given to the dry por-
tion because gases are not collected
and the collecting surface (a plastic
bucket) does not replicate the natural
surfaces of vegetation, soils, and
waters. Thus, present estimates of dry deposition
are based on limited research results under specialized,
short-term conditions.
The two major networks for wet deposition in North
America are the National Atmospheric Deposition Pro-
gram fNADP! in the United States and the Canadian Net-
work for Sampling Precipitation (CANSAP! in Canada:
Start No. of Type of
date sites Frequency of sampling collector
NADP 1978 108 weekly (weti and bi-monthly (dry) wet & dry
CANSAP 1977 59 daily, monthly composite wet only
The distribution of annual average pH of wet deposi-
tion on North America in 1982 is shown in Figure D-1.
Isopleths have not been drawn for the western part of
the continent because abrupt changes in topography in
mountainous areas require the development of modified
procedures for their construction. The regions of lowest
pH (4,2) in eastern North America roughly coincide with
the regions of highest man-made emissions of acid
precursors (primarily sulfur dioxide) in the midwestern
and northeastern United States and near the Sudbury
smelters in Canada. The continuing pattern of lowest pH
values in the northeastern United States and Canada sug-
gests that the impacts of acid-forming emissions are felt
most strongly within the regions where those emissions
are produced. This does not suggest that longer-range
transport is unimportant, however.
Variations of 30 to 50 percent in pH values sometimes
occur among sites within a given State. This may indicate
effects of local sources, insufficient quality control, or both.
These variations underscore the importance of long-term
data sets in describing geographical trends. Also, most
NADP/National Trends Network sites are in rural precipita-
tion in the United States. Because of the presence of
many local emission sources, many studies have found
precipitation in urban areas to be more concentrated in
acid-forming constituents, as a general rule, than precipita-
tion collected in rural areas.
Network data also show that concentrations of many
pollutants tend to be high when precipitation volume is
low. Thus, fogs and mists are more acidic than heavy
rains. This may be important in assessing damage to pH-
sensititve receptors.
Values of pH substantially less that 5.6 have been
reported in some remote areas of the world where an-
nual average pH values have been found to be as low
as pH 4.9. Such measurements have demonstrated that
a pH of 5.6, often considered "normal" for wet deposi-
tion in the absense of man-made, acid-forming gases, can-
not be considered a benchmark for identifying regions
affected by man-made emissions.
In North America,historical trends in precipitation
chemistry have been difficult to quantify because of dif-
ferences in past collection methods and sampling sites,
the brevity of the records available, and the relatively
modest changes in precursor emissions in recent years.
The limited data available from past studies suggest that
calcium concentrations may have decreased, nitrate con-
centrations probably increased, and sulfate concentrations
apparently changed little in the past 25 years. Data from
the mid-1950's show substantially higher alkalinity than
contemporary data, perhaps because of a drought in the
Midwest at the time. Recent studies reported in the
literature also indicate that pre-1960 alkalinity values may
have been overestimated by the analytical methods in
common use that the time.
There are no widely accepted methods for monitoring
dry deposition on -a routine nationwide basis. The limited
data available suggest that wet and dry deposition ac-
count for roughly equal amounts of acid deposits nation-
wide, with more dry deposition in arid climates, and less
in humid areas. Near emission sources, dry deposition is
believed to be a more important contributor of acid-
forming substances than wet deposition because of rapid
21
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settling of larger particles. Much additional research is
needed on dry deposition measuring methods; a great
deal of this work is now being done by agencies in the
Deposition Monitoring Task Group.
The monitoring networks begun since 1977 have
developed a fairly complete initial picture of wet deposi-
tion chemistry on a regional and national scale. But,
sizeable areas of the western United States are not yet
adequately covered, and the length of record is not yet
sufficient to determine long-term trends. As additional
sites are added to the National Trends Network and the
record of each site becomes longer, a more complete,
consistent, and tong-term data base will become available.
At present, subregional scale wet deposition patterns are
less well delineated, especially near sources and in ur-
ban areas Local variations in acidity are generally not well-
defined. Variations in the chemical composition of wet
deposition around local sources require intense study and
monitoring to delineate. Studies of this sort are being con-
ducted in a few urban centers, with more planned in
fut -e years.
Recent temporal trends in the chemistry of wet and
dry deposition are difficult to quantify reliably, with the
possible exception of the nitrate content of wet deposi-
tion, which shows increases roughly paralleling the in-
crease in man-made emissions of nitrogen oxides. The
difficulty in discerning recent trends is due to the short-
ness of the data record at most stations.
RESEARCH GOALS
AND ACTIVITIES
Planning and coordinating atmospheric-deposition
monitoring under the National Program is the responsibili-
ty of the Task Group on Deposition Monitoring. The goals
of the National Program’s deposition monitoring activities
are:
1. Determine the spatial and temporal variations in the
composition of atmospheric deposition within the United
States through a National Trends Network.
2. Develop methods for the reliable measurement of
dry deposition.
3. Continue and increase research on methods for
deposition monitoring.
4. Support a Global Trends Network (GTN) through
operating monitoring sites at remote locations throughout
the world.
Each of these objectives was emphasized in FY 1982.
PROGRAM ACCOMPLISHMENTS—
FY 1982
• National Trends Network. The design of the NTN
was completed. Recommendations for locations of 150
sites in 48 States (Figije D-2), were based on “Ecoregions
of the United States” established by the U.S. Forest Ser-
vice with consideration given to concentration gradients
and sensitive areas. Approximately 90 existing NADP
monitoring sites will be incorporated into the NTN. A site
review team began visiting each existing and proposed
NADP/NTN site and will issue approval or recommend
changes for all sites by the end of FY 1983. The
NADP/NTN is supported by a combination of Federal,
State, and private funds and will continue to be coor-
dinated as part of the National Acid Precipitation Assess-
ment Program. Data from NADPINTN will be used by
other Task Groups as background for their studies and,
in particular, by the Assessments and Policy Analysis Task
Group for their assessments.
Figure D-1 . — Precipitation-weighted annual average pH of wet
deposition—1981. (Based on data from the monitoring network of the
Natk)nal Atmospheric Deposition Program and from the Canadian Net-
work for Sampling Precipitation.
Sufficient data are now available from the NADP net-
work and the Canadian Network for Sampling Precipita-
tion to permit an analysis of the spatial and short-term
temporal trends in wet chemical deposition in North
America. A 1982 NADP report evaluating pH data from
these two networks through 1980 shows little apparent
change in the distribution of acidity in the United States
over the last 7 or 8 years, although there are few data
from the early period. Data from NADP confirm that
assessing future trends requires long-term monitoring
to overcome year-to-year variations.
• Global Trends Network. Within the GTN (Fig.
D-3), precipitation samples are collected in remote areas
of the world and returned to the United States for
analysis. Techniques developed in the GTN will be used
in the operations of the NTN, while research-related
data from the GTN will provide information on
background levels of precipitation acidity for input in-
to model calculations and for evaluating the overall acid
rain problem. The GTN was established in part to
measure precipitation chemistry in areas far from man-
made sources; such measurements have shown an
average rain acidity pH of about 5.0 at remote sites in
Hawaii and Amsterdam Island in the Indian Ocean. It
is anticipated that continued sampling from this pro-
gram will show trends of global acidity and help
describe the chemical climatology of different regions
of the earth.
• Quality Assurance. The quality assurance pro-
gram audits laboratory performance by regular submis-
sion of blind samples. Field measurement quality is
22
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checked by semiannual submission of performance
samples for analysis by over 100 site operators. Addi-
tionally, an experiment conducted in cooperation with
North Carolina State University is measuring the effects
of rain sampling frequency and within-site variability on
the precision of sampling atmospheric deposition data.
The results of this experiment are expected to con-
tribute to the assessment of the validity of using NTN
data in describing regional patterns of acid precipitation.
At six border locations (three in Canada and three
in the United States), U.S. and Canadian scientists col-
lect precipitation samples according to both countries’
protocols. The data from each collector at each site are
compared to detect differences arising from collection
techniques. This information will be extremely impor-
tant when trying to evaluate possible cross-border dif-
ferences in chemical composition and validity of com-
bining NADP/NTN and CANSAP data for trend analysis
or other purposes.
Dry Deposition Methods. In June 1982, an in-
tercomparison field study of dry deposition monitoring
and measurement methods was conducted for the Na-
tional Program by the Illinois State Water Survey. Thir-
teen laboratories from the United States and Canada
compared four micrometeorological methods, three
types of surrogate surfaces, concentration monitoring,
leaf washing, and material effects measurement. The
analyzed data will be reported at a symposium in the
spring of 1983.
Current plans call for measuring ambient air concen-
trations of relevant substances at monitoring stations
nationwide. During FY 1982, a pilot effort was begun
to compute dry deposition fluxes from air concentra-
tion and deposition velocities. Instrument shelters were
installed at three locations representative of the surface
types of the northeastern United States, especially
forests and croplands. These sites will provide oppor-
tunities for applying detailed research techniques for
direct flux measurement and for evaluating the deposi-
tion velocity calibration to be used at “concentration
monitoring” sites for a future dry deposition net rk.
• Data Base Management and Data Analysis.
The acid rain data base has grown during the year to
over 100,000 observations in the United States and
Canada. The networks currently entering data into the
data base include NADP/NTN, CANSAP, MAP3S, and
EPA’s Region IV Network. EPA has developed an In-
teragency Agreement with Pacific Northwest
Laboratories to design a more versatile Acid Deposi-
tion Data System to meet varying information demands.
Data analysis in FY 1982 included a prototype sum-
mary report on national acid deposition data trends and
S
D i
S
A
Figure D-2.— Locations of proposed National Trends Network (NTN) stations.
Figure D-3. — Location of Global Trends Network (GIN) stations.
S -— - - - - •- - - — - - — - -
H
.
—U-
‘4
•
‘iS .
Li
_ 0 1
• (
4
EXPLANATION
• NADP
• RCS/NOAA
£MAP3S
o TVA
4UAPSP
JNew Sites
23
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an investigation of new methods for spatial analysis. The
report examined new ways of presenting and simplify-
ing the large amounts of data developed in a monitoring
network, a technique for analyzing the confidence limits
of the spatial distribution of given concentrations, and ob-
jective improvements in network design.
• TVA Regional Trend Monitoring Network. Dur-
ing FY 1982 TVA continued to operate three regional air
quality trend monitoring stations. In addition to collecting
biweekly wet- and eight weekly-dry deposition samples,
these stations also monitor background concentrations
of suspended particulates, suspended sulfate, sulfur diox-
ide, nitrogen dioxide, ozone, and gaseous flouride.
Rigorous quality assurance/quality control procedures
were implemented at the TVA central analytical laboratory
for deposition analysis. A technical report “Atmospheric
Deposition in the Tennessee Valley: 1979-1980” was
published and presented at the 75th Annual Meeting of
the Air Pollution Control Association. Plans call for
upgrading one or more of these sites for inclusion in the
NTN.
• New Research Sites Established. Three research
sites will conduct special measurements and test newly-
developed equipment and methods for monitoring wet
and dry deposition. These sites will also serve as the stan-
dards for their regions. They are located at Pennsylvania
State University, the Walker Branch Watershed in Oak
Ridge, Tenn., and Niwot Ridge in a biopreserve in the
Rocky Mountains in Colorado.
FUTURE ACTMTIES
In FY 1983 the Task Group will concentrate on implement-
ing most of the sites of the NADP/NTN, developing
methods for monitoring dry deposition, and further im-
proving methods for monitoring wet deposition. Quality
assurance programs will be used to oversee the data col-
lection and analysis to assure data comparability among
the several operational and research networks.
National Trends Network. Coordination and opera-
tion of the NTN will continue, including establishing 20
to 40 new sites in cooperation with several Federal, State,
and private sector agencies. Site visitation and evalua-
tion of all existing and proposed NTN sites will be com-
pleted and the agencies named to operate those sites
started in FY 1983 and FY 1984. The Task Group will
produce a special study of the Global Trends Network
data using both recent and historical data.
Development of Dry Deposition Monitoring
Methods. Intercomparison field studies will be run, one
each at three core research sites in Oak Ridge, Tenn.,
Argonne, Ill., and State College, Pa. Development of Flux
Monitoring Methods: The performance of a variety of
micrometeorological methods will be tested and com-
pared with alternative techniques such as surface ac-
cumulation. Development of Concentration Monitoring
Methods: The temporal distribution functions for concen-
tration and velocity of deposition will be determined so
that optimum sampling and analysis procedures may be
specified for network operation. The sites at State Col-
!ege, Pa., and Oak Ridge, Tenn., are located near
calibrated watersheds and will provide comparisons be-
tween “concentration monitoring” and mass budget
measurement estimates of dry deposition fluxes.
Development of Automated Instruments. A pro-
gram is beginning to develop automated instruments to
determine the chemical composition precipitation at the
time of the precipitation event. First priority will be
developing an improved pH instrument; the goal is to
have a prototype available for limited field testing by the
end of FY 1983.
Plans through FY 1989. The timetable for implement-
ing various elements of the Deposition Monitoring Task
Group’s program is illustrated in Figure D-4.
24
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Network Design
National Trends Begin Site
Network ______________
(All Task Group
Agencies)
Data Analysis
(USGS. EPA, NOAA. DOA)
task Droops tdentity
Needs tnr NIN DIN
and Research
Components
nd Detection Met hod
retyped and Sested
yraan ADS System
wing Analysis
ware Ac lurred
Reeyatuat inn of NTN
Destgn Based on
Data Analysis
FutI Scale Implem
At Trace Metal
Analyses at
NTN and DIN L a
.0
Figure D-4—PropDsed program implementation straSegy, Deposition Monitoring
1982 1983 1984 1985 1986
Research and Methods Inoestigate Approaches Trace 1
Deve lopment - t Sample Collection Metals _______________ Organic ___________________
(USGS EPA NOAA DOE) for Trace Metal and . . Pilot Pilot
Drganic Apalysis
(EPA. NOAA. DOE) _ ry H HE E at ) ConlmueRese ch : .
Q ace nt !E Hs c
Oyerat anal Labs — I
Global Trends Network Net a k n Place ____________ _____________ — _ _ _ _ _ _ _ _
(NOAA) and Operational . ‘ — .
lPirst age Imolem Second Stage - Third Stage
____________________ I F rist ng Sites lnrp ementalion - lmplnm Complete —
Cpnrp ete New Sites 150 Sites
Inspection
P
0
Sit
On
L Ip
Ma
So
C
Task Group
Needs
Tvalaatian at
Information
tram NTN
Intormation air Dry
Deposition Manitnririg
Methods from Atmos-
pheric Pracess 00
Task Onna As Identity
Intarmation Needs
roar Monitoring
Networks
25
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. Aquatic Effects
BACKGROUND
The Aquatic Effects Task Group
works to meet specific objectives that
will provide information needed to
assess the effects of acid deposition
on aquatic ecosystems. A general
summary of current scientific
knowledge follows.
Acid deposition has been reported
in the literature as causing both long-
and short-term episodic depressions
in pH, and loss in alkalinity in some
lakes and streams in the United
States and Canada. The total number
of lakes and streams in eastern North
America thought to have been
acidified by acid deposition is a very
small percentage of the total aquatic
resource. Elevated concentrations of
toxic elements such as aluminum, and biological ef-
fects, including losses in fish populations, have been
reported to accompany some of these pH depressions.
However, in most of the reported cases, clear relation-
ships were not established between acid deposition and
observed effects.
Current scientific knowledge does not make it possi-
ble to derive quantitative loading effects relationships for
aquatic ecosystems. However, based on results of em-
pirical studies, interpretation of long-term water quality
data, and studies of sediment cores, it can be concluded
that acid deposition has caused long- and short-term
acidification of some low alkalinity surface waters. The
purpose of the extensive research efforts in the United
States and Canada is to develop such quantitative rela-
tionships as soon as possible.
Extent of acidification and sensitivity of lakes,
streams, groundwaters, and wetlands of the United
States. Sensitivity of surface waters to acidification is
usually assessed on the basis of alkalinity. Alkalinity
measures the extent to which water is buffered against
chemical changes caused when acidic substances enter
it. However, only a few historical records on surface water
chemistry exist that can be used to assess past trends
in acidification. The records available for areas exposed
to acid deposition show increases in sulfate and cor-
responding decreases in pH for some lakes and streams.
In most cases the historical data bases were not suffi-
ciently complete to determine if a cause and effect rela-
tionship existed.
The Adirondack Mountains, located in a zone receiv-
ing highly acid deposition, comprise one of the most sen-
sitive lake districts in the eastern United States. Fifty-two
percent of 214 high elevation lakes sampled in 1975 had
pH values less than 5.0. A study of 95 small, low alkalini-
ty lakes in New England for which historical data were
available showed that 64 percent had experienced signifi-
cant pH decreases. Two other studies have indicated pH
decreases in some lakes surveyed in Maine. On the other
hand, preliminary studies suggest certain lakes in Wiscon-
sin have shown a decrease in acidity over time.
Factors that control the susceptibility of natural
waters to acidification. A complex set of factors
governs the response of a body of water to acid. Geology
determines the geochemical materials (thus the geo-
chemical reactions) that acid precipitation encounters as
it passes through the watershed. The hydrodynamics of
the watershed determines the duration of contact of
precipitation with the reaction materials. Together, these
two factors govern potential chemical reactions, their ex-
tent, and their degree of occurrence. The addition of
minerals other than those that produce alkalinity is critical
to the aquatic ecosystem. Aluminum, in particular, ap-
pears to be mobilized by acidification of the terrestrial
ecosystem and then leached into the aquatic ecosystem
where it can affect fish and possibly other animals and
plants.
The processes controlling sensitivity and tolerance of
waters to acid loading are not yet sufficiently understood
to predict the short- and long-term effects of various
deposition rates on aquatic ecosystems. To generate this
needed information, the Aquatic Effects Task Group is
developing quantitative models that relate atmospheric
influences (such as sulfate or hydrogen ion concentration
of precipitation) and watershed-derived factors (such as
alkalinity or sulfate concentration in lakes! to each other.
Detailed mechanistic models are exploring relevant
physical and chemical processes in a watershed to
describe or predict changes. The Integrated Lake-
Watershed Acidification Study (ILWAS) sponsored by the
Electric Power Research Institute is an example. These
models were developed from specific data sets, and their
more general predictive value, as well as that of models
yet to be developed, remains to be determined by this
research objective.
27
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Biological processe . biological populations, and
aquatic communities affected by surface water
acidification. Nine rivers in Nova Scotia have lost their
Atlantic salmon populations while fish have survived in
other rivers in the same area that have higher pH and
greater alkalinity. In the Adirondack Mountains of New
York, comparison of data from the 1930’s with recent
surveys shows that at least 180 former brook trout ponds
are acidic and no longer support brook trout, although
a direct association with acid deposition has not been
established. The relative contribution of natural and man-
made sources and changes in land use to acidification
of these lakes and rivers, however, is not known.
Many species of amphibians breed in temporary pools
formed by the mixture of spring rains and snowmelt.
Many such pools are subject to low pH conditions. Em-
bryonic deformities and mortalities in the yellow-spotted
salamander have been observed in New York State where
the acidity of meltwater pools was 1.5 pH units lower
than that of nearby permanent ponds. Population den-
sities of the bullfrog and woodfrog were less in acidic
streams and ponds in Ontario versus ponds with higher
pH values. These data are very limited in scope and
therefore, the extent of the problem is not known.
With few exceptions, the mechanisms of effects of
acidification on fish, amphibians, and other aquatic
organisms are not understood. Biological changes can oc-
cur as pH drops below 6.0 and can become increasingly
severe as pH declines further. Many water bodies have
natural pH levels below 6.0. Aluminum and possibly other
toxic elements become available in acidic waters and con-
tribute to biological changes. These effects are currently
known only qualitatively, except for the relationship be-
tween aluminum and some fish species.
Potential for acidification of surface waters,
groundwaters. and wetlands to affect human health.
Studies conducted in Sweden found long-term chemical
changes in groundwaters from water-bearing rock forma-
tions in sandy soils near cities. Few data are available con-
cerning changes over time in groundwater quality in the
United States, although in a few cases waters from acidic
wells and municipal reservoirs are associated with
elevated concentrations of toxic metals leached from
domestic water supply pipes. But the linkage to acid
deposition, if any, remains unclear. A survey of water
systems and groundwaters in the Northeast is underway,
but the results are not yet available. Little is known con-
cerning possible health implications of wetland
acidification.
Mitigative (liming) techniques for restoring or pro-
tecting acidified aquatic resources of the United
States. Liming is one mitigative option for temporarily
protecting and possibly rehabilitating affected aquatic
systems. Used in this context, liming is a generic term
that indicates adding any “basic” material to surface
waters, sediments, or soils to neutralize them or increase
alkalinity. Liming is not considered a permanent solution
to surface water acidification, but symptomatically treats
the problem. Preliminary research on liming operations
(primarily in Scandinavia) has indicated that some short-
term protection and/or renovation of affected surface
waters is possible. However, these studies are not com-
plete and important questions remain on the long-term
biological consequences of liming, its costs, application,
materials and their chemical reactions, impact of episodic
events, and the problems of resource management (e.g.,
restocking programs).
In field tests in North America and Sweden powdered
limestone appears to be the most economical and effec-
tive reagent. However, it has disadvantages, such as
precipitation of aluminum on lake bottoms with possible
resolubilization during highly acidic episodes (such as
spring snowmelt). Liming of streams has also been at-
tempted, but with generally unsatisfactory results. Per-
manent limestone structures are ineffective because of
biological fouling, and lime slurries are quickly dissipated,
requiring continuous and expensive maintenance.
The benefits and costs of liming and other actions for
mitigating acidification and associated biological condi-
tions in the United States are under study.
RESEARCH GOALS
AND ACTIVITIES
The end point of the National Program’s aquatic effects
research is to quantify the effects of acid deposition on
surface and groundwaters and wetlands of the United
States, to describe how these effects can be corrected
at the site of the problem, and to determine the ecological
consequences of the remedial methods.
Research will also provide information needed to
evaluate the current effects of acidification on freshwater
chemistry; the likely sites of future water quality changes
if acid deposition rates remain the same, increase, or
decrease; and the extent and importance of changes in
the ecosystem’s plant and animal life associated with
changes in the chemistry of lakes, streams, and wetlands.
The aquatic effects research focuses on five major
objectives:
1. Quantify the extent of “sensitive” or “acidified”
lakes, streams, groundwaters, and wetlands of the United
States.
2. Identify and quantify the factors that control
tolerance, sensitivity, and susceptibility of surface and
groundwaters to acid deposition and determine how these
factors can be used to predict future aquatic acidification
under different loading rates.
3. Determine the relationships between surface water
acidification and biological processes, biological popula-
tions, and aquatic communities and how these relation-
ships can be used to predict future ecological effects.
4. Determine the potential for acidification of surface
waters, groundwaters, and wetlands to affect human
health.
5. Develop mitigative (liming) techniques for restoring
or protecting acidified lakes, streams, and groundwaters
of the United States.
Throughout FY 1982 the Aquatic Effects Task Group
reviewed all current and planned aquatic effects research
projects to (1) evaluate the relative overall priority of the
research; (2) clearly define specific project objectives and
determine their relevance to the research and assessment
objectives of the National Program; (3) identify research
deliverables in specific terms, and ascertain exactly how
and when those deliverables will be available; and (4)
assure that all researchers use compatible laboratory and
28
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field methodologies, or that deviations from a standard
methodology are made for valid reasons.
The Aquatic Effects Task Group held a partial research
peer review in February 1982. A Federal effects research
review a year later (in February 1983) (1) allowed the Na-
tional Program’s research to be reviewed in a comprehen-
sive manner rather than as a series of discrete agency
projects; (2) assessed the quality of the science; (3) pro-
vided a forum for interaction by field level scientists; and
(4) evaluated the progress of the various research ap-
proaches. Throughout 1983 the Aquatic Effects Task
Group will continue to critically evaluate all research to
be sure that each project contributes to the identified ob-
jectives, milestones, and deliverables.
PROGRAM ACCOMPLISHMENTS—
P1 1982
• Accelerated assessment of the extent of the
problem of acidification of lakes, streams, and
groundwaters of the United States. This multiagen-
cy effort comprises an assessment program to bring rele-
vant existing water quality data together on a national
basis for use in assessing the extent of sensitivity to
acidification. In FY 1982 this effort was accelerated to pro-
vide results in 1983 and 1984. Specific objectives are:
1. Identity and map the extent and degree of sensitivity
to acidification of lakes and streams in the United States.
2. Determine trends in the acidification of surface
waters.
3. Provide a verified, quality assured data base for
available methodology to predict surface water acidifica-
tion based on given deposition rates. The data base will
also help correlate geographic patterns of surface water
sensitivity and acidification with spatial patterns of
climatic, geologic, physiographic, edaphic, and land use
factors.
In FY 1982 various individual projects of the National
Program included a national inventory of existing water
quality data applicable to assessment of sensitivity and
acidification of surface and groundwaters, supplementary
field surveys in the southern Appalachians, data stored
in the Acidification Chemistry Information Database
(ACID), and a national map indicating general patterns
of surface water alkalinity (see Fig. E-1 insert on back
cover).
• The Aquatic Effects Task Group began a study
to identify. quantify, and predict the factors that con-
trol the susceptibility of natural waters to acidifica-
tion. This study will mold numerous research projects
into a nationwide source that will lead to a predictive
modeling capability. The Task Group has begun a
thorough review of the various models for predicting
acidification. One or more of these approaches (or others
to be developed) will be used by the National Program
to predict future acidification of surface waters based on
different acid loading rates for an FY 1985 assessment.
• A major report has identified the needs of
aquatic effects research. This report reviews acid
deposition phenomena in aquatic systems, develops a
framework for pulling together existing information, and
then evaluates and refines a preliminary model to estimate
effects of acid deposition on aquatic resources.
• A preliminary survey of New England surface
and groundwater supplies was completed.
Preliminary results showed that, in general, the water sup-
plies in the New York Adirondack region and in the New
England States are quite corrosive. The most notable ex-
ception to this was the water supplies of Connecticut,
which appear to be less corrosive than those in the other
States. With laboratory analysis nearly completed, it ap-
pears that the maximum contaminant level for lead is
seldom exceeded. Elevated concentrations have occa-
sionally been observed, especially in standing waters. This
study is being conducted to ascertain whether acid
deposition might affect municipal water supplies.
• The Aquatic Effects Task Group began a long-
term program to monitor the chemistry and plant
and animal life of surface waters in key sections of
the Nation. By quantifying current effects of a range of
acid loading rates, the long-term surface water monitor-
ing program is providing information needed to formulate
recommendations for acceptable loading rates of acid
materials from the atmosphere.
Aquatic Effects Task Group agencies cooperated in
developing a standardized samplinglanalysis protocol for
chemical survey and monitoring of surface waters. This
protocol will be completed in early FY 1983.
Sites for long-term monitoring of lakes and streams
have been identified. Close coordination and cooperation
among the agencies will result in an effective, compati-
ble network. Annual reports from each site will be com-
bined into an overall annual summary report, which will
be submitted to the Task Force.
• A number of new biological effects studies
started in FY 1982. Three different approaches (field,
laboratory, and population modeling) are being used to
identify and quantify the effects of lake and stream
acidification on aquatic life. Studies emphasize identify-
ing the operating stress mechanism (a toxicant and its
mode of effect) and its effects on species of economic
and recreational use, particularly fish and waterfowl.
Critical research issues to resolve before assessments
can be made are (a) the distribution of species in sen-
sitive waters in relation to current or future acidification;
(b) biological effects of surge versus continuous acid
loading; (c) individual and population effects of various
levels of pH, aluminum, and heavy metals on fish and
other aquatic life; and (d) sensitivity of key aquatic species,
particularly fish, at various life stages to sublethal effects
of low pH. The most intense work will center on areas
across the Nation currently receiving acid deposition
whose surface waters are highly sensitive to acidification
(Northeast, upper Midwest, Appalachian Mountains, sec-
tions of the Rocky Mountains, the Cascades, and Sierra
Nevada Mountains).
• An evaluation of mitigation strategies for restor-
ing or protecting lakes, streams, and watersheds has
progressed. An in-depth report by the Aquatic Effects
Task Group summarizes up-to-date available information
on liming; lists State, federal, and private sector contacts
on liming projects; and digests liming projects in the nor-
theastern and midwestern States. Current research pro-
jects and research in Scandinavia, Canada, and the United
States are included.
The Task Force organized and conducted a week-long
international workshop on liming. The Aquatic Effects
29
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Task Group developed a research strategy and set
priorities for field and laboratory projects addressing lim-
ing materials and application techniques and the biological
and chemical changes associated with liming.
• Laboratory and field tests are assaying the biological
and chemical consequences of liming and other mitigative
treatments of acidified and sensitive lake and stream
systems. This project concerns the development and
testing of management procedures and strategies by
which lakes and streams can be at least temporarily pro-
tected from the harmful effects of acid deposition,
acidification, and associated metal/ion toxicity. These
tests, involving both laboratory and field investigations,
include surface waters where fish populations have either
been reduced by acidification or are under stress because
of acidification. Another laboratory and field project was
begun on placing limestone gravel in spring upwellings
as a possible mitigation measure in acidic brook trout
lakes.
FUTURE ACTIVITIES
Major FY 1983 to 1985 priorities of the National Program’s
aquatic effects research are to (1) make substantial pro-
gress in assessing the extent of the problem and place
a comprehensive long-term surface water monitoring pro-
gram on line; (2) develop a better understanding of the
geochemical linkage between terrestrial and aquatic
systems; (3) begin biological effects studies that will result
in regional predictions of future acidification; (4) complete
drinking water surveys of the eastern United States; and
(5) begin field tests to evaluate liming options.
More specifically, highlights of expected FY 1983 ac-
complishments include:
Regional maps of sensitive waters of the United
States. Preliminary maps developed in FY 1982 are not
of sufficient detail or accuracy to allow for national
assessments. Detailed regional maps developed in FY
1983 and 1984 will provide much greater detail and be
based on more data.
Preliminary report on quantification of the extent
and scope of surface waters at risk in the United
States. Although national and regional maps are critical
to the assessment of surface waters at risk, a quantitative
and statistical analysis of all relevant data from the na-
tional survey (alkalinity, pH, sulfate, and others) will pro-
vide an inventory of acidified waters and simultaneous
analysis of watershed data, water chemistry, and at-
mospheric deposition data.
Preliminary report on analysis of causative factors
for alkalinity, pH decreases, and pH increases. Ap-
propriate data from the national survey will help analyze
historical trends in water chemistry and whether they can
be related to atmospheric deposition.
Report on historical trends in surface water
acidification from lake sediment coring studies. An
alternative approach to the detection and analysis of
historical trends in lake water chemistry is through the
study of lake sediment cores. Core samples yield indepen-
dent records of past chemistry and biology in the lake.
These findings can then be compared with trends de-
duced from historical analyses of water chemistry.
Complete upper Midwest synoptic surveys of
water quality and related plant and animal life.
Studies made over the past 4 years constitute an excellent
data base for comparison with future conditions in that
part of the United States most densely populated with
lakes.
Interim report on stream and reservoir survey of
the southern Appalachians. Low alkalinity, sensitive
surface waters in the southern Appalachians consist of
streams and reservoirs; natural lakes are essentially nonex-
istent. Both short-term surveys and long-term monitor-
ing will ascertain the distribution and numbers of these
sensitive waters and their response to acidifying forces.
Final report of sensitivity to acid deposition of
aquatic resources in the Rocky Mountain National
Park. This will assess the extent of the problem in a
pristine region and the consequences of environmental
degradation.
Report on trends at active lake and stream
monitoring stations. A multiagency effort is establishing
long-term study sites on strategically located lakes and
streams across the United States. Regular sampling of
lakes, streams, and precipitation will provide needed in-
formation on the response of sensitive surface waters in
different regions to atmospheric loading.
Report on methodology and data base needed to
predict biological (particularly fish) resources at risk.
This methodology will provide for an assessment of the
effects of increased acidification on fishery resources both
regionally and nationally.
30
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FY83 FY34 —F Y l l5— — FY86— isV ? FY88 FY89
ti ation
I Verify Inventory orj
Sensitine/Acidi fled
Surface Waters
[ SurveY Potentially Sensitive Waters ]
Verify Maps of
Sensi t ine/Acidif led
Systems
Map Sensitiv€ and Ycidi Vied SurfacV ______
Waters
uct S no ti Field Surveys of
Sensitive WaterS to [ valuate Ricmtic
Predict ions
Develop Quantitative Blethods for Evaluating Long-Term Develop Integrated Model of P. oti ) Validate Biotic Response Nodell
Fisheries Impacts and Trophic Interactions Responses to Acidification
Evaluate Existing Develop Regional Apply Regiofvl
I Geochemical Models of Sensitivity Sensitivity
L ° ° Sensitivity Geochemical Models Geochemical Models
[ Evaluate Effects of Acidification on Drinking Water Supplies
I
Conduct Stream and lake Ecosystem Studies Integrating Impacts of Freshoater
Acidification and Recovery on Biotic Structure and Function
Determine Chemical/Biological Effects of timing
Streams and Lakes
Mviii tor Selected SurYace Waters for Alkalinity/pH and Bivtic Trends
Assessments (Task Group I Data Requirements)
Figure E-2.—Proposed program implementation strategy, Aquatic Effects.
31
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r. Terrestrial Effects
BACKGROUND
Only recently have efforts been made
to establish the mechanisms by
which atmospheric acid is transferred
to aquatic ecosystems. If acid pre-
cipitation must pass through the ter-
restrial ecosystem prior to entering an
aquatic ecosystem, it will usually be
strongly influenced by the chemical
nature of the vegetation, soil, and
bedrock.
Aluminum movement from ter-
restrial systems has recently become
a primary concern. Aquatic biologists
have documented the effects of
aluminum on fish and other aquatic
organisms. It has been shown that
aluminum does move into the aquatic
system at a steady rate, increasing to
high levels during spring snowmelt and heavy rain-
fall periods, and that the aluminum is coming from the
terrestrial system, not the atmosphere. The availability of
aluminum in the soil solution has direct implications for
tree growth, and thus forest productivity. The tolerance
of crops to soil-water aluminum is well known, but the
toxicity data for forest trees and range plants are not
available.
Terrestrial effects research encompasses soils, water-
sheds, forests and range plants, and crops. A number of
uncertainties shroud the relationship of acid rain to the
dynamics of these systems. Whether acid deposition is
wet or dry, the interaction of ozone and sulfur dioxide
and the life stage of the plant can modify plant response
to acid deposition. That such factors vary by region adds
to the uncertainty.
Other natural stress factors, such as insects and
disease-causing agents, are capable of limiting forest and
range productivity in the absence of acid deposition. Even
if acid deposition should not prove to directly harm forest
and range vegetation, it remains important to find out if
it impairs the ecosystem's ability to rebound from com-
mon natural stresses--insects, disease, and drought
among others —and stresses from man-made pollutants.
Studies must consider how variations in precipitation
chemistry may affect plant response.
While there is general agreement that unmanaged soils
in forested and grassland areas in humid regions may be
sensitive to acidification from acid precipitation, there is
no indication to date that the soils have become acid
because of it or that forest production is being affected.
Soil acidification by natural processes may be more
significant than soil acidification by acid deposition. The
rate and extent to which such acidification is occurring
in nature, and the effects (if any) of acid rain on soil
microbial processes are little understood.
The most consistent conclusion to be drawn from
agricultural research at all scales and with all species has
been "no effect" at current average ambient pH levels
SpH 4.04.2). A few studies, including some with field corn
and soybeans, have reported negative impacts of acid
deposition, while still others showed a positive growth
response. The economic importance of corn and soy-
beans and their location within the region most heavily
exposed to acid rain and ozone warrants further studies
to understand the nature of their response.
RESEARCH GOALS
AND ACTIVITIES
The terrestrial effects research of the National Program
includes work on the direct or indirect effects of acid
deposition on three major components: forest trees and
range plants, agricultural crops, and soils and watersheds.
The objectives of the research are to address the follow-
ing key questions:
1. What are the long-term effects of acid deposition
on forest and rangeland productivity?
2. Can mathematical models be developed to estimate
economic losses in major crop plants?
3. What are the relationships of acid deposition effects
on soil chemistry to biological productivity?
4. What are the influences of soil weathering, leaching,
and organic decomposition on ecosystem linkages among
soil, water, and plant components?
5. Will acid deposition have a detrimental effect on
forest and range ecology?
6. Are there threshold doses above which crop pro-
ductivity will be adversely affected?
7. What are the ecosystem impacts of acid deposition,
and can management options be developed to counteract
them?
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8. What are the physiological and biochemical pro-
cesses by which plants may be changed by acid
deposition?
To determine the effects of acid rain on forest produc-
tivity, their magnitude, and how they work, research is
surveying trends in forest growth, determining through
mechanistic studies, whether cause and effect relation-
ships exist, and evaluating acid deposition’s effect on the
response of forest and range vegetation to other stress
factors.
Agricultural research is focusing on major economic
crops, such as corn and soybeans, and concentrating on
those questions that can be most readily addressed within
a 5-year time span. The emphasis is to generate realistic
response functions that can be used in an assessment.
Effects on soil productivity are also being emphasized,
as are mitigation measures with practical applications.
Studies on soils and watershed processes are determin-
ing the changes that occur after acid deposition reaches
the soil surface.
PROGRAM ACCOMPLISHMENTS-.--
FY 1982
nutrients from atmospheric sources could substantially
reduce fertilization costs.
• Some loblolly pine seedlings show resistance
to disease following acid rain exposure. Fusiform rust
is estimated to produce losses in yield in excess of $25
million per year in southeastern pine forests. Research
suggests acid rain may increase rust resistance in pine.
In response to simulated acid rain, some seedlings
showed increased rust resistance traits, others decreases
in fusiform rust galls.
Agricultural Crops
Several developments in methodology for studying acid
rain effects on agricultural crops have been tested dur-
ing FY 1982 that promise to improve evaluation. The am-
bient rainfall exclusion technique was perfected, a signifi-
cant development. Researchers at six sites are develop-
ing such facilities for assessing crop loss. Field research
with simulated rain, excluding ambient rainfall, is the state
of the art in crop loss assessment relative to acid rain im-
pacts. Significant progress in crop loss assessment is an-
ticipated from the results of the 1983 growing season,
as these key new experiments are performed.
CROP SENSITIVITY:
Forest Trees and Range Plants
Studies on forest and rangeland vegetation indicate that
the effects of air pollution in general, and acid deposition
in particular, are subtle and of long duration, and may
alter the dynamics of plant community growth and suc-
cession. To provide the information for both economic
and ecological assessments, studies emphasize the
mechanisms that affect growth or mortality.
Tree ring sampling initiated. Establishing regional
tree growth rate changes is an essential assessment step.
Changes in diameter growth can be easily converted to
estimates of volume, which can subsequently be
translated into economic terms. Testing is also underway
to determine if trees are taking up unusually large quan-
tities of metals; this is considered an indicator of an-
thropogenic activity. To assess growth rate changes over
time, sampling has begun of tree ring cores in over 600
trees in 70 forest stands in 14 eastern State& Those States
range from Maine to North Carolina, and extend west as
far as Arkansas and Missouri.
• Study of red spruce dieback started. Because of
both direct economic and aesthetic considerations, there
is concern about red spruce dieback in the eastern United
States, especially at high elevations. Dieback was general-
ly preceded by an abrupt reduction in growth which
began in 1960. At that time, a severe drought occurred
in this area and may have been a triggering agent.
Previous tree ring chronologies indicate fairly rapid
recovery in the same systems from earlier droughts.
Recovery from the current drought appears to be quite
slow or nonexistent, possibly because of interactions with
other stresses, both natural and anthropogenic.
• Pine seedlings vary in their response to acid
rain. Some pine seedlings showed greatest growth
response below pH 4.0, perhaps because of the nutrient
effects of sulfur or nitrogen. Since southern pine forests
are frequently fertilized, significant inputs of essential
• Potato study shows no apparent foliar injury
from acid rain. Potatoes are a major agricultural crop
in the northeastern United States. In a field study, a com-
mercially important potato cultivar was treated with
simulated acid rain of various pH levels, similar to am-
bient rainfall at that site. No apparent foliar injury resulted
from the treatment, even at levels as low as pH 2.7. Quali-
ty analysis of the 1982 tuber crop is in progress. This pro-
ject will yield dose response data for both crop yield and
crop quality. Both of these values are necessary for
economic assessment of impacts to potatoes. In addition,
information gained as a byproduct of the quality analyses
will aid in understanding the mechanisms of effects.
• No change observed in balance between clover
and fescue. Clover/fescue ratio is a good indicator of
stress; both are important forage species that frequently
are not as intensively managed as agricultural field crops.
Therefore, it is important to see if soil management should
be changed to maintain a clover-fescue forage system
in the presence of acid rain. Data gathered through the
first two harvests of this study showed no foliar necrosis
or differences in yield or species composition that could
be attributed to rain pH or soil management variables.
However, in both species, the crop’s nutritional quality
appeared to decline at the lowest treatment (pH 3.5), in-
dicating potential for long-range impacts on the nutrient
and, therefore, market values of the crop.
DOSE-RESPONSE RELATIONSHIPS:
• Soybean yields may or may not be adversely
affected by acid deposition. Studies indicate that yield
reductions of sensitive cultivars were caused by decreases
in number of pods at harvest, even without visible foliar
injury. Some cultivars, however, are resistant. These
results underline the need to develop damage functions
for representative vegetation across a range of genetic
and environmental variables.
34
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• A major field experiment established in the
corn/soybean belt of Illinois is dedicated to develop-
ing dose-response information on two varieties each of
soybean and field corn using ambient rainfall exclusion
and rainfall simulation techniques that permit study under
undisturbed field conditions. This major experiment will
significantly expand the data base on agricultural effects
for the 1985 assessment.
• Inhibition of corn yield. A study of field corn us-
ing simulated acid rain between pH 5.6 and 3.0 showed
inhibition of yield at pH 4.0 only, corroborating earlier
reports with the same crop, and indicating that factors
in addition to hydrogen ion are controlling the magnitude
and direction of the effect. Mechanisms associated with
the observed effect must be better understood before
predictive assessments are possible with corn.
• Concentration and ratios of ions. Acid precipita-
tion may stimulate plant growth and yield depending on
the environmental conditions and the concentrations and
ratios of ions in the simulant. Soybean yield varied de-
pending on the sulfate to nitrate ratio in precipitation
simulants; the response depended on pH. Since the
sulfate to nitrate ratio in precipitation varies by region, this
factor is an important consideration in regional assess-
ments leading to the 1985 assessment.
• Individual events. The response of radishes and
bushbeans to acid rain simulant was also significantly af-
fected by the chemistry of individual events. Peak acidi-
ty events may be more important in affecting plant
response than the total mean acidity during a growth
season. Since current deposition monitoring does not
measure peak acidity events, but rather, weekly average
concentrations, research such as this may provide
valuable feedback to research planning activities in the
Deposition Monitoring Task Group.
Soils and Watersheds
Watersheds represent a linkage between terrestrial and
aquatic systems critical to understanding changes in both
forest and aquatic productivity and stability. Chronic
disruption of nutrient cycling processes or the mobiliza-
tion of nutrients and toxic elements in terrestrial and
aquatic systems will probably cause long-term effects on
both forest and aquatic productivity.
Current studies are aimed at: (1) evaluating
characteristics that determine soil vulnerability in an at-
tempt to establish criteria by which individual soil types
might be categorized as to potential for either nutrient
loss or toxic element mobility; (2) identifying the principal
soil processes that can be altered by acid deposition, in
order to understand the mechanisms controlling nutrient
availability for plant growth; and (3) determining the role
that vegetative cover plays in modifying acid deposition
effects on both the terrestrial system and the transport
of ions to aquatic systems.
SOIL VULNERABILITY:
Soils exhibit a broad range of potential for change in
chemical and biological properties resulting from acid
deposition. Possible effects include leaching of essential
alkaline cations with subsequent decrease in soil fertility
in addition to release of aluminum and heavy metals.
Studies are underway to investigate a range of soils vary-
ing in their vulnerability to change.
Significant removal of nutrients observed in a
southeastern soil. Among the soils considered most
vulnerable, a sandy soil from the southeastern United
States was exposed in both field and laboratory to
simulated rain as low as pH 3.0. At pH 3.7, significant
amounts of calcium and potassium were removed from
the top 76 cm of this sandy soil. Magnesium, calcium,
ammonium, phosphorus, sulfate, and aluminum were all
higher in the soil solution at the surface and decreased
steadily with depth. Nitrate/nitrogen increased with soil
depth. Ions in soil solution were more concentrated dur-
ing dry periods or periods of low rainfall. All of these fac-
tors could have an effect on soil fertility and, therefore,
productivity and the economic return on investment.
• No significant changes noted at a New Jersey
site. Soil solution and stream pH at a forested site in New
Jersey were not directly related to precipitation pH, ap-
parently because of natural production of acids by the
soil. Large quantities of potentially mobile aluminum were
found in the upper mineral soil horizons and forest floor;
however, the sampling period did not include enough acid
precipitation events to permit evaluation of the relation-
ship between soil solution, aluminum concentrations, and
precipitation pH.
• Aluminum leaching found to vary by soil type.
A study of three contrasting northeastern forest soils
showed the soils vary in their susceptibility to leaching
of aluminum to acid precipitation. Two factors were sug-
gested as regulating aluminum mobility in these soils: the
form and quantity of the aluminum and the presence of
mechanisms that favor the retention of otherwise mobile
anions.
SOIL CONDITIONS AND PLANT GAO WTH:
• Acid rain causes varied response in nutrient for-
mation in some soils from northeastern watersheds.
In laboratory studies with soils from three northeastern
watersheds, simulated acid rain inhibited nitrogen min-
eralization in some soils, had no effect in other soils, and
stimulated nitrogen mineralization in still other soils.
Among the soil processes important to regulating nutrient
availability for plant growth are those involving the
mineralization of nitrogen by microorganisms. The nutrient
most often limiting plant growth and forest productivity
in the Northeast is nitrogen, and nearly all that nitrogen is
derived from the microbial mineralization of nitrogen.
Because few soils were studied, it is not possible to
predict the soils or regions in which the nitrogen-supplying
capacity of soils (and hence the provision of the limiting
nutrients for vegetation) will be inhibited, enhanced, or
unaffected by acid rain. Additional information from other
sites is needed to establish regional responses for assess-
ment purposes.
• Acid rain increases nutrient availability at a
southeastern site. Soil properties and environmental
conditions may also play an important role in microbial
processes, as indicated from the results of a southeastern
United States study where acid precipitation increased
the rate of both nitrification and mineralization. Denitrifica-
tion occurred in the acid sandy soils with low organic mat-
35
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ter content; however, the effect of acid precipitation on
denitrification is not clear at this time. Acid precipitation
of pH 3.7 did not have any significant impact on soil
biomass, respiration and enzymatic activity; however, the
soil type may be a very important influence.
• Sulfur accumulates in forested southeastern
watershed. It was observed that sulfate accounts for
about 60 percent of the anions present in North Carolina
Appalachian precipitation. This study of mineral cycling
processes in a forested southeastern watershed found ac-
cumulation of elemental sulfur, because of its adsorption
and transformation into nonmobile forms. Both processes
are very important in regulating soil and water chemistry
and acidity by retarding anion mobility and, thereby, ca-
tion nutrient loss from terrestrial systems.
WA TERSHED BUFFERING CAPA CITY
AND RESPONSE:
• Precipitation pH was not altered in one New
England watershed, though the source of acid
precipitation precursors may have changed. As part
of a long-term study of nutrient cycling budgets relating
to forest management, no significant shift in precipitation
pH was found at Hubbard Brook watershed in New
Hampshire. These same results, however, indicate a
decrease in the ratio of sulfate to nitrate, suggesting an
important shift in the source of acid precipitation
precursors.
• pH of precipitation altered by forest
ecosystems. Forest ecosystems can reduce the acidity
of ambient rainfall. Rainfall at pH 3.5 to 4.5 on a hard-
wood forest in New Hampshire was buffered to pH 5.0
by the time it reached streamfiow. A West Virginia water-
shed with low alkalinity received rainfall at pH 4.1; below
the tree canopy, it had risen to pH 4.2; in groundwater
at springs, it was pH 5.0; and at the outlet of the small
watershed, pH 5.9. Aspen forests growing on slightly
calcareous glacial till in Minnesota also effectively buffered
the impact of pH precipitation events.
However, in another Minnesota tree stand, while the
pH of precipitation passing through black spruce grow-
ing on peat land increased slightly, the wetland surface
peat added significantly to hydrogen ion concentration
and ultimately reduced pH to the 3.5—4.5 range. Red pine
growing on shallow soil over granite bedrock added a
slight amount of hydrogen ion to precipitation, but the
soil subtracted about the same amount. In this case, in-
coming precipitation is fed with lithe change in pH directly
to streams and lakes. The mixed or variable nature of
these observed responses demonstrates that variables
such as canopy species, soil, and bedrock clearly must
be accounted for in estimating deposition inputs to
aquatic ecosystems from terrestrial ecosystems.
Water quality data lacking in some south-
eastern States. A nationwide assessment of existing
water quality data indicates that there is insufficient in-
formation on water quality variations in small streams dur-
ing storms in southern Appalachia.
• Site-specific deposition data needed. To ex-
trapolate site-specific data to regional effects, it is
necessary to know if environmental conditions where the
data are gathered are representative of the region. The
extrapolated information is used in dry deposition models
to quantify acid additions to the terrestrial ecosystem.
Two types of currently available deposition models were
evaluated for their applicability to developing watershed
mass balance estimates. Although both models are state
of the art, both have proved to be either inaccurate for
most mass balance applications, or have inadequate
characterization of major measurement parameters. This
study has identified the fact that the quality and level of
resolution of the models tested will need to be improved
to support the level of detail needed for proposed
ecological and economic assessments.
FUTURE ACTIVITIES
In the near future, research findings will accelerate as
results of multiyear research activities are summarized.
Among expected results between 1983 and 1985 are
thresholds of damage to agricultural crops and dose-
response relationships, specifically for corn and soybeans.
This information will be used in developing models to
estimate economic impact.
In forest ecosystems, tree ring studies will indicate the
potential for determining growth changes related to acid
deposition, as well as abnormal accumulation of metallic
ions. There will be a preliminary report of soil nutrient
budgets responsive to acid deposition. Changes of forest
productivity correlated with acid deposition effects also
will be summarized for major forest types. The role that
various types and densities of vegetative cover play in
modifying acid deposition effects on both the terrestrial
system and the transport of ions to aquatic systems is
being studied. Work beyond 1985 will concentrate on
determining whether acid rain has predisposed trees to
moisture stress.
Understanding the effects of acid deposition on the ter-
restrial ecosystem will be greatly improved by soil studies
of aluminum and other metals, their mobility, and their
uptake by both forest and agricultural crops, coupled with
improved understanding of form and amount of acidic
materials delivered to the forest floor. A report on the
significance of hydrogen ion generated in soils will be
prepared in 1985 as will reports on aluminum mobiliza-
tion and on mineralization processes affected by soil
acidification.
From 1986 to 1988 efforts will be accelerated to
categorize soil types as to nutrient loss or toxic element
mobility, as will studies to determine which soil processes
controlling nutrient availability for plant growth will be
altered by acidic fluxes. By 1988 these studies will begin
to provide correlations that can be used to improve
models. This will greatly aid the understanding of the in-
fluence of vegetative cover and soil behavior on water
quality eventually reaching streams and lakes.
36
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1087
Report: siinif;conce
at internal external
H ’ generation
Reo ;sed reports
I. Al sobilicution
2. Microbial processes’
soil acidification
Correlations between
atmospheric depositcen,
terrestrial ecosystems
water entering aquatic
ecosystems --
Final report describing
correlations between
acid input to
terrec osyu and water
entering aquatic
ecosystems
Revised report on
atmospheric deposition,
terrestrial econystemn
and water entering
aquatic ecosystems
NOTE; There are no sneentorien of craps or forests scheduled be the
Terrestrial Effects Task Group. The Department of Agriculture maintains an
extensive crop reporting network and a forest survey. Roth of these functions
collect the data needed to support economic analysis of any detrimental or
beset icial effects of acid deposition that are revealed by this or other
research.
Figure F-i. — Proposed program implementation strategy, Terrestrial Effects.
CROPS
[ llt i i;°° : nlelj F n i re s t 1
I IRevssed report: critical ________
parameters
SOILS
J i TnpoTc1.j :cera t ioo t_is0dlfbt55e0tb0e j_..4inttH+seneratioo
I
_____________________ Al(sredlcflgs ) 1
FORESTS
Preliminary report: Report: acid/metal Revised report: Reeined report: Revised report: Final report:
cation notriest loss; mahilication/ I C’N soil capital metals mobilization metals nobilization metals mobilization
soil capital ecological processes 2 acid/metals pevmned report: _________ Revised integrated
______________________ _____________________ _________________ metals/ c d/ re pa e n del
Revised report: Al Report: changes in Preliminary _______ forest compositioo
effects on critical forest productivity integrated links
growth processes response model
WATERSHEDS
and
.1.
1
] Reossedrepor t on Revised report on
atmospheric deposition atmospheric deposition,
__________ terrestrial ecosystems terrestrial ecosystems
and water entering and water entering
aquatic ecosystems aquatic ecosystems
37
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G
Effects on Materials
BACKGROUND
Experience over the last century in
both European and North American
cities has shown that air pollutants ac-
celerate the deterioration of materials.
However, several factors complicate
quantitative assessments of the im-
pact of atmospheric pollutants, in-
cluding acid precipitation, on conven-
tional building materials. Building
materials degrade to some extent
with time, even in pristine en-
vironments, so it is important to dif-
ferentiate between normal weather-
ing and deterioration accelerated by
air pollution.
Distinguishing between the
relative amounts of damage caused
by specific pollutants and their trans-
formations in contact with various surfaces is even
more elusive. The role played by acid precipitation
is still a major unknown. This is especially true for the
acid precipitation stemming from long-range transport of
air pollutants.
The development of quantitative cause and effect rela-
tionships depends on the capability to correlate two in-
dependent data sets —materials deterioration and pollu-
tion monitoring.
Past attempts to estimate the materials damage costs
related to pollutants are of questionable value, because:
1. The effects caused by various pollutants cannot yet
be reliably separated from each other and from deteriora-
tion caused by natural agents such as moisture and
temperature.
2. Estimates of the quantities of materials exposed to
acidification are lacking.
3. The way society chooses among use, repair, and
replacement of materials susceptible to air pollution
damage is unclear.
Materials at risk are statuary and structures of cultural
value as well as commonly used construction materials.
These include man-made materials such as metals and
alloys, paint, plastics, cement and concrete, masonry, roof-
ing and siding materials, and natural materials such as
marble, limestone, granite, calcareous sandstone, and
other mineral substances. Inventories of the location and
amounts of sensitive materials present in the geographic
areas of concern do not exist. Such inventories must be
completed if the economic effects of air pollution damage
are to be assessed and comprehensive cost estimates
developed.
Chemical corrosion processes deteriorate calcareous
building materials and cause metals, particularly zinc and
copper, to lose their protective oxide coverings. Over the
years, a considerable amount of industrial research has
evaluated the relative susceptibilities of materials and
developed more resistant ones. However, little has been
done to quantify the susceptibility as a function of pollu-
tant concentrations or other exposure variables such as
humidity, temperature, wind direction and velocity,
precipitation quality and frequency, or the concentration
of airborne salt particles.
Climatic and meteorological conditions are important
unknowns with respect to materials damage, although
some information is available. For example, it is known
that high humidity increases the rate of attack of sulfur
dioxide on zinc, and that local variations in temperature
also can be expected to influence damage rates. Wind
velocity and direction can affect the deposition velocity
and also enhance surface abrasion by large airborne par-
ticles. An important role in materials damage also has
been ascribed to special events such as dews, frosts, and
fog in combination with dry acid deposition.
The principal air pollutants causing materials damage
are sulfur dioxide, nitrogen oxides, ozone, and particulate
matter. In addition to attacking surfaces directly, the first
two are precursors of particulate sulfates and nitrates that
can travel long distances and, as acid deposition, create
effects many miles from the original emission sources.
However, since pollutants are rarely encountered singly
and are thought to act synergistically, they must be ex-
amined in combination and in different proportions cor-
responding to actual conditions. Information regarding the
potentially important effects of ammonia and chlorine is
also unavailable.
RESEARCH GOALS
AND ACTIVITIES
Assessing damages to materials and cultural resources
by acid deposition was a major new FY 1982 initiative
of the National Acid Precipitation Assessment Program.
The Task Force is planning and beginning several ac-
39
-------
tivities to better understand and quantify the role of acid
deposition in degrading various materials and cultural
resources. The present state of the art of acid deposition
materials damage modeling and related economic effects
modeling is primitive and the required data bases are very
poorly developed. The Materials Effects Task Group has
designed a research strategy that will provide basic
understanding of damage mechanisms from which effec-
tive protective measures for historic and cultural struc-
tures may be developed and from which more accurate
economic estimates can be made.
The Materials Effects Task Group’s research strategy
addresses four key questions:
1. What portion of materials damage can be ascribed
to acid deposition?
2. Which materials are susceptible to which specific
air pollutants and to what degree?
3. What is the geographic distribution of susceptible
materials?
4. What are the specific rates of damage or amounts
of damage in economic terms?
PROGRAM ACCOMPLISHMENTS—
FY 1982
In its first year, the Materials Effects Task Group concen-
trated on developing interagency coordination and
cooperative study, and implementing new projects. Ef-
forts during FY 1982 concentrated on (1) expanding field
studies of materials deterioration; (2) intensifying efforts
to look retrospectively at materials damage on marble
tombstones, exposed bronze markers, and materials per-
formance data from industry-sponsored research; (3) selec-
ting and applying methods to measure air quality for the
purposes of materials damage research; and (4) develop-
ing methods to inventory common construction materials
as well as historic structures and monuments.
Research initiatives in FY 1982 included:
• Establishing new field sites. Two additional field
sites were established at Washington, D.C., and Hun-
tington Forest, N.Y. Unlike the first two sites at Chester,
N.J., and Research Triangle Institute, N.C., these new
locations did not have full environmental monitoring in-
strumentation and therefore various supplemental
monitors had to be installed. Atmospheric corrosion
testing, coordinated with simultaneous meteorological,
acid deposition, and air quality measurements, is being
conducted at these four field sites to quantitatively cor-
relate specific pollutants present in acid deposition with
materials damage. The corrosion responses of seven
metals are being evaluated over exposure cycles rang-
ing from 1 month to 3 years. The result will be dose-
response functions for these metals.
A related problem now under investigation is the pro-
er method of sheltering a set of samples from wet
deposition. This work has produced a prototype movable
cover activated by a rain sensor. This movable cover is
now being evaluated for possible installation at Bureau
of Mines sites. This will permit wet and dry deposition
effects to be studied separately.
• Calibrating static monitors for sulfur dioxide
and nitrogen oxides. These simple devices appear to
promise a much cheaper method of characterizing air
pollution levels at materials effects sites. However, the
literature contains little concerning their performance
under varying conditions of wind, humidity, temperature,
and combined pollutants. Therefore, experiments have
begun to study the response of these monitors, beginn-
ing with a 1-month field exposure during June 1982, as
part of a major project on dry deposition conducted at
Champaign-Urbana, Ill., for the National Program.
In this project, a variety of materials were exposed with
the static monitors to compare their relative rates of sulfate
and nitrate uptake. Extensive meteorological data were
collected simultaneously. In addition, a flow chamber for
calibrating the static monitors under controlled conditions
was designed and built at Research Triangle Institute. Ac-
tual operation of the flow chamber will begin in early FY
1983. The availability of properly calibrated static monitors
may ultimately permit operating materials exposure sites
without elaborate air quality monitoring equipment.
• Estimating damage functions from industry site
data. Much of the basic data are derived from commer-
cial material test sites. The National Bureau of Standards
(NBS) is collecting existing corrosion and material perfor-
mance data. Methods are being developed to reconstruct
past pollutant deposition levels for the regions and periods
of commercially-sponsored materials exposure testing.
Available material performance data have been identified
and will be compiled in FY 1983, including historical pollu-
tant levels and meteorological data. Correlation of these
data sets will provide rough, interim estimates of material
deterioration effects attributable to acid deposition until
more definitive damage functions can be developed by
field exposure corrosion testing.
• Estimating bronze deterioration rates. A project
to estimate bronze deterioration rates resulting from ex-
posure was begun in FY 1982. Bronze markers such as
U.S. Geological Survey surveyors’ benchmarks and Na-
tional Historic Landmark plaques will be studied. In FY
1982, NBS tested and refined a mylar replica method to
measure the rate of corrosion in the field. Bronze durability
as a function of deposition levels will be estimated.
• Estimating marble deterioration rates from
tombstones. Study of the differential rate of marble
weathering, as measured on Veterans Administration
tombstones, has produced a data base covering 3,500
individual stones. The data are now being analyzed and
correlated against environmental factors, including air
pollution levels. The final report is due in FY 1983. In ad-
dition, a report has been completed on maintenance prac-
tices in NPS cemeteries. The output of the tombstones
study will be a set of correlations between marble
deterioration rates and spatial and temporal variables, in-
cluding retrospective estimates of pollution levels.
• Pollution archaeology. Success of the retrospec-
tive studies of materials damage requires estimates of past
pollution levels. Since air pollution was not usually
monitored prior to 1960, these levels must be inferred
from other data sources. Two such efforts were begun
in FY 1982. One approach involves calculating air pollu-
tion levels from historical records of fuel consumption.
The estimates will use primarily local sources of data
covering sources such as home heating, industries, and
vehicles, including coal-fired locomotive& In addition, NBS
began to develop a method to measure levels of at-
40
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mospheric sulfur deposited on painted surfaces and
trapped between repaintings. If measuring sulfur levels
in lead paint layers prbves feasible, a field study collect-
ing paint samples from dated structures nationwide wilt
be started in FY 1983 to verify sulfur deposition levels
calculated from emissions inventories, and to refine
regional scale estimates of deposition levels.
Prototype in situ deterioration monitoring.
Diagnosis of actual cases of materials deterioration is the
practical application of results of field, lab, and retrospec-
tive research. As a prototype, deterioration of historic
structures at Mesa Verde National Park, Cob., wilt be
measured in parallel with environmental parameters. Na-
tional Trends Network parameters wilt be supplemented
by measures of gaseous concentrations, particulate com-
position, and temperature and moisture cycles. Field
measurement techniques perfected at the prototype site
will be available for general application nationwide.
Documenting protective treatments. Baseline
documentation of effective protective treatments for
masonry monuments and buildings was undertaken for
eight structures in FY I 9 . Structures were chosen based
on several criteria: masonry material, treatment material,
and location of structure. Materials include marble with
and without epoxy consolidants, sandstone with epoxy
consotidants, cleaned brick, and terra cotta. Locations in-
clude New York, N.Y., Portland, Ore., Minneapolis, Minn.,
Chicago, Ill., San Francisco, Calif., New Orleans, La., and
Boston, Mass. The results will be used to assess existing
techniques for protecting such structures against en-
vironmental decay.
FUTURE ACTIVITIES
In FY 1983, work will continue toward producing interim
damage functions for a 1985 assessment. Tombstone
data, bronze marker data, and material performance data
from industry will be correlated with reconstructed pollu-
tion histories. Several laboratories will begin to adapt ad-
vanced technology to increase the sensitivity of damage
measurements; this will shorten the time frame for deter-
mining damage function. Work will be undertaken to
characterize the mineralogy of major American stone
sources and to predict their susceptibility to attack by acid
deposition.
Chamber studies to investigate the role of moisture in
acid deposition upon material surfaces and the effec-
tiveness of protective treatments on statuary materials will
begin in FY 1983. Additional materials—marbles, bronzes,
and selected coating materials—will be added to the field
exposure program.
Another initiative will develop data on the distribution
of construction materials as related to population, history,
availability of materials, and land use. This data will be
incorporated into a land use classification that will pro-
duce an inventory of common construction materials.
The Materials Effects Task Group presently plans the
following FY 1983 outputs:
Tombstone study results—a report of marble
damage rates.
Bibliography of Effects of Acid Deposition on Cor-
rosion and Deterioration of Materials, 1980-1983--a
literature review covering existing knowiedge of materials
damage.
Description of field exposure sites and meth-
ods—a report setting forth for peer review the field ex-
posure program.
Specifications for measuring damage to cultural
resources—a document establishing the basis for in-
vestigating damage at cultural sites from acid deposition
and other causes.
41
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FY83
FY84
FY85
FY85 FY87 FY88 FY89
ATMOSPHERiC MONITORING
DAMAGE MEASUREMENT METHODS
MATERIALS DETERIORATION
RATE 5TUDIES
PROTECTION AND MIT1OATION F eI4 EvaIoM.on 01
Masonry Treatments
STRATEGIES
COST DATA COLLECTION
MATERIALS INVENTORY
ASSESSMENT
Figure G- Proposed program imp’ementation strategy, Effects on Materia’s and Cuftura Resources.
Esok O
nel r e at fl t s j
42
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IT. Control Technologies
BACKGROUND
The relationship between man-made
pollutants and acid deposition is not
fully understood, but three pollutants
have been linked to acid deposition.
Sulfur oxides and nitrogen oxides
have been analytically identified in
acidic deposits with the ratio of each
ranging from minor to major. Ox-
idants also have been highly cor-
related with the occurrence of acid
precipitation and are probably in-
volved in the atmospheric transforma-
tion of the gaseous oxides to acidic
nitrates to sulfates that are deposited.
Emissions from fossil fuel power
plants have been the focus of atten-
tion for possibly controlling the
release of acid precursors because na-
tionally this source produces a major share of the
sulfur dioxide and a sizeable portion of the nitrogen ox-
ides. However, other activities such as smelting, industrial
combustion and processes, transportation, and space
heating can all contribute significantly to the atmospheric
loading of sulfur and nitrogen acid precursors and ox-
idants. The following discussion primarily addresses the
utility source because our knowledge about the impor-
tance of other sources is less complete. All may contribute
significantly (locally and/or regionally) to the formation of
acid deposition, but their specific roles are still poorly
understood.
Table H-1 summarizes the major man-made acid
precipitation precursor pollutants, the major industrial
sources, applicable controls, and explains their operation.
For sulfur dioxide and nitrogen oxides, generally available
controls are either expensive or inefficient. However, im-
portant technologies being developed, such as low
nitrogen oxide burners and limestone injection multistage
burners (LIMB), could someday provide more cost-
effective control of acid precipitation precursors. For the
directly emitted acidic compounds, very little information
is available on the effectiveness of conventional control
technology.
Table H-2 focuses on coal-fired power plants, major
emitters of sulfur dioxide and nitrogen oxides pollutants.
The table summarizes technologies that can be retrofit-
ted to the sources of these man-made pollutants by per-
formance, commercial status, costs, applicability, and im-
portant problems.
Flue gas desulfurization (FGD) technology is capable
of highly efficient sulfur dioxide removal and has been
commercially available for over 10 years. However, its
capital costs are quite high; such systems would cost $60
to $90 million for a typical 300 MW coal-fired utility boiler.
Also, widespread use of such systems would generate
large quantities of wet solid waste product that must be
disposed of in an environmentally acceptable manner.
Physical coal cleaning, although significantly less ex-
pensive than FGD, can decrease sulfur dioxide emissions
only modestly since chemically-bound sulfur cannot be
removed with current coal cleaning technology.
While switching to low sulfur fuel can achieve signifi-
cant reductions, its capital costs can also be quite high —
particularly when major boiler derating is needed to ac-
commodate the lower fuel heat content of western low-
sulfur subbituminous coals or particulate systems that re-
quire upgrading because of different coal effluent
characteristics. Costs for this method also increase if local-
ly mined coal can no longer be used.
Among the emerging control technologies, low
nitrogen oxide burners may be particularly effective in
controlling the oxides of nitrogen and may offer relative-
ly inexpensive capital and operating costs, but achieve
no sulfur dioxide control.
LIMB technology appears capable of moderate to high
removals of both pollutants at less than 20 percent of FGD
costs. LIMB technology is now in the prototype stage,
but a demonstration may provide sufficient data by 1985
to permit industry to begin to evaluate its potential. Not
enough information is now available to determine if target
removal efficiencies can be met by LIMB without in-
troducing boiler operating problems.
TASK GROUP ROLE
The Control Technology Task Group is tracking all rele-
vant control hardware development efforts, and provides
the appropriate agencies with guidance related to the Na-
tional Program's objectives and requirements.
The interagency budget for the National Program does
not include Federal funds for control technology hardware
development because control technology activities are
43
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conducted under preexisting programs at EPA, DOE, and
TVA. The various reasons for controlling the primary man-
made acid precursors, sulfur dioxide and oxides of
nitrogen, make it difficult to directly assign the cost of
such emission control hardware work to such different
concerns as health, visibility, and acid rain. The National
Program is actively coordinating with the relevant ongo-
ing Federal control technology efforts to ensure that the
concerns relative to acid deposition are addressed. A sum-
mary follows of the relevant Federal research and develop-
ment activities in the existing control programs.
Technology Agency FY 82
($ in millions)
S02 Control1 EPA 2.0
S02 Control TVA 2.6
NOX Control2 EPA 3.9
LIMB3/Low NO, Burner EPA 7.2
Simultaneous NOX/SO2 DOE 6.2
Total 21.9
'SO, = sulfur doxkte
JNOX = oxides of nitrogen
3LfMB = limestone injection multistage burner
In addition to these Federal efforts, it is anticipated that
the private sector will play a major role in bringing prom-
ising new technologies to the commercialization stage.
TECHNOLOGY DEVELOPMENTS-
FY 1982
During FY 1982, the sulfur dioxide and oxides of nitrogen
control technology activities funded by EPA, DOE, and
TVA made significant progress in developing improved
methods for controlling these emissions. The Control
Technologies Task Group has identified the following
results as potentially relevant to addressing the acid
deposition issue:
• Successful initial tests of the Limestone Injec-
tion Multistage Burner (see Figures H-1 and H-2). En-
couraging initial results indicate the potential for LIMB as
a low-cost retrofittable combination nitrogen oxides and
sulfur dioxide control technology. The LIMB technique
uses sorbent injection of limestone during combustion
with low nitrogen oxides burners. This developing
technology may be able to reduce these pollutants' emis-
sions from utility boilers by over 50 percent. (EPA)
• Development of burner systems that could
reduce nitrogen oxides emissions by 75 percent. Ad-
vanced burner systems for wall-fired and tangential-fired
boilers have been tested that decrease nitrogen oxides
emissions about 75 percent. Since coal-fired utility boilers
generate 40 percent of the total nitrogen oxides from sta-
tionary sources, these new burner systems should have
an important influence on future emissions from utility
boilers. (EPA)
• Improved sulfur dioxide wet scrubbing tech-
niques. Wet limestone and lime flue gas desulfurization
process technologies have been improved by increasing
sulfur dioxide removal efficiency and reagent utilization,
upgrading reliability, and improving waste product
disposal. Innovations include adipic acid, magnesium, and
thiosulfate additives; forced oxidation; and scale preven-
tion in scrubbers and mist eliminators. These techniques
improve sulfur dioxide removal efficiency and process
reliability to over 90 percent while reducing costs. (EPA,
TVA and DOE)
• Evaluation of dry scrubbing process. The re-
searchers evaluated the effectiveness of spray dryer flue
gas desulfurization systems using lime, limestone,
nahcolite, and trona, and investigated the relative merits
of fabric filters and electrostatic precipitators for collec-
ting fly ash and sorbent material. This technology pro-
vides a new and lower-cost option than wet scrubbing
processes for controlling sulfur dioxide from certain utili-
ty boilers. (EPA and DOE)
• Assembled coal data bases. Data bases on the
quantity, sulfur content, heating value, ash content, and
desulfurization potential of U.S. coals were assembled.
These permit evaluation of the amounts of coal from each
State that can be used with different control technologies
for compliance with differing sulfur dioxide emissions con-
trol regulations or strategies. (EPA and DOE)
• Evaluated advanced simultaneous sulfur diox-
ide/nitrogen oxides flue gas treatment processes.
Progress was made in quantifying the cost and perfor-
mance relationships, and identifying other promising
emerging processes, such as electron beam irradiation,
for further research. From this research may well evolve
the next generation of air pollution control technology.
(DOE and EPA)
AIR ANO Fu€l MIXING OPTIMIZED
'OR tnOUCTIO* OF MO. niTH THE
TEMPERATURE PROFILE OPTIMIZED
fOR CAPTURE Of SO2 *ITM
CAIOMED LIMESTONE
Figure H-1. —Limestone Injection Multistage Burner For Simultaneous
IMOX and SOX Control.
44
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TABLE 141 CONTROL OPTIONS FOR MAN-MADE ACID PRECIPITATION PRECURSORS
Major Acid
Precipitation Pollutants
Major Sources
Applicable Control Approaches
Principles of Operation
Precursor Pollutants
Sulfur Dioxide (SO 2 )
— Electric Utilities:
primarily high-S coal & oil
power plants
Industrial Fuel Combustion:
primarily high-S coal &
oil combustion
— low sulfur fuel switching
(commercial)
physical coal cleaning (PCC)
(commercial)
— flue gas desulfurization )FGD)
(commercial)
— limestone injection multistage burners
(LIMB) (developmental)
Substitute naturally occurring
low-S coal or oil.
— Remove physicafy bound
sulfur (pyrite) from coal via
separation processes prior to
combustion.
React acidic flue gas with
alkaline liquids yielding either
a throwaway or saleable
sulfur compound product.
Inject limestone in boiler
through (ow-NO 3 burners to
react with sulfur gases to
produce a throwaway product.
Minimize air used for
combustion to reduce NO 3
production from air N 2 .
Replace old burners with
specially designed burners to
maximize fuel-rich early flame
conditions for NO 3 reduction .
— Treat flue gas with NH 3 in
selective catalysts to reduce
NO 3 to N 2 and 02.
Recirculate exhaust gas back
to cylinders to lower temp.
and lower oxidation of air
N 2 and NO 3 .
Special tailpipe catalytic
system to reduce NO 3 to
N 2 and 02.
Directly Emitted Acidic
Pollutants
— Electric Utilities: coal- and
— Umited information suggests FGD
— See SO 2 discussion above.
Acid sulfates;
predominantly
sulfuric acid mist.
oil-fired power plants
— Non-Utility Fuel Combustion:
and low-S fuel switching may provide
some level of control for coal
— Low excess ar operation
— Lo ering combustion air tends
to decrease oxidation of SO 2
to SO 3 \Mth subsequent sulfuric
acid formation.
co and oil combustors
Hyctogen Chloride
— l3ecthc Utilities:
— flue gas desulftrization IFGD(
(HOl
high-C co -flred po r
plants
— lndustri Boilers: high-C
limestone injection multistage burners
(LIMB)
— See SO 2 discussion above.
co i
Nitrogen Oxides (NO 3 )
—. low excess air (commercial)
— Electric Utilities ; coal,
oil, and gas fired
— Industrial Fuel Combustion :
coal, oil and gas boilers
— staged combustion (commercial) — Add overfire air ports to allow
fuel-rich early combustion
conditions to reduce NO 3 to
elemental N 2 and 02.
— low NO 3 burners list gen. commercial; —
2nd gen.
burners in demo phase)
flue gas cleaning )FGC(
(commercial in Japan)
Stationary Engines: large
diesels, gas turbines, and
— catalytic reduction
(demo phase)
—
Utilize combustion gas catalytic
systems to reduce NO 3 to N 2
IC engines
— combustion modification (demo phase)
—
and 02 either with NH 3 (fuel-
lean engines) or w/o NH 3
(fuel-rich engines).
Modify engine to encourage
staged combustion.
— Mobile Sources: autos and
trucks
— exhaust gas recirculation
(commercial since 1972)
— three-way catalyst
(commercial since 1982)
45
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TABLE H-2 RETROFIT CONTROL TECHNOLOGIES FOR COAL-FIRED UTILITY BOILER
Process
Rue Gas
Desulfurization
(lime or limestone
scrubbing)
Physical Cod
Cleaning
Low-Sulfur
Fuel Switching
Low-NOx Burners
(second generation)
Limestone
Injection
Multistage
(LowNox)
Burners (LIMB)
S02 and NOX
Removal
Efficiencies
90% SO*
Reduction
20 to 30% SO2
Reduction
60 to 80% S02
Reduction
60 to 70%
Reduction
50 to 60% SO2
Reduction
50 to 60% NOX
Reduction
Estimated*
Captial
Status Costs ($/kW) Applicability
Commercial 200 to 300 Most large utility boilers;
costs could sharply increase
over estimated values for
difficult retrofits.
Commercial 40 to 50 Centralized cleaning facilities
can allow broad applicability
Commercial 26 to 61 Most utility boilers
Early 2 to 7 Most modern utility boilers
Commercialization
Developmental 27 to 37 Most utility boilers
Problems
— High costs; especially for
difficult retrofits.
— Large quantities of wet
waste to be disposed of.
— Limited SO2 removal;
especially for difficult to
clean coals.
— Large quantities of pyrite
solid residue for disposal.
— Boiler derating sometimes
required.
— Potential displacement of
locally mined coal.
— NOX removal only; no
S02 removal.
— Technology will be
commercial no earlier
than 1985.
— Questions must be
resolved regarding
performance and boiler
reliability.
on 300 MW, 3% sulfur cott, and Dec. 1982 dotes.
CIEAN
FLUE GAS
WASTE DISPOSAL
Figure H-2 —Schematic of Integrated Limestone Injection Multistage Burner (LIMB) System.
46
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1. Assessments and Policy Analysis
BACKGROUND
Work on assessments and policy
analysis began when the National
Acid Precipitation Assessment Pro-
gram started in FY 1982. While the
other technical and scientific com-
ponents of the National Program date
back to the rise in scientific interest
in acid deposition, the assessment ef-
fort is directed toward specific goals
and objectives that were defined in
detail only when the Task Force
began planning the National Program.
Assessments and policy analysis
research must produce quantitative
methods that organize and display
scientific information in ways that
allow comparison of alternative policies. A wealth
of analytic methods is currently available: decision
analysis, technology assessment, benefit-cost analysis,
risk analysis, and so on, but seldom have they been com-
prehensively applied to regional air quality problems like
acid deposition.
Two primary efforts to study the implications of air
quality management decisions on a regional level have
recently been published. One of these, the Ohio River
Basin Energy Study, was sponsored by the EPA under
the direction of the U.S. Senate. The other, Costs and
Benefits of Sulfur Oxide Control, was prepared by the
Organization for Economic Cooperation and Development
(OECD) and treated the Western European situation.
Although both studies broke new ground in significant-
ly advancing the methods available for performing such
analysis, they also recognized substantial problems as yet
unresolved in producing definitive results. Chief among
these are ". . . the considerable uncertainties (partly due
to lack of knowledge) that exist in assessment of the dif-
ferent components of the sulfur problem ... the data
base is by no means well established. And, the 'science'
intended to improve this situation still requires a number
of years to reach maturity."(OECD, p. 8)
More recently, the Congressional Office of Technology
Assessment (OTA) has undertaken a comprehensive
assessment of The Regional Implications of Transported
Air Pollutants. The July 1982 Interim Draft of this report
clearly recognizes the large uncertainties in current
knowledge about the causes and consequences of acid
deposition. The OTA report makes a useful contribution,
attempting to summarize what is and is not known and
to suggest approaches to decisionmaking under uncer-
tainty. But the report also recognizes that the type of
benefit-cost analysis that is an objective of the National
Program is not currently feasible in the face of these
uncertainties.
RESEARCH GOALS
AND ACTIVITIES
The goal of the Assessments and Policy Analysis research
program is to build upon earlier studies and draw from
existing analysis methods to construct the means for com-
prehensive benefit-cost assessments. This capability will
be unique in at least two ways. First, it will be designed
to deal quantitatively with the range of uncertainty around
various data and their use. This will allow continuous
tracking of the research program while uncertainties
decrease over time. In addition, developing methods to
organize scientific results and apply them to policy ques-
tions early in the research program will ensure that the
National Program can produce information that is rele-
vant to making policy decisions.
The Task Force has defined the scope of the major
assessment in FY 1985 to encompass four areas: (1) an
assessment of current damages attributed to acid deposi-
tion; (2) an uncertainty analysis of key scientific areas,
especially emissions and atmospheric processes; (3) the
implications of uncertainty in these areas on policy alter-
natives; and (4) a description of the framework for the
integrated assessment methodology, including the status
of the development of its components, that will be the
basis of the 1987 and 1989 integrated assessments.
The 1985 date for the current damage assessment is
based on realistic projections of how soon critical scien-
tific information will be available. Ongoing research pro-
grams within the National Program will delineate the ex-
isting uncertainties in the science and the impact these
uncertainties have on policy alternatives.
More comprehensive assessments based on an in-
tegrated framework that combines emissions models,
source/receptor relationships and dose-response functions
will be possible in 1987 and 1989. At present, much of
the basic information for these assessments is unavailable
47
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but research projects within the National Program are
vigorously pursuing this information.
Figure I-i shows the information flow for the current
damage assessment component of the FY 1985 assess-
ment. The deposition information, inventories of sensitive
resources, and dose-response information are produced
by various technical components of the research program
and combined to produce an estimate of the magnitude
of physical damages. The assessments research program
is working toward a detailed accounting of economic
damages.
Figure 1-2 illustrates the framework for improving in-
formation and models of atmospheric processes and
similarly improving the way analyses of ecosystems and
effects come together to compare costs and benefits of
alternative policies. The key parts of this framework
should be available in 1986 and integrated assessment
results by 1987.
The Assessments and Policy Analysis program will
prepare integrated assessments of the research results
1985 CURRENT DAMAGE ASSESSMENT
produced throughout the National Program. These
assessments will involve interpreting the importance and
quality of the research results, developing estimates of
the benefits and associated costs of alternative control
and mitigation measures, and formulating guidance for
policymakers.
By applying benefit-cost assessments and special
studies as needed, the National Program Assessment
Group expects to answer the following key questions:
1. What is the physical, biological, and economic
significance of current and expected adverse or beneficial
effects from the deposition of acidic and acidifying
materials in North America?
2. How are the composition and distribution of acid
deposition in North America linked with emission patterns,
and what significance do uncertainties have for control
or mitigation strategies?
3. From what existing range of strategies for integrated
emission control and receptor-oriented mitigation can
policymakers choose?
4. Which strategies show the greatest promise of cost
effectiveness or optimal cost-benefit, and what bounds
of uncertainty should be placed around such conclusions?
5. What specific research would most effectively
reduce the physical, biological, and economic uncertain-
ties decisionmakers must face in choosing among
strategy options for dealing with acidic deposition?
PROGRAM ACCOMPLISHMENTS—
FY 1982
• Critical Assessment Document. This document
was requested by the Clean Air Science Advisory Com-
mittee. It differs from the future assessments planned for
the National Program in that it is restricted to examining
the current scientific literature in terms of its scientific
quality and limitations. It does not attempt a comprehen-
__
Figure -2— nputs for integrated assessments.
Figure ii — inputs for current damage assessment.
INTEGRATED ASSESSMENT 1987 AND BEYOND
48
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sive interpretation of the implications of this literature. A
draft of more than 1,200 pages was prepared for public
scientific review workshops in November 1982. This draft
is now being revised by its 55 authors and editors and
will be submitted in May 1983 for printing as a public
review draft.
Integrated Control Strategies Modeling Project.
On the basis of this research, a detailed report on sulfur
dioxide emissions from utilities for 1976 through 1980 has
been prepared. The data base from which the report was
produced is maintained on Federal Government com-
puters. The US. utility industry emissions information con-
tained in the U.S.ICanada Memorandum of Intent Work-
ing Group 3B final report has been taken from this source.
This project also analyzed projected emission rates to
the year 2000. These reports provide definitive in-
formation for Government policymakers on the current
and projected future emission rates of relevant pollutants.
Development and testing of methods for uncer-
tainty estimation. This project, begun in 1982, will pro-
vide (1) estimates of uncertainty in models and data
elements, especially important where direct validation can-
not be made; (2) estimates of the overall uncertainty aris-
ing from a combination of uncertainties about a series
of processes; and (3) a basis for including uncertainty in
the development of control or mitigation strategy. The
first phase of this effort is underway; a report in 1983 will
publish the results. This report will guide policymakers
on the scientific limitations to predicting the effectiveness
of proposed emission control programs.
• Sulfur and nitrogen over the eastern North
American airshed. Substantial progress was made in
developing a detailed atmospheric budget for all sources
of sulfur and nitrogen compounds in eastern North
America. This project will produce a final report during
FY 1983. An effort to develop a comprehensive mass
budget for sulfur and nitrogen fluxes, through integrated
atmospheric, terrestrial, and aquatic ecosystems, will build
upon this v rk. These emission inventories are also essen-
tial data for the atmospheric transport models used to
quantify source/receptor relationships to study emission
control options.
• Aquatic effects of acid precipitation. A model
was developed to estimate the dose-response relation-
ship (between surface water, pH, and number and species
of fish) for aquatic ecosystems using probabilistic damage
functions. Uncertainty in this analysis was handled by in-
terviewing experts in the specific area of aquatic biology
using a structured method to include their estimates of
probability or uncertainty. The model will be used to
estimate the economic damages expected from the
acidification of surface waters.
• Development of integrated assessment meth-
odologies. Policy analysis requires a consistent method
for using the many relevant data bases, models, dose-
response and economic relationships needed to predict
the benefits and costs of any proposed emission control
or mitigation. An Advanced Integrated Assessment
Methodology is being developed to link these several
analytical tools and relationships. Where appropriate,
uncertainties will be handled within the methodology. The
development of this methodology was begun in F? 1982
and will continue over the next several years as our scien-
tific understanding of acid deposition matures.
FUTURE ACTIVITIES
FY 1983, with the exception of the projects already
discussed, is the first year for the full program in
Assessments and Policy Analysis research. Assessment
research and development over the next 3 years will fall
into three activity blocks, as outlined in Table 1. Emphasis
will be placed on the first two blocks which are aimed
at the long-term development of an integrated assessment
methodology and at providing mid-course corrections to
the overall national research program. Additionally,
preparation of the 1985 assessment will require con-
siderable effort over this time period. -
The first block of activities focuses on developing a
methodology for integrated assessments. These assess-
ments combine available information on emissions
sources, atmospheric transport, and deposition of acidic
and acidifying materials; their transport after deposition
through the relevant physical and biological receptor
systems (both terrestrial and aquatic); and their effects
upon these systems with estimates of how they change
in response to changes in emissions or receptor-oriented
mitigation measures. An integrated assessment also in-
cludes calculated costs of such control and mitigation
measures. Performing an integrated assessment on a
number of possible control and mitigation measures builds
up a body of data for policy analysis.
Methods for conducting an integrated assessment of
the acid deposition problem require extensive develop-
ment. The first block is structured to break the develop-
ment work into the several major components required
to meet the first three key questions listed earlier. The
last element within the block assembles these com-
ponents into an Advanced Integrated Assessment
Methodology (a well-defined protocol by which to con-
duct assessments).
The second block of activities provides detailed plan-
ning, oversight, coordination, and review to construct
linkages for the Advanced Integrated Assessment
Methodology. These include quality assurance for the
assembled data bases and validation for the required
process-simulation models. Additionally, this block of ac-
tivities includes the actual assembly and integration of all
the analysis tools required by the Advanced Methodology.
The third block of activities applies the Advanced In-
tegrated Assessment Methodology to developing optimal
strategies for emission control and mitigation. Additionally,
other intermediate assessments and short-term policy
analyses are included within this block, thus addressing
the last two key questions.
A framework will be developed for integrating and
coordinating research and deliverables between the
Assessments and Policy Analysis Task Group and the
other Task Groups, including a critical path analysis of
the deliverables required from each, and will define the
spatial and temporal resolution required for different data
sets, relationships, or models. This analysis will identify
key elements of the framework which, if delayed, would
slow the overall assessment process. The integrating
framework will generally resemble the information flow
diagrams presented in Figures I-i and 1-2.
49
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This research framework should not be misinterpreted
to imply that the activities it outlines flow sequentially from
the concept of a methodology to eventual application.
In actual practice, this is a dynamic process with much
iteration and many feedback loops. The Task Group must
develop those feedbacks early in performing the work
outlined in the second and third blocks in order to guide
the development work in the first block.
Major reports expected in FY 1983 include the final
Critical Assessment Document, a report on sulfur and
nitrogen atmospheric budgets for eastern North America,
a report on uncertainty analysis methodology evaluation,
and a report on probabilistic dose—response damage func-
tions for aquatic effects of acidification.
Table 1—Tasks Group I Research Framework
A. Integrated assessment methods development
1. Develop and apply economic benefits assessment methods;
2. Develop advanced effects assessment methodology;
3. Develop advanced methods for source/receptor assessment;
4. Develop integrated methods for constructing emission control
and mitigation strategies; and
5. Develop advanced methods for integrated assessment.
B. Integrated assessment coordination and integration
1. Oversee assessment planning and coordination;
2. Coordinate data base development activities;
3. Coordinate model development and validation activities; and
4. Develop assessment model linkages.
C. Integrated assessment application and policy analysis
1. Perform and participate in special acientfficttechnical assessments;
2. ldentif i and analyze alternative emission control and mitigation
measures;
3. Preliminary policy analysis/applied integrated assessment; and
4. Review status of assessments of major policy issues.
50
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• In tern a tional A ct/v/ties
BACKGROUND
The Acid Precipitation Act of 1980 re-
quires the Interagency Task Force on
Acid Precipitation to coordinate U.S.
efforts with research performed in
other countries. The Task Force
established an International Activities
Task Group, chaired by the Depart-
ment of State, to encourage interna-
tional cooperation on acid deposition
research and monitoring.
Transboundary air pollution is of
widespread international concern.
The United States has actively par-
ticipated in a number of international
forums addressing long-range
transport of air pollutants crossing in-
ternational boundaries. In 1979, 34
governments, including the United
States and Canada and the European Economic
Community, signed the Long-Range Transboundary Air
Pollution Convention under the auspices of the United
Nations Economic Commission for Europe (UN/ECE).
In a separate, country-to-country agreement the United
States and Canada signed a Memorandum of Intent (MOl)
in 1980 to negotiate a transboundary air pollution agree-
ment. To assist in the negotiations, joint technical Work
Groups will compile all relevant data on the long-range
transport of air pollution, with major emphasis on acid
precipitation.
Although the MOI Work Groups and this Task Force
are two different entities with distinct functions, many of
the same scientists are involved in both efforts. The role
of the bilateral Work Groups is to establish a mutually-
agreed-upon technical basis for the U.S./Canadian
negotiations on transboundary air pollution. The Task
Force, on the other hand, is responsible for the long-term
planning and implementation of the U.S. National Acid
Precipitation Assessment Program.
RESEARCH GOALS
AND ACTIVITIES
The International Activities Task Group’s goals are to:
1. Encourage and facilitate productive interaction bet-
ween the U.S. National Program and other nations con-
ducting acid deposition research and monitoring activities.
2. Assist the Task Force and its Research Coordina-
tion Council in tracking international cooperative efforts.
3. Recommend to the Task Force ways to improve in-
ternational cooperation and identify opportunities to work
with other nations toward common research goals.
4. Inform the Task Force of activities, meetings, and
developments in other nations.
The U.S.-Canada Work Groups under the 1980
Memorandum of Intent took precedence over the Inter-
national Task Group’s activities in 1982. The U.S.-Canada
Work Groups have now essentially finished their primary
tasks, and the documents are under review in both coun-
tries. Thus 1983 will see a more active role for the Inter-
national Task Group, as it coordinates, tracks, and fosters
cooperative research between the United States and other
nations.
PROGRAM ACCOMPLISHMENTS—
FY 1982
In April 1982, the Task Force and its Canadian counter-
part, the Federal-Provincial Research and Monitoring Coor-
dinating Committee met and agreed to pursue greater
cooperation between the two nations’ research efforts.
The two research coordination groups declared that
working-level contacts between scientists of both nations
should be increased to develop proposals for specific
cooperative research, and that such proposals would then
be transmitted to the U.S. International Task Group and
the Canadian RMCC Secretariat. The International Task
Group and the RMCC Secretariat will serve as conduits
for the two-way flow of proposals until a specific proposal
is jointly approved by the Task Force and the Canadian
RMCC. Following approval, cooperative research will be
conducted directly by the appropriate bodies in the two
countries.
FUTURE ACTIVITIES
The United States is considering several proposals for ad-
ditional cooperative research with Canada. During early
1983, one or more should be ready to discuss with the
Canadians as a possible joint project. It was agreed at
51
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the Task Force/RMCC meeting in April 1982, to increase
cooperative efforts on quality assurance, especially in
precipitation monitoring, and these activities are being
expanded.
After initially focusing on developing closer coopera-
tion with Canada, the International Task Group wifl begin
working to foster complementary research on acid deposi-
tion with other nations and international bodies. For ex-
ample, the UN/ECE-sponsored Convention on Long-Range
Transboundary Air Pollution will go into effect during
1983, and the International Task Group probably will be
used to develop appropriate cooperative research projects
and information exchange arrangements under that
Convention.
52
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APPENDIX /
NATIONAL ACID PRECIPITATION ASSESSMENT PROGRAM
ACTUAL EXPENDITURES
FY 1982
($ in thousands)
DOA DOl
EPA SE ES NOAA DOE PS OS RN WA TOTAL
A. Natural Sources 600 $ 600
B. Man-made Sources 870 300 1170
C. Atmospheric Processes 3273 600 805 50 126 4854
D. Deposition Monitoring 797 253 127 700 497 75 585 3034
E. Aquatic Effects 1475 135 560 94 580 75 133 3052
F. Terrestrial Effects 1355 264 570 122 178 295 66 2850
G. Effects on Materials 250 178 428
H. Control Technologies (1 0,400Y (6200) (16,600)
I. Assessments and Policy 1105 260 1365
Analysis
Subtotals: 517 832 575 1460 75
TOTALS: $ 9125 1349 1900 2544 2110 325 $17,353
control Tethnofog es gures not ncluded n total. Theas frards for general development of SO, and NOr control
h&ctw e e propriated under other pree ,dstrng programs The Control Technologres Task Groop coorctnates the
efforts s4th the asassunient and reasach aclivrtes of the Natmnal Program.
53
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APPENDIX II
LIST OF TASK FORCE FY 1982 A CT/V/TIES
Date Activity Purpose
11/25/81 RCC Meeting Review draft material for inclusion in First Annual Report and receive
guidance for final draft
12/18/81 RCC Meeting Receive 0MB FY 1983 budget passback and guidance
1/26/82 Research Coordination Discuss and incorporate final changes to National Plan, review
Council Meeting Task Group functions.
2/1/82 Task Force Meeting Review and revise final National Acid Precipitation Assessment Plan.
2123/82 RCC Meeting Develop standard format for project descriptions in Operating
Research Plan (ORP) and review draft strategic long-term framework,
discuss purpose and format of Task Force’s First Annual Review
Meeting, discuss coordination with State and private sector efforts.
4/16/82 U.S./Canada Research Meet with the Canadian Federal/Provincial Research and Monitoring
Coordination Meeting Coordination Committee to seek ways to increase bilateral scientific
cooperation and to discuss mechanisms for continued coordination of
efforts.
4i20/82 RCC Meeting Review and approve ORP outline, detailed planning of First Annual
Review Meeting, announce mid-year FY 1982 budget report.
6/2/82 RCC Meeting Review Task Groups’ draft ORP’s.
6 (8/82 Task Force Meeting Review 0MB final comments on National Plan, discuss and revise
long-term framework and ORP, approve agenda for First Annual
Review Meeting, plan FY 1984 budget, examine proposed scope of
work for inventory of Federal/State acid deposition projects.
7/13/82 RCC Meeting Work on integration of Task Group and NLC inputs to ORP, review
status of Critical Assessment Document, agree to distribution list for
National Plan.
714/82 RCC Meeting Define interrelationships of Task Groups’ inputs and outputs, identify
specific crosscutting issues to discuss at First Annual Review
Meeting.
8/24/82 RCC Meeting Receive preliminary FY 1984 budget guidance from 0MB, review
first complete draft of ORP, finalize planning for First Annual Review
Meeting, discuss inventory of Federal/State research projects, report
on data management needs study.
9/8/82 Task Force Meeting Task Group leaders present initial FY 1984 budget proposals for
review and guidance.
9/8-10/82 First Annual Review Assess research progress, evaluate first draft of ORP, discuss pro-
Meeting posed research directions and priorities, examine interrelationships
among Task Groups.
921/82 RCC Meeting Task Group leaders discuss status of FY 1984 budget, review FY
1984 budget submission to 0MB.
921/82 Task Force Meeting Review and approve final FY 1984 budget recommendations to
0MB.
54
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APPENDIX III
GLOSSARY
ACID Acidification Chemistry Information Database
ASTRAP Advanced Statistical Trajectory Regional Air Pollution Model
AUSM Advanced Utility Simulation Model
CANSAP Canadian Network for Sampling Precipitation
CAPTEX Cross Appalachian Tracer Experiment
CEO Council on Environmental Quality
DOA Department of Agriculture
DOC Department of Commerce
DOE Department of Energy
DOl Department of Interior
DOS Department of State
EPA Environmental Protection Agency
FGD Flue gas desulfurization
GTN Global Trends Network
HHS Health and Human Services
ILWAS Integrated Lake-Waterstied Acidification Study
LIMB Limestone injection multistage burners
MAP3S Multi-State Atmospheric Power Production Pollution Study
MOl Memorandum of Intent
NADP National Atmospheric Deposition Program
NAPAP National Acid Precipitation Assessment Program
NASA National Aeronautics and Space Administration
NBS National Bureau of Standards
NLC National Laboratory Consortium
NOAA National Oceanic and Atmospheric Administration
NSF National Science Foundation
NTN National Trends Network
OECD Organization for Economic Cooperation and Development
ORP Operating Research Plan
OSCAR Oxidation and Scavenging Characteristics of April Rains
OTA Office of Technology Assessment (Congressional)
RCC Research Coordination Council
RMCC Canadian Federal/Provincia’ Research and Monitoring Coordinating Committee
T\JA Tennessee Valley Authority
UN/ECE United Nations Economic Commission for Europe
55
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Figure E-1 —Total alkalinity of surface waters.
-------
U .S. Environ entai Protection A eno
Library, Room 2404 PM. .211..A
401. M Street, S .W .
Washington, DC 20460
EPA-600/D-82- 333
Map and text
TOTAL ALKALINITY OF SURFACE
WATERS - - A NATIONAL MAP
by
James M. Omernik and Charles F. Powers
Corvallis Environmental Research Laboratory
U.S. Environmental Protection Agency
Corvallis, Oregon 97333
Abstract. This map illustrates the regional patterns of mean
annual alkalinity of surface water in the conterminous United
States. As such, it affords a qualitative graphic overview to the
sensitivity of surface waters to acidification. The map is based
on data from approximately 2500 streams and, lakes and apparent
spatial correlations between these data and macro-watershed
characteristics, especially land-use.
Key Words: surface water alkalinity, sensitivity to acidifica-
tion, water quality.
Introduction
The accompanying map represents the first step in a comprehensive project
to identify general patterns of surface water sensitivity to acidification.
The map results from the growing demand for accurate identification of
acid-sensitive aquatic areas of the conterminous United States and is part of
a continuing program to (1) inventory and synthesize, state-by-state, the vast
quantities of relevant water quality data; (2) conduct general field surveys
to fill data gaps; (3) prepare detailed regional maps and update national
maps; and finally (4) conduct extensive field surveys (including biological
parameters) of critically sensitive areas.
The map was developed from mean annual total alkalinity values of
approximately 2,500 streams and lakes and from the apparent relationships of
these data with land use and other macro-watershed characteristics such as
soil type and geology. Total alkalinity is used as an index of sensitivity
because it expresses the acid neutralizing capacity of water bodies and thus
their relative sensitivity or tolerance to acid inputs. The ranges of our six
map units were chosen to illustrate patterns of relative sensitivity on a
national scale. Although there is general agreement that total alkalinity
expresses acid sensitivity of surface water, there is lack of agreement on
exactly where the breaking points exist between sensitive, moderately sens
1
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itive, and insensitive waters. Hendrey et al. (1980) considered waters not
sensitiye to acidification when alkalinities exceeded 500 peq/l and of high
sensitivity when alkalinities were less than 200 ieq/l. The Ontario Ministry
of the ;EnVirOfllflent (1981) proposed that alkalinities between 0 and ‘40 peq/l
indicate extreme sensitivity and those between 40 and 200 peq/l moderate
sensitivity. Zimmerman and Harvey (1978-1979) have suggested a triad of
parameters to define acid sensitivity in surface waters: pH < 6.3-6.7,
conductivity < 30-40 imho/cm, and alkalinity < 300 peqll.
Gei eral patterns of average sensitivities of surface waters to acid-
ification are depicted by this map, not worst-case or best-case conditions.
Our intent is to show what one might expect to find in most surface waters
most of the time. Subsequent larger-scale maps of the more sensitive areas
will address worst-case conditions, ranges of conditions, and significant
regional and (to the extent possible) local relationships between alkalinity
and geology; soils; and climatic, physiographic, and human use factors.
Confidence limits for areas of greatest sensitivity will also be provided.
These maps will be compiled as detailed information is gathered andanalyzed.
For the present, however, there is an urgent need to understand the
relative sensitivity of surface waters in different parts of the country in
order to (1) provide a national perspective on the extent of the problem, (2)
provide’ logic and/or rationale for selecting geographic areas for more
detailed studies, and (3) allow more accurate regional economic assessments of
acid precipitation impacts on aquatic resources. .
Map Development
The data used to compile this map were selected and mapped according to
several, categories. Stream sites were listed separately from lakes, natural
lakes were distinguished from impoundments, and both stream sites and lakes
were separated into two groups -- those associated with watersheds of less
than 260 square kilometers (100 square miles) and those associated with
watershed areas of between 260 and 2600 square kilometers. (100 and 1,000
square miles). Except in areas that were very similar in land use, physlo-
graphy, and soils (e.g., the Great Plains), data associatedwith watersheds
larger than 2600 square kilometers (1,000 square miles) were excluded. As
might be expected, we found that the patterns of alkalinity values in streams
were quite similar to those of lakes in the same area. As the data were being
gathered and plotted, and geographical patterns of high and low alkalinities
developed, collection efforts tended to concentrate on these apparent areas of
greatest sensitivity.
Most of the data were obtained from the U.S.. Geological Survey via
STORET,an EPA computer-based water quality data storage and retrieval system.
The remainder came from. varied sources, principally the National Eutrophica-
tion Survey (U.S. Environmental Protection Agency, 1974, 1978a, 1978.b, 1978c),
the Pennsylvania Cooperative Fishery Research Unit (Arnold, .1981), and the
Tennessee Valley Authority (Meinert and Miller, 1981)... Although various
analytical procedures were used by the various agencies [ U.S. Geological
Survey and the Tennessee Valley Authority, single endpoint titration to pH
4.5; National Eutrophication Survey, colorometric end point (methyl orange);
2
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and Pennsylvania Cooperative Fishery Research Unit, double endpoint titra-
tion], the alkalinity values obtained are reasonably equivalent and, we feel,
comparable for our scale of spatial analysis.
Each data point was scrutinized to insure representativeness. To
accomplish this, it was necessary to keep the watershed size consistent with
the relative homogeneity of major watershed features such as physiography and
land use. In areas of relative heterogeneity, most of the data were associ-
ated with small watersheds (less than 260 square kilometers). Representative-
ness of the data was imperative for detection of spatial patterns of
alkalinity, possible correlations with patterns of other characteristics, and
ultimately, extrapolation of the data. To include data from sites having
large watersheds of widely differing characteristics (e.g. , the Willamette
River at Salem, Oregon, the watershed of which includes vast contrasts in
soils, geology, climate, and land use), or data downstream from major
industrial or municipal waste discharges, would mask these spatial patterns.
The data were plotted on a 1:3,168,000 scale base map of the United
States. Each site was represented by a small circle color-coded to approx-
imate value. The exact value of the site was noted beside the circle,
together with a designation for lake or stream. The spatial patterns of
alkalinity were then compared with maps showing characteristics that are
believed to be driving or integrating factors affecting alkalinity; e.g.,
bedrock geology and soils, land use and vegetation. Driving factors, as used
in this paper, refer to those that directly affect alkalinity (e.g., geology
and soils). Integrating factors, on the other hand, are considered those that
reflect combinations of driving factors; for example, land use and potential
natural vegetation reflect regional combinations (or an integration) of
driving factors such as soils, land surface form, climate, and geology. We
believe that the importance of each of these driving factors, and the
hierarchy of importance relative to the combinations of factors varies from
one region to another. Clarifying these regionalities is a major goal of our
overall synoptic analyses; they will be addressed in the text accompanying the
subsequent larger scale maps.
It became apparent early in this study that land use generally correlated
with alkalinity throughout much of the United States, and particularly in the
West. In general, surface water alkalinity was low in areas of ungrazed
forest and high where cropland predominated. In-between types of land use
generally reflected alkalinity values that corresponded to the degree of
agricultural use. However, the apparent relationship between land use and
alkalinity varied considerably; in some areas, particularly in the Southeast,
the relationship was poorly defined or nonexistent.
Except for some localized situations, we were not able to relate geo-
graphical patterns of surface water alkalinity with geological sensitivity as
depicted by bedrock or soil types. Recent studies by Kaplan et al. (1981),
McFee (1980), and Hendrey et al. (1980), based on county-by—county average
values, have demonstrated such correlations. Since alkalinity, in large part,
is a function of the nature of the rock and soil makeup of a drainage basin
(Cole, 1975), it did not appear unreasonable to expect similar results in this
mapping study. The lack of correlation is probably in large part a function
of study scale. Had our focus not been on the nation, but rather on a small
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region 6 r state, possible surface water alkalinity/geology and/or sn type
relationships may have been more perceptible. However, this lack of çorrela-
tion may be due to one or more of several other factors. First, inconsist-
encies and inaccuracies in rock and soil type maps are common between, and
even within, regions and between states. Second, the alkalinity in a lake or
stream reflects the characteristics of both rocks and soils in the watershed.
Even in ‘small watersheds, large spatial variations in rock and soil types and
depths can be found. Another confounding factor is that surface and sub-
surface ‘watersheds frequently are difficult or impossible to define, partic-
ularly in areas of karst ,or continential glacial topography (Hughes and
Omernik,. 1981). Apparent surface watersheds o’f streams and lakes in such
areas often differ greatly in area from the even more difficult to define
ground watersheds.
Because of the general correlation of land use with alkalinity, the
1:3,168,000 scale base map with alkalinity values was overlayed onto a color
enlargement of Anderson’s Major Land Uses map (U.S. Geological Survey, 1970).
When viewed on a. light table, the general land use patterns ‘and spatial
relationships of surface water alkalinity to land use could be visualized. By
studying these relationships and patterns, along with apparent local relation-
ships with geologic and soil characteristics, interpretations were made and
map units drawn to reflect these regional relationships.
Use of the Map
The development and usefulness of this map can best be illustrated by
comparison with a more familiar graphic -- an isometric map of mean annual
precipitation. 1 One should not use a precipitation map to predict the
precipitation that will occur during a particular year at a given location.
Rather, the map illustrates patterns of long term conditions. Few parts of
the United States typically experience a truly “norma] year” c1imati cally.
Generally, precipitation totals are somewhat higher or somewhat lower than the
mean; occasionally, total deviation from the mean is extreme. Admittedly,
precipitation maps may provide a more accurate indicator of their subject than
the alkalinity ma because of their more extensive data base (particularly
from the temporal standpoint). However, precipitation maps are compiled using
data from different geographical locations together with knowledge of apparent
associations of these data with physiographic characteristics, water bodies,
ocean currents, latitude, and other environmental factors. For example,
precipitation patterns in mountainous areas, where data are scarce or lacking,
are drawn to reflect the expected orographic effects of elevation and exposure
to weather systems. Much the same kind of qualitative analysis was used ‘to
compile the alkalinity map. It is based on values from more than 2,500 stream
sites and lakes throughout the United States, as well as knowledge of the
apparent’ associations between the alkalinity data and other spatial phenomena,
particularly land use.
1 McDowell and Omernik (1979) used this comparison to clarify the utility of a
set of national maps of nutrient concentrations in streams from rionpoint
sources (Omernik, 1977). The total alkalinity map was compiled in a similar
fashion as the nutrient maps but with more than two and one-half times as many
data points.
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As with a precipitation map, caution should be exercised when using this
alkalinity map. In many parts of the nation, nearly all of the surface waters
have mean annual alkalinity values within the range illustrated in the map.
In other areas -- particularly where there are complex variations in geology
and soil type, and other factors affecting acid sensitivity -- there are wide
spatial and temporal variances in alkalinity. For these types of areas, at
this scale of mapping, we were only able to estimate the mean annual alka-
linity of most surface waters; many may reflect higher or lbwer values.
Acknowledgments
Many people contributed to the development of this map. Especially
deserving of recognition is Andrew J. Kinney for his help in gathering,
scrutinizing, and plotting the data.
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