REVIEW OF U. S. ENVIRONMENTAL PROTECTION AGENCY
ATMOSPHERIC SCIENCES RESEARCH LABORATORY
DRY DEPOSITION AND MATERIALS EFFECTS PROGRAMS
Norbert S. Baer, Chairman
Pedro Albrecht
Cliff I. Davidson
Howard M. Liljestrand
Ivar H. Tombach
April 23-25, 1985
Prepared by
Research and Evaluation Associates, Inc
1030 15th Street. N.W., Suite 750
Washington. D.C. 20005
(202) 842-2200
109 Conner Drive. Suite 2101
Chapel Hill, N.C. 27514
(919)968-4961
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TABLE OF CONTENTS
Chapter Page
I. INTRODUCTION 1
1.1 Panel Mission and Responsibilities 1
1.2 Materials Reviewed 3
II. DRY DEPOSITION PROGRAM - Task Group D 4
2.1 Background 4
2.2 Task Reviews 7
2.2.1 Parameterization of Pollutant 7
Deposition Velocities
2.2.2 Development and Evaluation of Methods 8
to Measure Deposition Fluxes
2.2.2.1 Variance Method 8
2.2.2.2 Similarity/Heat Budget Method 9
2.2.2.3 Eddy Accumulation Method 9
2.2.2.4 Overall Evaluation of Direct 10
Methods Research
2.2.3 ASRL Concentration Monitor 11
2.2.3.1 Development and Evaluation 11
of the ASRL Concentration Monitor
2.2.3.2 Development of a Sized Particle 13
Collection System
2.2.4 Research Site Operation and Method 14
Evaluation
2.2.5 Evaluation of a Research Watershed 18
2.3 Proposed 30-Site Deposition Network 18
2.4 General Comments 22
2.4.1 Management Team/Project Staff 22
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TABLE OF CONTENTS (continued)
Chapter Page
2.4.2 Integration of Tasks to Achieve 22
Program Objectives
2.4.3 Related Research: Surrogate Surface 24
Methods
2.4.4 Program Strengths and Weaknesses 25
2.5 Recommendations (In Approximate Order of Priority) 25
III. MATERIALS EFFECTS PROGRAM - Task Group G 27
3.1 Background 27
3.2 Task Reviews 28
3.2.1 Field Studies 28
3.2.1.1 Structural Materials - Metals 28
3.2.1.2 Non-Metallics 31
3.2.1.3 Acid Rain Simulator 33
3.2.1.4 Site Monitoring 34
3.2.1.5 Aerometric Data Base 36
3.2.2 Chamber Studies 37
3.2.3 New Projects (FY 86) 38
3.2.3.1 Initial Effects on Painted 38
Wood Substrates
3.2.3.2 Effects on Concrete and 39
Masonry Structures
3.2.3.3 Effects on Roofing Asphalt 39
Shingles
3.2.3.4 Evaluation of Corrosion Monitor 40
at Exposure Sites
3.3 General Comments 40
3.3.1 Management Team/Project Staff 40
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TABLE OF CONTENTS (continued)
Chapter Page
3.3.2 Integration of Tasks to Achieve Program 41
Objectives
3.3.3 Relationship Between Field Studies, 41
Chamber Studies and Damage Functions
3.3.4 Related Research 45
3.3.5 Program Strengths 45
3.3.6 Program Limitations 45
3.3.7 Quality Assurance and Quality Control 46
3.4 Recommendations (In Approximate Order of Priority) 47
Appendix A Peer Review of the Acid Deposition, Dry 49
Deposition, and Materials Damage Program
Appendix B EPA-ASRL Peer Review Panel 51
Appendix C Process Evaluation Results 52
Appendix D ASRL Response to Reviewers' Comments 56
Appendix E Review of the Panel Report and Responses 65
by the Laboratory Director
Appendix F Clarification Comments by ASRL 67
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I
INTRODUCTION
1.1 Panel Mission and Responsibilities
The panel's mandate was to review two U.S. Environmen-
tal Protection Agency - Atmospheric Sciences Research Lab-
oratory (EPA-ASRL) programs: (a) Dry Deposition (Task Group
D) and (b) Materials Effects (Task Group G). Both efforts
are part of the National Acid Precipitation Assessment
Program (NAPAP). The specific tasks reviewed are listed in
Table 1.
The projects and the associated tasks were to be
reviewed from the standpoint of:
(1) objectives and technical approach, including
quality assurance and quality control;
(2) outputs planned;
(3) the relationship of the outputs to the goals of
the Agency; and
(4) the usefulness of the overall programs to the
scientific community and/or public welfare.
In attempting to meet this mandate, the panel has not
only commented on the individual tasks listed in Table 1,
but has also considered their relationship to the broader
goals of the Agency, i.e., development of a dry deposition
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Table 1
Descriptions of Tasks Reviewed
Dr Deosition - Tiak Group D
Parameterization of Pollutant Deposition Velocities
Development and Evaluation of Variance Method
Development and Application of S1n1lar1ty/Heat Budget Method
Development and Application of Eddy Accumulator
ASRL Concentration Monitor
Development of a Sized Particle Collection System
Research Site Operation and Methods Evaluation
Evaluation of a Research Watershed
H«t«rU1« Effeett - T««fc fit-nun R
Field Studies - Structural Materials (Metals)
Field Studies - Non-Metalllcs
Field Studies - Add Rain Simulator
Field Studies - Site Monitoring
Field Studies - Aeronetrlc Data Base
Chamber Studies - Chemistry of Acid Precipitation
Materials Effects
Nev Projects - Initial Effects on Painted Wood Substrates
Effects on Concrete and Masonry Structures
Effects on Roofing Asphalt Shingles
Evaluation of Corrosion Monitor at Exposure Sites
C on trie tor/Agency
Argonne
Argonne
NOAA
In-House
In-House
(RFP)
Argonne/NOAA
NOAA
Contractor /A ganev
BOMInes
Northrop
Northrop
Various
CSC
lJUk Kfl*
1452
1452
3014
3016
4037
5059
1452/3014
1014
laxk ILfU
3024
4059
3175
3114
4062
Northrop
3174
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network and estimation of economic damage attributable to
acid deposition.
1.2 Materials Reviewed
The panel has reviewed the information and materials
made available in scheduled presentations, draft manu-
scripts reporting results, interagency agreements, pro-
ject descriptors, and the most recent peer reviews of both
programs. It has visited the chamber facilities of the
on-site contractor and the RTF field test site. At its
request, a conference call was made to Bruce Hicks to
discuss the status of the NOAA deposition velocity para-
meterization project deemed critical to the concentration
monitoring approach.
The panel especially appreciated the willingness of
ASRL to arrange unscheduled meetings at short notice.
These additional meetings, which were requested by the
panel to augment the review process, provided important
information and enabled a more thorough review.
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II
DRY DEPOSITION MEASUREMENT PROGRAM - Task Group D
2.1 Background
The ultimate objective of the dry deposition program
of Task Group D is to determine dry deposition to surfaces
throughout the United States and to monitor future trends.
The dry deposition measurement program of ASRL has several
broad components directed at meeting this objective,
namely
(a) Research on micrometeorological methods for
determining dry deposition influences (the so-
called "direct" methods);
(b) Determination of dry deposition velocities over
various natural land surfaces;
(c) Development of a method to monitor atmospheric
concentrations of the chemical species of
greatest interest in dry deposition;
(d) Operation of three field sites for dry deposi-
tion measurement research; and
(e) Evaluation of the utility of a research
watershed for estimating dry deposition.
The relationships among these tasks are shown in the
diagram in Figure 1.
A major conclusion of research to date is that direct
measurement of dry deposition is difficult, and is not
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I 1979 DRY I
l DEPOSITION t
I WORKSHOP I
L--.— -J
i
R t 0 ON DIRECT METHODS:
1. EDDY ACCUMULATION (I-H)
2. SIMILARITY/HEAT BUDGET (NOAA)
3.
R 4 0 OF PROTOTYPE CONCENTRATION MONITOR (C.M.):
V. PARAMETERIZATION
d (ANL)
SUITABLE \ YES
FOR SITE CAL1B.,
RESEARCH,
QA 7
HNO,, N03", N02, SOj, 50^ , NHj,
NH4 , and II* (I-H, BATTELLE, RTI)
03 (I-H)
LARGE PARTICLES (RFP)
INTERCOMPARISONS (UNC, BATTELLE)
OPERATING
DRY DEPOSITION
NETWORK
< _
I -1
t NETWORK C.M. i
^ AND SITES i
, (EMSL) I
t_ _ _ _ _ _ _ J
NOAA: NOAA - OAK RIDGE
ANL: ARGONNE NAT. LAB
I-H: IN-HOUSE
Figure 1. Schematic Representation of the Components of
the ASRL Dry Deposition Measurement Program
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practical with current technology in a large surveillance
network. An alternate approach appears to be estimation
of dry deposition flux from measurements of the pollutant
concentrations and deposition velocities. Components (b)
and .(c) above address the two variables required for such
an "indirect" method, where concentrations would be
measured and the deposition velocity, Vj, would be esti-
mated by interpolation or extension of measurements that
have been made at a variety of research sites. In a
separate program, the Atmospheric Turbulence and Diffusion
Laboratory of NOAA is developing the methodology for esti-
mating V(j at sites where measurements are not available.
Component (a) is concerned with development of
methods that could be used in the field for deposition
flux research and for validating the estimates of the
indirect method. Component (d) deals with operating three
field sites where basic measurements of deposition flux
can be made and the indirect methods can be tested.
An alternative method for determining dry deposition
fluxes is being evaluated under component (e). Here, ASRL
is exploring the feasibility of direct determination of
dry deposition from the difference between measured wet
deposition input to a watershed and measured groundwater
and stream fluxes out of the watershed.
This section reviews the various tasks that comprise
these components and evaluates their design and execution
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from the perspectives of the program goals. In addition,
because the intended use of the methods is in a national
dry deposition trends network, we discuss briefly some
issues raised by our review that have relevance for the
implementation of that network.
2.2 Task Reviews
2.2.1 Parameterization of Pollutant Deposition Velocities
The objective of this task is to express deposition
velocities for each of several pollutant species as
functions of atmospheric conditions and surface condi-
tions. Various types of surfaces will be considered,
including cropland and deciduous forests in different
seasons. The eddy correlation method will be used to
measure V ., while meteorological data and surface charac-
teristics will be assessed simultaneously. Such informa-
tion will be used to develop the desired expressions.
This is an important task, since the link between
meteorology/surface observations and deposition velocities
is not well understood. However, the project description
is unclear as to the details of the parameterization. The
description implies that some form of mathematical model
will be developed. However, ASRL responses to reviewers'
questions indicated that no such models will be developed
as part of this particular task. Rather, the parameteri-
zations will consist of tables listing deposition
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velocities for various atmospheric and surface conditions.
The panel feels that more explicit definitions of
project tasks are needed, with clear statements of the
methods to be employed and the expected deliverables.
Despite problems with the project description, the panel
feels that parameterized listings of the deposition velo-
cities are worthwhile, and that the project is important
to the goals of Task Group D and should continue.
2.2.2 Development and Evaluation of Methods to Measure
Deposition Fluxes
2.2.2.1 Variance Method. Measurement of dry
deposition flux by the variance method may be more
appealing than other techniques if the method can be
developed. The primary advantage is that the necessary
measurements have resolution times which are slightly
relaxed compared with those needed for eddy correlation.
Pollutant monitors with time responses of 3-5 seconds,
rather than <1 second as needed for eddy correlation, may
thus be usable. The method was recommended for further
development by the 1979 Dry Deposition Workshop.
Initial results of this study of the variance method
indicate that ozone fluxes determined by this method agree
reasonably well with those determined by eddy correlation
when the former method is based on water vapor fluxes.
Agreement is poorer when heat fluxes are used, possibly
8
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due to greater sensitivity to the upwind fetch. Since
fast-response humidity sensors are expensive, and require
considerable maintenance, the variance method may be use-
ful primarily as a research tool. Initial work by the
contractor appears promising, and so continued work on the
project is worthwhile, even if the major utility of the
method is currently limited to the realm of research and
special studies.
2.2.2.2 Similarity/Heat Budget. Dry deposition
measurement by the similarity/heat budget (S/HB) method
offers the advantage that absolute turbulent fluxes need
not be measured. As a result, the method is less site-
specific than some of the other techniques. The time-
response requirements are similar to those of the variance
method. According to presentations made to the committee,
ozone is the only pollutant for which the S/HB method has
been successfully applied. However, the method is poten-
tially applicable for estimating the deposition of fine
particles.
This investigation of the S/HB method is in its early
stages of development. The technique appears to be worth
exploring, and continued funding is recommended.
2.2.2.3 Eddy Accumulation Method. This method was
developed in an attempt to overcome the problems of
measuring small concentrations of certain pollutants over
short time scales. The eddy accumulation method permits
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the species of interest to be collected over extended time
periods in two separate samples: one is activated by
upward-moving air and the other by downward-moving air.
The net flux to the surface is inferred from the dif-
ference of upward and downward fluxes.
An eddy accumulator has been built in-house by ASRL
and tested in the field. Unfortunately, data reported to
the panel from initial experiments involving water vapor
transport did not give reliable flux data. It is not
known whether the poor results were caused by data acqui-
sition problems or by fundamental difficulties with the
method.
The panel feels that work should continue despite the
disappointing initial results. The project is relatively
inexpensive, and although considerable additional develop-
ment work may be needed, the method offers promise as a
technique for pollutants which cannot be measured in real-
time.
2.2.2.4 Overall Evaluation of Direct Methods Research.
Based on work conducted over the past few years, it
appears that none of the micrometeorological methods dis-
cussed in this report (variance, similarity/heat budget,
and eddy accumulation) are likely to be useful for routine
monitoring of dry deposition by unskilled personnel.
Nevertheless, development of the methods for use in site
10
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calibration, quality assurance, and research purposes
justifies continued work as planned by ASRL.
2.2.3 ASRL Concentration Monitor
2.2.3.1 Development and Evaluation of the ASRL
Concentration Monitor. In order to measure atmospheric
concentrations of the gaseous and particulate species that
are of greatest interest for acidic dry deposition, ASRL
has developed a prototype device for the collection of
samples of these species. The design criteria for the
sampler include that it be usable reliably in a network to
measure mean day-time and night-time values of these
species over about one week periods with 15% or better
accuracy and precision. It is desired that analysis of
the samples be by the same methods used for wet deposi-
tion, for maximum comparability.
The development of this device appears to be
proceeding well. The basic design, including that of a
transition flow reactor, is well thought out and seems
sound. Many of the collection techniques for gaseous and
particulate species are based on accepted methods.
The test results shown to us for gaseous HN03, NH3,
SOpand N0« and for particulate SO^, N03, and NH^ give con-
fidence that the basic design is sound and that the ±15%
precision goal can be met. We were not shown data that
demonstrate whether the accuracy specification is being
11
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met for all of these parameters.
The sampler should be tested under a variety of
sampling and shipping temperatures, with realistic inter-
vals between sampling and sample analysis, to give further
confidence in its accuracy and precision under conditions
representative of network operation. Simultaneous
sampling for oxidants and NOX should demonstrate whether
or not the NO to N02 ratio is altered as Og is absorbed.
The planned improvements to the device to permit
sampling of H202 and 03 and for improved collection of HNOj
should be developed and tested. As discussed below, there
is an urgent need for this sampler for several purposes.
Therefore, even while the above improvements are being
developed in the laboratory, we recommend that several
such samplers should be deployed in the field to provide
an operational field evaluation before commitments are
made for permanent deployment.
The sampler does not yet have the capability of
measuring, or has not been tested for, other species of
interest to NAPAP, namely HC1, HCOj, Ca4*, PO^7 Na+, Mg**,
organic acids, and trace elements. Although it
should ultimately measure as many of these as practical,
these species are generally of less interest than those
which it already measures, or for which a sampling capabi-
lity is being planned. Therefore, we strongly recommend
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that deployment of this sampler should not await develop-
ment or verification of the capability to measure these
additional species.
2.2.3.2 Development of a Sized Particle Collection
System. A procurement request is being processed for
development of a method for sampling particles larger than
2 urn aerodynamic diameter with the concentration monitor
described above. The concentration monitor includes a
cyclone that excludes particles larger than 2 urn; the pro-
curement proposes modification to permit sampling in two
additional size ranges — 2-10 um and >10 urn.
The panel feels that an effort to measure 2-10 um
particles has merit and should be pursued. However, we
seriously question the merit of collecting the larger
particles by use of the airborne concentration monitor and
feel that the resources that would be devoted to this
purpose should be used elsewhere. The reasons for our
recommendation are numerous, and range from fundamental
questions about the scientific merit and validity of such
sampling to questions about the likelihood that such large
particle sampling can be accomplished at a cost that is
reasonable relative to its benefits.
Specifically, we point out that the deposition
velocity of such larger particles varies greatly with
particle size. Consequently, the range of sizes >10 um
must consist of several narrow ranges if the measurements
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are to have any meaning for dry deposition characteriza-
tion. An inlet that can sample particles >10 urn and that
maintains the same sampling characteristics over a wide
range of wind speeds would be relatively expensive to
develop and test. Finally, the possibility of gravita-
tional deposition of the larger particles in the flow
channels of the concentration monitor and its transition
flow reactor has to be considered.
We recommend that the resources available be
devoted to the 2-10 urn collector. That collector will
sample enough of the coarse mode of ambient aerosol to
identify whether it plays a meaningful role in acid
deposition. If research using the 2-10 jim collector indi-
cates that coarse particles do play a major role, then it
might be appropriate to undertake the more difficult task
of measuring particles larger than 10 urn. The issue of
>10 urn particle deposition may best be approached through
the use of surrogate surfaces (see Section 2.4.3).
2.2.4 Research Site Operation and Method Evaluation
Research (core) sites are necessary for the
measurement of parameters to determine dry deposition
flux, to field test the concentration monitoring techni-
ques, to intercompare methods of different theoretical
basis, and to gain experience applicable to the develop-
ment of the larger National Trends Network (NTN). Three
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sites are now operational: Argonne (funded through ANL),
Oak Ridge, and Penn State (funded through NOAA). Addi-
tional measurements are being taken at cooperative sites
at Champaign-Urbana (flat site of uniform surface), West
Point (flat site of broken vegetation), and Whiteface
Mountain (uniform vegetation on variable terrain).
One of the planned outputs of the effort at the
research sites is a manual for site planning and develop-
ment of NTN sites. While the choice of sites involves
many considerations, the need for a scientific basis for
the decision is critical. A poorly chosen site will
provide little useful data, be expensive, and erode confi-
dence in the ability to quantify the dry flux. It is
important, in the initial NTN site selection process, to
make use of the expertise gained from the research site
studies.
The choice of the three main research sites has been
well made, with careful consideration of the research
design. The initial emphasis is on uniform sites (the
easiest micrometeorological situation) of differing sur-
face/vegetation type, with extension to non-uniform sur-
faces and variable terrain. The time-integrated con-
centration monitoring techniques are being intercompared
with standard, realtime monitors as available. The use-
fulness of a 12-hour (day-night) sampling protocol is
being tested, as well as the concentration monitor system
15
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in general.
The concentration measurement and flux parameteriza-
tion protocols have thus far been addressing Oj, S02, HN03,
N02 and particulate matter. To meet the EPA goals, addi-
tional species are needed. Hydrogen chloride, ammonia,
nitrate aerosol, sulfate aerosol, and aerosol acidity have
all been previously identified as components of the net
acid flux which needed to be quantified. The alkaline
components, large particles and ammonia, have received a
lower priority than the acid species. However, both acids
and bases are needed to determine a net acid flux, and
thus should be considered in the design of research site
operations.
This effort is directed toward quantifying the dry
flux, which could be of magnitude equal to that of the wet
deposition. The uncertainties have been improved, but the
limiting factor is still the estimation of the dry deposi-
tion velocity (V
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long-term research. Improvements are expected in the
routines used to estimate V from the meteorological para-
meters as well as the surface characteristics and the
concentration parameter measurements.
The EPA goal is to estimate the dry flux over large
areas. However, the actual geographical areas over which
the concentration monitor is applicable are variable from
region to region, and are largely unknown. These will
need to be better understood for the NTN sites.
The dry flux measurement sites have added utility for
other Task Groups. While the research sites are designed
for method testing and protocol development, future moni-
toring sites should be cost-effective in their location.
In particular, dry deposition monitoring in the RTF area
should be directly coordinated with the materials effects
studies. A co-location of research activities between
Groups D & G in RTF, North Carolina would be desirable.
With respect to the usefulness of concentration
measurements and V estimations, it is uncertain what can
be expected as to sensitivity and precision. The concen-
tration measurement approach is anticipated to be accurate
within ±15% or better, and the V accuracy under the most
ideal site conditions currently ranges from ±30% for SO
to ±100% for fine particulate matter. These values imply
significant uncertainty in the final deposition flux esti-
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unavoidable. Improvements are needed to quantify the flux
within ±30% for all the above species which are important
to the net dry deposition acidity.
2.2.5 Evaluation of a Research Watershed
A preliminary field study of the feasibility of using
mass balance over a watershed (Penn State) to quantify the
wet and dry fluxes is near completion. The mass balance
approach is well founded, but a precision better than that
for the dry flux methods seems unlikely. This approach
would not have a general applicability.
The advantage of a watershed is that it provides a
check on the calculated dry flux and the measured wet
flux. It may be useful as an indirect confirmation of dry
flux measurements. However, since a watershed covers a
larger and less uniform area than the expected area of
representativeness for the dry flux sites, the results may
not be directly comparable.
The uncertainties associated with a watershed study
are large, and feasibility should be demonstrated before
future expenditures are made.
2.3 Proposed 30-Site Deposition Network
EPA/EMSL intends to deploy a nationwide network (NTN)
to measure trends in both dry and wet deposition. The
initial deployment of 30 sites is to take place in the
next two years, or so. Although this network is not the
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responsibility of ASRL, several of the ASRL activities
have bearing on the implementation of such monitoring, and
therefore we have taken the liberty of noting these cross-
laboratory implications.
The tentative plans for the 30 sites include equip-
ping each site initially with a monitor for (X.,
O
a device that samples ambient concentrations of key
species of interest to acidic deposition, and meteorologi-
cal instruments. The sites will not monitor dry deposi-
tion, but rather dry deposition will be estimated using a
concentration x V^ method currently under development by
the NOAA Atmospheric Turbulence and Diffusion Laboratory
(NOAA/ATDL).
Consequently, the quality of the trend data generated
by the network depends strongly on the quality of the
concentration measurements and the deposition velocity
estimates. Several methods could be considered for the
concentration measurements, including the ASRL Concentra-
tion Monitor, whose accuracy for the major species of
interest is likely to come close to the ±15% goal set as a
design criterion. The accuracy of the deposition velocity
estimates is likely to be poorer, however, and it could be
much poorer unless careful attention is paid to the design
of the network.
Bruce Hicks, the Director of NOAA/ATDL, indicated to
19
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the panel that the methodology they are developing for
estimating deposition velocity is highly preliminary. It
has only been tested against measurements at a few loca-
tions and only for S02, 03, and HN03 (and, with much
uncertainty, to N02); it has not yet been applied to par-
ticles. If the parametric method, at its present state of
development, were to be applied at an ideal site (one with
topographic and vegetative uniformity for at least 1 Km
around the measurement location) with properties similar
to those of the research sites. Hicks estimates that
weekly average deposition velocities would be accurate
within ±30% for 63 and SC^ (and, possibly N02) within ±50%
for HNO-J and ±.100% (rough estimate) for particles.
Hicks indicated that he was uncomfortable with use of
the ATDL method without considerable further development
and evaluation. He indicated that he had not been
approached concerning a site selection and measurement
approach appropriate for use with the parametric method.
It is clear that the success of the trends network
depends largely on reasonably accurate estimates of depo-
sition velocity. This places a sizeable responsibility on
ATDL for development of a suitable method for estimating
the deposition velocity. Major political decisions may
ultimately be made based on findings that depend on that
method.
This situation concerns the panel from two perspec-
tives:
20
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(1) There appears to be little communication between
ASRL and ATDL, and EMSL and ATDL, concerning the
deposition velocity method. Yet, both ASRL and
EMSL are undertaking projects under the
assumption that such a model will soon be
available.
(2) The selection of sites by EMSL for the 30-site
network is likely to be severely constrained by
the limitations of the deposition velocity esti-
mating method. EMSL needs to consider these
constraints in the network design. If it cannot
perform its task within acceptable accuracy
limits under these constraints, then it will
have to deploy sites at locations that will
provide lower accuracy (and hope the estimating
method will improve in the future). Alterna-
tively, it will have to delay the deployment of
monitors until the estimating method imposes
fewer constraints. In either case, acquisition
of acceptably accurate and complete dry deposi-
tion data would be delayed.
Considering these factors, the panel strongly recom-
mends that efforts be made to increase the level of
technical interaction between ASRL, EMSL, and ATDL on
issues related to dry deposition monitoring. Regular
meetings to review plans and progress are essential to
insure the highest possible probability of acquiring mean-
ingful data from the initial 30-site network.
The panel also recommends that the capabilities of
other qualified organizations be sought to assist develop-
ment of deposition velocity estimation methods. The cru-
cial role of the dry deposition velocity in obtaining flux
estimates for the 30-site network requires that a con-
siderable effort be devoted to parameterization of Vj .
21
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The overall efforts should be peer reviewed by experts to
maximize the chances of developing a viable method which
is of use to NAPAP.
2.4 General Comments
2.4.1 Management Team/Project Staff
Overall, the panel feels that the ASRL management
team represents a competent and motivated group of indivi-
duals. The presentations were reasonably well prepared.
The panel is pleased that ASRL has been candid and frank
concerning perceived weaknesses in their program. All
ASRL members with whom the panel interacted were receptive
to the critical evaluation being provided, and appeared to
be genuinely interested in obtaining feedback from the
panel to help improve their work. Similarly, the in-house
technical staff and external contractors appeared to be
competent in the areas being addressed.
2.4.2 Integration of Tasks to Achieve Program Objectives
The panel recognized the difficulties in coordinating
programs such as those in Task Group D. However, there
are a number of areas in which efforts toward better
coordination would be beneficial.
The manner in which the written material sent to
panel members was prepared is indicative of less-than-
optimal organization. For example, the in-house projects
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on the concentration monitor and eddy accumulator were
summarized by inclusion of one manuscript each, although
the bibliographies of both papers listed additional
manuscripts authored by ASRL personnel which were relevant
to the program objectives. The project descriptors for
the external contracts were incomplete in some cases
and provided little of the technical information needed
for proper evaluation. Without the scheduled presenta-
tions to the panel by ASRL members, as well as the un-
scheduled meetings with opportunities for additional ques-
tions, it would have been difficult to evaluate the pro-
gram. The panel feels that the written material submitted
for advance review should have provided enough information
to allow a reasonably thorough evaluation by individual
panel members prior to the meeting.
Several specific instances of coordination problems
were apparent. For example, field measurements in the
Materials Effects Program (Task Group G) have been
proceeding without accurate aerosol NOj or HNO3 monitor-
ing, in spite of development of an appropriate sensor by
ASRL (This is discussed in section 3.2.1.4.).
It would be especially useful for ASRL members to
have a better understanding of the deposition velocity
parameterizations being developed by NOAA, since the
success of the ASRL efforts depend, to a great extent, on
the success of these parameterizations.
23
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2.4.3. Related Research! Surrogate Surface Methods
Despite the sizeable research efforts at developing
micrometeorological methods, no funding is provided to
investigate surrogate surfaces. The reason for this is
probably historical: there have been sizeable expendi-
tures for acquiring NADP dustfall bucket data over the
past several years, which are now believed to have little
meaning. This unproductive use of resources has apparent-
ly prejudiced the feelings of many individuals researching
dry deposition against the use of any surrogate surface.
However, there is a growing body of evidence that
suggests surrogate surfaces may provide an inexpensive
means of acquiring direct dry deposition data applicable
to the goals of Task Group D. For example, several
gaseous species are removed efficiently by surfaces whose
aerodynamic resistance controls overall dry deposition. A
surrogate surface which reacts readily with these species
may provide direct estimates of the fluxes. An example is
the use of nylon surfaces to absorb HNO^. As another
example, deposition of large particles (greatly influenced
by sedimentation) may be easiest to measure with surrogate
surfaces rather than with airborne concentration measure-
ments; the latter requires accurate knowledge of the size
distribution to estimate fluxes, and sampling such large
particles is difficult.
24
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The panel recommends that research be initiated in
surrogate surface development. It should provide new
techniques for reliably and inexpensively measuring dry
deposition of some species.
2.4.4 Program Strengths and Weaknesses
The primary strengths of the program relate to the
competence of the personnel (in-house and external con-
tractors) , and the facilities available for conducting the
work. The objectives of the program are reasonably clear
and progress is being made toward achieving the objectives
in a way which will be of use to NAPAP.
The primary weaknesses of the program concern lack of
coordination in certain respects. Better communication is
needed among the external contractors, and between the
contractors and ASRL. Improved communication between Task
Groups is also needed.
2.5 Recommendations (In Approximate Order of Priority)
The recommendations that follow represent issues of
high priority discussed in detail and in context in this
portion of the report. In some cases, a single recom-
mendation synthesizes individual recommendations made for
several tasks. In addition to those given below, a number
of significant other recommendations appear in the general
discussion.
• Technical interaction between ASRL, EMSL and NOAA/
25
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ATDL on issues related to dry deposition moni-
toring and the proposed 30-site National Trends
Network should be increased, perhaps with regular
semi-annual meetings.
The capabilities of several qualified organiza-
tions should be sought to assist development of
deposition velocity estimations. The overall
efforts in this area should be reviewed periodi-
cally by a panel of experts from the international
scientific community.
Research in micrometeorological methods for dry
deposition measurement appears to be worthwhile
and should continue.
Spatial scales, over which the dry flux determina-
tions and concentration monitoring are representa-
tive, need to be identified.
The accuracy and precision of the ASRL Concentra-
tion Monitor should be evaluated over the range of
conditions likely to be encountered in actual
network operations.
Research into developing surrogate surfaces for
routine monitoring should be initiated. Particu-
lar emphasis should involve surrogate surface
design for assessing fluxes of reactive gases, and
of large particles which may play a role in
neutralizing depositing acids.
The collection of >10 urn airborne particles by the
ASRL Concentration Monitor is unlikely to be use-
ful, and should not be pursued.
Additional emphasis needs to be put on determining
the flux of alkaline species to determine a net
acid dry flux.
26
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Ill
MATERIALS EFFECTS PROGRAM - TASK GROUP G
3.1 Background
The ASRL program, Effect of Acid Deposition on
Materials, conducted for NAPAP, is primarily concerned
with those materials of construction deemed to be of broad
economic significance. They are listed as: galvanized
steel, weathering steel, exterior household paints, main-
tenance paints, automotive finishes, asphalt roofing
shingles, and concrete/cement.
The Materials Effects Program in ASRL is expected to
develop damage functions for these materials to
differentiate between the normal expected weathering and
accelerated weathering attributable to wet and dry deposi-
tion. These damage functions, the primary output of the
program, are to be provided to Task Group I (Assessments)
of NAPAP to permit comprehensive cost-benefit analysis of
acid deposition controls on materials damage effects.
Two related materials programs are the Gaseous
Air Pollutants (GAP) program of ASRL and the materials
effects research on stone and marble deterioration by the
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National Park Service (NPS). While the efforts of the
former are to a degree integrated with the ASRL effort,
that of the NPS appears not to be.
3.2 Task Reviews
3.2.1 Field Studies
3.2.1.1 Structural Materials-Metals (Task 3024).
Damage functions for seven metallic materials are being
developed from exposure data collected at five field
sites. The corrosion rates of the panels will be corre-
lated with data on weather, air pollutants and rain chem-
istry, all of which are being recorded simultaneously
with the exposure data. The seven materials are represen-
tative of the most common metals in the inventory. In our
opinion, additional metals need not be considered at the
present time.
The four sites at which measurements are now being
made are typical of rural (North Carolina and New York),
surburban (New Jersey) and urban (District of Columbia)
environments with low to medium concentrations of sulfur
dioxide. The opening of a fifth site in Steubenville,
Ohio, is a much needed extension of the program to cover
industrial environments with high concentrations of sulfur
dioxide. It would be desirable to open one more exposure
site preferrably downstream from a combined urban/in-
dustrial area.
28
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.The exposure racks at the North Carolina, New York
and New Jersey sites are installed in open areas with
natural ground cover. The weathering racks at the Dis-
trict' of Columbia and Ohio sites are located on the roofs
of buildings, subjecting the specimens to the heat radia-
tion from the asphalt roofs and emissions from roof top
vents. This creates microenvironments not typical of the
macr©environments, particularly with regard to the forma-
tion of dew. The researchers should modify the exposure
conditions in a manner that eliminates the microenviron-
ment effects. Microenvironments are also being created
below the transparent covers that shelter the weathering
racks against rainfall at the North Carolina site. These
racks should, accordingly, be modified.
Exposure times of one month are too short for mean-
ingful studies of the effect of weather and pollution. The
researchers did well to end these tests. The three-month,
one-year, and three-year exposure times are suitable for
studying the seasonal and short-term effects of atmos-
pheric constituents. We understand that longer exposures
may not be feasible under the time constraints of this
project. However, we strongly recommend the initiation of
long-term exposures. Most buildings and bridges last more
than 50 years. Damage functions cannot be reliably extra-
polated from 3 to 50 years. If the number of specimens
29
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from the same batch is limited, some replicate three-month
or one-year exposure tests could be converted to long-term
exposure tests.
The simultaneous acquisition of corrosion, weather,
and air pollution data is valuable. A successful correla-
tion of two sets may yield, perhaps for the first time in
the United States, the functions needed to estimate, over
a large geographical area the corrosion damage to metals
from acid deposition. The researchers should, without
delay, begin to correlate the exposure data with the
weather and air pollution data, so as to identify the
significant variables at an early stage of the program.
An understanding of the phenomena would allow, if needed,
adjustments in the experimental program.
We were not given an indication of the approach that
will be used to construct damage functions. As a word of
caution, we would like to emphasize that multivariate
regression analysis describes the data within the range of
the variables tested, but it is not a substitute for a
mathematical model founded on an understanding of the
physical-chemical mechanisms. The weight loss data must
be carefully examined and interpreted in terms of the
weather and air pollution data and the results of the
microanalysis of the corrosion products. The development
of damage functions should begin at once.
30
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3.2.1.2 Non-Metallics. Analogous to the task on
metallic materials, Section 3.2.1.1, the objective of this
task is to derive damage functions for exterior paints by
conducting field exposure studies. The intent is to
characterize the paint film damage in terms of erosion of
the film, its surface chemistry, and changes in surface
reflectance. The damage will be related to the meteoro-
logical, pollution, and rain chemistry data that are being
simultaneously monitored.
The approach raises questions with regard to the time
of exposure, type of substrate, and development of damage
functions. Three years may not be sufficient to signifi-
cantly damage the paint film, especially when that coating
is applied on a passive substrate such as the stainless
steel panels being used in this study. For example, the
service life of paint coatings on highway bridges fabri-
cated from carbon structural steel varies from about eight
years in the moist and chloride-contaminated microenvi-
ronments that occur in the Northeast and Midwest to about
30 years in the dry environments in the southwestern
states. The researchers face, in this task, a problem
similar to that in the field study of metals, namely, of
having to derive damage functions from short-term expo-
sures and extrapolating the results to long-term service
life. Longer exposures are needed.
31
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Our second comment relates to the type of substrate
on which the paint coating is applied. In our opinion,
the paints should be tested in combination with a
realistic substrate. We agree with the Paint Workshop's
recommendation to test a paint system on hot-rolled steel
substrate. Advice on the choice of a suitable paint for
hot-rolled steel should be sought from specialists, such
as the staff of the Michigan Department of Transportation,
Lansing, Michigan, who are the leaders in the qualifica-
tion of commercial paint systems. The proposed tests of
latex paint applied on western red cedar are discussed in
Section 3.2.3.1.
The third comment relates to the measurement of
damage. As noted in the Paint Workshop's recommendations,
failure is to be assessed visually in terms of blistering,
lack of adhesion, substrate rusting, and rust spots on the
film. We foresee difficulties in relating such visual
observations to weather and air pollution data, and quan-
tifying them in damage functions for a given paint/sub-
strate system.
We recognize that the paint industry may tradition-
ally have exposed samples at a 90°angle from the horizon-
tal. However, the choice of the vertical exposure for
testing the paints in this task, as compared to the 30°
exposure of the bare metallic samples (Section 3.2.1.1),
32
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introduces one additional variable, without providing any
advantages. Furthermore, a slanted surface may be better
for studying the effect of acid deposition.
We recommend that the researchers carefully review
their current plan for testing and analysis before they
continue with the field studies.
3.2.1.3 Acid Rain Simulator. The objective of the
study is to quantify separately the effects of wet and dry
acid deposition on steels and household paints exposed to
ambient weathering. Three conditions are being studied:
(1) dry only; (2) dry and ambient wet (4.5 pH average at
RTF for rain); and (3) dry and controlled wet (5.6 pH
spray).
It is well known that rain washing of pollutants off
the surfaces of weathering steel structures helps the
steel develop a protective oxide coating. Based on this
experience, one would, for example, expect higher cor-
rosion rates for weathering steel exposed to the "dry
only" condition, and lower corrosion rates when skyward-
facing surfaces are rinsed by the rain or the controlled
spray. The other materials being tested may behave in a
similar manner. Dry deposition will likely be the con-
trolling factor, with rinsing being beneficial. The
effect of the average 1.1 pH unit difference between the
rain and the spray water could be masked by the generally
33
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beneficial effect of rinsing. The expected results may
lead to the incorrect conclusion that the dry deposition
is damaging to the materials, the wet deposition is bene-
ficial, and the pH of the rain is not a factor.
The interpretation of the results needs to consider
conditions not modeled by the experiments. For example,
rain water collecting on horizontal and poorly drained
surfaces in actual structures can increase the effect of
acid deposition.
This experiment is elaborate and expensive. We
recommend not placing a simulator at the Steubenville site
until the researchers have fully characterized the results
from the RTF site and understood the significance of the
findings. Snowfall adds an uncertainty to the planned
exposures at the Steubenville site that needs to be re-
solved. The pH of the rinsing water at the RTF site
should be periodically checked.
3.2.1.4 Site Monitoring. Air quality and meteorology
are being monitored at all five of the exposure sites.
Local agencies perform the measurements at three of the
sites, with the primary purpose of the measurements being
other than the materials effects program. ASRL is sup-
porting the measurements at the Newcomb, New York, and
Research Triangle Park, North Carolina, sites.
Each site measures S02» NOX, and O3 continuously.
34
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Dichotomous samplers, specially modified to collect
samples over a one-week period, collect fine and coarse
fractions of PM-10 participate matter. These filters are
analyzed for mass, elements (by XRF), and 804 and NO3 (by
ion chromatography). Total suspended participates are
also measured similarly. Monthly-averaged rain samples
are analyzed for pH and various ions. Meteorology (wind
speed and direction, temperature, relative humidity, pre-
cipitation rate, and solar radiation) are measured con-
tinuously. It is expected that all of these variables
play a role in the deposition of acidic material to the
exposed samples.
The monitoring sites lack the ability to measure
gaseous nitric acid and the nitrate analyses of the dicho-
tomous samples do not properly reflect particulate nitrate
because of volatilization of some of the material on the
filters. We recommend adding a sampling method that
properly characterizes NO^ and HNC>3 at all sites; the ASRL
Concentration Monitor would serve this need.
Relative humidity is measured by hair hygrographs
that are calibrated infrequently. Such instruments are
known to easily change calibration. We recommend, as a
minimum, that their calibration be checked weekly by com-
parison with a psychrometer. Installation of a more
reliable humidity recording system would be preferable.
Although we recognize that such systems are expensive,
35
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they are compatible with electronic recording of the data,
which would reduce the costs of handling and reducing
recording charts.
Quality assurance procedures for the aerometric
monitoring at the sites appear to be uneven. The sites
operated by local agencies comply with EPA QA procedures
for monitoring, which are focused at concentration levels
near ambient air quality standards. The systems and
performance audits that will be performed for the sites
are desirable, and the planned calibrations at low concen-
tration levels are absolutely necessary. We hope that
these calibrations will be repeated at regular intervals.
3.2.1.5 Aerometric Data Base The compilation of the
aerometric data into a data base that is suited for analy-
sis is absolutely necessary for the success of the expo-
sure program. The aerometric data base management task
appears to be accomplishing this successfully.
However, the data base would be most effective if it
were designed for use with the data analysis procedures
planned for the program. We did not see that a plan for
data analysis had been formulated, or that the data base
design had been adapted to such a plan. This is a serious
shortcoming of the materials exposure program that is
discussed in greater detail in Section 3.3.3 below.
36
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There did not appear to be a procedure for applying
calibration factors to datar which may become necessary.
A desirable feature of the data base is the ability to
flag data that deserve special attention because of poor
quality, need for special calibration, or other factors.
We hope that this feature will be utilized.
3.2.2 Chamber Studies
The panel strongly supports the chamber study effort.
Host significant is the growing interest in characteriza-
tion of corrosion layers, mass balances, and reaction ki-
netics. This represents a marked strengthening of the ASRL
materials programs which in the past relied too heavily on
regression analysis of simple weight loss data. It is
important to recognize that the determination of reaction
mechanisms is essential to the development of mitigative
strategies and to the assignment, with confidence, of the
proportions of damage attributable to wet and dry deposi-
tion. It does not appear that the group has expertise in
corrosion mechanisms, or has sought the advice of appro-
priate experts. An understanding of corrosion mechanisms
will be essential, not only to interpretation of the data
obtained in chamber studies, but also for the inter-
pretation of field exposure data. For example, the rever-
sal in corrosion rates observed for Cor-Ten A and 110
copper exposed at the Washington, DC and RTF sites is
37
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possibly due to microenvironmental influences on reaction
kinetics and mechanisms. Yet, no attempt has been made to
explain these data from a mechanistic viewpoint.
3.2.3 New Projects fFY 86)
Four new projects with total support level of
$500,000 were described briefly. Two involved the
extension of materials effects studies to new areas,
namely concrete and masonry structures and asphalt roofing
shingles. A third proposed an expansion of the non-
metallic study to investigate initial effects on paint
films on wood substrates. The fourth encompassed
placement of corrosion rate monitors developed under the
GAP program at the five field exposure sites.
3.2.3.1 Initial Effects on Painted Wood Substrates.
The proposed extension of the painted surface study to
include wood substrates, chamber studies, initial effects,
and the mechanism of paint film failure is based, in part,
on the recommendations of the recent workshop on exterior
paints held at RTF. This use of industry expertise in a
cost-effective manner is to be commended.
Only a brief outline was given of the proposed work.
The panel is concerned that the substantial complexities
introduced by the new substrate (wood) will unduly
complicate the chamber study of paint films. Similarly,
the experimental designs for the FTIR and thermometric
38
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studies are not yet defined. It is recommended that the
initial effort be directed toward the development of ex-
perimental protocols and test methods. Field exposure of
paint films on wood substrates is considered premature.
Consideration should be given to the workshop
observations that: (1) historical field exposure data may
provide the best means of determining actual service life,
and (2) damage measurement techniques should correlate
with painting frequency.
3.2.3.2 Effects on Concretg^and Masonry Structures.
The extensive use and wide distribution of concrete
structures suggests that this material be investigated for
possible acid deposition effects. However, the well-known
role of chloride ion in the decay of reinforcing steel and
the strongly alkaline nature of the concrete matrix
suggests that a relatively small proportion of observed
damage may be associated with acid deposition. Since
substantial research and use experience are available, it
is recommended that a workshop be conducted at RTF to
review the state of concrete structure use experience and
damage mechanism research prior to initiation of the lab-
oratory study (Phase I), or the field survey involving
core sampling of existing structures (Phase II).
3.2.3.3 Effects on Roofing Asphalt Shingles. Asphalt
roofing shingles complete the list of construction
39
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materials of economic significance under consideration by
EPA. Some sense of service life cycles and failure
mechanisms is required before initiation of laboratory and
field investigations. It appears appropriate to limit the
effort for FY 86 to the initial literature survey (Phase
I).
3.2.3.4 Evaluation of Corrosion Monitor at Exposure
Sites. The panel was informed of the proposal to evaluate
corrosion monitors developed under the GAP program at
materials exposure sites. As noted in the 1984 review of
the GAP Materials Damage Program, the response of the
corrosion monitor to atmospheric pollution and raeterologi-
cal variables is not yet fully understood. It is not
obvious that this device will prove useful in the proposed
task of comparing short-term effects for the diverse
materials, e.g., steel, concrete, limestone, marble, paint
films, and asphalt, either in place or eventually to be
placed at the field exposure sites.
3.3 general Comments
3.3.1 Management Team/Project Staff
The management and project staff team has
demonstrated initiative, industry, and the ability to work
together effectively. They have made good use of the
workshop on paint damages to obtain guidance in an
unfamiliar area.
40
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The 1983 review panel for this project observed that
•the smog chamber studies may soon lead to questions of
corrosion mechanisms, a field with many experts." It is
disappointing that no effort has been made to follow their
recommendation that contact soon be made with such experts
to obtain guidance and to assure the success of the
studies.
3.3.2 Integration of Tasks to Achieve Program Objectives
The stated goal of this program is to "develop
materials damage functions that partition effects of wet
and dry deposition for use by Task Group I, Assessment, to
develop a cost benefit model." The panel believes that
inadequate attention has been paid to the uncertainties
associated with the use of damage functions derived from
short-term field exposure or chamber studies in the
development of the cost benefit model (Figure 2) that will
be used to conduct an economic assessment of acid deposi-
tion damage and to prepare an acid deposition control
strategy. This issue is documented in the following sec-
tion.
3.3.3 Relationship Between Field Studies, Chamber Studies
and Damage Functions
For results from controlled chamber studies to be
related to field studies and interpreted as damage
41
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COST BENEFIT MODEL
MATERIALS
DAMAGE
FUNCTION
—+
COST
FUNCTIONS
»-
MATERIALS
INVENTORY
t
—
ECONOMIC
ASSESSMENT
CONTROL
STRATEGY
• FIELD EXPOSURE PROGRAM
• CHAMBER EXPOSURE PROGRAM
Figure 2. Task Group G Effects on Materials
and Cultural Resources
42
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functions, physical-chemical mechanisms must be proposed.
The -models are tested statistically, and best fits of
coefficients determined. The hypothesis is well developed
before the use of statistical methods. The variety of
possible mechanisms and environmental conditions make
engineering approximations appropriate for the simplifica-
tion of the damage functions, but experimental design roust
be more than empirical measurements with regression
relationships. Otherwise, the response is known only over
the range of test conditions and cannot be extropolated to
new environmental conditions.
Once a model is proposed and tested, the
uncertainty in each bit of data must be carried through to
the final step of the determination of the damage
function. The propagation of errors must be determined
for the final results. The standard deviation among
replicate samples is not adequate for the interpretation
of overall uncertainty.
In the chamber studies, concentrations have been
measured for air species and metal and anion corrosion
products. A mass balance approach is being considered. In
practice, the small differences in relatively large
numbers makes the comparison of material lost with cor-
rosion products leached impractical. Once the products
are collected, linear relationships are considered between
43
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product species. Non-linear relationships (e.g., pH con-
trols of solubility) have not been considered/have not
been used, and measurements of carbonates (a corrosion
anion product) have not been made. Approximate linearity
may exist between many species, making it difficult to
determine the mechanism or cause of damage. This can be
partially alleviated by the use of more controls. How-
ever, it is doubtful synergistic effects will be under-
stood without an experimental design based on the test of
specific physical-chemical mechanisms. Even the transport
mechanism, such as thermophoretic effects in the dew con-
densation system, as compared to the real world, should be
reconsidered.
With the limitations of the understanding of the
chamber study results, the interpretation of the field
studies becomes phenomenological. The damage functions
for metals could be determined from the short-term chamber
study results. Expansion of the testing in the chamber
studies is needed to generate damage functions.
In the environmental conditions with the most rapid
corrosion, the surface resistance to the deposition
velocity should be determined. This parameter could be
related to the field studies, even with variable meteoro-
logical conditions.
The main concern in the link between chamber studies,
field experiments, and damage functions is that the damage
44
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is a long-term process, yet the best data for the damage
function will be based on short-term studies.
Considerations of long-term mechanisms and failures become
crucial. Long-term studies are needed, either under NAPAP
or air quality funding sources.
3.3.4 Related Research
The visit to the RTP field exposure site demonstrated
the substantial commitment of the National Park Service
(NPS) to field exposure studies for marble and limestone.
These materials should be considered for parallel chamber
studies under the direction of the Materials Effects
Program under review since the NPS has neither the
resources (smog chamber and associated hardware) nor the
expertise necessary to conduct such work.
3.3.5 Program Strengths
The selected experimental designs are being performed
well. The chamber studies are well controlled. ASTM
standard exposure procedures are followed. The results
are reproducible. The right metals have been chosen for
study. The simultaneous measurement of air quality in the
field appears excellent, with the exception of the omis-
sion of HN(>3.
3.3.6 Program Limitations
The materials effects program suffers from the in-
herent limitation of studying long-term processes over a
45
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relatively short time. This is recognized and may not be
avoidable.
There is some question of representativeness.
Standard methods have been used for reproducibility, but
there is a concern that precipitation acidity effects will
be largest on materials which collect/retain
precipitation. The orientation of test specimens mini-
mizes contact with wet precipitation and its effects.
In particular, snow has not been addressed. Its
importance to material damage in terms of snow melt is
unknown, but deserves consideration.
The major limitation is in the characterization of
the mechanism of corrosion. While overall rates are
empirically determined, the mechanism is still unknown.
With the high covariance of the depositions of chemical
species, the agent of corrosion is obscured.
An overall plan is needed to determine damage
functions from the field and chamber measurements.
3.3.7 Quality Assurance and Quality Control
Quality assurance and quality control are an integral
part of all environmental research. The researchers have
a healthy appreciation of the limitations of specific
analytical procedures. They have made commendable efforts
at upgrading the QA for continuous monitors used in the
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field and laboratory studies.
A few limitations were noted. The metal measurements
need to be confirmed by using split samples, and the
method of standard additions to the liquid samples.
Hydrogen peroxide is currently not considered in the cor-
rosion modeling of condensation on metals for lack of a
method of good quality assurance. This needs to be recti-
fied to provide a measure of oxidants. Samples are not
routinely subjected to a complete anion and cation
balance, a standard QA technique which also provides use-
ful information about acidity. Similarly, aerosol
measurements do not determine ammonium or acidity and
instead focus on nitrates, sulfates, and elements by XRF.
All chemical determination techniques should be tested for
quality assurance by either cross calibration with an
alternate technique, or internal consistency between
measurements with respect to mass, charge, or conductivity
for a percentage of the samples.
3.4 Recommendations fin Approximate Order of Priority!
The recommendations that follow represent issues of
high priority discussed in detail and in context in the
body of this portion of the report. In some cases, a
single recommendation synthesizes individual recommenda-
tions made for several tasks. In addition to those given
below, a number of significant other recommendations
47
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appear in the general discussion.
• Study of physical-chemical mechanisms for cor-
rosion should be incorporated into the research
design, and carried through to the damage
functions.
• A plan needs to be developed for the analysis of
exposure data, and the development of damage
functions.
• The aerometric monitoring at the materials
exposure sites should be augmented to include
nitric acid and proper measurement of particulate
nitrate. The ASRL Concentration Monitor could
satisfy this need.
• A series of workshops is recommended for obtaining
guidance for the proposed new efforts in paint
films on wood substrates, asphalt roofing
shingles, and concrete before field exposure and
laboratory studies are initiated.
• A modification of the field exposure program to
extend measurements to long-term exposures should
be initiated. Placement of a second acid rain
simulator at the Steubenville site should be
delayed until the results from the RTF prototype
are characterized and understood.
• Propagation of errors should be carried through
the testing.
• Effects of snow and irregular surface geometry
should be considered.
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APPENDIX A
AGENDA - PEER REVIEW OF THE ACID DEPOSITION,
DRY DEPOSITION, AND MATERIAL DAMAGE PROGRAM
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AGENDA
Peer Review of the Acid Deposition Dry Deposition
And Materials Damage Program
April 23 - 25, 1985
TIME
TOPIC
SPEAKER
Tuesday, April 23
8:00 - 8:15
8:15 - 8:30 a.m.
8:30 - 8:35 a.m.
8:35 - 8:45 a.m.
8:45 - 9:20 a.m.
9:20 - 10:15 a.m.
10:15 - 10:30 a.m.
10:30 - 11:00 a.m.
11:00 - 11:30 a.m.
11:30 - 1:00 p.m.
1:00 - 1:15 p.m.
1:15
2:00
2:30
3:00
2:00 p.m.
2:30 p.m.
3:00 p.m.
3:15 p.m.
(Raleigh Inn - Raleigh, NC)
Opening Session
Welcome
Peer Review Program Orientation
ASRL Peer Review Coordinator
(Closed Session)
Coffee and Donuts in Meeting Room
DRY DEPOSITION MEASUREMENT PROGRAM
Session Called to Order
Dry Deposition Measurement Overview
Direct Dry Deposition Methods
Extramural Projects
In-house Project
Concentration Monitor Projects
BREAK
Core Sites and Deposition Velocity
Parameterization
Questions and Discussion
LUNCH
Overview of Materials Effect
Research Program
MATERIALS FIELD EXPOSURE PROGRAM
Structural Materials
Deterioration of Non-Metal lies
Acid Rain Simulator
BREAK
C. Coley
R. Patterson
R. Patterson
K. Knapp
T. Ellestad
R. Speer
K. Knapp
T. Ellestad
J. Spence
D. Flinn, BOM
J. Spence
E. Edney, NSI
49
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- 2 -
TIME
TOPIC
SPEAKER
Tuesday. April 23 (cont.)
3:15 - 3:45 p.m.
3:45 - 4:15 p.m.
4:15 - 5:00 p.m.
5:00 p.m. - Until
Wednesday, April 24. 1985
8:30 - 9:30 a.m.
9:30 - 10:00 a.m.
10:00 - 11:00 a.m.
11:00 - 12:00 p.m.
12:00 - 1:30 p.m.
Site Monitoring
Data Base Management
Questions & Discussion
Reviewer Debriefing with Dr. Alfred H.
Ellison, Director, ASRL (M-303)
(Research Triangle Park, NC and
Raleigh Inn, Raleigh, NC)
Materials Chamber Exposure Program
Chemistry of Acid Precipitation
Effects on Materials (EPA: M-303)
New Projects
Site Visit - Materials Exposure
Visit Exposure Chambers
Site Visit - Dry Deposition
Measurement Methods (ERC Annex)
LUNCH (NIEHS)
National Institute of Environmental
Health Sciences Cafeteria
1:30 - 2:30 p.m.
2:30 -
Telephone Call to Bruce Hicks
Return to Hotel
Executive Session
Thursday, April 25, 1985 (Research Triangle Park)
8:30 a.m. - Executive Session (EPA/D-102)
J. Spence
J. Graham, CSC
Closed Session
E. Edney
J. Spence
E. Edney
D. Stiles, NSI
K. Knapp
Closed Session
Closed Session
50
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APPENDIX B
EPA-ASRL PEER REVIEW PANEL
-------
REVIEW PANEL
ACID RAIN (TASK GROUPS D & G) PROGRAM
April 23 - 25, 1985
Name:
Work Address:
Area(s) of expertise:
Name:
Work Address:
Area(s) of expertise:
Name:
Work Address:
Area(s) of expertise:
Name:
Work Adress:
Area(s) of expertise:
Name:
Work Address:
Area(s) of expertise:
Norbert S. Baer, Chairman
Professor of Conservation
New York University
14 East 78th Street
New York, New York 10021
212-772-5846
Materials damage effects, preservation of
cultural property
Pedro Albrecht
Department of Civil Engineering
University of Maryland
College Park, Maryland 20742
301-454-5228
Atmospheric corrosion of structural steels
Cliff I. Davidson
Associate Professor of Civil Engineering and
Public Policy
Carnegie-Mellon University
Pittsburgh, Pennsylvania 15213
412-578-2951
Aerosol deposition, trace elements
characterization and human exposure,
historical air pollution trends
Howard M. Liljestrand
Assistant Professor
Civil Engineering, Environmental Engineering
Group 8.6 ECJ
University of Texas
Austin, Texas 78712-1076
512-471-5602
Acid-base deposition mechanism-tracers of
acid/bases and receptor models, wet & dry
deposition mechanism of aerosols and gases,
reactions upon deposition to materials, box
models of the atmosphere, kinetic models
related to aerosol and acid producation.
Ivar H. Tombach
Vice President, Environmental Programs
Aero Vironment, Inc.
825 Myrtle Avenue
Monrovia, California 91016
818-357-9983
Visibility, aerosol physics, fluid mechanics
51
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APPENDIX C
PROCESS EVALUATION REPORTS
-------
ATMOSPHERIC SCIENCES RESEARCH LABORATORY
PEER REVIEW
Process Evaluation Results for the
Dry Deposition and Materials Effects Program
The Atmospheric Sciences Research Laboratory (ASRL) of the
U.S. Environmental Protection Agency convened a panel of scientific
experts on April 23-25, 1985, to review the Dry Deposition and
Material Effects Program. The panel consisted of five scientists.
These reviewers were asked to evaluate the process involved in
preparing and implementing this review. This report presents their
opinions of the process for this specific meeting.
The evaluation instrument was designed to assess the following
aspects of the process: (1) Preview Materials; (2) Process and
Logistical Information; and (3) the Review Meeting. A section was
also provided for reviewers to give their comments and recommenda-
tions. The reviewers were instructed to respond to 15 items by
circling numbers from 1 to 5 (with 1 representing poor; 2-fair;
3-good; 4-very good; and 5-excellent).
Only three of the five panel members have submitted a process
evaluation form. Overall, the reviewers' evaluation of the peer
review process was positive. Most of the areas in the instrument
generated "very good" and "good" ratings. Only two items were
rated fair. One panel member rated the utility of the preview
materials for outside reviewers as fair, commenting that they were
incomplete. The adequacy of time for review panel executive
52
-------
sessions also received one fair rating because the commenting panel
member felt more time was needed. None of the reviewers rated any
item as "poor". Table 1 presents a summary of the reviewers'
ratings, as well as their specific comments and recommendations.
53
-------
Preview Materials
Table 1
Review Cateqories
1
I Number of Reviewers
I Rating Each Item
1 Very
I Poor Fair Good Good Excellent
1. Written Qua'ity
2. Technical Quality
3. Utility for Outside Reviewer
4. Adequacy of Time Available
to Preview
1
2
1*
1 4
Process and Logistical Information
5. Meeting Purpose
6. Scheduling of Meeting:
Agenda/Format
7. Reviewer Responsibilities:
Time/Preparation Requirement
8. Overall Peer Review Process
9. Timeliness of Meeting
Notification
10. Timeliness of Logistical
Information
1 1
1 1
1 1
1 1
3
1 1
Review Meeting
11. Adequacy of Time for Discussion
With EPA Staff
12. Adequacy of Time for Executive
Session
13. Quality and Utility of
Presentations
14. Quality and Utility of Materials
Disseminated
15. Support Services and Activities
1" 2
1 2
TOTALS
17 17
* "incomplete"
** "need more time"
*** "very good support by Research and Evaluation
Associates Staff"
54
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Reviewers' Comments
"The lion's share of the useful review materials were distributed
after our arrival at RTP, or during (or after) presentations. This
made preparation of a first draft review report (as suggested in
the introductions) impossible."
"The support by the Research and Evaluation Associates staff was
excellent. The hotel facilities were poorly managed by the hotel.
The lodging was OK, though."
"The time needed to prepare a coherent report is somewhat more than
the time we were given, even though most of us gave up a good
portion of the night's sleep to get this job done."
"The only weakness in the review process is the time constraint on
Review Panel Discussion as the report is written. That a highly
responsible committee averaged 4-5 hours sleep, essentially skipped
dinner (24), skipped breakfast and lunch (25) during the period
Wednesday (24) 3 PM thru departure, Thursday (25) 3 PM and still
had but little time to discuss the completed draft report indicated
to this reviewer that the schedule is a bit tight."
Reviewers' Recommendations
"I would not eliminate any aspect of the review process but would
suggest that a later departure (session closing time) be scheduled
for the last day. I think we all agreed that one wants the best
posible draft submitted at the time of adjustment, rather than a
weak draft to be upgraded later."
55
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APPENDIX D
ASRL RESPONSES TO REVIEWERS' COMMENTS
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
ATMOSPHERIC SCIENCES RESEARCH Ufr.tUiRATORY
RESEARCH TRIANGLE PArtK
NORTH CAROLINA 27711
MEMORANDUM
DATE: July 8, 1985
SUBJECT: Response to Peer Review Garments on Materials Effect Program
FROM: John Spence, Project Manager
TO:
Ron Patterson
Technical Planning and Review Office
THRU: William Wilson
Acting Director, EMCD
1.
2.
3.
Reviewers' Comment
"The researchers should modify
the exposure conditions in a
manner that eliminates the
microenvironment effects.
Microenvironments are also
being created below the trans-
parent covers that shelter the
weathering racks against rain-
fall at the North Carolina
site. These racks should,
accordingly, be modified."
(p. 29)
"We understand that longer
exposures may not be feasible
under the time constraints of
this project. However, we
strongly recommend the initi-
ation of long-term exposures.1
(p. 29)
"The researchers should, with-
out delay, begin to correlate
the exposure data with the
ASRL Investigators Response
Meteorological instrumentation have
been installed adjacent to the material
exposure racks at the DC and Ohio sites
in an attempt to measure the microen-
vironment associated on the roof. Air
sampling is also taken at roof top at
both sites. In addition to these
measurements, a corrosion monitoring
device (developed under GAP), which
is an excellent time-of-wetness sensor,
is proposed for installation at all
material exposure sites in FY86.
The transparent covers installed by
BOM are considered experimental
devices that will likely be modified
during the study. The BOM has developed
the covering device to insure consistent
corrosion of samples under the device.
Under the NAPAP, the maximum exposure
time of materials is likely 3 to 5
years. Longer exposure periods (10-
20 years) are not possible within the
existing NAPAP.
Vfe agree. Correlation studies are
planned in FY86. The main problem
which could delay these studies is
56
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weather and air pollution
data, so as to identify the
significant variables at an
early stage of the program.
An understanding of the
phenomena would allow, if
needed, adjustments in the
experimental program."
(p. 30)
"We were not given an indica-
tion of the approach that will
be used to construct damage
functions. As a word of
caution, we would like to
emphasize that multivariate
regression analysis describes
the data within the range of
the variables tested, but is
is not a substitute for a
mathematical model founded
on an understanding of the
physical-chemical mechanisms.
(p. 30)
"The researchers face, in this
task, a problem similar to
that in the field study of
metals, namely, of having to
derive damage functions from
short-term exposures and ex-
trapolating the results to
long-term service life.
Longer exposures are needed."
(p. 31)
"Advice on the choice of a
suitable paint for hot-rolled
steel should be sought fran
specialists, such as the staff
of the Michigan Department of
Transportation, Lansing,
Michigan, who are the leaders
in the qualification of ccm-
mercial paint systems. The
proposed tests of latex paint
applied on western red cedar
are discussed in Section
3.2.3.1." (p. 32)
the computerization and validation
of the aeronetric data base.
Chamber exposures of materials and the
analysis corrosion products of field
exposed materials will provide insight
into the physical-chemical mechanisms
of degradation. This information will
support the development of damage
functions via multivariate regression
analysis of field exposure data.
In the non-metallics program, exposures
beyond 3-years are planned. This was
apparently missed in the review.
We agree. Test panels of an alkyd on
hot-rolled steel are being prepared
by the Steel Structures Painting Coun-
cil for exposure at the materials
sites in FY86. This study will be co-
ordinated with other exposure programs
of the alkyd paint that the Steel
Structures Painting Council is spon-
soring.
An Interagency Agreement (IAG) with
the Forest Products Laboratory is
57
-------
"We foresee difficulties in
relating such visual ob-
servations to weather and
air pollution data, and
quantifying them in damage
functions for a given paint/
substrate system." (p. 32)
"We recognize that the paint
industry may traditionally
have exposed samples at a 90°
angle from the horizontal.
However, the choice of the
vertical exposure for testing
the paints in this task, as
compared to the 30° exposure
of the bare metallic samples
(Sect ion 3.2.1.1), introduces
one additional variable, with-
out providing any advantages.
Furthermore, a slanted surface
may be better for studying
the effect of acid deposition.'
(p. 32)
"This experiment is elaborate
and expensive. We recommend
not placing a simulator at the
Steubenville site until the
researchers have fully charac-
terized the results from the
RTF site and understood the
significance of the findings.
Snowfall adds an uncertainty
to the planned exposures at
the Steubenville site that
needs to be resolved. The
pH of the rinsing water at
the KTP site should be peri-
odically checked." (p. 34)
planned for late FY85. This IAG will
involve laboratory testing of latex
paints applied on western red cedar.
The main problem with visual inspec-
tion of the field exposure alkyd
paints is the time it takes to see
film failure (substrate rusting).
The visual observations using color
photographic standards according to
ASTM procedures will be used. In
conjunction with the field exposures,
chamber exposures of the alkyd paints
are planned for FY86 to assess early
film failure under controlled pollu-
tant environments. This study will
investigate the use of thermography
and other techniques to detect early
film failure.
All of the painted panels are exposed
at 90° in accordance with ASTM D
1006-73. If painted wood substrates
are incorporated into the field expo-
sure program, panels will likely be
exposed at the vertical and horizontal
positions.
The placement of a mobile covering de-
vice at the Steubenville site is
scheduled for FY85 and should not be
delayed. The decision to place mobile
covering devices with simulated rain
at the RIP and Steubenville sites is
based on a two-year study of metals
and coatings using a covering device
at the KTP exposure site. The Steuben-
ville site has considerably higher
SC>2 levels than the RIP site. The
covering devices at both locations
will be used to separate the effects
of dry deposition (802) and clean rain
(pH 5.6) on materials degradation.
58
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10.
11,
12.
13.
14.
"The monitoring sites lack the
ability to measure gaseous
nitric acid and the nitrate
analyses of the dichotoroous
samples do not properly re-
flect particulate nitrate
because of volatilization of
seme of the material on the
filters. We reommend adding
a sampling method that pro-
perly characterizes NOo and
HN03 at all sites; the ASRL
Concentration Monitor would
serve this need." (p. 35)
"Relative humidity is measured
by hair hygrographs that are
calibrated infrequently. Such
instruments are known to
easily change calibration.
We reccnmend, as a minimum,
that their calibration be
checked weekly by comparison
with a psychrometer." (p. 35)
"The systems and performance
audits that will be performed
for the sites are desirable,
and the planned calibrations
at low concentration levels
are absolutely necessary."
(?. 36)
"We did not see that a plan
for data analysis had been
formulated, or that the data
base design had been adapted
to such a plan," (p. 36)
This information is needed for the
FY87 and FY89 assessment reports.
We agree. A request has been made to
Task Group D to consider placement of
dry deposition monitors including mea-
surement of nitric acid, at each of
the materials exposure sites in FY86.
Only the Newcomb site uses the hair
hygrograph to measure relative humidity.
Plans are to replace this unit in FY85.
"It does not appear that the
group has expertise in
corrosion mechanisms, or
has sought the advice of
appropriate experts." (p. 37)
In addition to the regular calibra-
tions and audits perfomed at the
sites, a complete system's and per-
formance audit of air monitoring and
meteorological instrumentation is
planned at least once a year.
The aerometric data base is being com-
puterized in standard SAPQAD format
for use by various organizations, NFS,
USGS, ANL, BOM, EPA, etc. who are
involved in exposure of materials at
the sites. Each of these organizations
will use this data base to develop
damage functions. This project will
not develop a plan for analysis of
their materials damage data.
The review panel fails to acknowledge
the corrosion expertise of F. Haynie,
who has published extensively on pol-
lutant induced corrosion, and D. Flinn,
S. Kramer and J. Carter at the BOM,
59
-------
15. "Yet, no attempt has been
made to explain these data
from a mechanistic view-
point." (p. 38)
16. "It is recommended that the
initial effort be directed
toward the development of
experimental protocols and
test methods. Field expo-
sure of paint films on wood
substrates is considered
premature." (p. 39)
17. "Since substantial research and
use experience are available,
it is reconmended that a work-
shop be conducted at KIP to
review the state of concrete
structure use experience and
damage mechanism research
prior to initiation of the
laboratory study (Phase I),
or the field survey involving
core sampling of existing
structures (Phase II)."
(p. 39)
18. "It appears appropriate to
limit the effort for FY86
to the initial literature
survey (Phase I).M (p. 40)
19. "It is not obvious that this
device will prove useful in
the proposed task of com-
paring short-term effects
for the diverse materials,
e.g., steel, concrete, lime-
stone, marble, paint films,
and asphalt, either in place
or eventually to be placed
at the field exposure sites."
(p. 40)
20. "The panel believes that in-
adequate attention has been
which is recognized as a leading go-
vernment laboratory on metallic
corrosion.
No interpretation of the corrosion
data was presented because this
phase of study is planned for FY86
when validated aerometric data and
3-year corrosion data are available.
We agree. A joint research program
involving the exposure of painted
wood substrates in controlled environ-
mental chambers is being planned by
EPA and USDA Forest Products Labora-
tory.
We agree.
We agree.
The evaluation of the corrosion moni-
tor by ASRL was not presented because
the work is within the GAP program.
Based on the results of the lab and
field test of this device, it is our
reccranendation to incorporate the
corrosion monitor into the field ex-
posure study.
The uncertainties associated with the
development of the damage functions,
60
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paid to the uncertainties
associated with the use of
damage functions derived
from short-term field expo-
sure." (p. 41)
21. "With the limitations of the
understanding of the chamber
study results, the interpre-
tation of the field studies
becomes phenomenological.
The damage functions for
metals could be determined
from the short-term chamber
study results. Expansion
of the testing in the chamber
studies is needed to generate
"damage functions." (p. 44)
22. "The visit tothe RTF field ex-
posure site demonstrated the
substantial commitment of the
National Park Service (NFS) to
field exposure studies for
marble and limetsone. These
materials should be considered
for parallel chamber studies
under the direction of the
Materials Effects Program
under review since the NPS
has neither the resources
(smog chamber and associated
hardware) nor the expertise
necessary to conduct such
work." (p. 45)
23. "The major limitation is in
the characterization of the
mechanism of corrosion.
While overall rates are
empirically determined, the
mechanism is still unknown.
With the high covariance of
the depositions of chemical
species, the agent of corro-
sion is obscured." (p. 46)
particularly the uncertainty of the
regression coefficients, will be
available to the users - the Assess-
ment Program (Task Group I).
We agree. (However, see responses
number 4 and 23.)
We agree.
The chamber studies are providing in-
sight into the role wet and dry acid
deposition play in the corrosion of
materials. Deposition velocities,
soluble corrosion products, etc. will
provide insight into the mechanism of
corrosion. However, a detailed charac-
terization of the mechanism of corro-
sion for all materials being studied
is beyond the funds available to this
program.
We have attempted to respond to the list of recommendations (p. 48) as
they appeared within the report. As we have discussed, the covering device
to be installed at Steubenville, Ohio should be completed in FY85. The
covering devices at RTP and Steubenville will be used to resolve the effects
61
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of dry deposition of SC>2 on materials within the timeframe of the NAPAP. The
effects of snow, ice, fog, etc. are not being addressed in this program be-
cause of the limitation of resources. We agree that irregular surfaced
materials should be included in this study. Vte are proposing to include
irregular shaped materials as well as field weathered materials as part of
our chamber program in FY86.
62
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DATE:
SUBJECT:
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
ATMOSPHERIC SCIENCES RESEARCH LABORATORY
RESEARCH TRIANGLE PARK
NORTH CAROLINA 27711
July 8, 1985
Response to Peer Reviewers Comments on Dry Deposition Program
FROM: Kenneth T. Knapp
Project Manager-,-Dry Deposition Project
TO: Mr. Ronald Patterson
Technical Planning and Review Office
Reviewers' Comment
1. "However, the project description
is unclear as to the details of
the parameterization." (p. 7)
2. The ASRL concentration monitor,
"the sampler should be tested under
a variety of sampling and shipping
temperatures, with realistic inter-
vals between sampling and sample
analysis,..." "...several such sam-
plers should be. deployed in the field
to provide an operational field eval-
uation before commitments are made
for permanent development." (p. 12)
3. "The sampler does not yet have the
capability of measuring, or has not
been tested for, other species of
"interest to NAPAP, namely HCL, HCO'o,
..." (p. 12)
4. "However, we seriously question the
merit of collecting the larger part-
icles by use of the airborne concen-
tration monitor and feel that the
resources that would be devoted to
this purpose should be used else-
where." (p. 13)
ASRL Investigators Response
The PO is revising the project
description of task 1452 on the
IAG with Argonne.
ASRL ran a short field test of 7
week-long test then turned the
systems over to EMSL who is now
doing the recommended evaluation.
The ASRL CM (sampler) collects
particles that can be analyzed for
these species. However, neither
time nor funding has permitted the
development of these measurements
at this time. While of interest to
NAPAP, they are low priorities.
I do not agree with the panels as-
sessment of the merit of collecting
particles larger than lOum. In fact,
several good proposed approaches were
received in the proposals for this
RFP. In the RFP. we gave a 3 to 1
priority to the smaller 2 to 10 pm par-
ticles but felt that if it were possible
we should start the research for the
greater than 10 urn particles as soon
as possible.
63
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10.
II.
5. "The issue >10um particle deposition
may best be approached through the us
of surrogate surfaces." (p.14)
"One of the planned outputs of the
research sites in a manual for site
planning and development of NTN sites."
"A poorly chosen site will provide
little useful data, ..." (p.15)
"To meet the EPA goals, additional
species are needed. Hydrogen
chloride, ammonia "
"a co-location
between Groups
Carolina would
of research activities
D & G in RTF, North
be desireable." (p.17)
"(1) There appears to be little
communication between ASRL and ATDL,
and EMSL and ATDL, concerning the
deposition velocity method."
"...interaction between ASRL, EMSL
and ATDL on issues related to dry
deposition monitoring. Regular
meetings to review plans and pro-
jects are essential..." (p. 21)
"The panel also recommends that the
capabilities of other qualified
organizations be sought to assist de-
velopment of deposition velocity
estimation methods." (p. 21)
"The panel recommends that research be
initiated in surrogate surface de-
velopment." (p. 25)
In the 1979 workshop on dry deposition,
many of the attendee felt that there
was no good evidences that surrogate
surfaces is a usable approach, thus it
was given a low priority. We are
not working on this since NOAA is
funding research in this area. We
will withhold judgement of the merit
of this approach until the NOAA work
is completed
While we donot disagree with this, the
output is not one of ASRL-EPA but a NOAA/
ATDL output funded by NOAA. Choosing the
NTN' sites is an EMSL/EPA function not
ASRL.
We intend to go after these but have
had to prioritize the pollutants by
NAPAP needs, research time available
and funding.
This is being worked on by EMSL and
John Spence (PM Group G).
While the Vd project is a NOAA fund-
ded ATDL/NOAA project, Bruce Hicks
(ATDL) has kept ASRL informed. I
don't know the extent of the communi-
cation between ATDL and EMSL. I agree
that some regular meeting is a good
idea. We have had several such meetings.
We are not in a position to recommend
this since it is a NOAA assignment. We
will be a part of the vigorous review
of the method.
As stated in response to number 5, this
is a low priority approach of question-
able application and we feel that the
NOAA support is sufficient at this time.
64
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APPENDIX E
REVIEW OF THE PANEL REPORT AND
RESPONSES BY THE LABORATORY DIRECTOR
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
< ATMOSPHERIC SCIENCES RESEARCH LABORATORY
*< PRO^C RESEARCH TRIANGLE PARK-
NORTH CAROLINA 2771 1
DATE: July 24, 1985
SUBJECT: Review of ASRL Responses to the Dry Deposition and Material Damage
Peer Review
FROM: Jack H. Shreffler
Deputy Director, AS: (MD-59)
TO: Ron K. Patterson
Peer Review Coordinator, TPRO, ASRL (MD-59)
THROUGH: Alfred H. Ellison
Director, ASRL (MD-59"
I have read the report of the peer reviewers on the Dry Deposition and
Material Effects Programs at ASRL based on the review held April 23-25, 1985.
I have also read the ASRL project managers responses to the various recommenda-
tions and criticisms contained in the review report. There were some mis-
understandings about the latitude available to ASRL in choosing methods, time
lines, or budgets and about the exact responsibilities vis-a-vis other lab-
oratories or agencies in NAPAP. Generally, the responses are complete and
relevant, although some further questions are highlighted below. By copy
of this memorandum I am instructing project managers to take some additional
action.
Dry Deposition
The reviewers were complimentary and highly supportive of the systematic
approach taken to assessing a number of dry deposition methods. A strong
recommendation was made to increase the interaction and communication between
ASRL, EMSL, and ATDT on issues related to dry deposition monitoring. Ken Knapp
should take every opportunity to increase the interaction and should be able to
demonstrate the positive effects of that effort in the future.
Material Effects
The peer reviewers praised the management and project staff as having
demonstrated initiative, industry, and the ability to work together. There
was strong support for the chamber studies. Field studies were also supported
with some reservations concerning methods. The response prepared by John
Spenca is complete in addressing all reviewer criticisms, although there are
two areas that I believe could use further elaboration. John should prepare
a follow-up memorandum for the report.
First, the response to comment 1 (Spence memo) seems to skirt an important
issue. The microenvironment may require a rather complex set of instruments
for characterization. Measuring only on the building top or under the canopy
will not answer the real question: What is the difference between the site and
a nearby representative location?
65
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Second, the reviewers several times mention study of corrosion'
mechanisms as a missing element (e.g., comments 14, 15, 23). Perhaps
the response to 23 is getting close, but I think there should be some
elaboration on what "insights" will be provided and how that differs
from a "detailed characterization of the mechanism."
In a conversation with John, I was told that agreements with comments
17 and 18 mean those actions will be taken.
cc: K. Knapp
J. Spence
66
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APPENDIX F
CLARIFICATION COMMENTS BY ASRL
-------
; L.
'• UKiTED STATES E.VViRC'-T/.Er.TAL PP.
RESE^-C'-n IKiA\C;i_E F-.-
NO"TH CAROLINA 277" '
MEMORANDUM
DATE: July 30, 1985
SUBJECT: Clarification of ASRL Response to Material
Damage Peer Review
FROM: William E. Wilson
Acting Director, EMCD '
TO: Jack Shreffler
Deputy Director, ASRL
Microenvironments (#1)
There were two questions raised regarding microenvironments. One has to
do with the stationary covering device used by the Bureau of Mines. Measure-
ments have shown a higher relative humidity under the shelter and the Bureau
of Mines plans to modify the covering device so that temperature and relative
humidity will not be different. The second question referred to the increased
temperature at rooftop sites due to absorption of light by asphalt roofs.
The reviewers recommended that "the researchers should modify the exposure
conditions in a manner that eliminates the microenvironment effects." At one
site the roof is covered with a light colored gravel which should reduce the
temperature over that of a black asphalt roof. We will investigate the
possibility of covering the black asphalt at the other site with light colored
rock.
We must emphasize, however, two factors. One, in deriving damage func-
tions the important considerations are that the environment to which the
specimens are exposed is adequately measured, not that it is characteristic
of any specific exposure condition, and that an adequate range of exposure
conditions are included in the set of exposure sites. Therefore, we do not
believe that the fact that the rooftop environment is different from a ground
level enviornment will reduce the accuracy or value of the resulting damage
functions. However, since the time-of-wetness is important we investigate
the possibility of modifying the one rooftop site that might have the time-
of-wetness lowered by the asphalt roof. The second fact is that because of
financial restraints we must install cur exposure racks at pre-existing
sites. Due to security problems many urban sites are placed on roofs.
At one site a rooftop vent will be extended to a sufficient height so
that the emissions will not impact the specimens during most wind conditions.
The buildings, a library and an office building are not expected to generate
emissions of significant concern.
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Mechanisms (#23)
The reviewers emphasized the need to determine the mechanisms of damage
in order to develop damage functions which could reliably apportion damage to
specific pollutants and which could be used to predict damage under a variety
of environmental conditions. We agree with the reviewers. We have been
making some progress in persuading NADAP to accept this viewpoint but still
do not have sufficient funds to implement an adequate mechanistic study. We
feel that the analysis of corrosion on the specimen surface and products in dew
and rain runoff from both field and laboratory samples will provide a useful
data base for research into damage mechanisms. We will use the reviewers
comments in the next round of program planning in an effort to obtain funds
to add research on mechanisms to the program.
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