United States
Environmental Protection
Agency
Atmospheric Research and
Exposure Assessment Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-92/106 October 1992
& EPA Project Summary
Fourth Progress Report: Quality
Assurance Support for the
National Atmospheric
Deposition and National Trends
Network Monitoring Activities
1990-1991
David S. Bigelow
The full report summarizes the qual-
ity assurance activities of the NADP/
NTN Quality Assurance Manager in 1990
and 1991. The main report documents
the accomplishments of the coopera-
tive agreement and makes recommen-
dations for the future operation of the
NADP/NTN network. The report sum-
marizes the progress being made by
the NADP/NTN monitoring program in
implementing its quality assurance
plan. The report discusses the valida-
tion of field pH measurements, nuances
of utilizing the networks PO4 measure-
ments, and NADP/NTN siting criteria.
Results of a laboratory audit and a com-
pendium of network documentation are
also presented. This report was sub-
mitted in partial fulfillment of Coopera-
tive Agreement No. CR816954-01 by
Colorado State University under the
sponsorship of the U.S. Environmental
Protection Agency (EPA).
This Project Summary was prepared
by EPA's Atmospheric Research and
Exposure Assessment Laboratory, Re-
search Triangle Park, NC, to announce
key findings of the research project
that is fully documented in a separate
report of the same title (see Project
Report ordering information at back).
Introduction
The National Atmospheric Deposition
Program/National Trends Network (NADP/
NTN) monitoring network is a cooperative
atmospheric deposition monitoring effort
of local, state, and federal agencies as
well as private industry. The program is
structured according to guidelines estab-
lished in the U.S. Department of
Agriculture's (USDA) Cooperative State
Research Service's (GSRS) Manual for
Cooperative Regional Research (USDA,
1986) and is administered through a Co-
operative Agreement between Colorado
State University and the USDA-CSRS. Fi-
nancial support for the program is pro-
vided by the program's cooperators and
includes significant contributions from the
U.S. Geological Survey (USGS), the
USDA-CSRS and the EPA. Other admin-
istrative entities contribute to the network
in proportion to the number of monitoring
sites their agency sponsors.
The network was established in mid-
1978 as the National Atmospheric Depo-
sition Program (NADP), a GSRS regional
research project. In 1983, the NADP as-
sumed responsibility for managing the day-
to-day operations of the National Acid
Precipitation Assessment Program's
(NAPAP) National Trends Network (NTN).
This action resulted in the current com-
bined, cooperative monitoring program that
is now known as the NADP/NTN monitor-
ing network. The NADP/NTN monitoring
network serves both the National Atmo-
spheric Deposition Program and the Na-
tional Acid Precipitation Assessment
Program, and will become a significant
part of the wet deposition component of
the Environmental Protection Agency's pro-
posed Clean Air Status and Trends Net-
work (CASTNET) monitoring program.
The NADP/NTN operates a network of
approximately 200 sites according to a
single set of protocols. The sites are dis-
tributed throughout the continental United
States and include non-conterminous lo-
cations in Alaska, Hawaii, American Sa-
moa, and Puerto Rico. Collocated sampling
Printed on Recycled Paper
-------
Is also periodically conducted in Canada
with both federal and Provincial monitor-
ing programs. Wet-only deposition samples
are collected on a weekly basis at each
sampling location according to standard
procedures. Chemical analysis and data
quality coding are conducted at a single
laboratory, the Central Analytical Labora-
tory (CAL) at the Illinois State Water Sur-
vey and a centralized data management
facility at Colorado State University makes
quality assured network data available to
scientists and policy-makers approximately
120 days after samples have been col-
lected. Specialized data summaries are
also developed at the Colorado State Uni-
versity, NADP Coordination Office to fa-
cilitate the use of network data.
Because the NADP/NTN monitoring pro-
gram both represents and relies on many
different public and private agencies to
accomplish Its goals, it is unique in its
structure and mode of operation. For qual-
ity assurance, this has meant that respon-
sibility for the development of quality
assurance programs is assumed by each
of the organizations who have responsi-
bility for managing specific pieces of the
network's operations (e.g., CAL, Coordi-
nation Office, USGS, EPA). Procedures
are reviewed and accepted by the various
NADP committees who have oversight re-
sponsibility for each network function. This
approach has been successful in bringing
considerable expertise together to solve
network problems for a very tow cost.
Considerable additional resources would
have been required to bring these at-
tributes Into a single organization.
Accomplishments
The Quality Assurance Manager reports
network activities semi-annualry, at each
annual and interim meeting of the NADP
Quality Assurance Steering Committee.
The reports are written and are distributed
as a part of the Committee's minutes. The
EPA contract officer for the Quality Assur-
ance Support for the National Atmospheric
Deposition Program/National Trends Net-
work Monitoring Program Cooperative
Agreement Is a permanent member of this
committee serving as a formal represen-
tative of the Agency. The Quality Assur-
ance Manager serves as the secretary for
this committee.
The Quality Assurance Manager partici-
pates in NADP Technical and Subcommit-
tee meetings (7 meetings); writing, revising,
and reviewing NADP/NTN documentation
(2 articles, 1 report, 1 poster, and 2 SOPs
produced); reviewing agency reports and
proposals that utilize NADP/NTN data or
documentation; and disseminating quality
assurance information to the various NADP
committees and scientists. In addition, the
Quality Assurance Manager serves as the
chairman of ASTM D22.06 committee on
Acidic Deposition and contributes regu-
larly to the Agency-sponsored Annual Eco-
logical Quality Assurance Workshops. The
Manager is also active in the Colorado
Ingres Users Association. Each of these
activities serves as a vehicle for obtaining
and documenting the quality assurance
activities of the network and for promoting
the evaluation and reporting of quality as-
surance data.
As a direct result of the Quality Assur-
ance Manager's activities, three articles
have been published, one report has been
submitted to the Agency and one poster
was presented at an NADP Technical
Committee Meeting. .In addrtjon, theJSual-
rty Assurance Manager has prepared or
assisted in the preparation of five propos-
als which support NADP activities. These
included proposals for the continuation of
this quality assurance support and the re-
newal of the USDA-CSRS National Re-
search Support Project (NRSP) which is
the primary funding mechanism of the
NADP/NTN monitoring program.
NADP/NTN Quality Assurance
Plan Implementation
In 1990 the network adopted a revised
quality assurance plan. This new plan is
much more detailed than the previous plan
(NADP, 1984) and for the first time at-
tempts to couple specific goals and objec-
tives with specific evaluation criteria. In
addition to developing the data manage-
ment and overall assessment chapters of
the Plan, the Quality Assurance Manager
was instrumental in editing the final ver-
sion for publication and for incorporating a
revision tracking procedure into the docu-
ment.
A second accomplishment has been the
develbpTnent" of' a" major computer'soft-
ware application that allows data users to
evaluate the quality of individual monitor-
ing stations in the context of the goals
and objectives set forth in the revised
quality assurance plan. This application is
the first of a planned series of applica-
tions that capitalize upon the centralized
quality assurance data that has been in-
corporated into the network's routine data
management activities. The application,
known as the Station Quality Assurance
Report, provides NADP managers, site
personnel, and data users with a report of
an individual station's data completeness,
representativeness, precision, bias, and
temporal comparability for its period of
record.
Review and Evaluation of
NADP/NTN Network Operations
Audit of the Central Analytical
Laboratory
A formal audit of the Central Analytical
Laboratory (CAL) was conducted July 10-
12, 1990. Significant in this audit was the
inclusion of two non-NADP affiliated team
members. In previous audits (the last one
was in 1986), the audit teams were com-
prised solely of NADP Network Opera-
tions and Data Management and Analysis
subcommittee members.
Briefly, no major deficiencies were
noted, and progress on previously identi-
fied concerns was evident. The CAL staff
was noted as continuing to provide the
networlc with high quality analytical and
program management services.
Informal Review of the Site
Visitation Program
An informal review of the Agency-spon-
sored Site Visitation Program was con-
ducted jointly by members of the
Coordination Office staff and the Research
Triangle Institute (RTI) site visitation project
personnel February 26-27, 1990. The re-
view provided an opportunity to evaluate
the previous round of site visits (round 2)
and to discuss ways of improving the qual-
ity and timeliness of information gathered
in conjunction with the site visitation pro-
gram.
Other topics discussed included the re-
definition of some data entry items passed
between the groups, the electronic pass-
ing of information, and the feedback
mechanisms for all persons involved with
the project. As a part of these discus-
sions, the Quality Assurance Manager pre-
sented examples of how the site visitation
program information was being used by
the^network and-other scientists to-evalu-
ate the quality of each site's location and
performance.
Validation of Field pH
Measurements
Field pH measurements made by the
network continue to generate controversy.
This is in part due to the increased scru-
tiny the measurements are receiving since
the network began distributing preliminary,
semi-validated values to the U.S. Geologi-
cal Survey for inclusion in their monthly
publication, National Water Conditions.
Efforts to improve the quality of these
measurements have included the imple-
mentation of a remedial action plan for
mediating poor performance in external
quality assurance programs and the de-
velopment of a validation procedure for
-------
including the values in seasonal data sum-
maries.
The external quality assurance, Intersite
Comparison Program was expanded to
include follow-up letters and site liaison
intervention when results of the semi-an-
nual audits were out of compliance with
network goals. Previously, out-of-compli-
ance pH measurements were simply
noted. With the new procedures, reasons
for poor performance can more readily be
identified so that corrective action can be
initiated by the NADP Coordination Office
or the USGS.
Field pH values have not received the
same level of validation as laboratory val-
ues in network quality assurance proce-
dures. This practice had been previously
accepted, because of the, lack of confi-
dence among network scientists in con-
trolling and documenting measurement
quality across all of the network's monitor-
ing stations. However, it has been dem-
onstrated that field measurements could
be evaluated confidently utilizing existing
NADP/NTN quality assurance information.
Troubleshooting the
Weaknesses and Future Needs
of the NADP/NTN Monitoring
Network
PO4 Measurement and
Reporting Practices
The Quality Assurance Manager began
investigating the network's PO4 measure-
ment and reporting practices in response
to a data user's request for quality assur-
ance documentation for this ion. Results
of this investigation were reported to the
Network Operations Subcommittee in the
spring of 1990 and led to the formation of
an ad hoc task group to further review the
network's policy regarding the measure-
ment and quality assurance reporting of
this ion. Perhaps the most interesting ob-
servation of the investigation was a marked
increase in the number of above detection
limit values reported by the network, be-
ginning in 1985. Discussions among task
group and committee members have reaf-
firmed the network's measurement prac-
tices but identified weaknesses within the
network's reporting practices for the ion.
The task group noted that a more com-
plete reporting of PO4 should be included
in laboratory quality assurance reports,
and that current QA reporting practices
may be inadequate to meet the needs of
many data users. These problems have
been overly exacerbated, however, by the
lack of an adequate quality caveat ex-
plaining the nuances of the NADP/NTN
PO4 data, and by the impartial reporting
practices of the network. The following
pieces of information were deemed critical
to the correct interpretation of the network's
PO4 data:
Lmore than 95% of the PO4 values
reported by the network are below
the detection limit of the methodology
used (currently 20 u.g/L),
2. the precision of the PO4 values at the
detection limit can be expected to be
no more than ± 100%,
3. the analytical method's detection limit
has been raised three times over the
course of the program to reduce costs
(3, 9, and 20 u,g/L) and the methodol-
ogy itself has changed from colorim-
etry to ion chromatography,
4. the prevailing opinion of network sci-
entists is that the usefulness of the
PO4 measurements, even at the ear-
lier detection limit of 3 jo.g/L, appears
to be questionable except for docu-
menting organic contamination, and
5. none of the methods used by the
network account for total phosphorus
nor do they appear to offer adequate
sensitivity in the range of concentra-
tions that would be useful for study-
ing loadings to aquatic systems.
Based upon discussions with a number
of scientists on the importance of atmo-
spheric phosphorus measurements, it
would appear that there is some interest
in obtaining more precise total phospho-
rous measurements in atmospheric depo-
sition. This interest, however, does not at
this time support a change in NADP/NTN
network PO methodology. Trends in
NADP/NTN PO4, though apparent even
when detection limits and methodology
changes are taken into account, are well
within the noise of the measurement pro-
cess. Current network funding would also
not support the implementation of a more
precise measurement methodology.
Review of NADP/NTN Siting
Guidelines
As a part of a Network Operations Sub-
committee initiative, the Quality Assurance
Manager reviewed NADP/NTN siting
guidelines to consider what changes would
be necessary to include monitoring loca-
tions that are currently outside of the scope
of the NADP/NTN program. These loca-
tions might include urban sites, coastal
sites (which are almost exclusively near
urban sources) and other potentially non-
regionally representative sites designed to
characterize a sub-regional ecologically or
politically important area (e.g., watershed,
National Park, etc.). The review pointed
out two basic obstacles to expanding the
scope of the current siting guidelines, i.e.,
emissions are currently the only regional
discriminator recognized in the guidelines,
and the guidelines are designed to ex-
clude rather than include sites. Regional
guidelines will be especially difficult to de-
velop under an increased scope if they
continue to be exclusionary, since many
of the guidelines will very likely be mutu-
ally exclusive of one other.
Equipment Refurbishing/
Replacement
The Quality Assurance Manager partici-
pated in three discussions of preventive
maintenance/service issues as a part of
his NADP subcommittee activities. These
included the refurbishing and replacement
of rain gages and Aerochem Metrics wet/
dry collector parts; the availability of re-
placement electrodes for field site pH mea-
surements; and the quality of the sampling
buckets that are resupplied to sites. The
discussions pointed out that while the net-
work has a set of procedures in place that
helps to mitigate these problems, it has
not adequately addressed the question of
the useful life or recall of its primary sam-
pling equipment nor has it adequately re-
solved its dependency upon a limited
number of critical suppliers.
Data Management
Improvements
Data Management activities continue to
take an ever increasing amount of the
Quality Assurance Manager's time. This
stems from both the lack of a separate
data management quality assurance posi-
tion in the NADP Coordination Office (as
there is with field and laboratory opera-
tions) and from the increased amount of
QA data now available through the pro-
gram. Numerous hardware and software
enhancements to the basic computer sys-
tems used by the NADP/NTN ,Cpqrdina-
tion Office have required additional
software scrutiny, and more network qual-
ity assurance data is becoming available
via electronic media. Both have begun to
require significant software maintenance.
Application development is also being done
by the quality assurance manager as there
are no other programming resources avail-
able to the Quality Assurance Manager
under the current funding limitations.
Over the past reporting period the soft-
ware of the operating system and data
base management systems of the NADP/
NTN Coordination Office were upgraded.
Spatial analysis software front-ends were
rewritten to make these utilities more ac-
cessible to project staff, and remedial ac-
tion tables were upgraded with more fields
per record and improved user interfaces.
Upgrades of quality assurance data struc-
•U.S. Government Printing Office: 1992— 648-080/60110
-------
lures and interfaces are handled by the
Quality Assurance Manager. Other sys-
tem enhancements are tested by the Qual-
ity Assurance Manager.
Centralized Documentation and
Quality Assurance Reporting
The Quality Assurance Manager's Of-
fice continues to serve as a repository for
NADP/NTN Monitoring Network documen-
tation. Both internal and external quality
assurance Information is now received and
evaluated on a routine basis. Results of
laboratory programs are reported annually
by both the Central Analytical Laboratory
and by the U.S. Geological Survey. Field
operation and data management report-
Ing is more informal, but most information
is readily available via the on-line data
base management system at the NADP/
NTN Coordination Office. Applications con-
tinue to be developed (such as the Sta-
tion Quality Assurance Report) which will
allow for the annual reporting of these
aspects of the program.
Recommendations
• Staffing levels should be increased to
albw for additional support staff to
accelerate the rate at which network
quality assurance issues can be re-
solved and to complete already iden-
tified quality assurance reporting
requirements.
• The QA manager should continue to
evaluate, document, and support net-
work data quality and network proce-
dures by preparing and publishing
integrated quality assurance reports.
These reports should be inclusive of
all years of operation through current
time.
• Increased support should be made
available to expand and accelerate
the gathering and data banking of
both external and internal quality as-
surance data that relate directly to
the NADP/NTN data set.
Increased support should be made
available to accelerate the develop-
ment of new quality assurance appli-
cation software to address additional
data quality objectives contained in
the NADP/NTN Quality Assurance
Plan.
The Quality Assurance Manager's
participation in auditing, document re-
views, and scientific meetings and or-
ganizations should continue to be
supported. These are important win-
dows through which the Quality As-
surance Manager can assess the
network's operations.
The Quality Assurance Manager
should become more involved with
quality; assurance planning_and coor-
dination of the Agency-sponsored
CASTNET program to increase the
usefulness of quality assurance infor-
mation that will be made available to
the CASTNET program.
DavkfS. Bigetowis with Colorado State University, Fort Collins, CO 80523.
Robert L Lamps is the EPA Project Officer (see below).
The complete report, entitled "Fourth Progress Report: Quality Assurance Support
for the National Atmospheric Deposition and National Trends Network Monitoring
Activities 1990-1991,' (Order No. PB92-194000/AS; Cost: $26.00; subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Off her can be contacted at:
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE ,
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-92/106
------- |