United States
Environmental Protection
Agency
Atmospheric Sciences
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S3-87/003 Apr. 1987
&EPA Project Summary
Validation Data for
Photochemical Mechanisms
K. G. Sexton, H. E. Jeffries, J. R. Arnold, T. L. Kale, and R. M. Kamens
The Quality Assurance and data pro-
cessing procedures and systems used
at the UNC outdoor smog chamber
facility are described. The intent of the
Quality Assurance effort is to insure the
collection, transfer, processing and re-
porting of accurate, high resolution data
without loss or distortion. This docu-
ment describes the analytical methods,
calibration techniques, and data pro-
cessing procedures that are employed
in the chamber program. A description
and examples of the format of the final
documentation and data file are given.
Also included are the Quality Assurance
steps and accuracy and precision
aspects of the data.
This Project Summary was developed
by EPA's Atmospheric Sciences Re-
search Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that Is fully docu-
mented In a separate report of the same
title (see Protect Report ordering In-
formation at back).
Introduction
The UNC smog chamber facility is used
to measure the reactants and products
that participate in the photochemical
smog formation process. The smog
chamber, located outdoors in rural North
Carolina, is an A-frame structure covered
with Teflon film. The chamber is parti-
tioned into two sections, each with a
volume of 156 m3, so that two experi-
ments can be conducted simultaneously.
The dual chamber is operated under
natural conditions of solar radiation,
temperature and relative humidity.
The data obtained in the facility are
used by atmospheric modelers to develop
and test kinetic mechanisms of photo-
chemical smog formation. In order to
successfully model the data, the user
needs to understand fully the standard
operating procedures that are employed
during the execution of the runs, the
methods that are used to process and
document the data, and the uncertainty
that is associated with the data. The
purpose of the Project Report is to provide
this information.
Quality Assurance Procedures
Generating useful data begins with an
understanding of the goals of the project
and the special needs and concerns in-
volved with conducting a successful out-
door smog chamber operation. The
Project Report describes the goals of the
chamber program, the facilities and
analytical support requirements and the
procedures that are employed to conduct
the experiments. Detailed discussions are
included of the checks that are followed
when setting up and executing a run, the
preventative maintenance schedules that
are followed and the types and frequency
of characterization experiments that are
conducted to elucidate chamber wall arti-
fact effects.
The system components, which are
described in detail, are designed to col-
lect, transfer, process, and report ac-
curate, high resolution data without loss
or distortion. Quality assurance checks
are made at every level of the program
and they are described in detail in the
Project Report. The calibration sources
employed and their traceability to National
Bureau of Standards sources are de-
scribed for each of the gaseous species
that are monitored during the chamber
runs. The calibration of the meteorological
sensors employed in the studies is also
discussed.
-------
Analytical Methods
A complete description of the analytical
instruments that are used to collect data
from the chamber facility are described
in detail. This instrumentation includes
eight packed column or capillary gas
chromatographs for hydrocarbon, organic
nitrate and inert tracer analysis; one liquid
chromatograph for DNPH-aldehyde analy-
sis; and automated wet chemical formal-
dehyde instrument, two ozone and NOX
chemiluminescent monitors; and a UV
ozone photometer. In addition, a complete
description of the methodology employed
to measure solar radiation is given. In-
cluded in this description is a discussion
of the accuracy of the radiometer mea-
surements and the calibration procedures
employed. To assist the user in under-
standing the data, a complete description
of the chamber facility including its
physical design, the air handling system
and the procedures used to inject pol-
lutants into the chamber is also included.
Documentation of the Data
The procedures, tools and techniques
for processing the experimental data are
described in detail. Data are acquired and
recorded on stripcharts and on four dif-
ferent computer systems using a variety
of specially designed software packages.
All data processed for each run are stored
on a single computer file. This file con-
tains quality assurance documentation
including the calibration information col-
lected during the run, the continuous
instrument data collected in the study
and the gas chromatography data that
are collected every 30 minutes during
the study. Also included on the file is a
discussion of any special problems or
concerns associated with the run and an
assessment of the overall quality of the
particular experiment. A scale of 1 to 10
is used to rate the run quality and the
factors used in assigning the rating
include quality of the sunlight during the
run; the degree to which the desired
target conditions for injection of the
organic and NOX reactants was achieved,
the completeness of the analytical data
and the conditions of the chamber during
the execution of the experiment.
H. E. Jeffries, K. G. Sexton. J. R. Arnold, T. L Kale, and R. M. Kamens are
with the University of North Carolina, Chapel Hill, NC 27514.
Marcia Dodge is the EPA Project Officer (see below)
The complete report, entitled "Validation Data for Photochemical Mechanisms,"
(Order No. PB 87-145 298'/AS; Cost: $30.95. subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Atmospheric Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
O- ^jiAlA-•:..,*
jjisji^fr
.j*.
Official Business
Penalty for Private Use $300
EPA/600/S3-87/003
OOOC329 PS
U S ENVIR PROTECTION AGENCY
REGION 5 LIBRARY
230 S DEARBORN STREET
CHICAGO IL 60604
------- |