ENVIRONMENTAL
MONITORING AND
SUPPORT LABORATORY
LAS VEGAS. NEVADA
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ON THE COl/E/?
This false color infrared image, acquired by a
NASA Landsat satellite, represents one of many
types of data used by EPA to monitor the
environment. It shoais an area oj about 34,000
square kilometers that includes Lake Mead
(upper right quadrant) and the city of
Las Vegas (left of Lake Mead).
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PROVIDING INFORMATION
FOR SENSIBLE CHOICES
The U.S. Environmental Protection
Agency was established as an advocate
for the American people in asserting
their right to a livable environment.
But the American people also have a
right to improve the quality of their lives
through technology. Technology that
may change the environment.
The key to sensible environmental
control is to determine which changes
are tolerable or useful and which must
be restricted because their harmful
effects on human health and welfare
outweigh their benefits.
That choice is not up to EPA. It's a
choice that has to be made by the
American people and translated into
legislation by their elected
representatives. EPA's role in that
decision is to provide information about
the nature and effects of pollution so
that informed and sensible choices can
be made.
This information comes from research
which involves a study of complex
interactions. First, the sources of
pollution must be identified and its
transport evaluated -- both to
determine where its effects are likely to
be felt and to analyze any changes it
undergoes after it leaves its source.
Then the exposure to critical receptors,
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usually human beings, must be
determined as do the effects on those
exposed.
From that information, criteria defining
acceptable limits for the pollutants are
developed, standards and regulations
adopted, implementation plans
developed and controls placed on the
sources.
Then the cycle repeats, because the
controls and the interactions they cause
must be evaluated to assure the
pollution is being abated and not
replaced with other adverse effects.
Each one of these steps requires
monitoring by methods that must be
accurate, reliable and cost effective. And
as new pollutants are identified, new
monitoring methods have to be
developed to detect and measure them.
The purpose of the Environmental
Monitoring and Support Laboratory at
Las Vegas is to help develop and apply
this necessary monitoring technology in
support of EPA regional and program
offices.
All of the Laboratory's research projects
can be traced to public laws that require
EPA to establish or enforce standards
limiting pollution. A research project is
not undertaken unless the information it
is expected to produce is necessary for
EPA to carry out its legal mandate.
Almost all of the Laboratory's projects
involve applied, rather than basic,
research. In other words, it seeks ways
to apply existing technology to
environmental problems, rather than
developing entirely new systems. This
keeps research costs low and provides
an operational monitoring capability in
the shortest possible time.
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DEVELOPING SYSTEMS
FOR MEASURING
ENVIRONMENTAL QUALITY
The Environmental Monitoring and
Support Laboratory at Las Vegas
conducts research and development
programs to optimize existing
monitoring networks and to develop
new comprehensive systems to monitor
specific pollutants.
Integrated Monitoring Systems
An important part of developing an
environmental monitoring system is
determining which measurements are
significant. Technology has long been
available to measure the concentration
of, for example, sulfur dioxide in air.
However, that information alone is
relatively useless in setting or enforcing
emission standards. We also have to
know the pollutant's sources, how it is
transported, the chemical and physical
changes it is likely to undergo in the
environment, and its availability to the
human population.
For this reason, the Laboratory
conducts studies on specific pollutants
that take into account all relevant
characteristics of each pollutant in air,
water and land.
Once a comprehensive data base is
established, it is exhaustively analyzed
and correlated, together with data from
health effects research conducted at
other laboratories. The goal is to identify
the fewest and simplest possible
measurements which, when found to be
within specified limits, assure that the
exposure of the human population to
that pollutant is at a level currently
believed to be safe (or, more
realistically, at a level where the adverse
health effects are small enough to be
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outweighed by the benefits from the
technology that produces the pollution).
The value of this systematic, integrated
approach was clearly demonstrated by
applying it to the problem of
environmental lead.
The first step in developing an
integrated monitoring system is to
identify those segments of the
population most likely to suffer adverse
effects from the pollutant being studied.
For many air pollutants, this critical
receptor is likely to be a person
suffering from a chronic respiratory
disease; for x-ray radiation, the critical
receptor is a pregnant woman. If
pollution standards can be established
to protect the critical receptors, then it
can be assumed the entire population is
being protected.
From the review of existing information
that precedes every research project, it
was determined that urban children under
six years of age are the critical receptors
of lead. But the more-than-10,000 pub-
lished studies on lead failed to identify
the relative importance of the various
ways a child can be exposed to lead.
For years, it was widely believed that
the highest exposure of small children to
lead was from lead-pigmented paints.
But the Laboratory's study indicates this
is a relatively insignificant source when
compared to lead emitted from
automobiles which settles inside homes
as dust and is ingested when a child
places his hands or a toy in his mouth.
As a result of this study, monitoring re-
sources that might have been spent iden-
tifying leaded paint now are likely to be
directed toward monitoring lead emissions
from automobiles and measuring
ambient concentrations of lead around
highways in populated areas.
Predictive Models
The Laboratory is applying and testing
mathematical formulas (models) that can
help scientists predict the effects on the
environment of specified events under
a variety of conditions.
For example, air monitoring networks
are being designed with the help of an
airshed simulation model that predicts
the concentration and distribution of
pollutants over a given area from
meteorological data and emissions
inventories.
Scientists use the model to predict the
pollution distribution for each weather
pattern that is likely to occur in the area
being studied. From this series of
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simulations, they make pollution
distribution maps. By overlaying the
maps, they find the locations where the
highest pollution concentrations should
occur most often. After the predictions
are verified with actual measurements,
these locations are selected as sites for
air monitoring stations.
In many areas, a few strategically placed
sampling stations can monitor air quality
for an entire metropolitan area, thus
reducing the cost as well as improving
the accuracy of air monitoring networks.
One predictive model under develop-
ment will help reduce pollution, in
addition to monitoring it. It predicts the
effects of injecting waste into the ground,
taking into account the physical charac-
teristics of the subsurface environment,
fluid characteristics of the wastes, and
the chemical changes that could occur as
the wastes interact with the underground
environment. This information will be
used to formulate rules and regulations
on subsurface waste injection that will
prevent contamination of underground
water (groundwater), which is the major
source of drinking water.
Biological Monitoring Techniques
In addition to mechanical and electronic
sensing techniques, the Laboratory is
studying the use of native plants and
animals to monitor pollution. Studies are
underway to determine the effects of
specific pollutants and combinations of
pollutants on plants and animals and to
identify ways these effects can be mon-
itored directly as well as from aircraft.
Collecting microorganisms and plant
tissues or monitoring vegetation from
aircraft may prove to be the most
effective and economical techniques for
fulfilling some monitoring objectives.
Experimental Farm
The Laboratory operates an experi-
mental farm for the U.S. Energy
Research and Development Administra-
tion (ERDA) at the Nevada Test Site, an
isolated nuclear testing area that begins
65 miles northwest of Las Vegas.
The farm was established to determine
whether radioactive contaminants from
the tests can enter the human food chain
through plants, animals and dairy prod-
ucts. It also is used to assess the effects
of pollutants on plants and animals.
The farm includes a dairy herd, a beef
herd, and other common farm animals
such as hogs, goats and chickens. It has
agricultural facilities and a reservoir.
A wide variety of pollutant transport and
transformation studies can be conducted
at the farm in a natural setting with
hazardous pollutants at concentrations
that could not be used in preliminary
Laboratory studies.
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Analytical Support
The Laboratory characterizes and
analyzes pollutants in environmental
samples for EPA regional offices and for
other Federal, state and local agencies
involved in environmental monitoring
programs.
State-of-the-art equipment is used and
new instruments and analytical
techniques are continually being
developed to increase the number,
precision and sensitivity of the
measurements that can be made.
The Laboratory is conducting a
research program that may allow it to
identify the exact source of pollutants
through chemical and physical analysis
of soil, biological, water or air samples.
Many pollution sources emit a mix of
pollutants that is characteristic of that
one source. Samples are being collected
around selected pollution sources and
analyzed for these pollutant mix
"signatures." Once a large data base is
assembled and categorized, it should be
relatively easy to trace the source of
pollutants found in future samples.
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Quality Assurance
Data from a number of Federal, state,
regional and local monitoring programs
are used to establish and enforce
pollution standards. To assure the
standards are meaningful and fairly
applied, measurements made by the
various monitoring authorities must be
intercomparable.
To help achieve this goal, the
Laboratory is establishing itself as a
center of excellence, where the facilities,
equipment, procedures and skill levels
available provide consistent results that
other laboratories can use as a point of
reference. The Laboratory has long
been recognized as a center of
excellence for radiation measurements
and is developing a similar capability for
trace metals and toxic materials in
biological material and soils. Other EPA
laboratories are responsible for quality
assurance of measurements for other
pollutants and for trace metals and toxic
materials in air and water.
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The Laboratory produces calibrated
samples of known concentrations of
pollutants that are provided to users on
request. These are used for calibration,
standardization and quality control.
The Laboratory develops EPA reference
methods for laboratory measurement of
environmental pollutants. Since the
laboratories that ultimately use these
methods will vary in size, facilites and
skill levels, the methods and the written
instructions that describe them must be
validated through collaborative tests at a
number of different representative
laboratories.
The Laboratory sends each participating
laboratory an identical set of numbered
samples that includes various concentra-
tions of a pollutant along with a descrip-
tion of the analytical method to be used.
Measurements made by the laboratories
are compared with the known concen-
trations to determine the success of the
method. When an analytical method
passes this test, it is published and dis-
tributed as an EPA reference method.
A similar testing service is offered to
assure other laboratories that their
measurements are accurate. Periodi-
cally, laboratories that participate in this
intercomparison program each receive an
identical sample of material that includes
a pollutant to be identified and measured.
They receive a report comparing their
results to the actual values and to the
mean of the measurements submitted by
all the participating laboratories.
The Laboratory assures the validity of
its own work through intercomparison
tests with the National Bureau of
Standards.
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MONITORING OPERATIONS
As part of its research activities, the
Environmental Monitoring and Support
Laboratory conducts field studies to
measure environmental quality in sup-
port of EPA regional and headquarters
program offices. These studies provide
the dual benefit of contributing important
information about the environment at
the same time new monitoring techniques
and instruments are tested and demon-
strated under actual field conditions.
They also provide Laboratory research-
ers with first-hand information about the
constantly changing problems and
requirements of day-to-day environ-
mental monitoring.
Water and Land Quality
The Laboratory studies water and land
quality together because they are inter-
dependent. Ordinarily, water quality is
the main consideration because it usually
has a more immediate and far-reaching
effect on human health than land quality.
Land use then would be examined to
determine its impact on the aquatic
system.
One example of the Laboratory's water
quality monitoring is its participation in
the National Eutrophication Survey, a
study of the effects of pollution on the
aging process of lakes and reservoirs.
The survey involved joint efforts of two
EPA laboratories, EPA headquarters
and regional offices, and state and
local agencies.
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I
The Las Vegas Laboratory's role in the
survey was to collect and analyze multi-
ple samples from more than 800 lakes
and reservoirs throughout the United
States, and prepare individual reports
on the trophic condition of each lake
and reservoir.
The Laboratory developed computer
programs to correlate data from all the
lakes and reservoirs in the study. From
this information, it has identified the
measurements that are the best indicators
of the water's condition and has suggested
guidelines that define limits for each of
these measurements which, if exceeded,
indicate unacceptable water quality.
Federal and state authorities can use
these guidelines in establishing water
quality standards and for setting prior-
ities in clean-up efforts.
To gather data quickly and economically,
the Laboratory developed an electronic
sensor package that can be lowered into
a body of water to measure temperature,
conductivity, acidity (pH), dissolved
oxygen and depth continuously as the
sensor package descends.
The package and associated electronic
monitoring equipment are installed on a
helicopter. The helicopter flies to the area
being studied, lands on the water and
lowers the sensor package into the
water. Scientists can determine water
quality at given depths by monitoring
the electronic instruments on board as
the sensor package descends. As the
package is raised, it can pump samples
from whatever depths the scientists
select for more detailed analysis in a
laboratory.
In addition to electronic monitoring sys-
tems similar to those used in the National
Eutrophication Survey, the Laboratory
uses mobile laboratories and monitoring
systems operated on land and from
watercraft along with more conventional
sampling techniques to monitor physical,
chemical and biological changes caused
by pollution.
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Air Quality
The Laboratory monitors air quality with
airborne and ground-based systems that
can identify pollutants and determine
their location and distribution.
Most of the Laboratory's air quality
studies involve the use of helicopters
that were originally acquired to collect
data for the Regional Air Pollution Study
(RAPS), a comprehensive research
project in St. Louis, Missouri to analyze
the movement of and chemical changes
in pollutants. The helicopters are out-
fitted with instruments to detect and
measure oxides of nitrogen, ozone,
carbon dioxide, sulfur dioxide, methane,
total hydrocarbons, airborne particles,
temperature, humidity and materials
used as tracers.
For long-range studies, the Laboratory
uses fixed-wing aircraft with monitoring
capabilities similar to those of the heli-
copters, plus the ability to continuously
monitor gaseous hydrogen chloride. All
the aircraft are equipped to collect air
samples in special non-reactive con-
tainers for later laboratory analysis. For
a monitoring assignment that requires
additional capabilities, the necessary
equipment can be added.
Air quality studies conducted by the
Laboratory deal with such problems as:
• Pollution being transported to areas
that may be as far as 100 miles, or more,
from the pollution source.
• The contribution of a specific type of
industry, or of a particular plant, to
ambient pollution levels. This information
can be used to set emission standards or
to verify compliance with existing
standards.
• Chemical changes that occur when
pollutants are released into the atmos-
phere and react with the air or with
other pollutants to form compounds
that may be more hazardous than the
original pollutant.
• Validating, or testing, mathematical
models (formulas) that predict air quality
over a given area under specified con-
ditions from meteorological and
emissions data.
• Providing data on pollution distri-
bution over an area under different
conditions to identify the locations that
have the highest pollution concentrations.
This information can be used by local
officials to determine where to establish
air monitoring stations.
Environmental Radiation
When it was established by the U.S.
Public Health Service in 1954, the
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Laboratory's purpose was to detect and
measure radioactivity that might be
released to public areas from nuclear
explosives tests.
Over the years, the Laboratory has
developed methods and equipment to
measure very small amounts of radio-
activity using aircraft, stationary instru-
ments on the ground, and mobile units.
Since 1963, nuclear weapons tests in
this country have been conducted
underground and designed so that radio-
active contaminants are not released to
the atmosphere or carried away by
underground water. The U.S. Energy
Research and Development Administra-
tion (ERDA), which conducts the tests,
has asked EPA to monitor for radiation
to provide an independent assurance
that radiation is being contained.
A continuing program of monitoring is
conducted on a regular schedule within
about 200 miles of the Nevada Test Site
and at other sites that have been used
in the past for nuclear explosive testing.
If radioactivity is released, the Labora-
tory is prepared to monitor it anywhere
in the United States.
Air sampling stations which draw air
through glass fiber filters to collect air-
borne particles are operated continuously
in Nevada and neighboring states. Three
times a week, the filters are replaced,
sent to the Las Vegas Laboratory and
analyzed for radioactivity. Some of the
stations are also equipped with charcoal
cartridges to collect samples of reactive
gases. Still another network of stations
collects samples for noble gases and
tritium in atmospheric moisture or
gaseous form.
Water samples are regularly collected
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from wells and surface supplies at more
than eighty locations near sites of under-
ground nuclear tests in Nevada, New
Mexico, Colorado and Mississippi. Some
of the samples are collected at depths of
more than 6,000 feet using a special
truck-mounted sampling rig.
Milk samples are also collected at loca-
tions surrounding the Nevada Test Site
from family cows as well as from com-
mercial dairies. Like the air and water
samples, the milk samples are analyzed
for radioactivity at the Las Vegas
Laboratory.
Before each nuclear test at the Nevada
Test Site, EPA radiation monitoring
technicians in specially equipped trucks
are stationed at locations off the site
that would be most likely to be affected
if any radioactive materials were acci-
dentally released.
An EPA aircraft equipped with air
samplers and radiation detectors flies
over the test area immediately following
the test. If any radioactivity is detected,
the aircraft flies in a pattern of hori-
zontal passes and vertical spirals so
technicians aboard can determine the
identity and amount of radioactive
materials released. They also report the
direction and rate of movement of the
radioactive effluent so that the techni-
cians on the ground can be positioned
in its path for monitoring and sampling.
Anytime there is a release of radioactive
materials, the Laboratory can activate
seventy additional air sampling stations
that are already in place in the 21 states
west of the Mississippi River. The
samplers are operated on request by
local residents or state or local agencies,
who send the filters to Las Vegas for
analysis.
The Laboratory has a similar arrange-
ment for collecting additional milk
samples. About 175 dairies in the 21
western states have agreed to send raw
milk samples to the Laboratory whenever
they are needed.
Aircraft Operations
The Laboratory maintains a small fleet
of rotary and fixed-wing aircraft in Las
Vegas to support its research and mon-
itoring activities. All the aircraft owned
by the Laboratory are military surplus
that have been modified and, in some
cases, rebuilt by the Laboratory for
environmental monitoring.
When additional aircraft are required to
fulfill research commitments, the Labor-
atory borrows them from other govern-
ment agencies or hires private contractors.
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Transfer of Technology
Most of the field studies conducted by
the Laboratory, either because of their
scope or because of the special nature
of the study, require new, or modified,
monitoring approaches.
Some only involve new uses for existing
equipment. Others require instrument
modifications, new combinations of
equipment, or entirely new procedures.
Sometimes, when data from a broad
study are correlated, shortcuts can be
found so that similar future studies can
be simplified. This was the case with the
National Eutrophication Survey. From
the data collected in that survey, Lab-
oratory scientists developed computer
programs that can provide all the infor-
mation normally needed to evaluate lake
water quality from measurement of only
four to six water quality parameters.
Previously, it was necessary to measure
at least 16 parameters.
Whenever a Laboratory field study sug-
gests improved monitoring methods that
could be used in future environmental
monitoring activities by Federal, state or
local agencies, or by private industry,
details of equipment required and rec-
ommended procedures are published
and made available to the public.
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This false color infrared photograph was made to monitor vegetation stress caused by
the strip mine in the center of the photograph. Healthv vegetation appears bright red. uirh
lighter shades of red indicating stress. Variations in the color of the water are due
to light reflected from the water's surface.
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REMOTE SENSING
Aerial surveys of the Earth's surface
have been used for years for military
reconnaissance and, more recently, for
general applications such as geologic,
agricultural and land use studies.
However, their application to environ-
mental problems is relatively new.
Historically, pollution monitoring has
been performed by collecting samples
for later chemical analysis in a labora-
tory. During the last three decades,
physical and automated methods have
been developed to provide continuous
measurements at specific monitoring sites.
Remote sensing supplements these con-
tact monitoring techniques. It provides
speed, perspective and mobility that
allow the U.S. Environmental Protection
Agency to collect important environ-
mental information that would be either
prohibitively expensive or impossible by
contact monitoring alone,
The Environmental Monitoring and Sup-
port Laboratory devotes more than half
of its remote sensing efforts to providing
technical assistance to EPA regions and
headquarters program offices. Among
these are studies to:
* Delineate the thermal mixing zones
from heated water discharged by electric
power generating stations.
• Inventory rivers for waste discharge
locations.
• Document harmful industrial air
emissions.
• Locate feedlot and associated pol-
lution sources.
• Document strip mining operating and
reclamation practices.
• Locate targets for contact monitoring
or compliance inspections.
* Locate and document major oil spills;
provide guidance for containment and
clean-up efforts.
• Determine the height of inversion
layers.
• Map the distribution of pollutants over
large areas.
• Analyze land use related to eviron-
mental concerns.
In addition to providing technical sup-
port, the Remote Sensing Division
develops and adapts new remote sensing
systems and assists in monitoring the
environmental impact of increasing
energy development.
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Remote Monitoring Systems
A wide range of remote sensing tech-
niques and equipment is available
because of research conducted for mili-
tary, agricultural and other applications.
The Environmental Monitoring and
Support Laboratory is taking advantage
of this research by finding ways to apply
existing technology to environmental
problems, rather than engaging in basic
research on entirely new systems.
In many cases, the Laboratory has even
been able to use existing data, gathered
for an entirely different purpose by
other agencies, to yield important infor-
mation about the environment.
Among the systems now in use or under
development are:
Aerial Photography - The Laboratory
uses two kinds of aerial cameras: map-
ping cameras, to photograph large areas
without distortion, and reconnaissance
cameras. The reconnaissance cameras
show exceptional detail because at the
instant of exposure the film moves to
compensate for the forward motion of
the aircraft. The cameras use black-and-
white, color and infrared film.
When interpreted by experts, photo-
graphs can be used to inventory pollution
sources such as waste outfalls, industrial
facilities, garbage dumps and feedlots.
Information from aerial photography can
help show environmental impacts of
energy-related activities like oil shale
extraction, strip mining, and rehabili-
tation of land disturbed by these activities.
EPA aerial photographs also are used to
estimate the population density in a pol-
luted or threatened area and to map oil
spills and aid in assessing their long-term
effects.
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Thermal Infrared Scanning - The
thermal scanner is sensitive to heat rad-
iated from the ground. A sensor in the
aircraft scans at right angles to the flight
path. As the aircraft moves forward, the
scanner covers adjacent strips on the
ground. The aircraft speed and scan
rate are controlled so that no ground
remains unscanned.
The scans are recorded on film to pro-
duce a continuous image of ground
features that resembles a photograph.
They also can be recorded on magnetic
tape, from which a computer can pro-
duce an isothermal map.
This technique can be used day or
night and is sensitive enough to show
temperature differences in water as low
as one degree Celsius. Infrared scans
are often used to show waste discharges
into waterways.
Multispectral Scanning -- Multispec
tral scanning is used to identify classes
of objects on the ground from the light
frequencies they reflect. Multispectral
scanning can be used to remotely deter-
mine whether land used for strip mining
has been properly reclaimed by identi-
fying the vegetation it supports. It also
shows promise in identifying water pol-
lutants and in monitoring land use.
Image Exploitation --An ongoing re
search objective is to extract every
possible bit of useful environmental
information from surveys conducted by
imaging monitoring systems.
Interpretation keys are being developed
as an aid to photo interpreters at
Federal, state and local agencies. The
keys describe and illustrate character-
istics of an aerial image that are eviron-
mentally significant.
This ponoramic color photograph is one of a series used to direct
clean-up efforts after an oil spill on the San Juan River in Utah.
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ISOTHERMAL CONTOURS
13:13:40 EOT
THERMAL INFRARED IMAGERY
COLOR AERIAL PHOTOGRAPHY
This composite color photograph (bottom) shows an area monitored by an airborne thermal
infrared scanner to determine the distribution of heated water discharged from a power plant.
Data from the scanner were recorded on film (center) and on magnetic tape. From the magnetic
tape, a computer generated an isothermal map (top). The center image shows thermal mixing
zones, with lighter areas indicafing higher femperafures. The isothermal map shows the actual
temperature in degrees Fahrenheit.
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The Laboratory also is working with
computer programs and techniques that
increase the speed, quantity and accu-
racy of information extracted from the
images.
Through a field station at Warrenton,
Virginia, the Laboratory maintains liaison
with other agencies that use aerial
imagery. This avoids duplication of effort
and makes data collected for other pur-
poses available to the Laboratory.
The Laboratory uses Landsat and
Skylab satellite images of the Earth pro-
duced by the National Aeronautics and
Space Administration (NASA) and aerial
photography produced by a variety of
government agencies.
Although most of these images were
made for such uses as land use studies,
mapping, and agricultural surveys, they
can also be interpreted to yield signifi-
cant information about environmental
problems.
This image was generated by a computer from data
collected by an airborne 11-channel multispectral
scanner. The computer has identified objects on the
ground from the light frequencies they reflect and
assigned a color to each of 28 classes of objects.
The colors are chosen arbitrarily and are not
necessarily related to the colors of the objects. In this
image, natural vegetation is shown as red, agricultur-
al crops as green and most soils as yellow. Different
classes of plants and soils have been identified and
appear as different shades of these colors, as shown
on the color key.
Not Classified
Ag. Vegetation II
Ag. Vegetation I
Ag. Vegetation III
Exposed (scraped) Soil I
Piled Topsoil
Natural Vegetation II
Natural Vegetation I
Exposed (scraped) Soil II
Coal
Cloud I
Mine Pit Bed
Mine Water
Disked Soil (AG) II
Piled Overburden
Disked Soil (AG)
Ag. Vegetation IV
R.R. Loop Soils
Disked Soil (AG) I
Natural Vegetation III
Natural Vegetation IV
Cloud II
Natural Vegetation V
Ag. Vegetation V
Natural Vegetation VI
Natural Vegetation VII
Disked Soil (AG) III
Disked Soil (AG) IV
Natural Vegetation VIM
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Lidar - - Lidar is similar to radar and
sonar. But, instead of using radio or
sound waves, it uses light from a laser.
The light, aimed at the ground from an
aerial platform, is reflected by particles
of liquids or solids suspended in the air
(aerosols). The light reflected back is
collected by a telescope, changed to
electrical pulses, and stored on magnetic
tape for later analysis. Simultaneously,
the recorded information can be dis-
played on a television screen on the
aircraft for immediate assessment of the
aerosol layers.
From this information, EPA scientists
can determine the range, concentration
and location of aerosols, height of in-
versions, and locations of pockets or
plumes of highly concentrated aerosols.
Earth Reflected Differential Absorp-
tion - - This is an airborne system which
uses two lasers to monitor specific
gaseous pollutants in the air. It takes
advantage of the fact that different sub-
stances absorb different frequencies
(colors) of light. The frequencies of the
lasers are adjustable. One is set so that
it is absorbed by the pollutant being
sought. The other is adjusted to a fre-
quency that can pass through the
pollutant unchanged. The difference in
the two beams, after they have been
reflected by the Earth and collected by a
telescope in the aircraft, indicates the
quantity and geographic distribution of
the specific pollutant under study. Pol-
lutants that can be monitored by this
system include ozone and sulfur dioxide.
Laser Fluorosensing - - Many sub
stances emit visible light (fluoresce)
when they absorb light in the blue or
ultraviolet range. The color and intensity
of this fluorescent emission is unique for
different substances and can be used to
identify them.
In laser fluorosensing, fluorescence is
produced in a remote target by illumi-
nating it with light pulses from a laser.
The fluorescent emission is collected
with a telescope and analyzed to identify
the specific pollutants being monitored
and to provide clues to their source.
Laser fluorosensing can be used to
identify water pollutants and to monitor
changes caused in vegetation by air
pollution.
fUlHESCHT TUttt
page 24
. U. S. GOVERNMENT PRINTING OFFICE: 1977—784-216
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Additional Information
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port Laboratory at Las Vegas has estab-
lished an Information Services Staff to
disseminate information about its activi-
ties and to refer requests for technical
information to the appropriate division.
Queries should be directed to:
Information Services Staff
EPA Laboratory
Box 15027
Las Vegas, Nevada 89114
Scientific and technical reports pub-
lished by the Laboratory are available
for purchase from the National Technical
Information Center, U.S. Department of
Commerce, Springfield, Virginia 22161.
A catalog of recent Laboratory publica-
tions is available from the Laboratory's
Information Services Staff. A catalog of
all publications produced by EPA's Office
of Research and Development, including
reports of the Las Vegas Laboratory,
may be ordered from Technical Inform-
ation Staff, U.S. Environmental Protec-
tion Agency, Cincinnati, Ohio 45268.
Both catalogs are provided free upon
request.
PHOTO CREDITS:
Cover NASA; Page 1: Hank deLespinasse; Page 2: E. H. Opsilos;
Page 3: Blair Pittman (EPA Documerica): Page 4: Hank deLespinasse;
Page 5: E. H. Opsitos; Page 6: Hank deLespinasse, Page 7: Top - Jimmie
Garrelt, Middle and Bottom - Mike Gordon; Page 8: E. H. Opsitos;
Page 9: Mike Gordon; Page 10: NASA; Page 11: Boyd Norton (EPA
Documerica): Page 12: Jimmie Garrett; Page 13: Gene Daniels (EPA
Documerica); Page 14: Mike Gordon; Page 15: Left • Mike Gordon,
Right - Jimmie Garrett: Page 16: Mike Gordon; Page 17: E. H. Opsitos;
Page 18: NASA; Page 23: Upper Left - E. H. Opsitos. Right - NASA;
Page 25: E. H. Opsitos
The Laboratory directly serves only
EPA regional and headquarters program
offices. However, others may take ad-
vantage of its services through the EPA
regional office that serves their state.
page 25
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