Dissolved
Oxygen (DO)
Oxygen
is present in aquatic systems as dissolved oxygen. Oxygen is necessary
to allow aquatic animals, microorganisms, and other chemical reactions
to survive in the aquatic system. Oxygen is introduced into the
stream system through plants (photosynthesis) and from the atmosphere.
Aquatic systems with running water (such as streams and rivers)
can dissolve more oxygen than aquatic systems with still water
(like lakes and swamps) because the water "churns" (and
has more interactions with the atmosphere). Only in deep holes
or in polluted waters does dissolved oxygen levels show any significant
decline.
Several complex interactions between plants, aquatic animals,
and microbial organisms determine the amount of dissolved oxygen
that is available in an aquatic system. DO levels also fluctuate
seasonally and over a 24 hour period. The amount of DO also varies
with water temperature and altitude. What does presence or absence
of DO mean to an aquatic ecosystem? In general, various sources
of competition for dissolved oxygen mean that some animals will
not be able to survive in the aquatic system due to low dissolved
oxygen.
Smith,
Robert Leo. "Elements of Ecology" HarperCollins, 3rd
Edition ©1992
excerpt from EPA's "Volunteer Stream Monitoring: A Methods
Manual"
Temperature
Temperature is a determining factor for biological and chemical
processes. As stated above, DO is one measure that fluctuates
with temperature. Most aquatic organisms depend upon certain temperatures
in order to sustain their life functions. Temperature also effects
the process of photosynthesis and the sensitivity of certain organisms
to toxic waste, parasites, and diseases.
excerpt
from EPA's "Volunteer Stream Monitoring: A Methods Manual"
pH
The degree of acidity or alkalinity, or pH, of water reflects
the carbon dioxide content as well as the presence of organic
acids and pollution. At higher levels, water is more alkaline
and at lower levels, water is more acidic. The higher the pH of
stream water, the richer natural waters generally are in carbonates,
bicarbonates and associated salts. Such streams support more abundant
aquatic life and larger fish populations than streams with acid
waters, generally low in nutrients.
Like temperature, pH levels effect both biological and chemical
processes. The level of pH in an aquatic system can hinder the
reproduction of certain organisms and can allow toxic substances
to become more readily available for uptake by aquatic plants
and animals. Over a period of time, cornerstone species in a habitat
with acidic waters can disappear, causing disruptions in the food
web as well the loss of other species.
Smith,
Robert Leo. "Elements of Ecology" HarperCollins, 3rd
Edition ©1992
excerpt from EPA's "Volunteer Stream Monitoring: A Methods
Manual"
Nitrogen
Nitrogen is another essential nutrient for plant and animal development.
It is necessary in the natural processes of organisms to sustain
life.
However, the amount of nitrogen that is occurring in lakes, rivers
and coastal waters is being aggravated through human inputs. Nitrogen
and phosphorus are major ingredients in fertilizers used in farming
methods, and large amounts of these chemicals are washed off farmland
into streams and other tributaries through rain runoff.
Excessive amounts of nutrients such as nitrogen speed up the slow,
natural nutrient enrichment process of streams and lakes, called
eutrophication. Too much nitrogen in these environments can cause
accelerated plant growth, algae blooms, and increase the amount
of material available for decomposition (which lowers dissolved
oxygen.) Often, this condition usually results in fish kills,
offensive odors, unsightliness, and reduced attractiveness of
the water for recreation and other public uses.
Baird,
Jack V. "Nitrogen Management and Water Quality" North
Carolina Cooperative Extension Service ©August 1990
excerpt from EPA's "Volunteer Stream Monitoring: A Methods
Manual"
Carbon
Monoxide
Carbon monoxide (CO) is a colorless, odorless and at high levels,
a poisonous gas, formed when carbon in fuel is not burned completely.
Less dense than air under ordinary conditions, is very slightly
soluble in water and burns in air with a characteristic blue flame,
producing carbon dioxide, the gas most responsible for causing
the "greenhouse effect" in the Earth's atmosphere.
It
is present in the exhaust of internal combustion engines (e.g.,
in automobiles) and is generated in coal stoves, furnaces, and
gas appliances that do not get enough air (usually because of
a faulty draft or for other reasons), and through natural sources
such as wildfires. As a component of motor vehicle exhaust, it
contributes about 60 percent of all CO emissions nationwide. In
cities, as much as 95 percent of all CO emissions may come from
automobile exhaust, and high concentrations of CO generally occur
in areas with heavy traffic congestion. Peak CO concentrations
typically occur during the colder months of the year when CO automotive
emissions are greater and nighttime inversion conditions (where
air pollutants are trapped near the ground beneath a layer of
warm air) are more frequent.
Carbon
monoxide enters the bloodstream through the lungs and reduces
oxygen delivery to the body's organs and tissues. Early symptoms
of carbon monoxide poisoning include drowsiness and headache,
followed by unconsciousness, respiratory failure, and death. First
aid for a victim of carbon monoxide poisoning requires access
to fresh air; administration of artificial respiration and, if
available, oxygen; and, as soon as possible, expert medical attention.
The
health threat from lower levels of CO is most serious for those
who suffer from cardiovascular diseases, such as angina pectoris.
At much higher levels of exposure CO can be poisonous to the point
where even healthy individuals may be seriously affected.
Firor,
John. The Changing Atmosphere Yale University Press, © 1990.
Pp. 4-5
U.S. EPA Office of Air and Radiation. 1997 National Air Quality
Status and Trends
Infoplease.com Encylcopedia www.infoplease.com
Ozone
Ozone
is a gas that occurs both in the Earth's upper atmosphere and
at ground level. Ozone can be good or bad, depending on where
it is found. "Good" ozone occurs naturally in the Earth's
upper atmosphere - 10 to 30 miles above the Earth''s surface -
where it shields us from harmful ultraviolet rays from the sun.
"Bad" ozone occurs in the Earth's lower atmosphere,
near ground level, where it is formed when pollutants emitted
by cars, power plants, industrial boilers, refineries, chemical
plants, and other sources react chemically in the presence of
sunlight. Ozone pollution is a concern during the summer months
when the weather conditions needed to form ground-level ozone
- lots of sun, hot temperatures - normally occur.
Ozone, the main ingredient of smog, presents a serious air quality
problem in many parts of the United States. Even at low levels,
ozone can cause a number of respiratory effects such as acute
respiratory problems, aggravation of existing asthma conditions,
significant temporary decreases in lung capacity of 15 to over
20 percent, inflammation of lung tissue, impairment of the body's
immune system defenses, making people more susceptible to respiratory
illnesses, including bronchitis and pneumonia.
Several groups of people are particularly sensitive to ozone -
especially when they are active outdoors - because physical activity
causes people to breathe faster and more deeply. Such groups of
people include active children, active adults who exercise or
work vigorously outdoors and people with asthma or other respiratory
illnesses.
United
States Environmental Protection Agency. Office of Air & Radiation/Office
of Air Quality Planning & Standards Health and Environmental
Effects of Ground Level Ozone Fact Sheet
United
States Environmental Protection Agency. AIRNow Homepage http://www.epa.gov/airnow/
Lead (Pb)
In
the past, automotive sources were the major contributor of Pb
emissions to the atmosphere. As a result of regulatory efforts
to reduce the content of Pb in gasoline, the contribution from
the transportation sector has declined over the past decade. Today,
metals processing is the major source of Pb emissions to the atmosphere.
The highest air concentrations of Pb are found in the vicinity
of nonferrous and ferrous smelters, and battery manufacturers.
Exposure to Pb occurs mainly through inhalation of air and ingestion
of Pb in food, water, soil, or dust. It accumulates in the blood,
bones, and soft tissues. Lead can adversely affect the kidneys,
liver, nervous system, and other organs. Excessive exposure to
Pb may cause neurological impairments, such as seizures, mental
retardation, and behavioral disorders. Even at low doses, Pb exposure
is associated with damage to the nervous systems of fetuses and
young children, resulting in learning deficits and lowered IQ.
Recent studies also show that Pb may be a factor in high blood
pressure and subsequent heart disease. Lead can also be deposited
on the leaves of plants, presenting a hazard to grazing animals.
United
States Environmental Protection Agency Office of Air and Radiation
Nitrogen
Dioxide (NO2)
Nitrogen
oxides (NOx), the term used to describe the sum of NO, NO2 and
other oxides of nitrogen, play a major role in the formation of
ozone. The major sources of man-made NOx emissions are high-temperature
combustion processes, such as those occurring in automobiles and
power plants. Home heaters and gas stoves also produce substantial
amounts of NO2 in indoor settings.
Short-term exposures (e.g., less than 3 hours) to current nitrogen
dioxide (NO2) concentrations may lead to changes in airway responsiveness
and lung function in individuals with pre-existing respiratory
illnesses and increases in respiratory illnesses in children (5-12
years old). Long-term exposures to NO2 may lead to increased susceptibility
to respiratory infection and may cause alterations in the lung.
Atmospheric transformation of NOx can lead to the formation of
ozone and nitrogen-bearing particles (most notably in some western
urban areas) which are both associated with adverse health effects.
Nitrogen oxides also contribute to the formation of acid rain.
Nitrogen oxides contribute to a wide range of environmental effects,
including potential changes in the composition and competition
of some species of vegetation in wetland and terrestrial systems,
visibility impairment, acidification of freshwater bodies, eutrophication
(i.e., explosive algae growth leading to a depletion of oxygen
in the water) of estuarine and coastal waters (e.g., Chesapeake
Bay), and increases in levels of toxins harmful to fish and other
aquatic life.
United
States Environmental Protection Agency Office of Air and Radiation
Particulate
Matter (PM-10)
Particulate
matter (PM) is the general term used for a mixture of solid particles
and liquid droplets found in the air. Some particles are large
or dark enough to be seen as soot or smoke. Others are so small
they can be detected only with an electron microscope. These particles,
which come in a wide range of sizes ("fine" particles
are less than 2.5 micrometers in diameter and coarser-size particles
are larger than 2.5 micrometers), originate from many different
stationary and mobile sources as well as from natural sources.
Fine particles (PM-2.5) result from fuel combustion from motor
vehicles, power generation, and industrial facilities, as well
as from residential fireplaces and wood stoves. Coarse particles
(PM-10) are generally emitted from sources, such as vehicles traveling
on unpaved roads, materials handling, and crushing and grinding
operations, as well as windblown dust. Some particles are emitted
directly from their sources, such as smokestacks and cars. Their
chemical and physical compositions vary depending on location,
time of year, and weather.
Inhalable PM includes both fine and coarse particles. These particles
can accumulate in the respiratory system and are associated with
numerous health effects. Exposure to coarse particles is primarily
associated with the aggravation of respiratory conditions, such
as asthma. Fine particles are most closely associated with such
health effects as increased hospital admissions and emergency
room visits for heart and lung disease, increased respiratory
symptoms and disease, decreased lung function, and even premature
death. Sensitive groups that appear to be at greatest risk to
such effects include the elderly, individuals with cardiopulmonary
disease, such as asthma, and children. In addition to health problems,
PM is the major cause of reduced visibility in many parts of the
United States. Airborne particles also can cause damage to paints
and building materials.
United
States Environmental Protection Agency Office of Air and Radiation
Sulphur
Dioxide (SO2)
Sulfur
dioxide belongs to the family of sulfur oxide gases. These gases
are formed when fuel containing sulfur (mainly, coal and oil)
is burned and during metal smelting and other industrial processes.
Most SO2 monitoring stations are located in urban areas. The highest
monitored concentrations of SO2 are recorded in the vicinity of
large industrial facilities.
High concentrations of SO2 can result in temporary breathing impairment
for asthmatic children and adults who are active outdoors. Short-term
exposures of asthmatic individuals to elevated SO2 levels while
at moderate exertion may result in reduced lung function that
may be accompanied by such symptoms as wheezing, chest tightness,
or shortness of breath. Other effects that have been associated
with longer-term exposures to high concentrations of SO2, in conjunction
with high levels of PM, include respiratory illness, alterations
in the lungs' defenses, and aggravation of existing cardiovascular
disease. The subgroups of the population that may be affected
under these conditions include individuals with cardiovascular
disease or chronic lung disease, as well as children and the elderly.
Together, SO2 and NOx are the major precursors to acidic deposition
(acid rain), which is associated with the acidification of soils,
lakes, and streams, accelerated corrosion of buildings and monuments,
and reduced visibility. Sulfur dioxide also is a major precursor
to PM-2.5, which is a significant health concern as well as a
main pollutant that impairs visibility.
United
States Environmental Protection Agency Office of Air and Radiation
TSP (Total Suspended Particulates)
TSP
is a measure of the particulate content of ambient air. Air monitoring
networks were changed in 1987 to measure PM-10 (replacing the
earlier TSP monitors). The new standard focuses on smaller particles
that are likely responsible for adverse health effects because
of their ability to reach the lower regions of the respiratory
tract.
United
States Environmental Protection Agency Office of Air and Radiation
Toxics
Release Inventory (TRI)
Following
a fatal chemical-release accident in Bhopal, India, the Emergency
Planning and Right-to-Know Act (EPCRA) provisions were enacted
to promote, among other things, providing the public with information
to provide the public with information on release of toxic chemicals
in their communities. This established the Toxics Release Inventory
(TRI) Program, a publicly available national database that identifies
facilities, chemicals manufactured and used at the identified
facility, and the annual amounts of these chemicals released (in
routine operations as well as accidents and other one-time events.)
The TRI contains information on specific toxic chemical releases
and other waste management activities from the manufacturing sector
of the U.S. economy and, since 1994, federal facilities. Each
year, facilities that meet certain thresholds must report their
releases and other waste management activities for listed toxic
chemicals to EPA and to the state or tribal entity where the facility
is located. Beginning in 1991, covered facilities were required
to report quantities of TRI chemicals recycled, combusted for
energy recovery, and treated on- and -offsite.
excerpt
from "1987-1996 Toxic Release Inventory User Manual"
U.S. Environmental Protection Agency, © July 1999
Wetlands
Wetlands
are defined as "Those areas that are inundated or saturated
by surface or ground water at a frequency and duration sufficient
to support, and that under normal circumstances do support, a
prevalence of vegetation typically adapted for life in saturated
soil conditions. Wetlands generally include swamps, marshes, bogs,
and similar areas.." It is divided into estuarine and freshwater
systems, which may be further subdivided by soil type and plant
life into bogs, swamps, and marshes. Because wetlands have poor
drainage, the area is characterized by sluggish or standing water
that can create an open-water habitat for wildlife. Highly productive
and complex ecosystems, wetlands help to regulate the water cycle,
filter the water supply, and prevent soil erosion. More significantly,
however, wetlands serve as spawning and feeding grounds for nearly
one third of the endangered animal and plant species in the United
States, and their ecological value in most other countries is
comparable.
The VEQI used wetland loss as a measure of ecosystem-level change.
Wetland loss has been included in several indexed measures of
environmental quality. Wetlands act as buffers from and filters
of pollution. Wetlands also reduce flooding, contribute to the
groundwater supply recharge and provide excellent habitat for
fish, shellfish, birds and insects.
Virginia
has about 1 million acres of wetlands; one-quarter are tidal and
three-quarters are non-tidal. Forested wetlands (swamps) are the
most common wetlands in the State. Both shores of the Chesapeake
Bay have extensive estuarine wetlands. Conversion to non-wetland
uses (agricultural, urban, industrial, and recreational), channelization
and ditching, and other causes have resulted in the loss of about
42 percent of Virginia's wetlands since the 1780's. Other estimates
gauge current wetland acreage as 50% of 1780s holdings.
Many wetlands were destroyed by urban growth and farming before
their value was recognized. More than half of U.S. wetlands in
the lower 48 states have been lost since colonial times. Federal
wetlands policy today is based on the wetlands provisions (1987)
of the Clean Water Act. The working concept is that of ""no
net loss,"" a concept that has been interpreted in various
ways by each federal administration.
http://www.epa.gov/owow/wetlands/facts/fact11.html
Infoplease.com
Encylcopedia www.infoplease.com
Firor, John. The Changing Atmosphere Yale University Press, ©
1990. Pp. 4-5
