pollution-resistant lower order of fish, such as carp,
replaces the original fish population. The amount of
oxygen in a body of water is therefore one of the best
measures of its ecological health.
If all the oxygen is used, an anaerobic (without air)
decomposition process is set in motion with a different
mixture of bacteria. Rather than releasing carbon
dioxide in the decomposition process, anaerobic
decomposition releases methane or hydrogen sulfide. In
these highly polluted situations, the river turns dark and
odors-like rotten eggs-penetrate the environment.
Heated water discharged into lakes and rivers often
harms aquatic life. Heat accelerates biological and
chemical processes that reduce the ability of a body of
water to retain dissolved oxygen and other dissolved
gases. Increases in temperature often disrupt the
reproduction cycles of fish. By hastening biological
processes, heat accelerates the growth of aquatic plants
such as algae. Finally, the temperature level determines
the types of fish and other aquatic life that can live in
any particular body of water. The effects of excessive
heat operate to change the ecology of an
area-sometimes drastically, rapidly, and irreversibly.
One of the most serious water pollution problems is
eutrophicationthe dying of lakes. All lakes go
through a natural cycle of eutrophication, but this
normally takes thousands of years. Lakes are deep and
have little biological life. Lake Superior is a good
example. Over a period of time, nutrients and sediments
were added and the lake became more biologically
productive and shallower. As nutrients continued to be
added, large algae blooms grew, the fish populations
changed, and the lake began to take on undesirable
characteristics. After an extended time, a lake can
become a swamp and finally a land area.
People greatly accelerate this process of
eutrophication when they add nutrients to the water.
Nutrients include detergents, waste food products,
fertilizers, and human wastes. The actions of people can,
in decades, cause changes that would take nature
thousands of years.
Polluted waters harm human health as well as the
natural environment. It is true that epidemics of typhoid,
dysentery, and salmonellosis borne by polluted water
are no longer serious public health threats in the United
States. However, it is still vital that we maintain
adequate protection of the public from these and other
pollution dangers. Often water must be treated to very
high levels before it is drinkable. Frequently, beaches
must be closed and shellfish left unharvested.
Inadequately disinfected municipal waste overflow
from combined sewer systems and runoff from animal
feedlots often create high bacteria densities in local
water supplies. Ships that are anchored far upstream can
contribute to a high bacteria count in a communitys
water supply. The Navy is exploring the use of many
devices and schemes to lessen the effect of waste
discharges in water.
Construction site work and repair and maintenance
of facilities have the immediate potential for becoming
polluting activities. Since the majority of construction
efforts take place on land, project supervisors must
identify potential pollution hazards and take steps to
minimize the effects. Some of the most common
pollution activities that affect the ground areas and water
ecosystems are grubbing and equipment repair
GRUBBING OPERATIONS. Large-scale
clearing and grubbing during the initial stages of a
project often produce damaging environmental effects,
such as increased soil erosion, reduction of atmospheric
oxygen, and destruction of wildlife habitat. Another
primary concern is the introduction of particulate matter
into streams and riverbeds. Particulate matter released
into waterways causes increased siltation and algae
To prevent these damaging effects you should save
as much vegetation as possible-trees, grass, and other
plants-to hold the soil in place. Consider allowing tree
rows to be left in place until the project is completed.
Replant cleared areas. Construct a shallow trench
around the perimeter of a project to help contain water
runoff into streams and rivers and to prevent siltation.
The decision to burn scrubs and stumps should be based
on atmospheric conditions. Burn only when conditions
are favorable and the material to be burned is totally dry.
A burn permit is required in all burning operations
on NCF projects! To prevent wild tires and production
of smog, do NOT use petroleum-base fuels to start fires!
Petroleum-base fuels do not burn completely, and the
residue seeps into the underground water table.
EQUIPMENT REPAIR OPERATIONS.
Repair and maintenance of CESE whether in the shop
or on the project site must always be under controlled
and closely monitored conditions. Lubricating oil, fuel,
hydraulic fluids, transmission fluids, and antifreeze
contain extremely volatile chemical properties. When
these petrochemicals are mixed with certain solvents or