Water and Water Pollution - Environmental Science - page 262

The shallow bay has become a huge pollution sink,
and only 1% of the waste entering it is flushed into the
Atlantic Ocean.
Phosphate and nitrate levels have risen sharply in
many parts of the bay, causing algal blooms and oxygen
depletion. Commercial harvests of its once-abundant
oysters, crabs, and several important fish have fallen
sharply since 1960 because of a combination of pollu-
tion, overfishing, and disease.
Point sources—primarily sewage treatment plants
and industrial plants (often in violation of their dis-
charge permits)—account for 60% by weight of the
phosphates. Nonpoint sources—mostly runoff of fertil-
izer and animal wastes from urban, suburban, and agri-
cultural land and deposition from the atmosphere—ac-
count for 60% by weight of the nitrates. According to
2004 study by the Chesapeake Bay Foundation, animal
manure is the largest source of nitrates and phosphates
from agricultural pollution.
In 1983, the United States implemented the Chesa-
peake Bay Program. In the country's most ambitious at-
tempt at integrated coastal management, citizens' groups,
communities, state legislatures, and the federal govern-
ment are working together to reduce pollution inputs
into the bay. Strategies include establishing land-use
regulations in the bay's six watershed states to reduce
agricultural and urban runoff, banning phosphate de-
tergents, upgrading sewage treatment plants, and bet-
ter monitoring of industrial discharges. In addition,
wetlands are being restored and large areas of the bay
are being replanted with sea grasses to help filter out
nutrients and other pollutants.
This hard work has paid off. Between 1985 and
2000, phosphorus levels declined 27%, nitrogen levels
dropped 16%, and grasses growing on the bay's floor
have made a comeback. This is a significant achieve-
ment given the increasing population in the watershed
and the fact that nearly 40% of the nitrogen inputs come
from the atmosphere.
Of course, there is still a long way to go, and sharp
cuts in state and federal funding have slowed progress.
Despite some setbacks, the Chesapeake Bay Program
shows what can be done when diverse groups work to-
gether to achieve goals that benefit both wildlife and
people.

borehole in the ocean floor) get most of the publicity
because of their high visibility. In fact, most ocean oil
pollution comes from human activities on land. According
to a 2004 study by the Pew Oceans Commission, every
8 months an amount of oil equal to that spilled by the
Exxon Valdez tanker into Alaska's Prince William
Sound in 1989 drains from the land into the oceans. Al-
most half (some experts estimate 90%) of the oil reach-
ing the oceans is waste oil dumped, spilled, or leaked
onto the land or into sewers by cities, industries, and
people changing their own motor oil.
Volatile organic hydrocarbons in oil immediately
kill a number of aquatic organisms, especially in their
vulnerable larval forms. Other chemicals in oil form
tar-like globs that float on the surface and coat the
feathers of birds (especially diving birds) and the
fur of marine mammals. This oil coating destroys
their natural insulation and buoyancy, causing many
of them to drown or die of exposure from loss of
body heat.
Heavy oil components that sink to the ocean floor
or wash into estuaries can smother bottom-dwelling
organisms such as crabs, oysters, mussels, and clams
or make them unfit for human consumption. Some oil
spills have killed coral reefs.
Research shows that most (but not all) forms of
marine life recover from exposure to large amounts
of crude oil within 3 years. Recovery from exposure to re-
fined oil, especially in estuaries and salt marshes, can
take 10-15 years. Oil slicks that wash onto beaches can
have a serious economic impact on coastal residents,
who lose income from fishing and tourist activities.
If they are not too large, oil spills can be partially
cleaned up by mechanical (floating booms, skimmer
boats, and absorbent devices such as large pillows
filled with feathers or hair), chemical, fire, and natural
methods (such as using cocktails of natural bacteria to
speed up oil decomposition).
But scientists estimate that current methods can
recover no more than 15% of the oil from a major spill.
Thus preventing oil pollution is the most effective and,
in the long run, the least costly approach.

Solutions: Protecting Coastal Waters
Preventing or reducing the flow of pollution from
land and from streams emptying into the ocean is the
key to protecting the oceans.
Figure 11-31 list ways for preventing and reducing ex-
cessive pollution of coastal waters. The key to protect-
ing the oceans is to reduce the flow of pollution from
land and from streams emptying into these waters.
Ocean pollution control must be linked with land-use
and air pollution policies because about one-third of
all pollutants entering the ocean worldwide come
from emissions of air pollutants.

Science: Effects of Oil on Ocean Life
Most aquatic oil pollution comes from human
activities on land.
Crude petroleum (oil as it comes out of the ground) and
refined petroleum (fuel oil, gasoline, and other processed
petroleum products) reach the ocean from a number of
sources.
Tanker accidents and blowouts at offshore drilling
rigs (when oil escapes under high pressure from a