Key Ideas about Ocean Pollution
- Of the total pollution load entering the oceans, about 75%
comes from human activities on land. The majority of nutrients,
sediments, disease organisms, poisons, and heat pollution comes
from land-based sources and enters the oceans from rivers (44%)
or from air pollution fallout (33%).
Shipping, accidental spills at sea, ocean dumping and mining accounts
for 23% of the ocean's pollution.
- About 46% of oil pollution comes from land sources; from oil
washed off roads by heavy rains and old oil dumped down drains.
About 9% of oil that reaches the oceans is airborne. 32% comes
from oil tanker operations and other shipping and 13% from accidents
at sea. Oil and tar are found on the surface of the sea almost
- Used oil contains chemical additives, arsenic, zinc and other
toxic metals that are a threat to living creatures.
- In New Zealand, 30 million litres of oil is disposed of every
year. Much of this damaged the environment when burned at low
temperatures, spread on roads to suppress dust, killing weeds,
and poured down stormwater drains or dumped in landfills. Only
7 million litres is re-refined by Dominion Oil.
- The Oil Recovery Group - made up of four major oil companies,
is working with the Ministry for the Environment to recover used
oil. The collected oil will be re-refined or burned at high temperatures
by Milburn New Zealand, a cement company in Westport. Ashes from
the used oil will be put into the cement to avoid environmental
- Pesticides and herbicides, heavy metals, plastic litter and
oil are major problems for marine life. These have been found
polluting the surface layer of the sea almost everywhere. They
may be the most damaging of all forms of pollution
and the most difficult to control.
- Excessive nutrients from sewage, forestry and farming cause
blooms of algae in coastal waters and
this may result in the death of other species of marine life and
poisoning of shellfish.
- In New Zealand, an estimated 400 million tonnes of soil is
lost each year through erosion and transport by rivers to the
sea. Voluntary and government-subsidised soil conservation programmes
have achieved only a localised reduction in soil erosion on hill
- Providing secondary sewage treatment for all New Zealand cities
would cost around $1 billion over the next decade. Sewage from
farm animals is considered one of the major problems of New Zealand
- International and National Laws are very important when it
comes to preventing marine pollution coming from ships. Tough
laws against oil pollution are responsible for reducing oil pollution
by 60% between 1981 and 1986.
- There are several important international laws, but the most
important is the Law of the Sea, a United Nations treaty on the
management of the oceans. The Law of the Sea says that participating
countries, like New Zealand, have legal control over their territorial
sea extending 12 nautical miles offshore and a 200 nautical mile
Exclusive Economic Zone within which a country has exclusive rights
to the natural resources. The Law of the Sea requires countries
to adopt the global treaties controlling pollution from ships
(MARPOL) and the London Dumping Convention that prohibits dumping
of toxic pollutants and radioactive wastes into the ocean.
- The MARPOL treaty prevents ships from dumping plastics and
other ship's wastes at sea. New Zealand will adopt this treaty
but must first install special waste collection facilities in
their ports so ships can get rid of them without importing dangerous
diseases or noxious pests.
- New Zealand's Maritime Safety Act prohibits spilling oil,
or other hazardous materials, into the water from ships. It also
controls the safety of ships and shipping, making sure New Zealand
ships, and ships visiting New Zealand, are seaworthy and will
not endanger people or the environment. The Maritime Safety Authority
of New Zealand develops and monitors maritime safety standards,
prevents marine pollution and responds to oil spills in New Zealand
- Enforcement is another matter. Illegal discharge of wastes
from ships is difficult to enforce because it can be done at night
or far at sea where nobody can see who did it. Often the amounts
of oil, garbage, and plastics are small and because the ships
are moving, it is virtually impossible to find out who did it.
Rather like people who throw cans and trash out of the window
of their car while driving along. Those people who love the sea,
or who care about the health of their waterways, will take the
trouble to carry the waste to a proper disposal place.
- The government relies on people in the community to report
pollution of the sea. The faster a pollution problem is spotted
and reported, the easier it will be to clean it up and the better
the chance the people responsible will be found. An oil spill
off-shore can be kept from reaching our beaches if the authorities
are notified quickly.
- If you see a major oil spill or some other hazardous chemical
spill, call your regional council and report it. Many councils
have a pollution hot line number to report spills. The Maritime
Safety Authority should be notified in the event of a maritime
accident or major oil spill. The marine duty officer can be reached
24 hours a day at (0508) 22 55 22.
Microsoft Oceans CD. (Hint. Use the alien guide).
Our Polluted Run Off National Geographic Magazine,