Download 3.20Ocean Pollution

Ocean Pollution
Problem:
• Pollution of the world's oceans is quickly
becoming a major problem on Earth.
• We know very little about the effect that
pollution has on the oceans but we
continue to dispose of chemicals, sewage
and garbage into it.
Toxic Ocean Pollutants
• Our waste, even in small quantities, have
huge effects on ocean communities and
species.
• Toxic pollutants in the ocean ecosystem
have massive impacts on the plants and
animals.
Some major types of pollutants:
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garbage
sewage
chemicals
radioactive waste
eutrophication
heavy metals
oil
Marine Garbage
• Garbage includes junked out fishing nets,
plastics, general household garbage
• In one case an island 300 miles from the nearest
inhabited island) had 950 pieces of garbage
ranging from plastics to tin cans.
• Garbage in the oceans is a serious issue as fish
entangle themselves in fishing nets and animals
sometimes eat trash products and die.
• There are numerous examples each year of
dolphins, sharks and whales entangling
themselves in fishing nets and dying from
oxygen starvation.
Oceanic Sewage Disposal
• Typically the problem with sewage is that it
causes massive nutrient loading in the
ocean ecosystem.
• When nutrient loading occurs there will
often be algae blooms in the water leading
to the loss of dissolved oxygen.
• After the depletion of oxygen levels from
sewage, many organisms in the ocean die
from being unable to breathe properly.
Oceanic Sewage Disposal Cont’d
• Other problems associated with sewage
include parasites/bacteria that require the
closing of coastal beaches and poisoned
shellfish fisheries.
• For the most part cities in the developed
world have sewage treatment facilities but
many of the cities in poorer areas have
little to no sewage treatment.
Chemicals
• These are toxic substances that are
released by the industrialized nations and
make their way into ocean systems.
• Toxic chemicals often enter ocean
systems through food chains and affect
organisms at different times and places
from where they were released.
Example: DDT
• (Dichlorodiphenyltrichloroethane)
• DDT was used for years as a pesticide on
farms.
• Later it was found that it does not breakdown,
This compound is relatively insoluble in water
and bonds strongly to particles.
• Although DDT is not used in the marine
environment it enters marine food webs
through land runoff, precipitation and dumping.
• DDT is absorbed by plankton but cannot be
metabolized.
• Since, it is not metabolized it accumulates in
the food chain until it reaches the top carnivore,
where more drastic effects are seen.
• For example, in marine birds, DDT interferes
with calcium deposition in the eggshells. The
eggs shells are extremely thin and therefore
easily broken.
Desalination Plants
• There are several concerns about the impact of desalination plants
on the marine environment. Various chemicals used to clean pipes
and to pre-treat the water, are later washed out in the effluent.
• One of the largest concerns is the release of highly-concentrated
salt water, sometimes into estuaries and rivers, where the salt
content is obviously much lower than in the open ocean.
Estuaries are important breeding and juvenile development habitats
for many species, because of their calm waters. Eggs, larvae and
juveniles are usually far less tolerant to environmental changes than
their adult counterparts, so changes in estuary oceanography could
have a large impact of brood stock of various fish and invertebrate
species.
Radioactive waste
• Radioactive waste enters the ocean from nuclear weapon
testing, the releasing or dumping of wastes from nuclear
fuel cycle systems, and nuclear accidents.
• Dumping of high-level radioactive waste is no longer
permitted in the ocean, but dumping of low-level wastes is
still permitted. Low-level waste contains less radioactivity
per gram than high-level waste. High-level wastes usually
have longer half-lives.
• For example, one common high-level waste that is
produced by spent nuclear fuel has a half-life of 24,100
years!
• It has been suggested that contained nuclear waste
should be disposed in the deep sea. So little is known
about the deep sea environment or the consequences of
containment leakage and failure, that the effects could be
devastating.
Eutrophication:
• The release of excess nutrients into coastal waters.
• Fertilizers used on land are washed into the ocean via
rivers and streams.
• High nutrient concentrations cause phytoplankton
blooms such as, red tides, various yellow and green
foams, slimes, and slicks. Although algal blooms are
natural, a higher frequency of their occurrence in the
past twenty years indicates an unhealthy ecosystem.
• The toxicity of recent blooms are increasing, which can
have a direct effect on the organisms that feed on them.
• Also, phytoplankton naturally contains DMS (dimethyl
sulfide) which is released from dead phytoplankton into
the atmosphere and can be changed to sulfuric acid to
eventually contribute to acid rain.
Heavy Metals
• Heavy metals in the water are dangerous
when they have a chance to built up inside
organisms.
• Organisms tend not to get rid of the metals
within them, so it accumulates over the
coarse of their life
• Examples: mercury, cadmium, arsenic
Oil Spills (1)
• The effects of an oil spill of
marine life depend on a number
of physical and biological factors.
• The distribution of the oil spill will
be affected by currents and wind
• In addition, the amount of oil
spilled will determine the
eventual geographic boundaries
of the impact area.
• The physical and chemical
properties of the oil will
determine the behaviour of the
slick, in terms of its thickness
and rate of spreading.
Oil Spills (2)
• Environmental conditions such as salinity, water
temperature, and type and slope of shoreline will
determine habitat effects and clean-up
procedures
• Some example habitats include sandy beach,
mud, cliffs, estuaries and open water. In terms of
difficulty of clean-up and relative vulnerability, a
salt marsh ranks the highest, followed by
eelgrass, mud, mixed-fine sediment, mixedcoarse sediment, rock, sand, algae (kelp) and
open water.
Oil Spills (3)
• Biological
characteristics of the
organisms affected
will determine the
severity of impact.
• These characteristics
include the type of
species, life stage
(larval, juvenile or
adult) and size.
Cleaning-up oil spills:
• 1. Dispersants: Oil can be broken down more quickly by
spraying dispersants (chemicals) on the oil slick from
boats or planes. This method only works on fresh, small
oil spills.
• 2. Booms: A boom has a floating skirt suspended down
in the water and a sail holding it above the water line.
The floating skirt stops the oil from passing. These are
used to prevent oil from entering delicate and protected
areas.
• 3. Slick-lickers: This method uses a belt of oil absorbing
material that sucks up the oil from the ocean water. The
oil is then squeezed out of the absorbing material into a
collecting bin.
Arrow
• February 4, 1970
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On February 4, 1970 ARROW was approaching
Port Hawkesbury under charter to Imperial Oil
Limited and just about to complete a voyage
from Aruba. She was carrying 10 million litres of
Bunker "C" oil bound for a paper company near
Point Tupper. Entering Chedabucto Bay, the
tanker encountered severe weather and gale
force winds. She ran aground on Cerberus
Rock, a well-known navigational hazard that lies
in wait just below the surface of the bay. While
it initially appeared that there was no threat of
fuel leakage, the heavy weather continued to
pound the stricken tanker. Imperial Oil issued
an oil spill alert and the crew were evacuated.
By the next day, an oil slick one mile long had
formed and on the 8th, the ship finally split in
two, with the stern sinking in deeper water.
Attempts to take off the cargo were not
successful nor were the attempts to recover her
stern. In all, about 10,330 tons of fuel were
spilled, coating 75 miles of the shoreline with
thick black sludge threatening wildlife and the
fishery. Shore cleanup was a long difficult
process as was the transfer of what was left of
the oil aboard ARROW to the barge.
Irving Whale
• 7 September 1970, the Irving Whale in approximately 67 m
(220 ft) of water. The location of the wreck in the centre of the Gulf of St.
Lawrence was approximately 60 km (32 nmi) northeast of North Cape,
Prince Edward Island
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Throughout the 1970s until its salvage in 1996, the Irving Whale continued to
experience minor leakage from its cargo vents and other valves. Throughout
the 26 year period it was submerged in the salt waters of the Gulf of St.
Lawrence, the thickness of the barge's steel hull was reduced by
approximately 5 mm (0.20 in) as a result of corrosion.00 km (54 nmi)
southwest of Cap du Sud-Ouest, Magdalen Islands.