Download Earth Science 14.1 The Vast World Ocean

Earth Science 14.4 Seafloor Resources
Seafloor Resources:
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The ocean floor is rich in mineral and
energy resources. Recovering them
however often involves technological
challenges and high costs.
As technology improves we are able to
access some of these resources more
efficiently. However some resources,
such as manganese nodules, remain
untouched.
Most of the value of nonliving
resources in the ocean comes from
energy products; oil and natural gas.
Seafloor Resources:
Oil and Natural Gas:
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The ancient remains of microscopic
organisms are the source of today’s
deposits of oil and natural gas.
These organisms were buried in marine
sediments before they could decompose.
After millions of years of exposure to
heat and pressure, the remains have
transformed into oil and natural gas.
The percentage of oil produced from
offshore drilling platforms has increased
from a small percentage in the 1930s to
roughly 30% (almost one third) of today’s
production.
Seafloor Resources:
Oil and Natural Gas:
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Part of this increase we have seen is due
to advances in oil recovery technology
and advances in offshore drilling
platform design.
Major oil reserves exist in the Persian
Gulf, in the Gulf of Mexico, off the coast
of southern California, in the North Sea
and in the West Indies.
Seafloor Resources:
Oil and Natural Gas:
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Additional reserves are probably located
off the north coast of Alaska, and in the
Canadian Arctic, Asian seas, Africa, and
Brazil.
One key environmental concern is the
concern about large oil spills from
accidental leaks during the drilling on
these enormous offshore platforms.
Seafloor Resources:
Gas Hydrates:
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Gas hydrates are compact chemical
structures made of water and natural
gas.
The most common type of natural gas is
methane, which produces methane
hydrate.
Gas hydrates occur beneath permafrost
areas on land and under the ocean floor
at depths below 525 meters.
Seafloor Resources:
Gas Hydrates:
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Most oceanic gas hydrates are
created when bacteria break down
organic matter trapped in oceanfloor sediments.
The bacteria produce methane gas
along with small amounts of ethane
and propane.
These gases combine with
sediments in deep ocean waters in
such a way that the gas is trapped
inside a lattice-like cage of water
molecules.
Seafloor Resources:
Gas Hydrates:
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Vessels that have drilled into gas
hydrates have brought up samples
of mud mixed with gas hydrates in
chunks mixed in.
These chunks evaporate quickly
when exposed to warm lowpressure surface conditions.
Gas hydrates resemble chunks of
ice but ignite when lit by a flame.
The hydrates burn because
methane and other flammable
gases are released as the gas
hydrates evaporate.
Chunk gas hydrate
Seafloor Resources:
Gas Hydrates:
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An estimated 20 quadrillion cubic
meters of methane are locked in
sediments containing gas hydrates.
This amount is double Earth’s
known coal, oil, and natural gas
combined.
Chunk gas hydrate
Seafloor Resources:
Gas Hydrates:
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One drawback to using gas
hydrates however is that they
rapidly break down at surface
temperatures and pressures.
In the future these ocean-floor
reserves of energy may help
provide our future energy needs.
Chunk gas hydrate
Other Seafloor Resources:
Sand and Gravel:
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The offshore sand and gravel
industry is second in economic
value only to the petroleum
industry.
Sand and gravel, which include rock
fragments that are washed out to
sea and shells of marine organisms,
are mined by offshore barges
using suction devices.
Sand and gravel are used for
landfill, to fill in recreational
beaches, and to make concrete.
Other Seafloor Resources:
Sand and Gravel:
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In some cases, materials of high
economic value are associated with
offshore sand and gravel deposits.
Gem quality diamonds, for example,
are recovered from gravels on the
continental shelf offshore of
South Africa and Australia.
Other Seafloor Resources:
Sand and Gravel:
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Sediments rich in tin have been
mined from some offshore areas
of Southeast Asia.
Platinum and gold have been found
in deposits in gold-mining areas
throughout the world.
Some Florida beach sands are rich
in titanium.
Other Seafloor Resources:
Manganese Nodules:
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As described earlier,
manganese nodules are
hard lumps of manganese
and other metals that
precipitate around a small
object. They are found in
fields in deep ocean areas.
They contain high
concentrations of
manganese, iron, and
smaller concentrations of
copper, nickel, and cobalt.
manganese nodules
littering deep ocean floor
Other Seafloor Resources:
Manganese Nodules:
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These alloys are used in highspeed cutting tools, powerful
permanent magnets, and jet
engine parts.
With current technology,
mining of the deep-ocean
floor for deposits of
manganese nodules is
possible but not economically
profitable.
Other Seafloor Resources:
Evaporative salts:
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When seawater evaporates,
the salts increase in
concentration until they can
no longer remain dissolved.
When the concentration
becomes high enough, the
salts precipitate out of
solution and form halite
(salt) deposits.
These halite deposits can
than be harvested. At right
is the process from the
website of a commercial salt
greenhouse system in
Marshfield Maine.
How We Extract Natural Sea Salt from Ocean
Water
1. Our solar greenhouses, known as "salt houses"
are filled with fresh sea water from the Gulf of
Maine.
2. The sea water evaporates naturally, from the
heat of the sun and the drying effects of the wind
blowing through the greenhouses.
3. Over a period of time, fleur de sel floats on the
pool surface, then grows and sinks to the floor to
form the salt bed.
4. When all of the water has evaporated, the sea
salt is ready to be packaged as natural Maine Sea
Salt™, seasoned with our natural ingredients, or
smoked over a wood fire.
Other Seafloor Resources:
Evaporative salts:
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Halite is widely used for
seasoning of food, curing,
and preserving foods.
It is also used in agriculture,
in the clothing industry for
dying fabrics, and to de-ice
roads.
How We Extract Natural Sea Salt from Ocean Water
1. Our solar greenhouses, known as "salt houses" are filled with
fresh sea water from the Gulf of Maine.
2. The sea water evaporates naturally, from the heat of the sun and
the drying effects of the wind blowing through the greenhouses.
3. Over a period of time, fleur de sel floats on the pool surface, then
grows and sinks to the floor to form the salt bed.
4. When all of the water has evaporated, the sea salt is ready to be
packaged as natural Maine Sea Salt™, seasoned with our natural
ingredients, or smoked over a wood fire.
Computer lab Assignment:
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Use the internet and the links on the
following page to research and write a one
page (4 paragraphs) mini-report on one of the
topics listed below.
DO NOT CUT, COPY OR PASTE: PUT IN YOUR
OWN WORDS.
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Undersea oil reserves and offshore drilling
Undersea natural gas reserves: mining
Undersea gas hydrates: mining
Undersea mining of precious metals
Commercial sea-salt production
Seafloor Resources:
Links to Underwater Mining Information:
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CSIRO Marine and Atmospheric Research
Deep Sea Metals
Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER)
International Cooperation in Ridge-Crest Studies (InterRidge)
International Seabed Authority (ISA)
ISA Central Data Depository
Kermadec Arc – Deepsea Research (on mineral deposits), Institute of
Geological and Nuclear Sciences, New Zealand
Korea Ocean Resources Development Institute
Leibniz Institute of Marine Sciences at the University of Kiel (IFM-GEOMAR)
Marine Georesources & Geotechnology, Taylor & Francis
Marine Minerals, U.S. Geological Survey
Marine Technology Society
Nautilus Minerals, Inc.
Neptune Minerals, Inc.
New Zealand American Submarine Ring of Fire (on mineral deposits)
Society of Mining Metallurgy and Exploration
South Pacific Applied Geoscience Commission (SOPAC)
Submarine Ring of Fire 2004, Mariana Arc (on deepsea hydrothermal vents)
United Nations Law of the Sea