Earth Science 14.4 Seafloor Resources

1. Earth Science 14.4 Seafloor Resources

2. Seafloor Resources: • 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.

3. Seafloor Resources: Oil and Natural Gas: • 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.

4. Seafloor Resources: Oil and Natural Gas: • 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.

5. Seafloor Resources: Oil and Natural Gas: • 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.

6. Seafloor Resources: Gas Hydrates: • 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.

7. Seafloor Resources: Gas Hydrates: • Most oceanic gas hydrates are created when bacteria break down organic matter trapped in ocean-floor 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.

8. Seafloor Resources: Gas Hydrates: • 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 low-pressure 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

9. Seafloor Resources: Gas Hydrates: • 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

10. Seafloor Resources: Gas Hydrates: • 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

11. Other Seafloor Resources: Sand and Gravel: • 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.

12. Other Seafloor Resources: Sand and Gravel: • 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.

13. Other Seafloor Resources: Sand and Gravel: • 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.

14. Other Seafloor Resources: Manganese Nodules: • 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

15. Other Seafloor Resources: Manganese Nodules: • These alloys are used in high-speed 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.

16. Other Seafloor Resources: Evaporative salts: • 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 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.

17. Other Seafloor Resources: Evaporative salts: • 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 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.

18. Computer lab Assignment: • 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. • Undersea oil reserves and offshore drilling • Undersea natural gas reserves: mining • Undersea gas hydrates: mining • Undersea mining of precious metals • Commercial sea-salt production

19. Seafloor Resources: Links to Underwater Mining Information: • CSIRO Marine and Atmospheric Research • Deep Sea Metals • InstitutFrançais 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