Section 3 - Ocean Resources
Earth Science
Chapter 20
Section 3 - Ocean Resources
E.Q.: What are some important resources of the oceans and how does water pollution pose a threat to marine organisms?
STANDARDS:
SES1.e. Identify the transformations and major reservoirs that make up the rock cycle, hydrologic cycle, carbon cycle, and other important geochemical cycles.
SES6. Students will explain how life on Earth responds to and shapes Earth systems.
a. Relate the nature and distribution of life on Earth, including humans, to the chemistry and availability of water.
Objectives
•Describethree important resources of the ocean.
•Explainthe threat water pollution poses to marine organisms.
Fresh Water from the Ocean
Methods of Desalination
desalination- a process of removing salt from ocean water
•One method of desalination is distillation. During distillation, ocean water is heated to remove salt.
Nation's First Large-Scale Desalination Plant Delivers Drought-Proof Water Supply
February 20, 2008
Clearwater, FL — The nation's first large-scale seawater desalination plant is delivering drinking water to more than 2.5 million residents of the Tampa Bay area. It's a timely solution as continued drought is forecast across the southeastern United States.
While parts of Alabama, Georgia and North Carolina are facing exceptional drought conditions, officials in west-central Florida say their residents are benefiting from the nation's first drought-proof drinking water supply, a project pioneered by the area's regional utility, Tampa Bay Water.
"Nearly a decade ago the Tampa Bay region suffered from an extreme drought, just as we are currently, and at that time we explored how we might drought-proof our system so that this didn't have catastrophic consequences," said Jerry Maxwell, General Manager of Tampa Bay Water, "As we did so seawater was a natural place for us to look. We live in Florida, we are on a peninsula, surrounded by seawaters, and even though it hadn't been undertaken on a large-scale, it seemed the natural thing to do."
Cost was the reason the utility had not considered seawater desalination in the past, Maxwell said. But when technology advances brought the cost of desalinated water down significantly, the utility felt the time was right.
The Tampa Bay Seawater Desalination Plant can produce up to 25 million gallons per day of drinking water. The process works like this: About 44 million gallons of water from a nearby power plant cooling system is diverted to the plant. There, it goes through pretreatment steps to remove algae and other particles. Using reverse osmosis filters, 25 million gallons per day of freshwater is separated from the seawater.
•Another method of desalination is freezing. This process requires about one-sixth the energy needed for distillation. This process is still in the planning stages.
•Reverse osmosis desalination is a popular method for desalinating ocean water
Mineral and Energy Resources
Petroleum
•The most valuable resource in the ocean is petroleum found beneath the ocean floor.
•Offshore oil and natural gas deposits exist along continental margins around the world.
•About one-fourth of the world’s oil is now obtained from offshore wells.
Map of the northern Gulf of Mexico showing the nearly 4,000 active oil and gas platforms.
Nodules
Polymetallic nodules, also called manganese nodules, are rock concretions on the sea bottom formed of concentric layers of iron and manganesehydroxides around a core.
•Nodules are a valuable source of manganese, iron, copper, nickel, cobalt, and phosphates.
•However the recovery of nodules is expensive and difficult because they are located in very deep water.
•Because country borders are observed only close to land, the question of who has the right to mine minerals from the ocean floor has not been answered.
Trace Minerals
•The concentration of most other useful chemicals that are dissolved in the oceans is very small.
•The extraction of minerals found only in trace amounts is too costly to be practical.
Food from the Ocean
Fishing
•Because fish are a significant food source for people around the world, fishing has become an important industry.
•But when the ocean is overfished, or overharvested, over a long period of time, fish populations can collapse.
•A collapse may damage the ecosystem and threaten the fishing industry.
marine open water fish farm in La Spezia Italy
Aquaculture
aquaculture - the raising of aquatic plants and animals for human use or consumption
•A major problem for aquaculturalists is that the ocean farms are susceptible to pollution and that the farms may be a local source of pollution.
•Under the best conditions, an ocean farm could produce more food than an agricultural farm of the same size.
The UNH Open Ocean Aquaculture Demonstration project is a thirty acre site near White Island, Isles of Shoals. Submerged cages host research in open ocean aquaculture.
Rope cultured blue mussels is a UNH Open Ocean Aquaculture Demonstration project that has developed operational methods and husbandry practices for production of high quality mussels in exposed open ocean environments. The success of this project has expanded the potential for commercial development of shellfish farming in the open sea.
More about mussel ropes: the ropes are suspended from a horizontal longline, submerged 50 feet below the surface. The ropes are 36 feet long and produce up to 10 lbs. of mussels per foot, 360 lbs. per rope. As many as eighty ropes can be suspended from a single longline, which can produce more that 20,000 lbs. of mussels per year.
READING CHECK
List the benefits and problems of aquaculture.
Aquaculture provides a reliable, economical source of food. However, aquatic farms are susceptible to pollution and they may become local sources of pollution.
Ocean-Water Pollution
•The oceans have been used as a dumping ground for many kinds of wastes including garbage, sewage, and nuclear waste.
•The growth of the world population and the increased use of more-toxic substances have reduced the ocean’s ability to absorb wastes and renew itself.
•Ocean-water pollution threatens both marine organisms and humans by damaging food resources in the ocean.
Patch pollution in Peru
Do we have to kill everything?