Ocean Intro Notes- Introduction to Ocean Resources and Water Chemistry Goal: To introduce ocean resources and water chemistry.

Ocean Resources and Oceanography The oceans are reservoirs of salt water, nutrients, minerals and dissolved gases. These materials make it possible for the oceans to support a great diversity of living things. Humans also benefit from the many resources the oceans provide.

Ocean Resources and Oceanography Resources for Survival Organisms get everything they need from their environment. Natural resources – materials from the environment that are used by living things Dissolved gases Nutrients Minerals

Ocean Resources and Oceanography Respiration – the process by which organisms obtain energy Oxygen is used to release the energy stored in food Some ocean animals, like whales and dolphins, get the oxygen they need by coming to the surface and breathing in air Fish and other ocean organisms take in oxygen that is dissolved in ocean water

Ocean Resources and Oceanography Critical to the survival of many ocean organisms - dissolved oxygen, as well as carbon dioxide(CO2) Some of the dissolved oxygen in ocean water enters the water from the atmosphere Most dissolved oxygen is produced by algae and tiny aquatic plants called phytoplankton. They produce the oxygen through the process of photosynthesis

Ocean Resources and Oceanography During photosynthesis, oxygen is released as a waste product The oxygen-rich waters of streams and rivers also add dissolved oxygen to oceans Carbon dioxide is required for photosynthesis Some carbon dioxide enters the ocean water through the atmosphere Most carbon dioxide in ocean water is produced as a waste product of respiration Carbon dioxide is also released into ocean waters through the decay of wastes or organisms or their remains.

Ocean Resources and Oceanography All organisms require food to survive Ocean organisms that carry out photosynthesis make their own food using dissolved carbon dioxide and water Animals and other organisms that do not carry out photosynthesis obtain the food they need by eating other organisms

Ocean Resources and Oceanography Two resources the oceans provide to people are salt and fresh water. Desalination – the process used to separate the salt from seawater and reclaim both materials. During desalination, ocean water is boiled until the liquid water evaporates and the salt is left behind. The evaporated water is captured in a container, where it is cooled so it will condense back to a liquid.

Ocean Resources and Oceanography Other Resources Around 75 million tons of ocean fish are harvested for food each year Shrimp, oysters, crabs, mussels, lobster, and other shellfish are also harvested for food. Seaweed is an important resource – kelp and other types of seaweed are used as thickening agents in ice cream and jellies Seaweed is also very important in many Asian countries

Ocean Resources and Oceanography Although the resources seem endless because the ocean is so large, unfortunately due to advanced technologies, fishing operations are catching fish faster than the populations of the fish can reproduce Regulations and good management practices can help to ensure that any ocean resource remains sustainable

Ocean Resources and Oceanography Oceanography – the study of the physical properties of the ocean. The four oceans that make up the world ocean differ from each other in size and depth They also differ in temperature, currents, and physical properties, such as density, salinity and pH In fact, scientists can identify the ocean from which a water sample was taken just by analyzing these properties

Ocean Resources and Oceanography Scientists use technology at the ocean surface to map ocean depths Sonar – which stands for Sound Navigation and Ranging – is a method of determining the depth of the ocean using echoes Sonar equipment on a ship sends out a sound pulse, which travels to the ocean bottom. The pulse then bounces off the ocean floor and returns to the ship. Because scientists know the speed of sound in water, they can use the time it takes the pulse to return to calculate the depth of water.

Ocean Resources and Oceanography Like continents, the ocean floor has surface features and scientists have used sonar technology to create a map of the ocean floor The map shows the locations of features such as underwater mountains, canyons, and trenches The maps also help scientists understand tectonic plate processes

Ocean Resources and Oceanography Scientists also use remotely operated vessels (ROVs) and piloted vessels to explore deep oceans. An ROV is attached by tether to a research ship Scientists on ship can use a remote control device to steer the ROV and operate equipment that obtains samples of water, rocks and other organisms from deep ocean areas.

Ocean Resources and Oceanography Piloted vessels allow scientists to see the ocean floor with their own eyes Scientists with Alvin one of the first piloted deep-ocean vessels, discovered the first deep-ocean hydrothermal vent communities in 1977. This discovery showed that some of Earth’s organisms make food using energy from chemicals that come from Earth’s interior rather than from the sun.

Ocean Water Chemistry The scientific explanation for the ocean’s saltiness: During the early stages of Earth’s history, when the ocean covered much of the surface of the planet, undersea volcanoes erupted, spewing chemicals into the water. Gradually, the lava from these volcanic eruptions built up areas of land. Rain fell on the bare land, washing more chemicals from the rocks into the ocean. Over time, these dissolved substances built up to the levels present in the ocean today

Ocean Water Chemistry On average, one kilogram of ocean water contains about 35 grams of salts – that is 35 parts per thousand Salinity – the total amount of dissolved salts in water The substance know as table salt – or sodium chloride – is the salt present in the greatest amount

Ocean Water Chemistry When sodium chloride dissolves in water, it separates into sodium and chloride particles called ions. Other salts, such as magnesium chloride, form ions in water in the same way Together chloride and sodium make up almost 86% of the ions dissolved in ocean water Ocean water contains smaller amounts of about a dozen other ions, including magnesium and calcium, and other substances that organisms need, such as nitrogen and phosphorus

Ocean Water Chemistry Salinity in the ocean varies from 34 and 37 parts per thousand. Near the surface, rain, snow, and melting ice add fresh water to the ocean, lowering the salinity there Salinity is also lower near the mouths of large rivers such as the Amazon and Mississippi

Ocean Water Chemistry Evaporation, on the other hand, increases the salinity, since the salt is left behind as the water evaporates In the Red Sea, where the climate is hot and dry, the salinity can be as high as 41 parts per thousand Salinity can also be higher near the poles. As the surface water freezes into ice, the salt is left behind in the remaining water

Ocean Water Chemistry Salinity affects several properties of ocean water. Ocean water does not freeze until the temperature drops to about -1.9°C. The salt acts as a kind of antifreeze by interfering with the formation of ice crystals Salt water also has a higher density than fresh water Because the saltwater has a higher density, seawater has a greater buoyancy – meaning it will lift or buoys up less dense objects floating in it

Ocean Water Chemistry Two dissolved gases in the ocean that are necessary for living things are oxygen and carbon dioxide. Carbon dioxide is 60 times as plentiful in the oceans as in the atmosphere.

Ocean Water Chemistry The temperatures in oceans vary. The broad surface of the ocean absorbs energy from the sun; because warm water is less dense than cold water, this warm water stays as a layer on the surface The temperature of water affects the amount of dissolved oxygen it can hold The cold waters in the polar regions contain more dissolved oxygen than warm, tropical waters

Ocean Water Chemistry As the ocean changes in depth, the temperature decrease the further down you go – there are three temperature zones in the ocean. The first zone, the surface zone, typically extends from the surface to between 100 and 500 meters Next is the transition zone, which extends from the bottom of the surface zone to about one kilometer The temperature drops very quickly in the transition zone, to about 4°C Below the transition zone is the deep zone, where the temperature is below 3.5°C

Ocean Water Chemistry As you increase in depth, the pressure also increases. The average depth of the ocean floor is 3.8 kilometers where the pressure is about 400 times greater than air pressure at Earth’s surface Pressure is one obstacle facing scientists who want to study the ocean A diver can only descend safely about 40 meters To survive in deeper water, scientists must use a submersible

Ocean Water Chemistry Submersible – an underwater vehicle built of strong materials to resist pressure In a submersible, scientists can directly observe the ocean floor, collect samples, and study deep ocean water chemistry