Geo 160 Study Guide 2

12) Ocean water pH changes from the surface zone to the deep zone. Why does this occur, and how is this related to the CCD?

*Colder water favors dissolution of atmospheric CO2 , resultingin greater acidification, *Lower pH due to ocean acidification raises CCD, reduces calcifiers' habitats. Carbonate Compensation Depth (CCD) Corals / Reefs

8) List the three main gases dissolved in the ocean, and explain why they are important to marine life. Also know the percentages of each gas within the ocean and atmosphere.

*Nitrogen A-78% W-47.5%, Carbon Dioxide A-0.03% W-15.1% Oxygen A-21% W-36.0% Dissolved gases, especially oxygen, are important, since it provides dissolved oxygen for aquatic organisms to "breathe" in. Also, the carbon dioxide dissolved in the ocean helps lessen the amount of carbon dioxide in the environment. helps crustaceans create shells. Nitrogen.. used for upper layers of the ocean mixing with the atmosphere. making oxygen.

13) Why is the ocean becoming more acidic? How will this affect the CCD? Explain why increasing acidification is harmful to ocean life

*When carbon dioxide enters the ocean, it combines with seawater to produce carbonic acid, which increases the acidity of the water, lowering its pH *A consequence of the oceans becoming more acidic is the binding up of carbonate ions, which are used by marine creatures to make their calcium carbonate shells and skeletons Carbonate Compensation Depth (CCD) = lysocline = saturation horizon

11) How do humans make the ocean hypoxic? Why is this a problem?

*agricultural and urban run-off. Farmers use phosphorus and nitrates to grow their crops, which eventually find their way to the Mississippi River. *While the Gulf relies on nutrients such as nitrogen and phosphorus to stimulate marine life growth, too much of a good thing can be deadly.

10) What is hypoxia, and how does it occur naturally in the ocean?

*dead zone" is hypoxia,. The lack of oxygen in these waters. *Excessive nutrients stimulate the growth of algae. As the algae die, they decay and rob the water of oxygen. The algae also prevent sun light from penetrating the water. Fish and shellfish are deprived of oxygen, and underwater sea grasses are deprived of light and are lost.

12) The sound maximum zone in the ocean is within the surface zone. Why does it exist there instead of deeper underwater?

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15) A fishing vessel at the ocean's surface is trying to determine the exact location of a school of fish nearby. So, the vessel emits a sound which can reflect off the fish and return to the vessel, giving the captain the location of the school. But, the school of fish dove a little deeper underwater and the captain was unable to track them with his sonar. What happened?

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5) Salt ions slow the rate of ocean-water evaporation. Explain why this happens.

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Relate your discussion to the chloride and iron ions, as we did in class.

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10) Review the worksheet diagram "Density Stratification of Ocean Water", and be able to draw the temperature, salinity, and density curves for the ocean.

...Diagram

6) Water becomes less dense as its temperature decreases from 39 to 32 degrees Fahrenheit. Why is this phenomenon important?

A unusual effect occurs. When the water drops to 30 degrees F the freezing point of water it forms ice crystals. Ice less dense than liquid water. This is why ice floats on liquid water

1) Explain why the following statement is true: "Ocean water is chemically complex". Relate this statement to the idea that the ocean is Earth tea.

All elements of Earth are present in the ocean. From trace amounts to vast quantities.

3) Ocean sediment can be well-sorted or poorly sorted. Explain why.

Based on the particle / grain size the energy of waves and currents and submarine fans move sediment constantly. Not leaving even layers of sediment.

7) What is the CCD, why does it exist, and how does it control the distribution of planktonic biogenous sediment on the deep ocean floor? Make a simple sketch to illustrate this.

Below ~ 15,000 feet, calcareous sediment (the Calcium-carbonate Compensation Depth or CCD) calcareous sediment will dissolve *Biogenous Sediment - originates within the ocean due to the deaths of marine plants and animals. CCD -where the dissolution of CaCO3 balances production and CaCO3 can no longer accumulate -always below the lysocline... higher precipitation means larger difference between the lysocline and CCD -Pacific ocean is largely below the CCD

2) List the most abundant salt ions in the ocean.

Cloride 19 PPT Sodium 10.6 PPT table salt.

9) What is cosmogenous sediment, and how does it get to the ocean floor?

Cosmogenous Sediment - is from space ( the cosmos ) product of asteroids or smaller meteoroids.

10) Be able to correctly fill out the worksheet "Distribution of Ocean Sediment".

Diagram

9) In class we sketched the curves representing the levels of dissolved oxygen and carbon dioxide gases within the ocean. Be able to draw and label the curves for each gas within the ocean. Why does the amount of each gas change with increasing depth below the surface?

Diagram

13) Practice drawing the curve for the velocity of sound in the ocean, and label the sound maximum and sound minimum zones. Why does the sound minimum zone exist?

Diagram A zone of minimum sound velocity exists at a depth of roughly 1,000 meters (about 0.6 mile) called the sofar (sound fixing and ranging) channel. Sound signals that originate in the sofar channel tend to stay in the channel rather than escaping. The sound may travel enormous distances in this channel; explosions set off in the channel in Australia have been heard in Bermuda.

5) Why is water's high heat capacity so important to planet Earth?

Earths water keeps the world cool. It moderates the earth's temperature. Along the coast is usually 20-30 degrees cooler than the IE

7) If ocean elements DID NOT have limited residence times, what would happen to the ocean's salinity over a period of billions of years?

Elements with short residence times (such as iron and aluminum) are relatively reactive, or insoluble in sea water; they are easily removed and are unevenly distributed throughout the ocean. the ocean waters would become very salty. Resident times = average amount of time a substance remains in the ocean

7) When water evaporates, what is happening? What does this do to the water that remains behind?

Evaporation removes H20 from the ocean's surface, but the salt ions stay behind. H20 water molecules move from liquid to gas state.

11) What does "remote sensing" refer to, and briefly explain three ways that oceanographers employ remote sensing to learn more about the ocean floor.

Gathering information about the ocean floor without acquisition of sediment. 1.Acoustic reflection - bouncing high frequency sound off the ocean floor and converted into a detailed map of ocean floor. 2.Seismic profile - Broadcast of a low frequency sound signal which penetrates into the ocean floor. X-ray view of the ocean floor. 3.Underwater photography - by divers using scuba gear or submersibles. Images useful for sediment study.

4) What is "heat capacity", and why does water have such a high heat capacity?

Heat capacity refers to how much heat a substance can absorb before noticalbly changing temps. Metal has low heat capacity.. changes in high temp. Water has a high capacity because it takes a lot of heat to change the water temp. Heat must break the Hydrogen bonds of water before retaining the heat.

3) Be able to define "heat".

Heat is the rate of vibration of atoms in a substance, its temperature. The size of the mass + speed of vibration = heat. More vibration causes more heat.

8) Know the ocean environments for the following hydrogenous sediments, and be able to explain how each forms: manganese nodules, phosphate hardground, and halite.

Hydrogenous Sediment - Is composed of mineral crystals that form and settle ( participate ) directly from the ocean. -precipitated from dissolved material in water -forming from within the water column

9) Be able to explain why the ocean is stratified.

Ocean is stratified based on the density. Stratified by salinity and temperature variations from the ocean surface to ocean floor. Cold and salty water is dense so it sinks. Warm and low salinity water is least dense so it rises near the ocean surface. 3 layers 1.Surface zone 2.Transition zone 3.Deep zone

5) You are dredging the deep ocean floor far offshore for manganese nodules, but instead you have pulled up large, angular cobbles and boulders. Explain how these large rocks were deposited on the deep ocean floor. (Hint: think "icebergs".)

Rafting Ice Bergs - Ice breaks free from Glaciers. -large rocks (sharp and angular) on top of icebergs (haven't gone through a lot of sedimentary processes) -when the ice melts, the rocks are deposited to the bottom of the ocean

4) Explain how a salinometer and a refractometer measure the salinity of ocean water. Each device has advantages over the other. Please elaborate.

Salinometer - uses electricity to test the conductivity of a water sample. Good very precise Refractometer - hand held tool that measures the degree of light refraction as it passes through a water sample. Good they are portable and inexpensive and easy to use. Bad not precise.

12) Which method of physically recovering sediment, grabbing or coring, provides more detailed information about Earth's history? Explain.

Sediment coring provides more detailed information. A core contains an undisturbed sample of ocean sediment with details of chronology preserved of the ocean bottom.

1) Be able to give a general definition for "sediment".

Sediment forms in layers of Loose gravel , skeletal fragments and mineral crystals. Contains fossils and valuable minerals -reveals: past climates, ocean floor movements, circulation patterns, nutrient supplies, ocean chemical history, and ocean currents

2) Relate the sorting of sediment, from near shore to far offshore, to sediment grain size and settling velocity.

Sm. clay Med. silk Lrg. sand Size of grain determines velocity -energy dependent -smallest grains in basins -coarse grains nearer the coast -deposits of higher grain size = deposits by a higher energy environment

14) What are the valuable natural resources contained by ocean sediment, and where are they found?

Table salts phosphorus manganese nodules hydrogenous sediment *These sediments may contain phosphorite, iron, copper, lead, gold, tin, diamonds, and other minerals. Because these minerals wash into the ocean from land, most of them are found in areas near shore. *It is currently too expensive to mine many of these minerals. *Some minerals are found away from shore. Nodules are lumps of minerals that are scattered across the deep-ocean floor. The nodules are small at first, but they can build up over millions of years to a size of as much as a meter across. Nodules contain valuable manganese, iron, and cobalt, which are used to make metals such as steel.

4) List and discuss the different ways that terrigenous sediment is delivered into the ocean.

Terri = land Genous = Origin From streams / rivers into oceans , ocean waves , submarine fans deposit clay, silk and sand deeper into the ocean floor. a. sand on shelf b. silt on slope c. clay on rise Streams - by weathering + erosion of mountains Continental shelf - erosion of granite into feldspar + quartz which is local sand on our beaches. Offshore wind - blows clay + silt far out that settles on ocean floor. Explosive volcanic eruption - hurls tiny dust particles into ocean includes sediment and rocks. Thick ash = active volcano. Ashes float around the world. IE. Great extinction of life (Great Permian Extinction) Coastal cliffs - erode dropping large boulders / rocks onto shore. Lrg boulders act like barrier reefs.

6) Large terrigenous (sand and gravel) and biogenous sediment grains (shallow-water gastropod and mollusk shell fragments) are sometimes found within submarine-fan deposits out on the continental rise. With regard to the typical distribution of sediment in the ocean, why is this unusual, and how does such coarse sediment make its way out onto submarine fans?

Terrigenous Sediment - Originates on land and enters into the ocean by 5 different processes. The fan uses energy from currents and waves and riptides to bring more coarse sediment out onto the submarine fans.Turbulence currents carry them down to the fans also. so you will get all different various sizes.

17) From space, Earth appears to be a blue planet. Why is this?

The Earth is called the "blue planet" because the surface is composed mostly of water. Over 70 % of the Earth's surface is water. Water looks blue from space mainly because it reflects the blue atmosphere.

16) Why do blue and green wavelengths of light penetrate more deeply into the ocean than red and orange wavelengths?

The colors of the spectrum (red, orange, yellow, green, blue, indigo and violet) can be remembered using the mnemonic device: ROY G BIV The colors in the middle of the visible spectrum (yellow, green and blue) penetrate seawater to the greatest depth, while colors of longer (violet) and shorter (red and orange) wavelengths are absorbed and scattered more rapidly.

13) Ocean sediment can tell earth scientists about Earth's history. Explain

The core samples show layers of the earths layers and why changes and transformations occurred over the years.

2) Why is water cohesive, and why does it adhere to solids?

The polarity of the water sticks to solids surfaces that usually have a weak charge. Water molecules bond to each other via weak hydrogen bonds.

14) How did the ATOC program use the sound minimum zone to tell whether or not Earth's climate is warming

U lower sound speaker into sound minimun zone.. If it bends and tries.to.exit if the sound increases the water is warming.. Decreases its cooling

8) Explain how the freezing of ocean water affects the density of unfrozen water below ocean ice.

Variations of water density can cause water masses to sink or rise. The saltier the water the denser the water. In general the cooler the water the denser the water.

1) Water is a polar molecule. What does that mean, and why are water molecules polar? Make a sketch of the water molecule.

Water molecule composed of 2 hydrogen atoms Covalently bonded ( strong bond ) to one oxygen atom. Water is polar because the atom has a +end and a -end. The hydrogen atoms tend to bond to one side of the oxygen atoms making water a polar molecule.

11) Many marine animals use sound for navigation and hunting instead of light. Explain why this is so.

whales and dolphins use sound for navigation, hunting, and communication. Sound waves travel faster and farther underwater than they do in air.

3) What happens to salt crystals when they are placed in water. Include the terms dissolution and diffusion in your explanation.

when salt crystals are placed in water, the positive end of the water molecule attracts the negatively charged chloride ions and the negative ends of the water molecules attract the positive sodium ions. As a result, the salt will dissolve once the attraction between the water and the ions overcomes the attraction the ions have for one another. Once dissolved, the positive sodium ions and negative chloride ions will associate with the oppositely charged polar ends of many water molecules.