Oceanography Test 2

What conditions exist below the CCD?

- high acidity - cold temperature - high carbon dioxide concentration

What is the approximate depth of the calcite compensation depth (CCD) in the ocean?

3 miles(4.5 kilometers)

How many grams of salt are in 1 kilogram of seawater with average salinity?

35

On average, at what ocean depth does calcite readily dissolve into seawater?

4500 meters(`14,764 feet)

How much heat energy is needed to turn 1 gram of water at 100 degrees Celsius into water vapor?

540 calories of heat energy

How much heat energy is needed to melt 1 gram of ice?

80 calories of energy

What did the discovery of tillite in South Africa reveal about southern Africa's past?

An ice sheet covered southern Africa 300 million years ago.

What is calcareous ooze composed of?

At least 30% the remains of calcareous organisms.

Why does calcareous material dissolve below the CCD?

Below the CCD, weak acid is formed, which dissolves calcareous material.

If seawater becomes too acidic, what process will buffer the change in pH?

Bicarbonate ions combine with hydrogen ions, causing the pH to rise.

Sediments derived from the remains of the hard parts of once-living organisms are called __________ sediments.

Biogenous

What would happen if the depth of the CCD were above the top of the mid-ocean ridge?

Calcareous ooze would not be found below the CCD

Two common types of chemical compounds found in biogenous sediments are __________ and __________.

Calcium carbonate;silica

The presence of what type of macroscopic sediment would provide evidence of a meteorite impact on Earth?

Chondrite. Microscopic=tektites

The sea floor provides the largest reservoir of usable energy in the ocean, and likely the world, in the form of ______________.

Clathrates

Is there relatively high or low seawater salinity in the low latitudes? What combination of factors explains the salinity at low latitudes?

Compared to high latitudes, there is higher salinity due to higher evaporation, but the salinity is slightly lower close to the equator due to an increase in runoff there.

Why might ocean floors be better than continental locations for studying long-term changes in the size of ice sheets?

Continental records are fragmented and discontinuous, missing parts of the climate record.

The two major types of microscopic, planktonic organisms that produce siliceous oozes are __________ and __________.

Diatoms;radiolarians

Diatomaceous earth, which is composed of silica, __________ above the CCD and __________ below the CCD.

Does Not Dissolve

Generally, what has been the pattern of global temperature change during the past 70 million years?

Earth's average temperature is approximately 15° cooler now than than it was 70 million years ago.

What must break in order for water to change from solid to liquid to gas?

Hydrogen bonds between water molecules

In the figure above, is this body of water composed of freshwater or saltwater? How can you tell?

It cannot be determined if this body of water is fresh or salty just by looking at the photo, because both freshwater and saltwater appear blue in large quantities.

Which of the following statements is true of water in a solid state?

It is rigid and forms a three-dimensional crystalline shape. Water molecules in ice remain in a relatively fixed position and are not as mobile as they are in the liquid state, where there are fewer hydrogen bonds

Is there relatively high or low seawater salinity in the high latitudes? What combination of factors explains the salinity at high latitudes?

Lower salinity due to high precipitation and runoff and melting icebergs, and low evaporation due to cooler temperatures

What physically breaks hydrogen bonds between water molecules as ice melts?

Movement of water molecules

In which setting would calcareous ooze be most likely to form?

On the crest of a seamount under warm surface water.

Why doesn't siliceous ooze dissolve after it accumulates on the seafloor?

Once deposited on the seafloor, siliceous organisms bury each other.

A sediment sample dominated by microscopic lithogenous sediment grains would be classified as a ___________.

Pelagic Deposit

Which of the following materials could form a siliceous ooze?

Radiolarians,diatoms,silicoflagellates

How does the addition of salt affect the freezing and boiling points of water?

Salt increases the boiling point and decreases the freezing point of water.

How does the addition of salt affect the density of water?

Salt increases the density of water to 1.028 grams per cubic centimeter at 4°C.

Which of the following processes decrease seawater salinity?

Sea ice melting, river runoff, and precipitation

How does siliceous ooze accumulate on the seafloor if silica-based residues are dissolved slowly at all depths?

Silica tests accumulate faster than seawater can dissolve them.

How does the pH of seawater change when bicarbonate ions dissociate into carbonate ions?

The PH decreases and the seawater becomes more acidic

Why does temperature NOT initially increase as energy is added after ice begins to melt?

The added energy is used to break hydrogen bonds between water molecules.

Which statement accurately describes the interaction between a water molecule and sodium chloride as it dissolves?

The negative oxygen end of the water molecule is attracted to the positive sodium ion.

How does the pH of seawater change when carbonic acid molecules dissociate into bicarbonate ions?

The pH decreases and the seawater becomes more acidic.

How does the analysis of forams in ocean sediment cores reveal climate change?

The presence and relative dominance of different species of forams reveal different global climate conditions.

What conditions are necessary for siliceous ooze to accumulate on the seafloor?

The surface waters must be nutrient rich.

Why are water molecules in a gas phase able to move rapidly and independently of each other?

There are no hydrogen bonds between water molecules in a gas phase, so each water molecule acts as an individual.

What do manganese nodules, metal sulfides, and evaporites all have in common?

They all precipitate from water oversaturated in their respective minerals. Hydrogenous

Where do calcareous oozes exist on the seafloor?

Underneath areas where calcareous organisms live, above the CCD.

Why do some organisms thrive in warm surface waters?

Warm water is generally saturated in carbonate.

Why is water able to dissolve salt?

Water molecules are polar and are attracted to the electrically charged ions that form salts.

What is calcareous ooze?

a fine-grained, deep ocean sediment containing the skeletal remains of calcite-secreting microbes

The tests from which of the following organisms will dissolve below the CCD

coccolithophores, foraminifera

What determines the acidity or alkalinity of seawater?

concentration of hydrogen ions (H+)

What three steps are required for calcareous ooze to exist below the CCD?

deposition of calcite shells above the CCD, cover of these shells by a non-calcareous material, and movement of the sea floor over millions of years.

Which of the following organisms thrive in cold surface waters?

diatoms, radiolarians, and siliceous organisms

Forams, which are composed of calcium carbonate, __________ above the CCD and __________ below the CCD.

do not dissolve above; do dissolve below

If all the water in the ocean was evaporated and only the solid salt was left behind, how much salt would there be?

enough to form a layer about 500 feet thick that covers all of Earth

Which of the following processes increase seawater salinity?

evaporation, sea ice formation

Which of the following processes can provide fresh drinking water from seawater?

freeze separation of sea ice distillation of evaporated seawater melting of icebergs

Siliceous ooze is particularly abundant on the seafloor at __________ and at __________.

high latitudes; equatorial upwelling zones

Which of the following substances releases the most hydrogen ions when dissolved in water?

lemon juice

What is the limiting factor in determining the accumulation of siliceous ooze/calcareous ooze, respectively?

productivity/water depth

In which of the following substances are there equal numbers of hydrogen ions and hydroxide ions?

pure water

Which of the following substances releases the most hydroxide ions when dissolved in water?

sodium hyrdroxide

What is the calcite compensation depth, or CCD?

the ocean depth below which calcite is unstable and will dissolve quickly

What process allows siliceous organisms to thrive in areas along the equator?

upwelling