Ch 3 Test

Question 1

Why is the transparency of the ocean important to
living organisms?

Answer 1

*It heats sea water, warming the surface layers
* It provides energy required by
phytoplankton.
* It is used for navigation by animals near the
surface.

Question 2

What do water molecules
do to light as it passes
through water?

Answer 2

Absorbs and scatters it.

Question 3

Why is the ocean water
bluish-green?

Answer 3

Since blue and green
wavelength are absorbed the
least, they are the most
available to be reflected back.

Question 4

What is attenuation?

Answer 4

A decrease in the intensity of light over distance. The higher the attenuation the murkier the waters

Question 5

What affects attenuation?

Answer 5

Attenuation is due to absorption by pigments and scattering by molecules and particles

Question 6

Where would water of high attenuation be?

Answer 6

Coastal waters. High particle suspension.

Question 7

Where would water of low attenuation be
found?

Answer 7

Open ocean waters

Question 8

Secchi Dish

Answer 8

• Simple tool used to
  measure attenuation.
  *White disk is lowered
  into the water. When it
  just disappears from
  sight, depth is
  measured.

Question 9

Coastal waters showing an area of high attenuation.

Answer 9

*Reflected subsurface
light is used for
mapping chlorophyll
concentration from
space.

Question 10

Pressure

Answer 10

• Increases at a rate of about 10 x
  the air pressure at sea level per
  100 meters of depth.
• Humans can safely dive to about
  130 feet(40 m).
• Modern submarines dive to only
  about 1950 ft(600 meters.)

Question 11

Pressure increases at a rate of about 10 x the air pressure at
sea level per 100 meters of depth. Why?

Answer 11

As ocean depth increases, so does
pressure. Rate of 1 atm per meter of
depth.

Question 12

HOV Deepsea Challenger

Answer 12

Can with stand pressures of 16,500 pounds per square inch.

Question 13

Why would gas bladders and lungs shrink or
collapse, as pressure increase in water?

Answer 13

*The high pressure.

Question 14

• Sound travels faster in water than in air. Speed of sound in salt water
  ______ m/s.

Answer 14

1500

Question 15

why is there is no sound travel in a vacuum tube or in outer space.

Answer 15

Sound needs molecules to travel through. In water, molecules
are much closer together than in air.

Question 16

Which sound travels farther in water, high frequency sound or low
frequency sound?

Answer 16

Low frequencies (high frequencies are dissipated
too quickly because of the higher energy). Speed
increases with increased temperature, pressure and
salt content.

Question 17

• The distance that sound travels in the ocean varies
  greatly, depending primarily upon water

Answer 17

temperature, pressure, and salinity

Question 18

Temperature

Answer 18

– faster in warm than in cold(molecules are moving
faster)

Question 19

Pressure

Answer 19

• faster in higher pressure than in lower(molecules are
  closer together in high pressure)

Question 20

Salinity –

Answer 20

speed of sound is faster in seawater than freshwater. Speed
of sound in freshwater is 1435m/sec)

Question 21

How does sound locate objects?

Answer 21

Sound is reflected back after striking an object. The time required for
the return of a sent sound signal can be measured.

Question 22

deep sound channel.

Answer 22

The sound speed minimum at a depth of 1000 meters. occurs because of the properties of sound
and the temperature and pressure differences at different depths in
the ocean.

Question 23

Salinity

Answer 23

the ratio of the mass of dissolved substances to
the mass of the water sample

Question 24

What is the typical salinity of seawater?

Answer 24

3.5 %

Question 25

Is it just sodium and chlorine that make up the salinity?

Answer 25

No; S, Mg, Ca, K also account for most of the salinity. (Sodium and chlorine account for about 85 % of the dissolved solutes.)

Question 26

What unit is salinity typically measured in?

Answer 26

(ppt); (‰); Parts per thousand; 35 g of salt per 1000 g of seawater.

Question 27

Modern unit for salinity measurement

Answer 27

psu(practical salinity units)  psu = ppt

Question 28

Salinometer

Answer 28

– instrument used to measure salinity

Question 29

overall salinity of the ocean?

Answer 29

35 (‰)

Question 30

River input

Answer 30

Areas of lower surface salinities

Question 31

Deep sea vents

Answer 31

Higher salinity

Question 32

Seasonal variation

Answer 32

– lower surface salinity in the rainy months or when river runoff is high (due to melting snow and ice). Higher salinity, due to evaporation in the dry, warmer months.

Question 33

Sea ice formation

Answer 33

when seawater freezes, dissolved ions cannot fit in the ice’s crystalline structure. Unfrozen seawater is left behind that has a higher salinity.

Question 34

Sea ice melting

Answer 34

lowers salinity (ice is fresh water)

Question 35

Brackish water

Answer 35

about 10‰ (or 1%). Found in areas where freshwater and saltwater mix. Ex. Rivers flowing into the sea.

Question 36

Hypersaline water(brine)

Answer 36

excessive amount of salts found in seas (or inland lakes)that are in warm climates with not a lot of incoming circulation from the ocean. Ex. Red Sea

Question 37

Does fresh water have salinity?

Answer 37

Yes, just not pure water. Tap water has low salinities of 0.8(‰) to 0.3(‰).

Question 38

How does an increase in salinity influence water’s density?

Answer 38

As salinity increase so does the density.

Question 39

How does an increase in temperature influence water’s density? A decrease?

Answer 39

Increase temperature, decrease in density. As water molecule movement increase due to an increase in temperature, the volume expands causing a decrease in density.

Question 40

How does an increase in pressure influence water’s density? A decrease?

Answer 40

As pressure increases so does density. More molecules per square meter.

Question 41

What are the most important elements for the organisms

Answer 41

oxygen and carbon dioxide, and nitrogen

Question 42

What is the main source of oxygen in the oceans?

Answer 42

Phytoplankton

Question 43

How is carbon dioxide produced in the ocean?

Answer 43

Respiration & decomposition

Question 44

Where are more dissolved gases found, based on latitude, and why?

Answer 44

More dissolved gases are found in the higher latitudes. Gases dissolve better in cold water that in warm. As temperature decreases so does the kinetic energy of the gas molecules. Less gas expands and rises so less escapes from the body of water.

Question 45

The carbon that is found in organic molecules is part of the _______molecule in the atmosphere. Hint: animals produce it during respiration.

Answer 45

CO2

Question 46

What process converts this inorganic molecule into an organic molecule? ___________________Hint: plants/phytoplankton.

Answer 46

photosynthesis

Question 47

Why is the rate of atmospheric CO2 increase such a cause of concern?

Answer 47

While the pH of the ocean is still basic, it is more acidic than it used to be. Since the pH scale is logarithmic, this means that the oceans are 30% more acidic now than they were in pre-Industrial times.

Question 48

Which organisms are most at risk from ocean acidification and why?

Answer 48

Organisms such as coral, mussels, and clams use carbonate ions and calcium to make their shells or skeletons.

Question 49

If there were no scattering and only absorption of light by seawater, what color would the oceans appear? Explain your answer.

Answer 49

If there were no scattering and only total absorption of light the oceans would appear black because no light would be return to the observer’s eye. Remember: oceans appear bluish-green because that is the color least absorbed and returned to the eye.

Question 50

Explain how light and sound in seawater are affected by changes in the water’s density.

Answer 50

Since sound needs a medium to travel through, sound speed is increases with increases in salinity. The more particle to travel through, the faster sound travels. The speed of light is decreases with increased salinity. Light is absorbed and scattered by water molecules. The increase in particles in the water causes an increase in scattering.

Question 51

What does a Secchi disk measure?

Answer 51

A Secchi disk measures the transparency of water by use of a white disk(or white and black disk) that is lowered by a line into the water to a depth that it just disappears from view.

Question 52

How does hydrogen bonding produce the surface tension phenomenon of water?

Answer 52

At the surface between air and water, water molecules arrange themselves in an ordered system, hydrogen-bonded to each other laterally and to the water molecules beneath. This arrangement creates a weak elastic membrane

Question 53

What happens to the arrangement of water molecules when water freezes?

Answer 53

When water freezes, additional hydrogen bonds are formed between each molecule and the molecules become arranged in a fixed lattice. This lattice contributes to the larger volume water has solid ice than it has in it liquid phase.

Question 54

Why does the addition of rain and river water to the oceans not decrease the ocean’s overall salinity?

Answer 54

Rain, river water, and sea ice melting can all contributed to the decrease in the overall salinity of the ocean there are other processes that increase the salinity of the oceans. Evaporation, sea ice formation, and deep sea vents/volcanoes. Input = output

Question 55

Explain the relationship between carbon dioxide and the pH of the oceans. Why is the buffering of seawater important?

Answer 55

Carbon dioxide gas dissolves in seawater to form carbonic acid (H2CO3). Carbonic acid dissociates in seawater to form bicarbonate, HCO3- , and H+, and then H+ and CO32-. The addition of the hydronium ion (H+ ), increase the acidity of seawater and thus lowers the pH. Buffering is important because biological systems cannot survive wide swings in pH. Examples: a lower pH causes calcium carbonate to dissolve more easily. Many organisms that have shells and skeletons and have trouble making these structures if less calcium carbonate is available. Also, a lower pH can affect marine organisms by suppressing their immune systems, interfering with metabolic rates, and disrupting their internal chemical balance.

Question 56

How does the salinity of mid-ocean surface water change with latitude? What atmospheric processes produce these changes?

Answer 56

Mid-ocean surface salinity is lower than average at the equator due to high precipitation. North and South of the equator at around 30 °N and 30 °S there are zones of high evaporation that elevates the surface salinity and at 60 °N and 60 °S zones of high precipitation that lower salinity. In the polar regions, where precipitation is high, salinity is low. Also, in the polar region there is seasonal change. High surface salinity is produced during sea ice formation(salt does not fit in the crystalline structure of ice and remains in the water). Low salinity is produced during sea ice melting.`

Question 57

Why does seawater have a lower freezing point and a higher boiling point than freshwater?`

Answer 57

The presence of salt makes it harder for water molecules to bond to form ice, because salt cannot fit in the ice’s crystalline structure.

Question 58

. Why does deep-water contain more dissolved carbon dioxide than surface water?

Answer 58

Deep water is colder than surface water and cold water holds more gas. As temperature decreases as depth increases, gas will become more dense and sink. Also, at the surface photosynthesis takes place, removing some of the CO2 in the water. In the deeper ocean, photosynthesis does not occur (no light) but respiration continues by the animals that live in the deep ocean.

Question 59

Why is there a smaller temperature difference between day and night ocean surface temperatures compared to day and night land surface temperatures?

Answer 59

Due to water’s high heat capacity, the ocean does not experience large variation of surface temperature. Land has a smaller heat capacity than water which allows land to gain and lose heat more rapidly than water.