Oceanography E:2

During photosynthesis, water is

an electron donor

The hydrogen and oxygen atoms within water molecules are held together by:

covalent bonds

Other than the hydrogen and oxygen in the water molecules themselves, what are the two most abundant ions in seawater?

Sodium (Na+) and chloride (Cl-)

The Principle of Constant Proportions states that:

The ratio of major salts in seawater from different places in the ocean is constant

The saturation state Ω quantifies whether:

a mineral dissolves or precipitates

Why is the ocean good at taking up CO2? (2 points) What maintains the influx of CO2 from the atmosphere to the oceans? (2 points)

equilibrium reactions has CO2 go immediately to HCO3 keeping CO2 concentrations in ocean < those in air downward gradient established by higher concentrations in air

The wavelengths of light that penetrate deepest into the ocean are

green and blue

The most abundant dissolved gas in seawater is:

nitrogen

What is the carbonate pump and how does it work? (2 points)

phyto use DIC to make PIC, it sinks, it dissolves in deep waters where CaCO3- is undersaturated

The pE is describes the:

the activity of neutrons

The pH describes the:

the activity of protons

Most of the world ocean has the temperature properties of:

the deep and bottom waters

The salinity of the ocean, at the present time, seems to be:

In equilibrium, with dissolved components entering equal to dissolved components leaving

The property of water that accounts for the ability of liquid water to absorb heat without a change in temperature is called:

Latent heat

Which transfers more heat?

Latent heat of vaporization

In general, the water column is vertically stable because:

Less dense water sits on top of more dense water

What is the oxidation state of Cr in Cr2O72-?

+6

You dissolve 1 mole of NaCl in 500 mL water. What is the molarity (M) of Na+ and Cl- are in solution?

2 M of Na+, and 2 M of Cl-

What is the average pH of today's ocean?

8

What is the average salinity of the oceans?

About 35 o/oo (parts per thousand) or grams/liter

What causes deviations from equilibrium gas concentrations between the ocean and atmosphere?

All do

The depth to which light can penetrate the ocean depends on:

All of the statements are true

Which form of water is most dense?

Liquid salt water

The hydrogen bonds of water molecules account for which of the following?

All the answers provided are relevant

What do light and sound have in common?

All the answers provided are true

Which of the following statements about pH is not true?

As a whole, the pH of the ocean is mildly acidic

At the current pH of the ocean, most of the inorganic carbon in seawater is present in the ocean as:

Bicarbonate (HCO3-) ions

Which gases in water are most influenced by biology? (2 points)? What biological processes influence their distribution? (2 points) Describe their concentrations and the processes that control their concentrations in surface (upper 100m) (2 points), subsurface (~200-1000m) (2 points) and deep water (>2000m) (2 points)?

CO2 and oxygen photosynthesis and respiration oxygen high and CO2 low in surface due to ps > resp oxygen min and CO2 higher in subsurface due to resp > ps both increase due to pressure in deep water

Depth profiles of CO2 show that:

CO2 is enriched in deeper waters

Why is the pH of the deep ocean lower than that in surface waters? (2 points) How can the pH of the surface ocean (or shallow ocean) change dramatically on short time scales? (2 points)

CO2 more soluble at depth because of low temp and high pressure (CO2 can accumulate from respiration) photosynthesis drawing down DIC or respiration liberating DIC

Describe the ocean's solubility pump and how it works? (2 points)

CO2 more soluble in cold water so is taken up in polar waters and sinks as a result of deep water formation

Which is the best example of a non-conservative constituent in seawater

Carbon dioxide (CO2)

The oceans are said to be in chemical equilibrium because:

Chemically, what comes in is about equal to what goes out

An element that is always present in seawater in constant proportion and reacts very slowly in the ocean is:

Conservative

What are pycnoclines, haloclines, and thermoclines? (3 points) Describe how the thermoclines look in tropical, temperate, and polar oceans (3 points). Would you expect the water column to be more stable in polar, tropical or temperate oceans? (1 point) Why? (2 point)

Depths in the ocean where density, salinity, and temperature change rapidly with depth, respectively. (3) Tropical thermocline is steepest with largest temp difference, temperate is less steep and seasonally variable, polar has barely any temp difference between surface and subsurface water so is almost linear. (3) Polar is least stable (1) because easiest to mix because surface and subsurface waters have similar densities (2).

More heat is transferred from the equator to the poles in the ocean than by the atmosphere.

False

The amount of gas that seawater can hold in solution (or the gas solubility) is greater:

In colder water

With respect to controlling atmospheric carbon dioxide, the "solubility pump" is most important:

In polar waters

The transmission of sound by water can best be described by which of the following statements:

It is faster than transmission by air

Water reacts with/dissolves ions because:

It is polar

Once an element or dissolved substance reaches the ocean:

It may stay or be removed depending on the fluxes affecting the residence time of that particular element

Because of the increase in atmospheric CO2, the ocean is becoming:

More acidic

Nonconservative constituents of seawater are:

Often tied to biological cycles or are chemically reactive

The minimum velocity layer for sound is important because:

Sound is trapped in this layer so can be transmitted very efficiently for long distances there

Residence time is:

The average length of time an element spends in the ocean

We can determine salinity if we know:

The chlorinity of a water sample

Which of the following directly contributes to the oxygen minimum layer?

The decomposition of organic matter

The carbonate compensation depth is:

The depth below which carbonate minerals (calcium carbonate and carbonate skeletons/shells) dissolve

Increases in acidity in the ocean can result in:

The dissolution of carbonate minerals or carbonate skeletons/shells of organisms

Which is true about hydrogen bonds?

They occur between hydrogen and oxygen atoms of neighboring water molecules

Why are the components of salinity in seawater different from those in freshwater? (2 points)

because they react with crustle material when heated seawater interacts with mantle at spreading centers (hydrothermal activity)

The pH of the ocean is buffered primarily by what acid-base pair?

bicarbonate-carbonate

With increasing ocean acidification in a future ocean, coccolithophores will have increased difficulties in

calcifying

With increasing ocean acidification in a future ocean, coccolithophores will have increased difficulties in:

calcifying

Why is photosynthesis a redox reaction? Explain. (2 points

carbon dioxide is reduced and water is oxidized

The ocean is slow to heat and slow to cool. This is related to a property of water known as:

high heat capacity

Most of the carbon on earth is stored:

in marine sediments and sedimentary rocks

Gas transfer velocity (K in cm/hr) increases with:

increasing wind speed

If a compound is at chemical equilibrium in seawater, what do I need to know to calculate its residence time? (2 points)

input or export rate and concentration

If our planet were without its ocean, but otherwise the same as it is today, would surface temperatures be more extreme than they are now (that is, higher high temperatures in summer, and lower low temperatures in winter), less extreme, about the same or what. Why do you think that? (2 points)

more extreme, high heat capacity of water

Describe to ocean's biological C pump and how it works. (2 points)

organisms in surface water take up DIC, convert it to organic matter that can die or be grazed and sink to bottom waters

How are oxygen isotopes important for understanding paleoclimates? (2 points)

organisms lock in the isotopic conditions of oxygen in surface water when they form calcium carbonate

The buffer capacity of the ocean maintains its:

pH

pH is defined as:

pH = - log [H+]

The ocean's deep sound channel (SOFAR layer) is characterized as a zone in which:

sound is trapped in a horizontal band at the velocity minimum layer

The most pronounced thermoclines occur in:

the tropics

Acid-base equilibrium reactions in seawater are important because

they can buffer seawater from changes in pH

Conservative constituents of seawater generally have long residence times.

true

Why do "dead zones" develop in the summer (2 points)? And what causes them to dissipate in the fall? (2 points)

water column is stratified in summer due to warming of surface wind driven mixing resupplies oxygen

The density of a parcel of seawater will increase:

when the salinity increases