Week 1

Question 1

ocean biogeochemistry

Answer 1

interactions of processes that control the cycling of key element, like carbon

Question 2

what are the 3 components of oceanography?

Answer 2

-physical
-chemical
-biological

Question 3

why does the ocean matter when it comes to global warming?

Answer 3

air-sea exchange of carbon dioxide impacts atmospheric carbon dioxide, modifying the greenhouse effect

Question 4

key elements in the ocean

Answer 4

carbon, nitrogen, phosphorus, iron, silicon, and oxygen

Question 5

DIC

Answer 5

dissolved inorganic carbon
CO2 dissolved in the ocean

Question 6

photosynthesis converts DIC to

Answer 6

POC (particulate organic carbon)
DOC (dissolved organic carbon)

Question 7

biological pump

Answer 7

Transport of carbon from the
surface to the deep ocean by biological processes
(mainly through sinking organic matter).

Question 8

solubility pump

Answer 8

Combined influence of physical and chemical processes on ocean concentrations of dissolved CO2 and air-sea exchange (independent of biology).

Question 9

aerosol effect

Answer 9

when we burn fossil fuels, it releases particles into the atmosphere which helps reflect solar energy away. also affects cloud formation

Question 10

Pre-industrial atmospheric CO2 concentrations were

Answer 10

quite stable for thousands of years, ~280 ppm

Question 11

Anthropogenic activities have increased atmospheric
CO2 concentrations by

Answer 11

> 120 ppm since the mid-1800’s, recently exceeding 400ppm.

Question 12

Atmospheric CO2 concentrations were ~80 ppm lower
during glacial (ice age) periods, much of this
carbon was likely stored

Answer 12

in deep ocean

Question 13

photosynthesis

Answer 13

plants combine carbon dioxide, water, and
light energy to form plant biomass

Question 14

respiration

Answer 14

Oxygen is used to break down biomass to
produce carbon dioxide, water and energy

Question 15

remineralization

Answer 15

The breakdown of organic matter into
elemental and nutrient constituents (aka decomposition)

Question 16

Gross Primary Production (GPP)

Answer 16

total carbon “fixation“ (photosynthesis), conversion from CO2 to C-biomass

Question 17

Net Primary Production (NPP)

Answer 17

total carbon fixation by plants - their respiration costs. Organic matter supplied by NPP is available to support heterotrophic organisms.

Question 18

phytoplankton account for how much total photosynthesis in the ocean?

Answer 18

95%

Question 19

Euphotic Zone

Answer 19

thin layer at ocean surface (~100m) with enough light to support photosynthesis

Question 20

the most common growth-limiting nutrients for
phytoplankton in the oceans are

Answer 20

nitrogen, phosphorus, iron, and silicon

Question 21

nitrogen

Answer 21

nitrate, NO3- and ammonium NH4+

Question 22

phosphorus

Answer 22

phosphate, HPO42-

Question 23

silicon

Answer 23

silicate, H3SiO4- (aka H4SiO4 silicic acid)

Question 24

iron

Answer 24

most dissolved iron ions are bound to organic molecules called ligands (>99%), very small amount as free Fe ions

Question 25

How does the biological pump effect the concentration of organic matter in the ocean? How are the exported nutrients returned?

Answer 25

It depletes surface concentrations and increases deep ocean concentrations. Ocean mixing and circulation eventually returns these exported nutrients to surface waters.

Question 26

How does the biological pump move the organic matter?

Answer 26

Mainly through sinking POM (>90% of export) and through mixing and advection, which can carry POM and DOM produced in surface waters into the ocean interior.

Question 27

POM

Answer 27

particulate organic matter

Question 28

DOM

Answer 28

dissolved organic matter

Question 29

Wind Mixing

Answer 29

direct mixing by winds. pretty shallow, can extend to ~100m

Question 30

Convective mixing

Answer 30

occurs at higher latitudes, can mix much deeper than wind mixing (>>500m)

Question 31

Surface mixed layer

Answer 31

surface layer where rapid mixing results relatively uniform concentrations of passive tracers (i.e. DIC, nutrients, phytoplankton, etc) can range from a few meters to hundreds of meters depth, with convective mixing

Question 32

pycnocline

Answer 32

sharp change in density with depth

Question 33

thermocline

Answer 33

change in temperature with depth

Question 34

halocline

Answer 34

change in salinity with depth

Question 35

typically there is a ____ at the base of the surface mixed layer, may appear only seasonally.

Answer 35

pycnocline

Question 36

density is a function of

Answer 36

temperature and salinity

Question 37

Density ____ as temperature _____

Answer 37

increases decreases

Question 38

Density ____ as salinity _____

Answer 38

increases increases

Question 39

Stable (or stratified) water column

Answer 39

lighter waters over denser waters weak vertical exchange

Question 40

Unstable water column

Answer 40

denser waters over lighter waters convective mixing will result with strong vertical exchange

Question 41

At _____ the temperature profile ______, with increased stratification during summer months, weakened during winter.

Answer 41

mid-latitudes varies seasonally

Question 42

_____ are strongly stratified by _______.

Answer 42

low latitudes temperature

Question 43

____ at mid- to high latitudes is a key route for deep ocean _______.

Answer 43

convective mixing nutrients to return to the surface

Question 44

The second major return route is through ______________, which brings deeper waters to the surface.

Answer 44

wind-driven upwelling

Question 45

Vertical mixing largely determines the ______ to surface waters. The depth of the surface mixed layer also controls the _______ experienced by the phytoplankton.

Answer 45

flux of nutrients light levels

Question 46

Increased mixing can _______ to surface waters, but may also lead to _______ of phytoplankton growth rates, if they spend too much time at depth.

Answer 46

introduce nutrients light-limitation

Question 47

seawater is how much percent pure water (H2O)?

Answer 47

96.5%

Question 48

3.5% of seawater is dissolved matter. how many ppm is this?

Answer 48

35 parts per thousand

Question 49

Iron and aluminum are highly ______, resulting in short residence times due to ____________.

Answer 49

particle reactive particle scavenging

Question 50

Iron and aluminum are removed from the ocean waters to the sediments by _______ then particle sinking (bio pump), AND _____ onto particles

Answer 50

biological uptake by adsorption (scavenging)

Question 51

____ species have a strong tendency to stick (or adsorb) to sinking particles, eventually transferred to sediments.

Answer 51

particle reactive

Question 52

____ is one of the key nutrients that limits phytoplankton growth and thus NPP in the oceans.

Answer 52

iron

Question 53

Iron _____ is scavenged more slowly than free Fe irons.

Answer 53

bound to ligands

Question 54

For our key nutrients (N,P,Si, and Fe) the main sources to the oceans are _____ and _________, and the main sink is __________.

Answer 54

rivers aerosol deposition burial in the sediments

Question 55

Recently is has been shown that the hydrothermal vents (where the heated waters come out of the sediments are also strong ______ to the oceans.

Answer 55

sources of iron

Question 56

Rivers are a source of ___ to the oceans in the form of bicarbonate ions resulting from the weathering of rocks on the continents.

Answer 56

DIC

Question 57

The riverine sources of N and P have more than doubled since preindustrial times due to

Answer 57

fertilizer runoff (N and P) fossil fuel burning N emissions and subsequent deposition runoff (N)