Introduction To Chemistry & Biology

Question 1

What are the two scales that must be considered when looking at ocean processes?

Answer 1

Spatial and Time

Question 2

Give an example of a short, small scale ocean process

Answer 2

Capillary Waves

Question 3

Give an example of a long, large scale ocean process

Answer 3

Climate Change

Question 4

3 Methods of Collecting Ocean Data

Answer 4

1. NIO Bottle
2. Niskin Bottle
3. Rosette

Question 5

What should be considered when analysing seawater?

Answer 5

That it is more complex than freshwater, you need to preserve and maintain oxygen levels and the matrix effect should also be considered

Question 6

How do you avoid absorption and contamination of trace elements?

Answer 6

Keep them in an acid solution

Question 7

Is seawater electronically neutral? What do we also need to consider?

Answer 7

Yes it is but we have to think about atomic mass rather than % by weight. You can do this by comparing negative and positive atoms (e.g. Cl and Na)

Question 8

What is the equation for calculating the number of moles of ions?

Answer 8

Moles of Ions = Concentration / Atomic Weight

Question 9

What is the average concentration of dissolved salts in the oceans?

Answer 9

3.5% (35 ppt or 35 g/l)

Question 10

What controls surface salinity?

Answer 10

Climate (Evaporation and Precipitation)

Question 11

What is the global distribution of salinity?

Answer 11

Large in the tropics but low at the poles and directly on the equator

Question 12

What is the Constancy of Composition of Seawater?

Answer 12

The concentrations of major dissolved ions can vary from place to place but their relative proportions will remain virtually constant

Question 13

Which element is used for references Constancy of Composition of Seawater?

Answer 13

Chlorine

Question 14

What are the 6 variations of the major Constancy of Composition of Seawater?

Answer 14

1. Enclosed seas or estuaries
2. Anoxic basins
3. Shallow seas
4. Hydrothermal vents
5. Evaporates (e.g. Red Sea)
6. Pore waters

Question 15

What is conservative behaviour?

Answer 15

Major ions that are only affected by physical mixing processes

Question 16

What is non-conservative behaviour?

Answer 16

Minor ions that are affected by biological and chemical processes, distribution is independent of salinity

Question 17

What do we assume all elements in the seawater to come from?

Answer 17

The Geochemical Balance

Question 18

How old are the oldest surface sediments on the seafloor and why aren’t there any older than this?

Answer 18

200 million years and because of plate tectonics

Question 19

What are the three groups of elements?

Answer 19

1. Those where the weathering supply is adequate and there is a removal mechanism
2. Elements that are very reactive in seawater and absorb into particles
3. Those where the weathering supply isn’t enough and another source is needed

Question 20

What is a residence time?

Answer 20

It gives an idea as to how long an element will remain in solution before being removed

Question 21

What do residence times assume?

Answer 21

That the ocean is in a steady state (rate of input = rate of removal)

Question 22

What is the residence time equation?

Answer 22

T=A/Input so Amount/Amount per Time = Time

Question 23

Why do we use residence times?

Answer 23

Because all chemical and biological processes have to be seen in a physical context

Question 24

Major un-reactive elements have……

Answer 24

Long Residence Times

Question 25

Minor reactive elements have…..

Answer 25

Short Residence Times

Question 26

What concentration does a major element have?

Answer 26

> 1mg/l

Question 27

What concentration does a minor element have?

Answer 27

<1mg/l

Question 28

How many major elements are then in seawater?

Answer 28

11