1. Which color in the image above represents the approximate direction of the 18
ID: 289576 • Letter: 1
Question
1.
Which color in the image above represents the approximate direction of the 18O-Temperature relationship for ice cores and CaCO3 shells from a marine sediment core? Select the two correct answers from the choices below.
(mutiple solution)
purple=ice core
black=ice core
black=marine shells
red=ice core
red=marine shells
purple=marine shells
2.
We know fossil fuels are the source of recent carbon emissions (since 1850) because:
A. The 13C of the atmosphere is increasing
B. The 14C of the atmosphere is decreasing
C. The 13C of the atmosphere is decreasing
D. The 14C of the atmosphere is increasing
A + D
B + C
In the 1950s and 1960s, a series of atomic bomb tests added large amounts of Carbon-14 to the atmosphere. The figure above shows the change in the 14C concentration in the atmosphere over the last ~60 years. The spike you see around 1965 corresponds to the accumulation from atomic bomb tests. Remember: 14C is basically (14C/12C).
Due to radioactive decay alone, how much would the atmospheric 14C have decreased since 1965 (i.e. in the last 53 years)? Given: half-life of Carbon-14 is 5730 years.
< 1%
< 50%
< 90%
4.
In the previous question, you looked at the amount of radioactive decay expected for the C-14 added through bomb tests in the 1960s. Knowing that the half-life of C-14 is 5730 years, what you do think the reduction in atmospheric 14C since 1965 is due to?
Remember: 14C is basically (14C/12C).
A. Radioactive decay
B. Ocean uptake
C. Dilution by fossil fuel emissions because fossil fuels contain lots of Carbon-12
D. B & C
Apurple=ice core
Bblack=ice core
Cblack=marine shells
Dred=ice core
Ered=marine shells
Fpurple=marine shells
high ow low TemperatureExplanation / Answer
Correct answers will be as follows:
1. red = marine shells, purple = ice cores
2. Correct answer is A.
3. LESS THAN 1 %
4. C: dilution by fossil fuel emissions
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