Carbon Cycle
Problem Set 11 Solutions
1) (We skipped this problem)
2)
CO32- (U/Ca)
CO -3-now
U / Canow
3.2 ppm
=
=
= 1 / 2 0.7
-CO 3 Miocene
U / CaMiocene
6.4 ppm
CO -3-now
CO -3-Miocene
= 121mol / kg
0.7
Ca + + now CO3 now = Ca + + Miocene CO3 Miocene
C

Carbon Cycle
Problem Set 11
Due: Thursday, April 24, 2008
1) If at some time in the past, the CO2 content of the atmosphere was three times lower
than todays and the earths tropical temperature was 8 colder than todays (i.e. 18 C
instead of 26C), roughly

Carbon Cycle
Homework 10 Solutions
1. If f is the fraction of C deposited as calcium carbonate, then (1-f) is the fraction
deposited as organic matter. We can then write the equation:
f (2) + (1 f )(28) = 5
Solving for f :
f = 0.77
So calcium carbonate de

Carbon Cycle
Homework 10
Due: Thursday, April 17, 2008
1. If you were to measure the 13C of organic matter and calcium carbonate in a given
rock layer and got the following values, what would be the proportions of organic
matter and calcium carbonate buri

Carbon Cycle
Homework 9 Solutions
1. Your answers will vary depending on the data and year you use. A correct answer
will take the total number of students enrolled in a year (for all undergraduates,
this number is somewhere between 7000 and 8000) and div

Carbon Cycle
Problem Set #9
Due: Thursday, April 10, 2008
For these problems you will need to use the following equation:
Residence time = (Total inventory)/(input or output rate)
where total inventory is the total amount in the reservoir, andinput or out

The Earths Carbon Cycle - Spring 2008
Problem Set 8 Solutions
1.
The boron isotopic composition of borate flattens out at lower pH than at present, making
11
B a less sensitive indicator of pH. Since lower ocean pH corresponds to higher pCO2, this
means

Carbon Cycle
Problem Set #8
Due: Thursday, March 13, 2008
1.
Looking at slides 8 and 27 from Lecture 7, are B/Ca and 11B likely to be more
accurate at reconstructing pH during times of lower or higher pCO2 than present?
Why?
2.
What are two potential comp

The Earths Carbon Cycle - Spring 2008
Problem Set 7 Solutions
1. See graph below.
To solve the two end-member problem, you know:
y-intercept = -23.945
C-3 plants 13C= -27
C-4 plants 13C= -12
-23.945=(-27)(x)+( -12)(1-x)
-23.945=(-27)(x) -12 + 12(x)
-11.94

Carbon Cycle
Problem Set #7
Due: Thursday Mar 6, 2008
1. This problem is intended to give you some more practice using isotopic information to
get quantitative answers. A Keeling Plot, named for Charles Keeling who first used the
technique, can be used to

The Earths Carbon Cycle - Spring 2008
Problem Set 6 Solutions
Super Problem #2
The amount of C added to the ocean/biosphere/atmosphere system by coal burning (which is
equivalent to the amount of coal burned) is equal to the difference between the amount

The Earths Carbon Cycle - Spring 2008
Problem Set 5 Solutions
1.
For this problem, Im assuming a sandstone aquifer with a porosity of 30%.
a)
3 10 9 barrels
42 gallons 3785 cc
m3
6 = 4.77 10 8 m 3 CO2 (supercritical liquid)
barrel
gallon 10 cc
4.77 10 8

Carbon Cycle
Problem Set #5
Due: Thursday, February 21, 2008
These two problems are designed to give a sense of scale for carbon sequestration plans.
1. One carbon storage mechanism ready for use involves deep (>800 m) aquifers filled
with saline porewate

Carbon Cycle
Problem Set #4 Solutions
1. The simplest way to do parts a) and b) is to use the fact that
Average age = 1/
where is the growth (or decay) constant. For part a, =0.03; for part b, =0.01. These
values give us average ages of 33 and 100 years,

Carbon Cycle
Problem Set #4
Due: Thursday Feb 14, 2008
1. In this problem, recall our discussion in class of how to calculate the average age of
anthropogenic CO2.
a.
Assuming that CO2 release rates start at 1 GtC/yr and increase by 3% a year,
what is the

Carbon Cycle 2008
Solutions to Problem Set #3
5. Given: pCO2 = 560 atm
Alkalinity = 2100 mol/kg
Kc = 1445
[CO2] = 20 mol/kg
Were trying to solve for [CO32-] and [HCO3-].
To solve by iteration using Excel or a similar program:
-guess a value for [CO32-] (s

Carbon Cycle
Problem Set #2 solutions
1. Were trying to explain a O2 of -32 ppm - -42 ppm = 10 ppm and a CO2 of 15 ppm 30
ppm = -15 ppm, where O2 and CO2 refer to the differences between measured changes in
atmospheric O2 and CO2 and those that would be e

Carbon Cycle
Problem set #2
Due: Thursday, January 31, 2008
The graph below represents changes to atmospheric CO2 (+15 ppm) and O2 (-32 ppm)
over the 10-year period from 1990 to 2000 observed by Ralph Keeling. The dashed line
shows the changes in both gas

Carbon Cycle
Problem Set #1
Due: Thursday, January 24
1) This problem will give you some practice with stoichiometry as well as a sense of the
contributions of gasoline-powered cars to atmospheric CO2 levels.
a) If your car gets 30 miles to the gallon of