Carbon budget and storage
Day _______________________________________
Learning Objective(s):
AZ DOE---Grade 6, Strand 4, Life Science, Concept 1
PO7: Describe how various systems of living organisms work together to perform vital
functions (respiratory and circulatory)
AZ DOE---Grade 6, Strand 4, Life Science, Concept 3
PO 1. Explain that sunlight is the major source of energy for most ecosystems.
PO 2. Describe how the following environmental conditions affect the quality of life:
•water quality
•climate
•population density
•smog
This lesson was developed to introduce the concept of ecosystem carbon storage. By
burning a continuum of carbon-containing soil types, this lesson demonstrates that 1)
soils that come from ecosystems that store carbon have more calories than those
ecosystems that don’t store a lot of carbon, 2) a certain climate creates more favorable
carbon storing conditions.
Materials:
 Soil samples
 Soda cans
 Paper clips
 Balance
 Matches
 Food items (marshmallows, nuts, cheetos)
 Graduated cylinder
 Tin foil soil burning platform
 thermometers
 H2O
During
Snack
minutes
-Methane Fire (make sure to get pre-approval so school firewalls don't
interfere)
Engage
-Students are shown a sample soil that will be ignited.
-Sample is ignited and students are asked What is smoke, Why does
something burn, Where is the soil going? Where does the soil matter
come from?
-Finally, students are shown samples of peat and desert soils from
Phoenix, and asked the following question: ÔWhat is the difference
between these two soils?" and ÔWhat is the difference in the ecosystems
from which these soils come from?Ē
Explore
1-Students are broken into smaller groups
2-Students are given three soil types
minutes
3-Students use a calorimeter to measure the amount of energy in each
soil type. The calorimeter readings will be a proxy measure for C storage,
because C in soil will ignite.
Explain
-Students are formally introduced/reintroduced to ecosystem production,
ecosystem respiration, and the ecosystem C balance (C balance =
production – respiration), like a bank account.
-Definitions provided for ecosystem, photosynthesis, respiration, carbon
storage, etc.
-Students asked to put their calorimetric readings into the C balance
framework and conditions that lead to those ecosystems (e.g. What soils
had the highest readings? What are characteristics of the ecosystems that
__ minutes
these soils come from?)
-Ask lots of questions here and really get the students involved. Be sure to
use this time to clarify why you did or did not find differences in
calorimetric readings.
For example, ask the students about where the soils came from and how
those ecosystems where the soils came from are different.
Get them thinking about the factors that influence carbon storage (mainly
climate).
__minutes
__minutes
Expand
-Having demonstrated a gradient of carbon storage (energy) across several
soil types, the expand will have students form predictions about the
amount of energy in common foods.
- Rerun the experiment using foods instead of soil types.
- Explain to the students the types of compounds in the provided food
(marshmallow – sugars, nuts – fat / protein, etc.)
Evaluate
-Students will be asked to draw a picture using the prompt, "How would
you design an ecosystem that will store the most C?"
-Students will then share their drawings and comment on one another's
ideas.
-Return to the questions posed in the engage section.
Calorimetric Soil Measurements:
1. Obtain a soil sample from one of three different ecosystems.
2. Weigh the sample prior to placing in the calorimeter.
3. Write down observations about soil sample (e.g. characteristics, sandy, small
particles, woody, pine needles, etc.)
4. Develop hypothesis of where your soil sample is from (e.g. geography,
temperature, precipitation).
5. Tell students that calorimetric reading is how much energy (or calories) that
their soil has. Higher changes in H2O temperature means more organic
energy rich carbon.
6. Place the cut can on the bottom. The sample should be attached by using the
soil burning platform (Fig. 1. right side).
7. Use a graduated cylinder to put 100 mL of DI H2O in the intact can.
8. Place a thermometer in the top can opening (Fig. 1.).
9. Record the initial temperature of the water.
10. Carefully light the sample with matches in the can below.
11. When the sample finishes burning, record the highest temperature of H2O
that you observed.
12. Calculate the calories contained in the soil sample using the equations found
below.
13. Repeat for all three soil types using new H2O every time.
14. Repeat experiment using the different food types using the paperclip stand to
burn the samples.
Fig. 1. Homemade calorimet
Thermometer is placed in th
The right panel shows the so
Data collection table:
Item
Before
burning
mass (g)
After
burning
mass (g)
∆ mass
(g)
Initial H2O
temp (˚C)
Final H2O
temp (˚C)
∆ Temp
(˚C)
Table for calculations:
Q = mc *∆T
m = mass of H2O, where 1 mL of H2O = 1 g.
c = heat capacity of H2O = 1 cal/g ˚C
∆T = change in water temperature (˚C)
Item
Calories
required*
Calories per
g**
*multiply ∆ temp by 100
**divide calories by the ∆ mass (g) of the sample
***Divide the calories per gram by 1000
Food calories
per g***
Soil Type
Phoenix Lawn
Low desert
Miracle gro
peat soil
Annual
Temp
~82
~87
~37
Annual
Precipitation
??
8”
10”
Calorimetric
Reading
Table 1. Data table for predictions about where the soil originated and amount of
energy contained within the soil.
Food Item
Marshmallow
Cheeto
Nuts
Predicted food calories
Measured food calories
Table 2. Data table for predictions about food items and amount of energy
contained within the each food item.
Fig. 2. Simplified CO2 cycle.
Carbon storage results when
there is more photosynthesis
across the entire ecosystem
(GPP) than there is carbon loss
through plants breathing and
animals breathing. Ecosystems
that store the most carbon have
the largest gap between
incoming carbon (again, GPP)
and outgoing carbon to the
atmosphere. This carbon is lost
when plants and animals
respire CO2 to the atmosphere.
Terms and Definitions:
Photosynthesis: Is the biochemical conversion solar energy and other atmospheric
components to produce energy. This process can occur in plants and soil microbes.
6CO2 + 6H2O + light energy  C6H12O6 + 6O2
Gross primary production (GPP): is the net carbon input in an ecosystem. Net
photosynthesis expressed at the ecosystem level.
Net primary production (NPP): Total amount of photosynthesis in an ecosystem
minus plant or microbial energy lost for maintaining and growing tissues
(respiration).
Net ecosystem production (NEP): Total annual carbon accumulated by an
ecosystem (GPP – ecosystem respiration). Ecosystems with higher NEP will be
ecosystems that store more carbon.
Respiration: is the biochemical process that converts carbohydrates into carbon
dioxide and water. This is energy expended to maintain and build structures.
Ecosystem: System of all organisms in an area and the physical environment in
which they interact.
CO2 : An abundant gas in Earth’s atmosphere. When used in photosynthesis, the
carbon molecule from this gas becomes part of the carbohydrate that makes up new
plant and microbial mass.
Calorie: the amount of energy required to raise 1 g of H2O
Glucose: A carbohydrate that is formed in the process of photosynthesis.