LifeInAGreenhouse
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San Jose State University *
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4L
Subject
Geology
Date
Apr 3, 2024
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Uploaded by ProfMonkey16171
Geology 4L: Life in a Greenhouse
Learning Goals:
●
Use methods derived from current scientific inquiry to form evidence-based opinions about
science-related matters of personal, public, and ethical concern. Part 1 Atmospheric Composition and Concentration
In this lab we will investigate:
●
the composition of Earth’s atmosphere and the fact that although carbon dioxide, methane and other greenhouse gases have powerful effects, their atmospheric concentrations are very small.
●
increasing levels of atmospheric carbon dioxide (CO
2
) as measured in several places around the world. ● sea level rise, one of several consequences of greenhouse warming.
_____________________________________________________________________________ Part 1: Composition of Earth’s atmosphere
GEOL 4L Life in a Greenhouse Lab
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INTRODUCTION
As shown in the diagram to the left, nitrogen and oxygen make
up the vast majority of Earth’s atmosphere. Greenhouse gases such as carbon dioxide and methane are present in very small amounts and are considered trace gases
. Trace gases account for ~ 0.1% of the atmosphere;
CO is the most abundant of these, accounting for about 93% of
the total.
GEOL 4L Life in a Greenhouse Lab
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2
It does not necessarily take a large quantity of a substance to have a significant effect. For example, contaminants in polluted water and greenhouse gases in Earth’s atmosphere are commonly measured in parts per million (ppm)
, parts per billion (ppb)
, or even parts per trillion (ppt)
.
Atmospheric concentrations of greenhouse gases are typically expressed as ppmv (parts per million by volume).
In the activity below, you will explore how many dilutions of a pure substance (food coloring) are needed to produce a concentration of 1 part per million
.
To help you envision the concept of 1 part per million consider the following examples:
1 part per million (ppm) is equivalent to:
●
1 12-oz can of soda pop/30-meter swimming pool
●
1 3-oz chocolate bar/football field ● 1 penny (1 cent) out of $10,000
PROCEDURE
●
Use a marker to label ice cube tray "cells" 1 to 10.
●
Fill your plastic cup about half full of water for eye dropper (or pipette) cleaning.
●
In cell #1, place 10 drops of food coloring. This represents a pure substance, or a
concentration of 1 million parts per million
.
●
Take one drop of the food coloring from cell #1 and place it in cell #2.
●
Rinse the dropper in one of the plastic cups to remove all traces of food coloring.
●
Add 9 drops of clean water to cell #2 and stir the mixture. The mixture is now
diluted to 1/10th of the original concentration, or 100,000 parts food coloring per million parts of solution.
●
Take one drop from cell #2 and place it in cell #3.
●
Rinse the dropper again.
●
Add 9 drops of clean water to cell #3 and stir the mixture.
●
Repeat the above procedure for cells #4 to 10 (remember to clean the dropper between uses).
1.
After each dilution, record the new concentration in Table 1 (p. 3). For each cell, express the concentration of food coloring as ppm, a fraction, and as a percentage
. When your table is complete, answer the questions below.
2.
In which cell did the solution become colorless? __
cell6
____
Is there any food coloring in this cell? _yes_
___ How do you know? Just saw there is no any color.
GEOL 4L Life in a Greenhouse Lab
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3.
Cell #1 contains food coloring with no water added. What is the percent concentration offood coloring in cell #1?
___
100%__
_____
Hint: 100 percent can be written as the fraction 100/100. Complete the following fraction so that both sides are equal: 100/100 = __
1,000,000_
_________/1,000,000
4.
In which of your cells is the concentration of food coloring closest to the concentration (in ppm) of nitrogen in Earth’s atmosphere? ___
cell1
___
5.
The current level of CO2 in the atmosphere is 406 ppm
. What percentage of the atmosphere does that represent? __
0.0406%_
_______ Show your work
.
Table 1
Cell
1
2
3
4
5
6
7
8
9
10
Do you see color?
yes
yes
yes
yes
yes
no
no
no
no
no
ppm
1,000,000
100,000
10,000
1000
100
10
1
0.1
0.01
0.001
Concentration
(as a fraction)
1/1
1/10
1/100
1/100
0
1/10000
1/100000
1/100000
0
1/1000000
0
1/100000000
1/100000000
Concentration
%
100
10
1
0.1
0.01
0.001
0.0001
0.00001
0.000001
0.0000001
Part 2: Life in a Greenhouse
People have been using greenhouses to help plants grow for a long time. Light and heat energy from the sun enter the greenhouse through the glass, and are absorbed by the objects (like plants) in the greenhouse. While light easily passes into and out of the glass, heat does not and it becomes trapped. The “greenhouse effect” is the name given to the role the atmosphere plays in warming the Earth. You can think of the atmosphere as a blanket of gases wrapped around the Earth. Certain gases in the atmosphere are especially good at trapping heat in the air. Over time, this has led to gradual “warming up” of the Earth.
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In this activity, your job is to develop and test a model that will
illustrate what happens to the temperature of the air around the
Earth when heat is trapped within the Earth’s atmosphere. The
question we’ll ask is:
How does the air temperature in an open container compare to
that of a closed container with air and another with CO
2,
, all of
which are exposed to direct light from the sun or 100 watt
bulb?
To answer this, we will build a model with the following:
●
Greenhouse with natural mix of air (= a tennis ball
container with a little soil, and a cap on top)
●
Greenhouse with increased concentration of CO
2 (= a
tennis ball container with extra CO
2 pumped in, and a cap on top)
3.
Take two tennis ball containers and fill each with about 5 cm of soil.
4.
For the first tennis ball container, label it “closed air”. Put a cap with a single hole drilled out on the container and
carefully push the probe of a digital thermometer through the hole in the lid. Adjust the probe inside the tennis ball container so that it is not touching the walls.
5.
For the second tennis ball container, label it “high CO
2
”. Put a cap with two holes drilled out (large and small) on the container. Do the same thing you did for the “closed air” container with threading the probe through the lid and into the container – the probes in both containers should be the approximately the same height above the soil (about 2 to 3 cm above the soil line is ideal).
GEOL 4L Life in a Greenhouse Lab
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4.
Next, thread the tubing from the CO
2 production device through the large hole in the tennis ball lid and push it down towards the bottom of the tennis ball container.
5.
Place enough baking soda in the flask to cover the bottom.
6.
Pour about 40ml of vinegar into a 250ml beaker.
7.
Put the tip of the 30ml syringe into the vinegar making sure the plunger is all the way down. Keep the tip of the syringe below the surface as you pull back on the plunger to fill it to the 30ml mark. If you get air bubbles in the syringe, empty it, and repeat the procedure again.
8.
Carefully put the tip of the syringe into the open hole on the black rubber stopper.
STOP! Have your instructor check your setup to ensure the experiment is correctly prepared!
Instructor initials: ___________
9.
Push out the vinegar into the flask with the baking soda.
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10.
You’ll start to see the mixture bubble – you are creating carbon dioxide gas. Quickly remove the tubing from the tennis ball container and seal up the hole with a small plug or tape. (Be sure to leave the temperature probe in
the tennis ball container.)
11.
Put the containers 5 cm from a light (do not turn on the bulb yet). If you are outside, place the containers in full sun.
12.
Record the temperature of each thermometer before you start the experiment in the Data Table under “0” time in minutes.
13.
Turn on the light (or place the containers in the sun) and record the temperature data of each thermometer every minute for 10 minutes. Record your data in your Data Table.
14.
After 10 minutes have passed, your instructor will tell you how to clean up your equipment.
Data Table
Time In
Minutes
Temperature of
Closed Container
with Air
Temperature of
Closed Container with High CO
2
0
25
25
1
27
27
2
27
30
3
27
32
4
28
32
5
29
33
6
30
33
7
30
34
8
30
34
9
30
35
10
30
35
Total Change in
Temperature from 0 to
10 Minutes
5
10
GEOL 4L Life in a Greenhouse Lab
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VISUALIZING YOUR DATA
You will now make a graph of your data to see how temperature changed with time. First plot time on the X axis.
What is the minimum number for time in your datasheet? 0
What is the maximum number for time in your datasheet? 10
These are your X axis values.
Plot temperature on the Y axis.
What is the minimum number for temperature in your datasheet? 25
What is the maximum number for temperature in your datasheet? 35
These are your Y axis values.
Then, plot your numbers for each tennis ball container, using a different color marker.
Key:
Closed air
Closed CO
2
26
25
0
1
2
3
4
5
6
7
8
9
Group Data Table
Group Name
Total Change in
Temperature for
Closed Container
with Air
Total Change in
Temperature for
Closed Container
with High CO
2
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Now make another graph using the group data table, but use Excel. What kind of graph is appropriate for these data?
Part 3: Tracking atmospheric levels of carbon dioxide (CO
2
)
This portion of the lab focuses on the levels of atmospheric carbon dioxide (CO
2
) that scientists have measured at permanent observatories at South Pole at three different stations in different parts of the world. We will use these data to investigate
● processes that might control variations in atmospheric CO
2 levels during the year, and ● processes that might explain the long-term trend in atmospheric CO
2 levels.
______________________________________________________________________________
In 1958, scientists (notably Professor Charles Keeling) began to use high-precision equipment (e.g., infrared analyzers) to measure the abundance of atmospheric CO
2 at selected sites around the globe. Among the initial sites were Mauna Loa, a 13,000-foot mountain on Hawai’i, and a station just a few miles from the South Pole. Measurements were begun at later times at other stations (e.g., 1973 for Barrow, Alaska).
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1. Familiarize yourself with the locations of these three
1.
Examine the three graphs. The curve on each graph connects monthly measurements, though it’s difficult or
impossible to see the points for individual months at this scale. A.
What is the variable being measured? Year
B.What units are used to express this variable? ppmv
GEOL 4L Life in a Greenhouse Lab
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measuring
stations.
2.
Look at the three graphs again. Although they represent different time intervals and none show a perfectly smooth curve, all of them show the same long-term pattern. Describe this pattern in 1-2 sentences .
The numbers below show the monthly (numbered 1 through 12) readings for 2003 and 2004 at each station. The last GEOL 4L Life in a Greenhouse Lab
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column is the annual average. According to the three places, we can know the value is almost stable. The different point is MLoa and S Pole are increased, Barrow is decreased.
MLoa
1
2
3
4
5
6
7
8
9
10
11
12
avg
2003
374.7 375.6 376.1 377.6 378.4 378.1 376.6 374.5 373.0 373.0 374.4 375.7 375.6
2004
376.8 377.4 378.4 380.5 380.6 379.6 377.8 375.9 374.1 374.2 375.9 377.5 377.4
Barrow
1
2
3
4
5
6
7
8
9
10
11
12
avg
2003
379.0 382.3 381.4 381.4 382.2 380.8 371.0 364.7 368.3 372.5 378.6 382.5 377.0
2004
382.6 383.2 382.2 383.8 383.5 380.5 371.8 366.5 367.9 373.5 379.2 382.3 378.1
S Pole
1
2
3
4
5
6
7
8
9
10
11
12
avg
2003
371.9 371.8 371.7 372.0 372.3 372.6 373.0 373.4 373.9 373.8 373.6 373.6 372.8
2004
373.6 373.4 373.8 373.9 374.1 374.5 374.8 375.4 375.5 375.6 375.5 375.2 374.6
3.
Plot the 2004 results from all three stations on the same graph below. Connect the points for each site with a smooth curve, and label each curve with the site name. Although the data you have graphed are several years old (recall that the current level of CO
2 in Earth’s atmosphere is more than 399 ppm
), the patterns would be similar for more recent data.
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Each of the three curves should clearly show a cycle known as a short-period oscillation.
Our goal is to determine the cause of these oscillations. First, let’s analyze some aspects of the curves you plotted.
4.
In what months of 2004 were the maximum and minimum values of CO
2 recorded at each station?
Maximum (month)
Minimum (month)
Mauna Loa
May
10 October
9
Barrow
South Pole
5 may
4
9 8
11
10
1
2
GEOL 4L Life in a Greenhouse Lab
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5.
What is the amplitude of the oscillation? In other words, what is the difference (in ppm CO
2
) of the maximum and minimum value at each station?
Mauna Loa: __6.5_____ ppm
Barrow: ___1.73____ ppm
South Pole: __2.2_____ ppm
6.
Interpret your results (in terms of the geographic locations of the three sites) to answer the following questions. A. Why do the oscillations occur? Because photosynthetic activity is the cause of seasonal CO2 swings, regions with more plants will experience larger fluctuations. Photosynthesis also occurs in the oceans, but little of this CO2 actually moves into the atmosphere, which is why only land photosynthesizes drive sea- sonal cycles.
B. Why do the oscillations peak when they do?
C. Why is the amplitude of the South Pole station so much smaller than that of the other two? The South Pole is farther from sources of CO2, and has less plant activity.
GEOL 4L Life in a Greenhouse Lab
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N
ow let’s look farther back in time at atmospheric CO
2 levels
. Though precise measurements only began in 1958, scientists have been able to sample “fossil air” from the early 1900s and even the 1800s in tightly sealed bottles of wine of known vintage, and in old brass buttons with sealed air gaps. They have also been able to sample and date fossil air in ice layers. The Law Dome ice cores in Antarctica sampled ice over a thousand years old (below).
7.
The cores from Law Dome show that the amount of CO
2 in the atmosphere was fairly constant from 1000 A.D. until about what year? ___
1800
_________
8.
Thinking back on your world history, why did CO
2 emissions begin to increase around that time? because of the industrial revolution started and fossil fuels that people are burning for energy.
9.
How did the rate of increase in CO2 emissions change at that time, and how can you tell from the graph? It ‘rate suddenly substantial rise from end of 1800.
10.
List three human activities that add CO
2 to the atmosphere. 1. Burning fossil fuels. 2. Releasing chemicals into the atmosphere. 3. Reducing the amount of forest cover
Part 4: Sea Level Rise
A. Melting ice and sea level change
The table below shows the volumes of Earth’s present-day glaciers and the potential sea rise, expressed in meters, if all of the ice at each location melted. Note that potential sea level rise is left blank for Greenland.
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In this part of the lab, you will calculate how much sea level would rise if all the ice on Greenland melted. You will be making several assumptions in order to simplify these calculations.
Table 1. Estimated potential maximum sea level rise from the total melting of present-day glaciers.
Location
Volume (km
3
)
Potential sea
level rise (m)
East Antarctic ice sheet
26,039,200
64.80
West Antarctic ice sheet
3,262,000
8.06
Antarctic Peninsula
227,100
.46
Greenland
2,620,000
6.5
All other ice caps, ice fields, and valley glaciers
180,000
.45
Total
32,328,300
Modified from Williams and Hall (1993). See also http://pubs.usgs.gov/fs/2005/3055/
. km
3
, cubic kilometers; m, meters]
Follow these steps to make your calculations.
1.
Convert the volume of ice to the volume of water
To determine how much sea level would rise as a result of a given volume of ice melting, you first need to calculate the volume of water that would result from melting.
Ice is less dense than water. It has a density that is 0.9 times (90%) that of water. Therefore, when one km
3 of ice melts, it
will decrease its volume by 10%.
Thus, the conversion factor you need is: 1 km
3 of ice = 0.9 km
3 of water
a)
Volume of ice in Greenland ice sheet: _____2620000___________________ km
3
b)
Calculate the volume of water using resulting from melting of the Greenland ice sheet (show work and units!) Volume of water _________2358000________________ km
3
2620000x0.9=2358000
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2.
Calculate sea level rise
The surface area of the oceans basins is 361,000,000 km
2
a)
Sea Level Rise =
Volume of Water (km
3
)____
=
_____
2358000
_______km
3 Surface Area of Ocean (km
2
)
361,000,000 km
2
= ____0.0065_____km
Now fill in the blank areas of the table (potential sea level rise from melting Greenland’s ice and the potential total sea level rise if all of Earth’s glaciers melted).
Now convert your answer to units with which you may be more familiar.
a)
Sea level rise in meters (m): ______6.5__________ (
Note: 1 km = 1,000 m
)
Show your work.
b)
Sea level rise in feet (ft.): _______21.32____________ (
Note: 1 m = 3.28 ft
.)
Show your work.
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B.
Local sea level rise
In the previous section we considered we considered how much global sea level would rise as the result of melting glaciers.
In contrast, local sea level rise is affected by several factors including topography and whether a coastal area is sinking or being uplifted.
Do the activities below and then answer the questions on the next page.
1.
Fill your container 1/3 with water.
2.
Place ruler in the water so that it is exactly vertical.
3.
Draw a picture of the ruler and cup exactly as you see it:
4.
Tilt the ruler so that it is at approximately a 45 degree angle.
5.
Draw a picture of the ruler and cup exactly as you see it:
Questions:
1.
If you were to add more water to the cup which would record a higher level of water, the vertical ruler or the tilted ruler? ______tittled ruler would record a higher level of water________________
2.
Which covers a greater area, the tilted ruler or the straight ruler? Why?
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Titled ruler covers a greater rea because the titled ruler measured along the slope of the surface.
3.
Which coastal area, A or B, shown on the figure (note that this is cross-section view, from the side) below has a greater chance of disappearing if sea level was to rise 20 feet? __A______ Use what you learned in the activities above to explain.
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