Download How Much Does Acid Rain Hinder the Growth Height of Brassica

How Much Does Acid Rain Hinder the Growth Height of
Brassica rapa Plants Without Other Environmental Stressors?
Author(s) Redacted
Abstract: Brassica rapa plants are one of many plants in the environment that are affected by
“acid rain”. According to the Environmental Protection Agency, acid rain is “a mixture of wet
and deposited material from the atmosphere that contains a high acidity level of nitric and sulfuric
acid.” The acidity of the mixture can stunt the growth of plants due to the lack of nutrients and
the effect of the mixture on the tissue and roots of the plant. However, there are several other
factors that need to be considered when observing the effects of acid rain on the environment.
Such stressors that contribute include air pollutants, insects, disease, drought, or very cold
weather. We tested the effect that “acid rain” had on the growth height of Brassica rapa plants by
eliminating such stressors, in order to find the effect of only “acid rain” on the plant. The growth
of the Brassica rapa plants was measured by comparing the height of watered plants to the height
of plants exposed to “acid rain”. The relationship between the growths of the controlled was
compared to the plants affected by “acid rain”. The height of the plants that were exposed to the
“acid rain” measured much shorter than those of the controlled. The results showed a relationship
between the difference in height, color, and mass of the Brassica rapa plants of both the
independent and controlled plants.
Introduction:
Over the years, scientists, foresters, and others have noted a slowed growth of some
forests. Leaves and needles turn brown and fall off when they should be green and healthy. In
extreme cases, individual trees or entire areas of the forest simply die off without an obvious
reason.
After much analysis, researchers now know that acid rain causes slower growth, injury, or
death of forests. Acid rain has been implicated in forest and soil degradation in many areas of the
eastern U.S., particularly high elevation forests of the Appalachian Mountains from Maine to
Georgia that include areas such as the Shenandoah and Great Smoky Mountain National Parks.
Of course, acid rain is not the only cause of such conditions. Other factors contribute to the
overall stress of these areas, including air pollutants, insects, disease, drought, or very cold
weather. In most cases, in fact, the impacts of acid rain on trees are due to the combined effects
of acid rain and these other environmental stressors. After many years of collecting information
on the chemistry and biology of forests, researchers are beginning to understand how acid rain
works on the forest soil, trees, and other plants.
Methods:
The plant Brassica rapa was grown in both a controlled environment and an environment
that was manipulated by simulated acid rain (water and vinegar set to a pH balance of 4.) A
station was set up that contained Styrofoam cells where the seeds would be planted, seeds,
fertilizer, soil, anti-algal squares, cell wicks to assist water absorption, felt, and a water basin.
Additional materials included spray bottles, a plastic cover from a shoebox sized container, saran
wrap, skewers, and bees.
Each trial, the control and experiment, consisted of 16 cells. The seeds were planted and
cared for in the exact same fashion and manner aside from replacing the water being sprayed on
the control with “acid rain” in the experiment. Both were sprayed with three puffs three times a
week.
To make the apparatuses that the plants would grow and live, wicks were placed in each
cell and extended through the cell as to absorb water from the bottom into the cells. Then the
cells were filled with soil, 2-3 fertilizer pellets, and 3 seeds, and then covered by saran wrap to
prevent the soil from receiving the spray. Watering basins were created by filling shoebox sized
plastic containers with water, adding the anti-algal squares to the water, putting one end of the
felt into the water, putting the lid onto the container, and placing the remaining felt on the lid of
the container.
After the apparatus was assembled, the plants were watered with the contents of their
respective spray bottle, using the plastic lid to prevent the control and experiment from being
cross contaminated and from then on watered every 2 days in the same manner. They grew under
fluorescent lights to simulate daylight, and the experiment lasted 40 days due to the short life of
Brassica rapa.
As the plants grew, skewers were placed alongside the plant so that they would grow
upright. Within approximately two weeks, when flowering began to occur, bees were skewered
and used for pollination. At the end of the experiment the plants were harvested and the number
of leaves, number of pods, number of seeds, the weight, and the length were recorded for each
surviving plant.
Results:
Control Plants
55
50
45
40
35
Height of plant (cm)
30
# of pods
# of seeds
25
pre‐weight (g)
20
dry weight (g)
# of leaves
15
10
5
0
1
2
3
Figure 1 Control Plants
4
5
6
7
8
Plant #
9
10
11
12
13
14
Experiment Plants
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Height of plant (cm)
# of pods
# of seeds
pre‐weight (g)
dry weight (g)
# of leaves
1
2
3
4
5
6
7
8
9
10
11
12
13
Plant #
Figure 2 Experiment Plants
Figure 1 shows the results of the control plants. These plants were sprayed with “acid
rain”. Figure 2 shows the results of the experimental plants. In the control group, 14 plants grew.
In the experiment group, 13 plants grew. The average height of the control group is 24.3 cm
while the average height of the experiment group is 8.8 cm. We also counted the number of pods
and seeds per plant to see what affect the different liquids had on them. In the control group, the
average number of pods was 9 with an average of 17 seeds, while the experiment had an average
of 0.5 pods and 0.1 seeds. Most of the flowers of the experiment group never grew or died
quickly after being sprayed with the “acid rain” solution. The leaves, however, did grow. The
average number of leaves for the experiment group was 3. The control group had lots of flowers
and leaves. The average amount of leaves for the control group was 4. We also noticed that
within seconds of being sprayed with the “acid rain”, the green leaves became spotted white. The
solution had an immediate effect on the leaves.
Table 1 Control Data
Plant
#
Height (cm)
root length (cm)
leaves
pods
seeds
pre‐weight (g)
dry weight (g)
1
7.5
4.2
5
0
0
0.01
0.01
2
7
2.2
5
1
0
0.04
0.04
3
15.5
3.7
5
3
7
0.26
0.04
4
16.7
4.8
3
2
3
0.27
0.03
5
30.5
4.4
4
18
5
0.47
0.1
6
31
2.6
3
26
3
0.59
0.14
7
34.6
3.9
3
17
52
2.02
0.38
8
36.3
4
0
11
30
1.25
0.25
9
39.4
6.5
5
12
33
1.5
0.31
10
30.2
4.1
4
5
32
1.14
0.24
11
27.5
4.1
2
7
37
1.15
0.22
12
16.6
3.2
9
4
9
0.28
0.08
13
31.4
4.3
3
20
24
1.06
0.2
14
15.8
4.4
9
3
6
1
0.2
Table 2 Experiment Data
Plant
#
Height (cm)
root length (cm)
leaves
pods
seeds
pre‐weight (g)
dry weight (g)
1
19
5.9
11
0
0
0.28
0.04
2
16
2.6
6
1
1
0.37
0.06
3
13.5
1.4
0
4
0
0.01
0.01
4
8.3
1.7
5
0
0
0.03
<0.01
5
10.4
3
5
0
0
0.01
0.02
6
10.2
4.5
1
0
0
0.01
0.01
7
5.5
0.3
0
0
0
0.02
<0.01
8
2.3
2.5
4
0
0
0.02
<0.01
9
4.2
0.6
4
0
0
0.01
<0.01
10
9.2
5.4
0
0
0
0.02
0.01
11
6.4
3.7
2
0
0
0.01
0.01
12
4
1.6
4
0
0
0.01
<0.01
13
5.7
3.6
2
0
0
0.01
<0.01
Calculations/Error Analysis:
Average number of leaves per plant
Control: 4
Experiment: 3
Average length of plant including root (cm)
Control: 24.3
Experiment: 9.1
Average length of root (cm)
Control: 4.0
Experiment: 2.8
T-Test
for entire plant length:
Control: standard deviation (σ) = 10.76, n= 14, Z=8.45
Experiment: standard deviation (σ) = 4.96, n= 13, Z= 6.41
Discussion:
The results of this experiment clearly show that the growth in plants subjected to “acid
rain” is significantly hindered compared to those plants that received only water. The final length
of the control plants was 15.2 cm longer on average than the final length of the experimental
plants.
By controlling the amount of moisture that comes from the soil, we were able to test
whether it was the “acid rain” coming down on the part of the plant above ground that had any
effect. There were some margins of error in this experiment. Although we did use saran wrap to
try to protect the soil, this method was not completely accurate. Small rips in the saran wrap
were hard to prevent and hard to fix, and they also meant that some water could seep through. To
improve this aspect in a future experiment, it is suggested that a more durable material be used to
prevent ripping and unwanted seepage.
There were two pieces of data in particular that stood out. The average number of leaves
per plant in the control group was very similar to the average number of leaves per plant in the
experimental group. The average root lengths of the control and experiment groups were also
very similar. This could indicate a correlation between root length and the number of leaves a
plant grows. It is interesting that although the entire plant lengths of the experiment group were
much smaller than the plant lengths of the control group, the root lengths were so similar. This
tells us that perhaps we were able to prevent most of the “acid rain” solution from running into
the soil, and therefore the roots of the experiment plants were able to grow as well as the control
plant roots.
References
"Acid Rain Students Site: PH Scale." US Environmental Protection Agency.
http://www.epa.gov/acidrain/education/site_students/phscale.html (accessed September
22, 2011).
"Effects of Acid Rain - Forests | Acid Rain | US EPA." US Environmental Protection Agency.
http://www.epa.gov/acidrain/effects/forests.html (accessed September 22, 2011).
"What is Acid Rain? | Acid Rain | US EPA." US Environmental Protection Agency.
http://www.epa.gov/acidrain/what/ (accessed September 22, 2011).
Wisconsin Fast Plants Growing Instructions. North Carolina: Carolina Biological Supply
Company, 2001. Print.