PURPOSE
The purpose of this experiment was to determine the effect of acid rain on the biomass of radishes.
I became interested in this idea when my family started to plant a garden. We watered, fertilized and weeded the plants. Not all of the plants grew. They died within a week or two. I wonder it could have been caused by acid rain. My parents also told me once how the rain may be affecting the crops. They told me about some chemicals that get in rain.
The information gained from this experiment could help gardeners and farmers with their crops. It could also help warn those who might contribute to acid rain, such as, factories, truck-drivers, and others who drive a automobiles.
HYPOTHESIS
My first hypothesis was that the plant’s biomass would be less as the water pH decreased (became more acidic).
My second hypothesis was that the survival rate of the radishes would decrease as the pH decreased.
I based my hypotheses on a book “Acid Rain” by Gail B. Stewart. It stated, “In the last twenty years, rain has been associated with other, less pleasant ideas. Scientist, especially those who study the environment, has found that not all rain and snow are pure. In whatever form, much of the water that comes from the sky is laced with deadly chemicals that turn into acid. The acid builds up in lakes and rivers. It kills the fish and insects that live in the water. Acid rain has also damaged many of our forests. It is harmful to some crops. There is also more and more evidence that acid rain is hazardous to human beings.”
EXPERIMENT DESIGN
The constants in this study were:
• The number of radishes in each group (36).
• Number of seeds in each cell (2).
• The amount of liquid given to each plant.
• When each plant is watered when needed.
• The depth the seed is planted in the soil (1 cm).
• The distance each light is from the ground (30cm).
• The amount of time each plant gets light (14 hr 6:00am-8:00pm).
• The temperature each plant grows at (76ºf, 24°c).
The manipulated variable was the pH level in the water given to the different groups of plants.
The responding variable was the plant growth (mass) of the radishes.
To measure the responding variable, I used a triple beam balance to weigh the plants after they were uprooted.
MATERIALS
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QUANTITY
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ITEM DESCRIPTION
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288
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Early Scarlet GLobe
radish seeds used (144 for experiment)
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4
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Syringes (12 ml)
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2
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"Easy Grow"
planters (72 cells)
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2
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Bags of potting soil
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2
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Fluoresent Lights and
fictures
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1
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Triple beam balance
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1
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Greenhouse (L76cmx
W601cmx H86cm)
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4
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Plastic bottles
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4
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paper bowls
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1
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Light Timer
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1
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Pencil marked at 1 cm
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PROCEDURES
I. Prepare soil in planting containers
A Put enough soil in each planter cell, evenly,
so that each cell has soil up to the
top.
B Shake planter and tamp it on a counter so that the soil is loosely packed.
C Sprinkle more soil on the cells so that there is soil until the planter cells are filled to the rim.
D Put water in a paper bowl and pour water in
each cell. Water each planter cell individually, so they are slightly soaked.
E Repeat this step if soil is not fully wet.
F Add more soil until cell is filled to the rim of the planter.
G Repeat steps above for the other trays that you may have.
II.
Plant Radish seeds in planter
A
Mark a pencil 1cm from the tip.
B Make 2 small holes in soil diagonal from each other to the 1 cm mark.
C Put 1 seed in each hole.
D Put each seed into its hole, 1cm deep.
E Cover the seeds and pat the dirt lightly onto the seeds.
III.
Water the plants
A
Check the bottom tray for water.
B Check the soil and see if it is dry
C Always water every cell with the same amount and at the same time (depending on how much they need).
IV.
Mixing the pH levels
A
Ask a local laboratory to mix 4 different water pH levels.
B They used distilled water (H2O) and added sulfuric acid (H2SO4) to make different levels of acid rain.
C They made pH levels 6.0, 5.0, 4.0, and 3.0 and labeled them.
D Label groups of 36 plants as “6.0,” “5.0,” “4.0,” and “3.0”.
V.
Treat plants with pH levels
A
Repeat the step three of watering the plants except.
While giving the plants toxins check on them daily for: Health, Growth, Color changes, and Leaves.
VI.
Measure Plants for Biomass:
A Pull each radish plant carefully out of its
planter cell and remove dirt.
B Weigh all plants from group together on Triple Beam Balance
C Count plants in this group and divide the mass by the number of plants to get the average.
D Repeat these steps until each group has been done.
RESULTS
The original purpose of this experiment was to determine the effect of acid rain on the biomass of radishes.
The results of the experiment were that the pH level of 6.0 groups was the healthiest group in biomass by a large amount and the group 5.0’s biomass was the least. The pH level of 6.0’s group biomass averages are 0.27g. 5.0’s were 0.23g. 4.0’s were 0.25g. 3.0’s were 0.24g.
CONCLUSION
My first hypothesis was that the plant’s biomass would be less as the water pH decreased (became more acidic).
The results indicate that the overall pattern was for plant mass to decrease as pH decreased. However one group, the 5.0 pH group, did not follow the pattern and had the smallest average biomass. For this reason, my first hypothesis should be rejected, until more research is done.
My second hypothesis was that the survival rate of the radishes would decrease as the pH decreased.
The results also indicated that my 2nd hypothesis should be rejected because all the groups survived at an equal rate.
After thinking about the results of this experiment, I wonder how acid rain would affect different plant species such as soybeans or tomatoes.
If I were to conduct this project again I would do several things differently. I would have used 2-3 times more plants. I would have used a more accurate scale so that I would have more accurate results. I also would have tested my seeds before planting to make sure the germination rate was near 100%. I also would have grown them in the sunlight in late spring.
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