FINAL: THe Effect of Acid Rain on Plants

This topic submitted by Jessica, Susan, Tya, Amy ( at 3:56 PM on 12/10/02. Additions were last made on Wednesday, May 7, 2014. Section: Cummins

Natural Systems 1 Fall, 2002 -Western Program-Miami University

The Effect of Acid Rain On Plants

By: Amy, Tya, Susan & Jessica

Professor Hays Cummins

WCP 121/123 Section F

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In today's commercialized, fast-paced society, it often seems that the most important things in life are overlooked. Factories and vehicles are producing so much pollution that the government cannot (or does not want to) keep up with the legislation required to stop them. What could be more important in our lives than the environment in which we live?

One growing environmental problem in the United States is acid rain. Emissions from factories and cars seep into the rainwater that nourishes vegetation across the country. Our study examines the effects that acid rain has on bean plants.

Research Questions:

• How will different concentrations of acid affect the growth and appearance of bean plants?

• At what rate will each group of plants deteriorate?br>

• What is the ideal acidity of liquid for the bean plants to thrive?

• How does this relate to acid rain in our environment?


• If we conduct our experiment by the process described below, then the concentration of the acid used to water the plant will be inversely proportionate to the height of plant growth; also, the higher concentrations of acid will cause the leaves to turn yellow or be smaller than the leaves of the plants that have been treated with lower concentrations of acid.

• If we conduct our experiment by the process described below, then the plants' rate of deterioration will depend on the concentration of the acid within water; the plants treated with the higher acidic pH levels will deteriorate more quickly than those with lower pH levels.

• If we conduct our experiment by the process described below, then we will find that the ideal acidity of water for the bean plants we tested will be between 5 and 6.

• If we conduct our experiment by the process described below, then we will see that the acidity of the local rainfall is detrimental to the area plant growth.

In this research experiment, we plan to determine the ideal acidity of water for plant life. After finding this value, we will compare it to the average pH of local rainfall to determine the possible damage to the local plant growth. Knowing the ideal and actual levels of acidity could potentially be helpful in planning for future landscape additions and solving current problems in the terrain.

This research is interesting to our group because of the possible future uses of the results. We are all concerned about what kind of environment we, and our families will have in the future. Knowing the acidity of local rain can help determine a solution for the problem. We were also interested in this project because the members of our group enjoy working in the greenhouse. This project provides an opportunity for us to explore working with plants in a controlled environment.

Background Information and Research Relevance

Our research on acid and its affect on the growth of bean plants can be related on a larger scale to acid rain and its impact on our environment. In what seems to be a small part of environment, acid rain is a huge contributing factor to the harm of ecosystems. Acid rain is generally made up of acidic gases that have dissolved in rain- water. Nearly 70% of acid rain consists of sulfur dioxide (SO2). Rain-water usually has a pH level of about 5, but it can be lowered to 4 or even 3 due to the acidic gases in the environment. These gases are generally the pollutants of energy companies and other highly polluting sources in our environment. Almost everything in our environment is affected because of acid rain. Lakes and rivers lose fish populations due to the acidity of the water. The nutrients in trees are dissolved such as calcium, magnesium, and potassium. Buildings, especially those that are limestone, are affected by acid rain. People too are affected by acid rain because of everything that happens to other aspects in the environment. Drinking water is one of the things that has been affected by acid rain as well. Due to its prevalence, many things have been done to prevent acid rain. Large companies have taken actions to monitor their amount of pollution that enters the atmosphere and people have turned to alternative energy uses to reduce the problem.

Our research on acid and its affect on the growth of bean plants can be related on a larger scale to acid rain and its impact on our environment. The articles listed at the bottom of the page provide some information on this environmental hazard.

Specific Research Design

We plan to grow 180 bean plants and test the effect acid has on the growth and appearance of the strongest specimens of these plants. We will then relate the previous result to the effect acid rain has on the environment. We plan to collect rainwater and test the pH level of the precipitation.

The 90 bean plants remaining after we weed out the weaker specimens will be used to construct a data table that we will use to discuss the results acid rain has on the environment. We will divide these 90 plants into five separate groups. Each group will contain 18 plants. Group One, the control group, will be watered with distilled water with a pH of 7. The remaining groups will be watered with different mixtures of acid and distilled water to attain the desired pH; Group Two will receive the mixture of sulfuric acid with a pH of -1; Group Three will receive the mixture of sulfuric adid with a pH of 1; Group Four will receive the buffer solution with a pH of 4; Group Five will receive a nitric acid mixture with a pH of 5. Each group will be watered twice a week with their specific solution. The volume of the solutions will be the same: .5 L; they will be premeasured so any member of the group can apply the solutions. The plants will be measured twice a week on the days that they are watered. The same person will measure to ensure accuracy. Along with measuring growth, photographs will be taken weekly to note the physical changes that result from the different concentrations of acid. The results of each group will then be compared to the control group of plants.

All five groups of plants will also receive fertilizer weekly. Fertilizer will serve as another control of an extraneous variable because if fertilizer was not present, all of the plants could show signs of stunted growth due to a lack of proper nutrients. The plants will be watered and measured for a total of six weeks. This time period will be long enough to show accurate results after the water/ acid mixture was continuously given to the plants.

After calculating the amount of acid to add to the distilled water to obtain the desired pH, we will test the solutions by using pH test strips. The plant group that shows the most growth and healthy appearance will in turn show what the ideal pH of water for bean plants is.

This design will ensure that we answer all of the specific research questions. We will find the ideal pH of rainwater. However, we will also study the effects of acid rain by relating our data to a natural environment. We will use measurements and photographs to study the individual results of an acid/ water mixture on plants.

Materials & Methods

We will need the following materials for our research project:

Use of the greenhouse - to conduct our experiment

5 half flats (3 6-packs in each) - to plant the seeds in

180 bean seeds - to grow in the experiment

Sulfuric acid - to mix with water to treat beans

Nitric adid - to mix with water to treat beans

Buffer solution - to treat beans

Distilled water - to water the control group

Storage flasks - to store the acid/water mixes

Soil - to plant the seeds in

Fertilizer - to maintain constant nutrition

Digital camera - to record appearance

pH strips - to test accuracy of our mixtures

Measuring device - to measure the length/height of the bean plants

To involve the class in our project, we would like to give a survey about common knowledge of acid rain. We are interested to see how much people know about the topic. We would also like to see if our peers' knowledge of the dangers of acid rain is exaggerated due to the media coverage. As another part of our class involvement, we would like to give a presentation on the ways we can prevent the air pollution that causes acid rain. We will also involve the class in a guessing game about acidity and pH. If our experiment is far enough along when we give this presentation, we will also show the effects of the acid on our bean plants as well. We will have digital photos of our plants, and, if time permits, we can take the class to the greenhouse to see our experiment.

After meeting with Hays to discuss our data, we determined that our data is statistically sound. We have a sufficient amount of samples and set up the data to keep the separate plant trays separate.

We protected ourselves from biased results from having the same person mix the acid every time. Every time the plants were measured, one person did it. Another person was the waterer. The last person was the one that planted all of the seeds to ensure that no favorablity was given to one tray over the other.

To record our data, we made a spreadsheet that will be filled out every time the plants are measured.

We mapped out our research project through the end of November. Click here for our calendar.


In direct response to our research questions, we found that:

(1) The growth of the bean plants and their appearance were most affected by the highest levels of acidity. The graph below shows the average heights of the different trays of bean plants. An obvious inversely proportionate relationship can be seen between plant height and acidity.

(2) We found that the bean plants with the higher acidity deteriorated much faster than the lower levels of acidity.
The pictures below show the changes in plant appearance over two weeks time.



Tray 1, pH = 7 (Distilled Water)

Tray 2, pH = -1 (Sulfuric Acid)

Tray 3, pH = 1 (Sulfuric Acid)

Tray 4, pH = 4 (Buffer Solution)

Tray 5, pH = 5 (Nitric Acid)

(3) Combing the information above, we determined that, besides the distilled water, the plants that grew the most and had the healthiest appearance were that of tray 5: the nitric acid with a pH of 5. This graph supports that conclusion.

(4) Through research and discussion, we found that one reason the pH of 5 might have worked better than the rest of the acids is that it was made from nitric acid, which contains elements useful to plants. Knowing this, it might help the world in a broader scope to focus first on facroty pollution, which gives off sulfuric gases, then on vehicles which give of nitric gases.

We used our final
data sheets
to insert the information into StatView to make these graphs.

We presented our findings in a PowerPoint

Discussion and Conclusion

Our results corresponded well with past research. Previous studies found that, while acid rain is generally not helpful to plants, they can tolerate a certain level of it. We found that the plants could not tolerate the pH of -1 and could just barely survive with a pH of 1. Of course, distilled water generated the best plants, but the growth and appearance of the plants that were treated with the solution that had a pH of 5 were not that bad off.

For further investigation, students might want to consider testing local vegetation
in its natural environment.

Literature Cited

(1) Effects of Sulphuric Acid on the De
terioration of Carbonate Stones and Surface Corrosion - This article is about the effects of sulphuric acid, the main component of acid rain, on other parts of the environment. The study found that the acid rain caused some erosion of rocks in the surrounding area.

(2) Relationship Between Precipitation Chemistry and Meteorological Situations - This article is about a study done in Spain concerning the effects of acid rain on ancient ruins. This is article is helpful to our study because it clearly defines different categories of acid rain, providing clear definitions of the specific pH required to constitute each classification.

(3) The Canadian Acid Rain Strategy - This article is about public policy concerning acid rain post-2000. Canadian officials are trying to work with the United States to write laws and regulations regarding the emission of sulphur dioxide, the main pollutant causing acid rain.

(4) Effects of Simulated Acid Rain on Pinus densiflora: Inhibition of NetPhotosynthesis by the Pheophytization of Chlorophyll - This article provides information on how acid rain affects the process of photosynthesis in the Pinus densiflora. The acid reduces the rate in which the plant photosynthesizes due to the increased amount of chlorophyll.

(5) Soil Calcium Depletion Linked To Acid Rain And Forest Growth In Eastern U.S. - This article discusses the impact of acid rain in soil throughout the eastern United States. Calcium has been depleted due to amounts of acid rain. As a major component in soils, calcium helps to neutralize the acids
from acid rain, but in turn it has been significantly decreased due to the rain. Sugar maples and red spruce trees have been most affected by this depletion of calcium in the soil.

(6) Effects of Acid Rain on Soil Humic Compounds - In this study, a natural soil was treat with acid rain until a soil pH of 4 was obtained. The study found that soluble organic compounds were released as a reslt of their simulated acid rain.

(7) The Acid Rain Differential Game - This is a research paper that introduces a game about acid rain. Participants have to control the levels of sulphur dioxide emitted with respect to surrounding countries. This article is helpful to our study because it shows the importance of environment awareness toward other countries.

(8) Relationship Between The Acidity and Chemical Composition of Rainwater and Climatological Conditions - This study was conducted along a transition zone between large deserts and Mediterranean climate in Israel. It discusses the variance in the pH of the acid rain collected during several consecutive winters.

(9) Recovery from Acidification - This article discusses the effects of ammonium sulphate and sulfuric acid, with pHs of, on soft water environments. The artificial rain solutions used in the study affected the plants growth. The addition of ammonium sulfate increased the rain's acidity decreasing plant life. Plant life decreased with the addition of ammonium sulphate in the artificial rain and increased with the addition of sulfuric acid.

(10) Effect of Cropping Systems on Soil Chemical Characteristics - This article emphasizes soil acidification and discusses causes of soil acidifcation other than acid rain. Legumes are capable of raising the acidity of soil, increasing the pH value.

(11) Impact of Chemical Composition of Legume Residues - This article further discusses the negative effects of legume residues in soil. The legume residue assists in the accumulation of acid in soil. The article also talks about the impact of initial soil pH on pH change of a soil after residue incorporation.

(12) Light and CO2 Effects of Simulated Acid Rain - This article refers to the increase in acidity that decreases the rate of photosynthesis specifically in bean plants. The increasing levels of acid in the soil and production of excess Hydrogen decrease the rate of photosynthesis.

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