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What is the effect of acid rain on plant growth?

Acid Rain

Introduction: (Initial Observation)

Many damages to the plants, buildings and other structures are contributed to the acid rain. Acid rain is relatively a new phenomena because it is caused by gases from burning coal and natural oil. You may have noticed that the air is cleaner and fresher after a rain. Have you wondered what happens to the fumes and gases and particles in the air during a rain. They are all washed by the rain. The highest amount of such pollutants are absorbed by the rain drops in the first few minutes of a heavy rain.

When gases such as sulfur dioxide (SO2) and Nitrogen oxide (NO and NO2) are absorbed by the rain, they are converted to sulfurous acid and nitrous and nitric acids. That is what we call acid rain.

In this project we will study the effect of acid rain on plants..


This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “Ask Question” button on the top of this page to send me a message.

If you are new in doing science project, click on “How to Start” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.

Project advisor

Information Gathering:

Find out about acid rains and their effect on the environment. Read books, magazines or ask professionals who might know in order to learn about the effect of acid rain on plants. Keep track of where you got your information from.

Following are samples of information you may find:

As the name suggests, acid rain is just rain which is acidic. The rain becomes acidic because of gases which dissolve in the rain water to form various acids.

About 70 percent of acid rain comes from sulfur dioxide (SO2), which dissolves into the water to form sulfurous acid with formula H2SO3.

Source: http://www.maltaweather.info/pollution.html

Acid rain is rain or any other form of precipitation that is unusually acidic. It has harmful effects on plants, aquatic animals, and infastructure. Acid rain is mostly caused by human emissions of sulfur and nitrogen compounds which react in the atmosphere to produce acids. In recent years, many governments have introduced laws to reduce these emissions.

Source: http://en.wikipedia.org/wiki/Acid_rain

What is acid rain?

The term “acid rain” is commonly used to mean the deposition of acidic components in rain, snow, fog, dew, or dry particles. The more accurate term is “acid precipitation.” Distilled water, which contains no carbon dioxide, has a neutral pH of 7. Liquids with a pH less than 7 are acid, and those with a pH greater than 7 are alkaline (or basic). “Clean” or unpolluted rain has a slightly acidic pH of 5.6, because carbon dioxide and water in the air react together to form carbonic acid, a weak acid. Around Washington, D.C., however, the average rain pH is between 4.2 and 4.4.

Source: http://pubs.usgs.gov/gip/acidrain/2.html

Acid Precipitation

Rain is naturally acidic as a result of the reaction of water vapor, carbon dioxide and nitrogen in the atmosphere. The acidity can increase through the intro­duction of sulfur dioxide and nitrogen oxides into the atmosphere. This can occur nat­urally from vegetation decay, volcanic eruptions, or even sea spray. The primary human contributions stem from fossil fuel combustion, particularly from electric power plants and automobile exhaust.

The term “acid rain” is used most often, but “acid precipitation” is more accurate since it can also reach the ground as dry particles in dust and smoke.

Source: http://www.enviroliteracy.org/article.php/2.html

Which seeds are good for this experiment?

Beans and other legumes are a good choice of seeds for this experiment. They are widely available and you may already have them at home. Bellow is a list:

•Adzuki Beans
•Black Beans
•Black-eyed peas
•Broad Beans (Fava Beans)
•Butter Beans
•Calico Beans
•Cannellini Beans
•Chickpeas (Garbanzo Beans)
•Great Northern Beans
•Italian Beans
•Kidney Beans
•Lima Beans
•Mung Beans
•Navy Beans
•Pinto Beans
•Soy Beans, including black soy beans
•Split Peas
•White Beans



Do not touch the seeds by bare hand.

Doing this may contaminate the seeds and affect their germination and growth.








Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

The purpose of this project is to see how acid rain affects the growth of certain plants.

I became interested in this idea while looking for a project in the environmental science. I noticed that EPA (Environmental Protection Agency) has lots of introductory information in their website that can help me start.

The information gained from this project may be used as a warning to prevent acid rains or prevent its harmful effects.

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

This is a sample of how you may define the variables:

The independent variable (also known as manipulated variable) is the frequency of acid rain. Possible values are: 33% of the times, 66% of the times, 100% of the times.

The dependent variable (also known as responding variable) is the growth of each plant. Also observe and record other conditions of plant including to color of leaves and visual health of the plant). Use a centimeter ruler to measure the plant growth (responding variable), which is the height of the plant.

Control variables are temperature and light. Make sure all plants are grown under the same environmental conditions.

The constants in this study are:

*The type of plant tested.
*The amount of water each day.
*The amount of soil in each pot.
*The type of soil in each plant.
*The size of the pot.
*The shape of the pot.


Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.

My hypothesis is that plants watered with acid solution grow slower than plants watered with regular water.

I base my hypothesis on pictures [See Pictures] of plants claimed to be damaged by acid rain.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”


Experiment 1: How do acidic solutions affect plant growth?

Introduction: For this project we spray the plants with our home made acid rain and regular rain. For acid rain you may use vinegar. Vinegar is easily accessible to most students.

If you do have access to the sulfuric acid* and pH paper*, you may make a more realistic acid rain. To do that fill up a plastic container with about half gallon tap water. Then use a dropper to add sulfuric acid one drop at a time to the water and mix by swirling until the pH of acid is about 3.

* Sulfuric acid is also known as battery acid for cars and is available trough auto part stores. Both sulfuric acid and pH paper are also available from ChemicalStore.com.


    1. Fill each pot to the top with the potting soil.
    2. Label 3 pots as Control. (You will water these with clean water)
    3. Label 3 pots as low acid. (You will water these two days with clean water and one day with acid rain)
    4. Label 3 pots as medium acid. (You will water these one day with clean water and two days with acid rain)
    5. Label 3 pots as high acid. (You will water these only with acid rain)
    6. Place two seeds into slightly moist soil in each pot.
    7. Water the seeds and soil with clean water.
    8. Place all pots under a source of light. (Natural light or fluorescent light)
    9. Every day, water with clean water and place in the light.
    10. Repeat providing light and daily watering with clean water until each plant has fully expanded a pair of leaves. (Too much water can damage the seeds. Give enough water to keep the soil moist, not soaked). When all plants have at least one pair of leaves you can start the main part of your experiment to see how acid rain affect their growth. That will be the first day of your experiment. All you have done before this were just preparations. Some students may skip the preparation part and just buy 12 small plants from a local nursery.
    11. Pour 1 liter of distilled water into one of the empty spray bottles. Label the bottle as CLEAN RAIN.
    12. Pour 1 liter of vinegar or other home-made acid rain in another bottle. Label the bottle as ACID RAIN.
    13. Use the following watering schedule to water the pots of each group with pure water and acid rain. In order to prevent cross contamination, you may temporarily separate the pots from the rest of group for watering and put them back after watering.
    14. Repeat steps 15-18 until obvious results.

Watering Schedule after growing two leaves in all pots:

Day Control Group Low Acid Group Medium Acid Group High Acid Group
1 Pure water Acid Rain Acid Rain Acid Rain
2 Pure water Pure water Acid Rain Acid Rain
3 Pure water Pure water Pure water Acid Rain
4 Pure water Acid Rain Acid Rain Acid Rain
5 Pure water Pure water Acid Rain Acid Rain
6 Pure water Pure water Pure water Acid Rain
7 Pure water Acid Rain Acid Rain Acid Rain
8 Pure water Pure water Acid Rain Acid Rain
9 Pure water Pure water Pure water Acid Rain
10 Pure water Acid Rain Acid Rain Acid Rain
11 Pure water Pure water Acid Rain Acid Rain
12 Pure water Pure water Pure water Acid Rain
13 Pure water Acid Rain Acid Rain Acid Rain
14 Pure water Pure water Acid Rain Acid Rain
15 Pure water Pure water Pure water Acid Rain
16 Pure water Acid Rain Acid Rain Acid Rain
17 Pure water Pure water Acid Rain Acid Rain
18 Pure water Pure water Pure water Acid Rain
19 Pure water Acid Rain Acid Rain Acid Rain
20 Pure water Pure water Acid Rain Acid Rain
21 Pure water Pure water Pure water Acid Rain

15. In each daily observation record the plant height, record the visible health condition of the plant and possibly take a picture to show the negative effects of acid rain.
16. Every day calculate the average plant height of each group and write them in your results table like this:


Average Plant heights in different groups

Day Control Group Low Acid Group Medium Acid Group High Acid Group
1 11.2 cm 11.7 cm 11.5 cm 11.6 cm


Materials and Equipment:

This is a sample list of materials. Your final list of materials may be different.
12  Plastic pots
4    Spray bottles
1     pH metercfr or pH paper
2    Eye droppers
4    Liters of distilled water
1     Marking pen
8    Marking pen
1     Source of light
1     Bag of Potting soil
1     Bottle of lemon Juice
24  Seeds (Beans and other legumes)

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

In your results write what happened to the plants watered with regular water and what happened to the plants watered with acidic water. You can also use your results table to draw a graph. The following sample graph is for a similar experiment in which one group only received clean water the other group only received acidic water. (The accuracy of this graph has not been verified. Your results may be different).


If you do any calculations, write your calculations in this section of your report.

Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.


Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

This is a sample:

    • What would happen if I would use less acidic water?
    • What would happen if I would use a different plant?
    • What would happen If I would use a different type of acid?

If I were to conduct this project again I would probably add less acid to that solution and I would also test more plants.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.

References/ Bibliography:

List your References in this part of your report.

http://www.epa.gov/acidrain/effects/index.html, US EPA, Last updated on Friday, June 8th, 2007

http://www.maltaweather.info/pollution.html, Malta Weather Services 2003

http://www.epa.gov/acidrain/education/site_kids/index.htm , US EPA

“Acid Rain,” Compton’s Interactive Encyclopedia, 1995

“Acid Rain,” Compton’s Interactive Encyclopedia, 2000

Brooks, John “Acid Rain” Chicago, Illinois, 1997 pp. 2-37

Likens, Gene E. “Acid Rain,” World Book Encyclopedia, 1991 Vol. 1 p. 27

Sample Research Report, by Eric D. 11 years old, 1999-2000

This report has not been verified for accuracy and validity of its content. It is provided as is. Students must make their own reports.

Acid Rain is the common name for acid deposition, such as rain, snow, sleet, hail, and other forms of polluted precipitation. Acid deposition is a worldwide problem for all natural things including bodies of water, forests, and other things. Pollution is the cause of all acid deposition.

There are many types of pollution that cause acid precipitation. A big one is cars and their exhaust. The usage and burning of fuel and oil creates a lot of exhaust. Another big pollution problem is factories and refineries that burn fuel, oil, and coal. Then certain chemical compounds, including sulfur dioxide and nitrogen oxides, from fossil fuels, rise and mix with water vapor, and falls in a form of precipitation. As factories have been getting more and taller smokestacks, Acid precipitation has been moving more around the world. Acid precipitation is worst in eastern North America, Northwestern and Central Europe, throughout Asia, and other scattered places around the World. As more factories and refineries are built, and the smokestacks get taller, the wind blows the polluted air to other countries, sometimes hundreds of miles away.

The pH Level
Acid rain’s acid level is measured by the pH level. The scale is measured on a 1-14 number scale, 1 being the most acidic and 14 being the most alkaline. A 7 is not either acidic nor alkaline, being known as distilled water. To measure the pH level of acid precipitation, scientists use a pH meter or a pH paper. On average, a normal pH level for acid precipitation is around 5.6. The more pollution in the atmosphere, the more acidic the acid precipitation is going to be. Depending on the pH level, acid precipitation can do a lot of damage.

The effects of Acid precipitation are getting worse as more cars are manufactured and sold to the public and as more factories are built and opened for people to work in. Acid precipitation harms thousands of lakes, ponds, rivers, and streams worldwide. Depending on the pH level, acid precipitation could kill and damage almost all of the aquatic life, including the animals, plants, and all of the other living things in that body of water. The acid rain also kills everything around that body of water, including the trees, bushes and the grass around the surface of the water. Some scientists also believe that Acid Rain does damage to stone buildings and stone statues. They believe it erodes away the stone. Acid shock is a very interesting form of the acidifying of a body of water. It happens during the spring. The acid snow melts and flows into a body of water. Its called acid shock because it turns a normal lake or other body of water into a very acidic body of water in a very short amount of time.

There are not very many ways to prevent acid rain and other acid precipitation. Scientists are trying to think of more ways to prevent acid precipitation. There are already a few methods of cleaning up the atmosphere, including cutting back on fuel, oil, and coal burning. Some factories throughout the world have coal washers. That prevents air pollution, but the water from the coal gets dumped into a sewer and creates more sewage problems. There have been several attempts to stop local factories by people in the past, but then realized they couldn’t live because the factories provided warmth and electricity, so they couldn’t shut them down. After people got taller smokestacks, the pollution was getting better there, but worse in other countries. The reason is the wind blew the clouds hundreds of miles away. Also, some people have tried to stop driving as much, but at the end, everybody was driving again, doing just as much of it as they were before if not more. The pollution would be less in that area, but worse in other areas, so the people in that area would drive more, thinking its okay.

Acid Rain and all other acid precipitation are a world wide problem. Even in areas with out the factories and vehicles have acid precipitation because the wind blows the pollution to other parts of the world. The main causes of acid precipitation are cars and their exhaust and the other is factories and the burning of fossil fuels. Certain chemical compounds such as nitrogen oxides and sulfur dioxide mix with the moisture in the air and are formed into clouds and then produce acid precipitation. To measure the acid level of acid precipitation, scientists use either a pH meter or a pH paper. The scale is on a 1-14 scale, 1 being the most acidic and 14 being the most alkaline. The average acid level is around 5.6. Depending on the pH level acid precipitation can do a lot of damage. The effects of acid precipitation are getting worse as more cars and factories are made. Acid precipitation is damaging thousands of lakes, ponds, rivers, and streams worldwide. There aren’t many forms of prevention, but the best form of stopping air pollution is washing the coal before it is burned. The con to that is the remains of dirty water from the coal is dumped and it causes more sewage problems.