Science project

The Effect of Acid Rain on Marigold Plants

Research led to my hypothesis that the change in height of the plant would decrease by 25% from the control for each 1pH level, the flowers and sprouts growth would decrease by 10% for each 1pH change and the observed health of the plant would decline.

Materials and Methods: Six acidic watering solutions were made by adding vinegar to distilled water, with differing levels of acidity ranging from pH3.2 to pH6.0. The solutions were used to water 29 similar marigold plants (replanted to create identical conditions) in groups of 5 for 10 days. Each day, the plants' heights were measured, the number of flowers and sprouts were counted and general observations of the plants' health were completed.

Results: Growth rate declined from the control (pH6), beginning at an 8.3% decline at pH5.5 and ending in 1252.8% at pH3.2. The change in number of flowers increased, then declined at below pH 3.75 leading to a decrease from pH6 in flower growth by 34.37% at pH3.2. The change in number of buds or sprouts compared to pH6 dropped by 26.7% at pH 5.5 to a decline of 475% at pH3.2. Combining the increase in buds/sprouts and flowers, there was a decline in growth compared to pH6 at lower than pH 5.5. The counts declined by 66.7% at pH4.3 to 298% at pH3.2. The higher acidity levels led to the unhealthy appearance of plants beginning on day 10 with pH 4.3 and earlier with more acidity, resulting in day 4 with pH 3.2.  

Increased acidity had a negative effect on the health and growth of plants. The growth rate and rate of flower and sprout growth combined declined. The observed health of the plants declined immediately.

Conclusions/Discussion: Increased acidity had a clearly negative effect on the health and growth of plants. The growth rate declined and the rate of flower and sprout growth combined declined. The observed health of the plants declined immediately with the addition of acid solutions.  The effects of acid rain on plants needs to be communicated to the public immediately so that we can implement solutions or curb behaviors that will save our Earth!

Summary Statement: In order to replicate the detrimental effects on plant health by acid rain, I duplicated various region's watering solutions with different levels of acidity and added them to plants over 10 days causing the growth rate, rates of flower and sprout growth, and the observed health of the plants to decline with increased acidity levels. 

Help Received in Doing Project:My mother taught me how to use the graphing feature in excel, but I did all the input, formatting and analysis.


Earth Science


6th Grade





Safety Issues


Time Taken to Complete Project

10 Months

The purpose of this experiment was to find out how acid rain affects the growth and health of plants. I became interested in this experiment when I saw a movie about toxins in the environment at school. I researched online about environmental toxins and became fascinated with acid rain. I chose to test on marigold plants after researching for fast-growing, flowering plants. The information from this experiment will help people understand the importance of curbing air pollution from coal-burning factories, power stations, transportation and furnaces.

Materials and Equipment

  • Distilled water, bottled (3 gallons)
  • 32 fl. Oz/473ml of white vinegar
  • pH test strips with small increments of at least .2 of change between 2.0 and 7.0 or a scientific pH meter with .2 increments of pH change. (I purchased pH strips at Ward's Natural Science at , catalog #15V3152 and #15V3153.)
  • Marigold plants - 29 (1 flat), 10 - 20 cms in height (small with the same potting soil, the same size and the same producer.)
  • Ruler with 30 centimeter measurements
  • Color digital camera to take pictures of plants at different intervals.
  • Potting Soil, 16 quart Master Gardener All-Purpose organic potting soil
  • Plastic cups, 8 oz. (1 cup or 250ml)
  • 500ml or 2 cup measuring cup
  • 6 large, 48 oz. (6 cup/1500ml) reusable plastic containers with lids
  • Medicine dropper measuring up to 1tsp/5ml with .1ml increments
  • Clean metal teaspoon for stirring (5ml)
  • Lab notebook with lined paper to document results
  • Permanent marker
  • Paper towels
  • Index cards to write the plant numbers on to identify them in the pictures
  • Pencil or pen to record results
  • Clock indicating hour and minute.
  • Computer (with a word processor and spreadsheet program) and printer to write report and print out results
  • Location that gets consistent sunlight and room for all plants
  • House thermometer indicating degrees in 1 degree increments


My research on acidic watering solutions and their effect on the growth of marigold plants can be related on a larger scale to acid rain and its impact on our environment. Studying acid rain is very important because acid rain can be very harmful to the environment, buildings, monuments and humans.

Soil acidity affects the way plants grow, beginning with their roots. The acidity inhibits the growth of roots and the absorption of necessary minerals through the root cell walls. This can drastically weaken plants, causing them to grow very slowly or turn yellowish in color. Some plants may have difficulty absorbing nutrients at all in highly acidic soils. If acid levels remain high, harvests will be smaller, seeds will not grow well and the plants may eventually wither and die.

In addition to the damage to forests and crops, acid rain also causes damage to buildings, monuments and stonework by causing them to weaken, wear down, rust faster and deteriorate. 

Acid rain raises the acidity in lakes and streams causing fish to grow more slowly, eggs to not hatch, fish to die and the animals that eat the fish die or move away as their food supply goes away. 

Acid rain is also harmful to humans. The tiny particles created by acid rain can cause respiratory diseases like asthma or chronic bronchitis or make existing conditions worse.

Terms and Concepts for Background Research

What is pH?

Acidic and basic are two opposites that we use to describe chemical compounds. Acidity is measured by using a pH scale. A pH scale runs from 0 (the most acidic) to 14 (the most basic) and measures how acidic an object is. A substance that is neither acidic nor basic is called neutral, and has a pH of 7. Normal water is about a pH of 6 to 7. Normally clean rain has a pH value of 5.6, which is slightly acidic. However, when rain combines with sulfur dioxide or nitrogen oxides produced from factories and automobiles, the rain becomes much more acidic. Typical acid rain has a pH value of 4.0. For optimum growth, most plants need a soil that has a pH range from 5.8 to 7.0. A decrease of pH from 5.0 to 4.0 shows a 10-fold change in the number of hydrogen ions in the solution. You can measure acidity with litmus paper (which only measures whether it is acidic or basic), pH paper (which measures in increments typically between 3 and 10), or a scientific pH meter which has various increments depending on the manufacturer.

My research indicated that to increase the level of acid in the water, I should add vinegar. Using pH measuring strips to monitor the results of adding the vinegar to distilled water, I was able to replicate many levels of acidity in water.

What is acid rain?

All rainwater is slightly acidic, a pH of 5.6, due to dust and pollen particles it can pick up when the droplets form. However, when rain contains pollutants, the rainwater can become very acidic. Acid rain is any type of precipitation (rain, sleet, snow, fog, gasses, morning dew and dust) that has been made acidic by pollutants in the air.

As pollutants rise and move in the air, they can combine with moisture in the clouds where SO2 and NOx  react with water and oxygen. This forms sulfuric acid and nitric acid in the atmosphere. Sunlight increases the speed of these reactions. Rain, snow, fog, sleet and other forms of precipitation then mix with the sulfuric and nitric acids and fall to the ground as acid rain. This type of acid rain is called wet deposition.

Pollutants can be carried by the wind for very long distances. Half of the acidity in the atmosphere comes from acid pollutants falling directly on plants, trees, buildings, equipment, lakes and any exposed surface. This is called dry deposition. If these gasses and particles are washed from trees and other surfaces by rain, the runoff water contains acid from acid rain and dry deposition, making the water even more acidic than from the rain alone. This combination of wet and dry deposition is called acid deposition.

What are the effects of acid rain?

Acid rain can be extremely harmful to forests, lakes and streams, and humans. 

In forests and crop fields, it can seep into the ground and dissolve nutrients such as magnesium and calcium that trees need to be healthy. In addition, acid rain causes aluminum to be released into the soil, which makes it difficult for trees to take up water. The pollution causes haze by scattering light back towards the sky. Haze reduces the amount of light available for plants to use in photosynthesis, causing problems with creating food for plants. Acid rain also wears away the protective waxy coating on leaves, causing damage to leaves and brown spots. The leaves are then unable to use photosynthesis to turn the energy from the sun into food, making the tree or plant unhealthy. The result is trees that grow more slowly, leaves or needles that turn brown and fall off, weakened trees unable to withstand cold, insects or disease, and death.

Acid rain also causes an increase in acidity and aluminum levels in lakes and streams which is deadly to aquatic wildlife. Acid rain flows to streams, lakes and marshes after falling on forests, fields, buildings and roads and then being washed into them. Acid rain can also fall directly into these water areas. Most lakes and streams have a pH between 6 and 8. As lakes and streams become more acidic, the numbers and types of fish and other plants and animals that live in the water decrease. They leave or die. At pH 5 most fish eggs cannot hatch. At lower pH levels, adult fish can die.

Acid rain damages buildings, statues, monuments and cars. Acid rain will eat away at stone, metal, paint or almost any material exposed to the weather for a long period of time, speeding up their deterioration and making them appear old and worn down, reducing their beauty. Marble and limestone are dissolved by acid rain as it reacts with the calcium carbonate, causing many buildings and monuments to be damaged. According to the Environmental Protection Agency, this repair can cost billions of dollars and historical monuments can never be replaced.

Finally, acid rain is harmful to humans. The tiny particles created by acid rain can cause respiratory diseases like asthma or chronic bronchitis or make existing conditions worse. This causes more time off work, makes people less healthy and sometimes leads to death.

Causes of Acid Rain:

Human activities are the main cause of acid rain. Over the last 30 years humans have released so many chemicals into the air that they have changed the mix of gases in the atmosphere. Factories and coal-burning electric power plants release the majority of sulfur dioxide and much of the nitrogen oxides. In addition, the exhaust from cars, trucks and buses and the gas from burning oil and natural gases release nitrogen oxide and sulfur dioxide into the atmosphere. There are also natural sources of acids such as volcanoes, geysers and hot springs. They contribute only a small portion of the acidic rainfall in the world. It is the large amounts of acids produced by human activities that cause the ecosystems to be off balance.

Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. Acid rain then mixes with non-acidic materials, such as air, soils, bedrock, lakes, and streams. As these materials are washed away by rain, the acidity increases and causes damage to crops, trees, lakes, rivers, and animals.

Why is it important to study its effect?

The pH of the water supplied to a plant influences its growth because it affects the availability of needed nutrients from the soil so they don't reach plant roots. Soil pH decreases the solubility of nutrients and minerals that are needed for plants to grow. Solubility is important because fourteen of the seventeen plant nutrients that are necessary for plant growth are derived from the soil. Without these nutrients, plants can get diseases including brassicas and club root.

Studying the effect that acid rain has on the growth and health of marigolds will help document the more global negative effects of acid rain so that solutions can be identified.

How will the height, number of flowers, number of buds/sprouts and overall health of a marigold plant be affected by increasing the acidity of the daily watering solution to replicate acid rain concentrations?


If I increase the acidity of the watering solution, then I believe the rate of growth of the marigold plants will decrease. I believe that for each 1pH increase in the acidity, the plants will grow at a rate that is 25% less than normal, eventually resulting in the death of the plant with the highest acid rain amount. I also believe that the flowers will show measurable signs of unhealthiness including a decrease of 10% at each 1pH increase in the acidity in the number of flowers, a 10% decrease in the amount of sprouts, and plant death at the most acidic pH. I base my hypothesis on acid rain's effects on the maple trees in Vermont and New Hampshire, the red spruce trees in New York and the decline in spruce forests in the Appalachian Mountains. We can also look at the dead pine trees in Germany's Black Forest. By replicating the acidic conditions in these areas, the results should be similar. In the United States alone, according to the United States Geological Service, the average pH levels of rain in certain areas are as low as 4.3. Los Angeles fog has been measured at 2.0 at times. We can see the effects in these areas on trees, crops and other vegetation.

Independent Variable:  the acidity of the water provided to the plants daily.

Dependent Variable: the change in marigold plants including height, sprouts and flowering, and overall health as indicated by smell, color, and droopiness.

Controlled Variables:
  • Sunlight for all plants - put in a garden window that allowed the same sunlight for all plants and observed at night to allow for the maximum exposure to sunlight per day.
  • Soil content - replant all plants immediately using the same amount of soil from the same package.
  • No wind - conducted inside
  • Shock from transport from store - didn't change solution until the 3rd day to allow the plants to adapt to their new surroundings and soil.
  • Plants - all purchased from the same store, the same flat of plants from the same grower. Plants were selected based upon consistency of health at onset.
  • Water - all plants were given the same amount of water at the same time each day.
  • Room Temperature - conducted indoors with temperature between 70 - 75 degrees Fahrenheit (21.11 - 23.89 degrees Celsius)
  • Daily Changes - amount of time between measurements was the same amount of time so that the change rates could be determined correctly.

Control Sample: Plants using water solution #1- distilled water

I plan to observe marigold plants over a period of 10 days and test the effect acid watering solution has on the growth and appearance of the plants. I will then relate the results to the effect acid rain has on the environment.

  1. Prepare marigold plants: 
    • Rinse the plastic 8 oz. cups with water thoroughly. Do not use soap because it can coat the plastic container and may be harmful to the plants. Dry the cups with a clean paper towel.
    • Fill the 8 oz. cups with 6 oz. of Master Gardener All-Purpose organic potting soil. Put a 3 cm. hole in the middle of the soil for the marigold plant.
    • Gently pull out the marigold plant from the flat and tap the soil out of the roots. Put the plant inside the hole in the middle of the 8oz. plastic cup. 
    • Label each 48 oz. container with a number grouping and letter, using the permanent marker. 5 plants will be labeled for each pH level (1 - 5), 4 plants for 6. For the plants within each number, label them a through e. So, for each group you will have 5 plants in the sample, except group 6 which will have 4 plants in the group. (ie: 1a, 1b, 1c, 1d, 1e, 2a, 2b, 2c…)
  2. Prepare the vinegar solutions:
    • Using the measuring cup, add 500 mL (2 cups/16 oz) of distilled bottled water to each 48 ounce plastic container, numbered 1 - 6. Distilled water must be used because tap water may contain chemicals, like chlorine or chloramines, which could harm the plants.
    • Using the pH strips, test the pH of the water in container #1. When using pH strips, dip a clean pH strip in the solution while holding the end. Wait for 2 seconds and then read the result. Record the pH on a data table like the example one below after step 3. Do not add any vinegar to this container. Double check your result.
    • For containers 2-6, use the medicine dropper to add vinegar to the water, one container at a time. After adding each addition of vinegar, mix the water with a clean spoon and measure the pH with the test strips. The goal is to create five different solutions with increasing amounts of acidity, ranging from just below the pH of distilled water (using the measurements for container #1 as a guide) to a pH array in the acid rain range of 3 - 5 (the acid rain range according to Environment Canada is 1-5, the average acid rain pH according to the United States EPA is 4.3). Most normal rainfall falls into the pH range of 5 - 6. Container #2 should have the fewest drops of vinegar and thus be the least acidic (except for the control, distilled water, in #1). Container #6 should have the most drops of vinegar and thus be the most acidic. Record the number of milliliters required to achieve the pH level required. Double check your results using fresh pH strips.
Amount of Vinegar
0 drops
18ml (3.65 tsp)
36ml (7.3 tsps)
45ml (9.13 tsps)
54ml (11 tsps)
125ml (25 tsps)
  1. Observe and document your results:
    • At the same time each night within a 1 hour period (to give them a full day of sunshine), observe the plants and write down observations in the data table. (See forms used in log book)
    • Measure heights of each plant (consistently measuring from the top of the soil to the top of the highest stalk), number of flowers and sprouts (noting each), and make observations about each plant such as color changes, smell, dead flowers, droopiness, etc. Be consistent in the method of measuring and observing.
    • Mark down your observations in a table which lists the plant number, height, number of flowers/sprouts, and other observations. Observations include changes in the smell, color of flowers, wilting, dead flowers, etc. Double check.
    • After making your observations, place an index card with the day number next to each group of plants and take a picture of each group of plants each day from a distance that will show all plants in the picture. Continue this step for each day through day 10.
  2. Water Plants with various acidic solutions:
    • For the first two days, water each plant with 4 oz. (½ cup or 150ml) of distilled water since they were just replanted into dry soil. On the second day water each plant with the medicine dropper with 10 mls (2 tsps.) distilled water from container #1. This 2 day control watering will allow the plants to adjust to their replanting without affecting the results.
    • Beginning on Day 3, recheck the pH levels of the acidic watering solutions. Then water the plants using the medicine dropper with 10 ml (2 tsps) of the appropriate acidic (vinegar) watering solution. Plants labeled 1a - 1e get watered with watering solution 1, plants labeled 2a - 2e get watered with acidic solution 2, etc. Wash the dropper out with distilled water in between each move to the new acidic solution. For each day after, continue to water the plants with 10ml (2tsps) of the appropriate acidic solution.
  3. Place plants in an area inside where they receive the exact same amount of sunlight. The average temperature of the location should be between 70° - 75° Fahrenheit or 21.11 - 23.89 degrees Celsius. 
  4. Complete steps 3 - 5 through Day 10.


Note: Since the acidic solutions were added beginning on Day 3 to allow plants to adjust to the replanting, the changes were compared to Day 3.

Height Changes (Growth):

The acidic watering solutions did have an effect on the plants. See the chart below for the effect on the plant growth. As the acidity of the water increased (the pH level went lower), the growth rate declined dramatically. The initial changes in pH showed steadily increasing growth declines with significant declines at the 3.75 and lower pH. While there is a high standard deviation, this trend still shows in the detailed graphs shown in the log book.

Note: Lower pH means higher acidity.

Watering Solution

Average Growth (Mean)

Standard Deviation from Mean (Average)

% Growth Change from pH 6 solution

Median Growth
1 - pH 6
2 - pH 5.5
- 8.3%
3 - pH 4.3
- 13.9%
4 - pH 4.0
- 26.4%
5 - pH 3.75
-169.4% - almost dead
6 - pH 3.2
-1252.8 dead
Flower Changes:

The number of flowers declined once the acidity of the water reached a pH below 3.75. The plants in the pH of 4.0 - 6 showed an increase in flower growth from the control, pH 6. While there is a high standard deviation, this trend still shows in the detailed graphs in the log book

Watering Solution

Average Change in Number of Flowers

Standard Deviation from Mean (Average)

% Change from Control pH6
1 - pH 6
2 - pH 5.5
3 - pH 4.3
4 - pH 4.0
5 - pH 3.75
6 - pH 3.2
Buds/Sprouts Changes:

The number of buds or sprouts declined in growth as soon as the acidity of the water increased (pH becomes lower). The counts decreased at an increasing rate until the highest acidity level resulted in no sprouts or buds at all. While there are high standard deviations, this trend still shows in the detailed graphs in the log book.

Watering Solution

Average Change in Number of Sprouts

Standard Deviation from Mean (Average)

% Change from Control pH 6 solution

1 - pH 6
2 - pH 5.5
3 - pH 4.3
4 - pH 4.0
5 - pH 3.75
6 - pH 3.2
Because sprouts and buds turn into flowers, it is important to observe the combination of those changes. There is a decline in growth as soon as the acidity of the water increases from pH 5.5 (pH of average rainwater without acid rain conditions). The counts decreased at an increasing rate until the highest acidity level resulted in no flowers, sprouts or buds at all. The standard deviations are high because there was a wide spread around the average, but the detailed graphs show the trends are still there.


Watering Solution

Average Growth (Mean)

Standard Deviation from Mean (Average)

% Growth Change from pH 6 solution

1 - pH 6
2 - pH 5.5
3 - pH 4.3
4 - pH 4.0
5 - pH 3.75
6 - pH 3.2
In addition, by observing the plants I could see that the overall health of the plants watered with higher acidity water were not as healthy as the plants watered with lower acidity water. The plants were wilting, the flowers were droopy, the colors dulled, the sprouts didn't open, and the leaves began to turn brown. The plants showed signs of unhealthiness (including shriveling flowers, wilting, etc.) by day 4 with pH 3.2 ending in death, day 8 with pH 3.75, and day 10 with pH 4.3 and pH 4.0. No change was seen with pH 5.5.


  1. My hypothesis that if I increase the acidity in the watering solution (similar to acid rain), then the rate of growth of the Marigold plants will decrease was correct. After 8 days of differing pH levels in the water, the rate of growth slowed by 8.3% with the first increase of acidity, 13.9% with the second increase of acidity, 26.4% in growth decrease for the third increase in acidity and then for the last two levels of acidity, the growth was extremely negative at a 169.4% decrease for pH 3.75 and a decrease of 1252.8% in the highly acidic pH 3.2 as the plants began to die. The highest acidity level solution caused the plants to die after only 1 day of watering with the high acid water. Starting with an acid level of 4.3, I saw the plants starting to die by day 10 (as shown by their shriveling and wilting) and start to die earlier with each increase in acid level.
  1. My hypothesis that for each 1pH change in acidity, the plants will grow at a rate that is 25% less than normal, eventually resulting in the death of the plant was partially incorrect. From pH of 6 to the pH of 4, there was a decrease in growth of 26.4%. It initially took 2 pH level changes to register a 25% decline in growth. The first ½ pH increment resulted in a growth change of 8.3%, or a 16.6% rate for 1 pH. The rate of change was similar by pH increment until pH4. The rate of decline in growth was much higher than 25% at that point. In fact, the result of acid rain was even worse than expected, resulting in death of all plants at pH of 3.75 and lower (higher acidity levels). So yes, the increased acidity level did result in plant death but the rate of decline was not in a steady line. The decline of growth started off slower than I expected and then increased much more than I expected.
  1. My hypothesis that the flowers will show measurable signs of unhealthiness including a decrease of 10% at each 1pH increase in the acidity in the number of flowers, a 10% decrease in the amount of sprouts, and plant death at the most acidic pH was mostly incorrect, although my anticipation of a negative effect was correct. For flowers alone, my hypothesis was incorrect. Acidic solutions up to a pH of 3.75 is actually good for the plant's flowers, then at a pH of 3.2, they declined by 34.37%. For sprouts/buds growth, my hypothesis was incorrect because I understated the negative effects of an acidic solution. Instead of a 10% decline, they declined beginning at a decrease of 27% and ended in a decrease of 475% with the highest acidic solution.  Most importantly, if you look at new growth (buds and sprouts) combined with the flowers, instead of a steady 10% decline as I had predicted, the results show a 67% decline beginning at pH of 4.3, and continuing to rise up to a decline of 298%, eventually leading to the death of the plant. My hypothesis about plant death was correct. The plants showed signs of unhealthiness (including shriveling flowers, wilting, etc.) by day 4 with pH 3.2 ending in death, day 8 with pH 3.75, and day 10 with pH 4.3 and pH 4.0. No change was seen with pH 5.5.

If I were to improve on this experiment, I would observe the plants for another 7 days. I would also spend more time creating more even differences in pH levels. It took a lot of time to get the desired result of pH. Now that I know the dramatic effects of the changes in pH level, I would like to have even greater accuracy, using a very high caliber scientific pH meter rather than pH strips which may leave room for judgment on the colors. I would also expand this project to include plants and animals, as in a lake environment.

Why is studying the acid rain effects on plants important? 

Acid rain is a complex environmental problem which affects the United States and many other countries around the world. Since acid rain and its effects have dramatically increased over the last 30 years, we need to study its effect so that we can inform the public. We can then promote actions to stop acid rain, including education, conserving energy, and minimizing the miles driven by cars and trucks by using alternative "clean" transportation such as bikes or walking. We can encourage the government to pass laws to limit nitrogen oxide and sulfur dioxide production, increase research funding for alternative energies and ways to decrease coal pollution. Finally, we can inform the public of car pollution and encourage low emission vehicles.

We can sponsor uniform acid rain measurement stations, like the ones set up by the United States Geological Service, all over the world. We should not only measure the acid rain levels, but collect data on large sections of trees and plants so we can more accurately gauge the effects of small changes in acid rain on the environment. This will help us quantify the financial impact it has on industries and the environment so we can justify some corrective actions or buffering measures to lower the acidic content of areas and support limits on industry. The international treaties currently in place between the United States and most European countries and Canada should be revised based upon these studies and enforcement actions installed. We have made some steps forward with the implementation of the Acid Rain Program established by the Clean Air Act Amendments of 1990 that implemented a program to use both regulatory and market based approaches to controlling air pollution. We need to continue to measure the impact and change the programs as needed.

Questions for Future Research

After completing this project, I would like to look into corrective measures for high acidity conditions. This would include looking into buffers, or things that would offset the increase in pH such as nitrogen and sulfur which can have an effect on the pH levels of rainfall. Freshwater lakes commonly are slightly basic. pH's in the range of 6.5 to 8.2 are best for most plants and animals, and below 5.0 is lethal to many fish. A lake's ability to buffer acid water is a function primarily of the concentration of carbonate (CO3) and bicarbonate (HCO3) ions. In areas with limestone (CaCO33) bedrock, surface waters have high concentrations of carbonate and bicarbonate and therefore are able to resist change in pH. The pH of a well-buffered lake does not change dramatically following a storm or snowmelt period because the acidity becomes neutralized by these ions. In regions where the bedrock is granite, the soils and surface waters are naturally low in alkalinity. One such region is the Adirondack Mountains, where approximately 20% of the lakes are too acidic to support fish life. Soil pH can be raised by adding limestone, wood ashes, cottonseed meal, sulfur or pine needles. Another approach to restoring acidic lakes is to add lime to the lake itself, to the streams flowing into it, or to the watershed land. This can be simulated in an experiment using baking soda (NaHCO3), horticultural lime, or a stomach antacid such as Tums, which is made up of CaCO3. Some salts in soil may also act as buffering agents. 

In addition to testing the effectiveness of buffering agents, I would be interested in testing different types of soil to see if the type of soil effects acidity.

I would also like to research the acid rain effects on humans. Are there any health problems caused by acid rain? Does it affect our sources of food, water and air?


The conclusions I reached by doing this experiment can be used in educating the world on the harmful effects of pollution from coal-burning factories, power plants and transportation. It will motivate people to take corrective actions personally, support additional research into corrective matters by governments and support legislation to limit pollution by factories contributing to acid rain conditions.

As you can see from this experiment, acid rain is very deadly. It affects all organisms and ecosystems in our world. We need to find ways to help stop pollution from getting into the air and to protect plants, buildings, monuments, lakes, streams and wildlife from the harmful effects of acid rain. We need to communicate to the public the problem so that we can take the corrective actions of polluting less, correcting damage and establishing controls to limit pollution in the future. The longer we wait to seriously attempt to reduce acid rain, the more endangered our Earth will become for everything and everyone who lives on it.


Parks, Peggy. Acid Rain. Detroit: Thomson Gale, 2006. (Excellent book that went over how acid rain is formed, the effects, how it is spread and finally, how it can be stopped. It also has a good glossary of terms that helped me understand the science.) 

Petheram, Louise. Acid Rain. Mankato, MN: Capstone Press, 2003 (This book went into more detail than the first book. It also talked about measuring acid rain with the pH scale which really helped me in my experiment. It also had the detailed effects on nonindustrial areas, human health, forests, crops, water life and buildings. It talked about solutions.)

On-Line Sources

"Acid Rain - Effects Felt Through the Food Chain."  National Geographic. 10 May 2010. Available  (This site contains acid rain facts, pictures, acid rain effects and solutions. This confirmed information I had received from the Environmental Protection Agency.)

Agee, Sarah. "Acid Rain and Aquatic Life." Science Buddies 22 April 2009. On-line. Internet. 3 May 2010 Available (One of many projects reviewed initially to choose a project. Although I didn't choose to test aquatic life, this project got me more interested in acid rain.)

Environmental Protection Agency. "Effects of Acid Rain - Forests." On-line. Internet. 10 May 2010. Available (Great overview of the effects of acid rain and how it occurs.)

Environmental Protection Agency. "pH Scale?" Acid Rain Students' Site On-line. Internet. 10 May 2010 Available (This site helped me understand the pH scale and how I would use it in my experiment. It taught me about pH strips and their meaning as well as what acidity was.)

Environmental Protection Agency. "What Can You Do?" Acid Rain Students' Site On-line. Internet. 10 May 2010 Available (This site goes the next step and told me what students could do to help the acid rain situation. It also gave me some new ideas about future steps.)

Environmental Protection Agency. "What Causes Acid Rain?" Acid Rain Students' Site On-line. Internet. 10 May 2010 Available (This site helped me understand the science behind acid rain - how the SO2 and NOx mix with water to form acid rain.)

Environmental Protection Agency. "What is Acid Rain?" Acid Rain Students' Site On-line. Internet. 10 May 2010 Available (This site gives a broad overview of acid rain and why it is harmful. It gave me a good beginning to do more research on things briefly mentioned.)

Environmental Protection Agency. "What is Being Done?" Acid Rain Students' Site On-line. Internet. 10 May 2010 Available (This gave me some good information on the regulatory changes being made and other things we can do.)

Environmental Protection Agency. "Why is Acid Rain Harmful?" Acid Rain Students' Site On-line. Internet. 10 May 2010 Available (This site went into detail about the effects of acid rain. It helped me to understand in detail why a solution needs to be found.)

Kichura, Venice. "How does pH affect plants?" eHow. On-line. Internet. 10 May 2010 Available (This site talks about the availability of nutrients to the plant being affected by the pH. It also talks about other effects on the plant such as plant disease. This is where I first learned that limestone could counter acidic soil.)

Lacoma, Tyler. "How Does the Acidity of Soils Affect Plant Growth?" eHow. On-line. Internet. 10 May 2010 Available (This site talks about measuring acidity with pH scales. It also talks about the effect on the roots of the plant with increased acidity.)

USGS. "Water Properties." Water Science for Schools. On-line. Internet. 20 April 2010 Available (This site talks about the importance of pH, how it is measured and the effect of acid rain on the Hydrogen ion concentration across the US. It helped me decide my procedures for my experiment and showed me the importance of the experiment.)

Young-Bolen, Sharlene. "The Effect of Acidity on Shrub Growth" eHow. On-line. Internet. 19 April 2010 Available (Includes good information on what can be done to change the acidity of the soil. This gave me some good ideas for my next steps.)

Retail Stores

Home Depot - Jeffrey Strong, Garden Manager - gave me good information on what types of plants grow quickly and flower. After initially looking at ground cover, we focused on flowering plants, deciding on the marigold.

Orchard Supply Hardware - Steven Halloway, Garden Supervisor - directed me to marigolds as a quick-growing plant that flowers almost immediately upon bringing them home.

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