The Effect of Precipititation on the Acidity of Western Pond Final Discovery Lab

This topic submitted by Brian Hollingsworth, Elaine Ivie, Jen Mackall, Jessica Neuman, Tom Schmidt ( Schmidtw@muohio.edu ) on 12/14/03 .

Natural Systems 1 Syllabus---Western Program---Miami University

Abstract
Our Natural Systems group studied how rainfall affects the acidity of Western Pond, located on the campus on Miami University in Oxford, Ohio. For four weeks, we compared the amount of precipitation to the pH of the pond water and then analyzed our results. We found that there was a small correlation between a decrease in the pH level of the pond as the amount of rainfall increased. Generally, after periods of precipitation, the water was more acidic. However, the findings were not compelling enough to show an obvious connection between pH levels and precipitation. In many areas of the country, anthropogenic forces have caused rain to become unnaturally acidic, leading to unsafe living environments for plants and animals.

Introduction

Our Natural Systems group wanted to know to what extent rainwater impacted Western Pond. The quality of the water could affect the aquatic life living in the pond, as well as plants and animals that come in contact with the water after it leaves the pond. Sulfur dioxide (SO2) and nitrogen oxide (NO) are released into the air, usually from electric generation power plants burning fossil fuels. When it rains, these particles are deposited back to the earth in what is called Òacid rain.Ó While rain is naturally slightly with a pH of around 5.5, sulfur dioxide and nitrogen oxide gasses can lower the pH to approximately 4.3 (United, 2003). Often times, the cause of acid rain is industries located several hundred miles from the location where the effects take place. For example, industry in Ohio is blamed for the dying forests in New YorkÕs Adirondack Mountains (Adirondack, 2003). Our group wanted to know if the effects of acid rain were felt in Oxford, Ohio. We predicted that as the amount of precipitation increased, the acidity of the pond would lower. In a larger context, our experiment could tell us how rain, however acidic (lower pH) or basic (higher pH) it is, affects Western Pond.

View of Western Pond located on Miami UniversityÕs Campus

Relevance
Acid rain is caused by gasses released into the air reacting with rainwater to create acidic solutions. When this precipitation falls to the earth, if can have adverse effects on plants, animals and aquatic life. In the U.S., over 17 million tons of sulfur dioxide (the leading contributor to acid rain) are released into the atmosphere each year. Areas most impacted by acid rain are those that have soil and water that is weak in alkalinity. Alkaline-richness allows acid to be neutralized (Environment, 2003).
Bodies of water that become too acidic can no longer support a healthy, diverse amount of aquatic life. Plants that live in water are best suited to water in the pH range of 7.0 to 9.2. As pH drops below 6, some fish and plants can no longer survive (Environment, 2003). As sensitive fish and other organisms die off, the species that feed on these are also impacted. Thus, acid rainÕs effect on a few sensitive species can cause the food web to become unbalanced. Additionally, water that is too acidic can lead to the inability for female fish to reproduce or spawn fish with birth defects (Environment, 2003).

Picture of two swans that live in Western Pond

Specific Research Design
To determine the pH level of the water in Western Pond we used a pH tested from the Peer Science Center located in Boyd Hall. Every Monday and Thursday for four weeks, we gathered water samples in 100 milliliter beakers from three locations on the perimeter of the pond. These three locations are indicated on the map later in this report. The purpose of the three locations was to ensure that an average of the pondÕs water was measured, incase a localized chemical caused a change in the acidity in one area. We then took our three samples to the Peer Science Center and measured the pH levels and recorded them on our data sheet. After measuring the three substances, we then averaged the three pHs together.
The second part of our experiment was recording the rainfall for each day in Oxford, Ohio. This information was obtained from the Ohio Agricultural Research & Development CenterÕs website. This information provided told us the precipitation for each day as measured from the Miami University Weather Station. We then compared the pH levels we recorded with how much rainfall had taken place between each measurement.
At the end of our experiment, we entered our findings into the computer program StatView. The program found that our precipitation and pH level recordings indicated a trend that was 95% accurate. This supported our hypothesis that the pH decreases as rainfall increases.

Materials and Methods
In order to measure the pH of the water samples, it was necessary to use a pH tester from the Peer Science Center located in Boyd Hall. The pH tester we used was battery powered and provided a digital display accurate to the hundredth. To calibrate the pH tester, we had to insert the electrode into a substance that had a known pH of 7 and then a substance with a known pH of 4. Calibration had to be done each day we tested to ensure accuracy of our results.

Picture of Elaine calibrating a pH tester.

The following is a copy of the precipitation data we obtained from the Ohio Agriculture Research and Development Center.

Date Precipitation

11/6/03 0.14
11/7/03 0
11/8/03 0
11/9/03 0
11/10/03 0
11/11/03 0.85
11/12/03 0.11
11/13/03 0
11/14/03 0.01
11/15/03 0.05
11/16/03 0
11/17/03 0
11/18/03 0.48
11/19/03 0.11
11/20/03 0
11/21/03 0
11/22/03 0
11/23/03 0
11/24/03 0.41
11/25/03 0
11/26/03 0
11/27/03 1.09
11/28/03 0.37
11/29/03 0.01
11/30/03 0
12/1/03 0
12/2/03 0
12/3/03 0
12/4/03 0.04

The following page is a map of Western Pond with the three spots we measured from marked with ÒXÕs.Ó

The following is a copy of our data sheet we used to record our measurements.

Date pH 1 pH 2 pH 3 Average pH Rainfall per day Rainfall between testing days

6-Nov 7.43 7.49 7.51 7.48 0.14 0.14
10-Nov 7.74 7.73 7.79 7.75 0 0.85
11-Nov 7.13 7.11 7.16 7.13 0 1.47
13-Nov 7.85 7.82 7.88 7.85 0 0.11
17-Nov 7.85 7.87 7.84 7.85 0 0.06
20-Nov 7.7 7.66 7.72 7.69 0 0.59
24-Nov 7.46 7.47 7.43 7.45 0.41 0.41
1-Dec 7.89 7.87 7.91 7.89 0 1.47
4-Dec 7.68 7.64 7.71 7.68 0.11 0.11

Graphs formulated by the StatView program are provided on the following page.

The timeline we used to complete our experiment is provided below.
November 2 Ð Plan project, learn how to use equipment
November 10 Ð Measure pH
November 11 Ð Measure pH
November 13 Ð Measure pH
November 17 Ð Measure pH
November 20 Ð Measure pH
November 24 Ð Measure pH
December 1 Ð Measure pH
December 4 Ð Measure pH
December 7 Ð Combine and analyze data, prepare for class presentation
December 9 Ð In-class presentation
December 10 Ð Revise report
December 11 Ð Revise report
We aimed to measure the pondÕs pH level every Monday and Thursday, but due to school breaks this was sometimes not possible. When this occurred, we measured on the days closest to our target dates.

Results & Conclusions
We discovered a correlation between an increase in precipitation and an increase in acidity, as predicted in our hypothesis. Every time it rained, the pH went down slightly. However, we do not believe the results to be extremely significant as the change in pH was relatively small (the lowest average pH was 7.13 and the highest was 7.89) and could have been caused by sources other than rainfall. For example, chemicals introduced upstream from the pond could have effected the chemical composition of the water. Also, the pH changed by small amounts even when no precipitation was recorded. It should be noted that even small changes in acid levels can affect aquatic life and plants that receive water from the pond and stream. We are not suggesting that small changes are insignificant, but rather that are results may be prone to randomness and thus we cannot fully conclude that rain has a definite, strong impact on the pH of Western Pond. It should also be noted that all our measurements were taken when the precipitation was in the form of rain. Had it snowed during one of our tests, this might have altered the results because the precipitation would not have infiltrated the pond water to the same extend as rain.
In future experiments, it may be useful to test the pH of water upstream and down stream from the pond, or to see what types of aquatic life live in the pond and what their sensitivities are to pH change. It would also be beneficial to measure the influx and discharge of the pond for each day to determine how much water travels through the pond.

References
Adirondack Cooperative Loon Program. (2003). Effects of Acid Rain on Loons. Retrieved November 29, 2003, from http://www.adkscience.org/loons/ acidrain.htm
Environment Canada. (2003). Acid Rain and Water. Retrieved December 1, 2003, from http://www.adkscience.org/loons/acidrain.htm
United States Environmental Protection Agency. (2003). EPAÕs Clean Air Market Programs Ð Acid Rain. Retrieved November 29, 2003, from http://www.epa.gov/airmarkets/acidrain

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