Katherine LeaverDecember 10, 2012

Environmental Systems &Societies Internal Assessment #1 (Widewater Fieldstudy)

Dissolved oxygen is the biogeochemical level that is tested in this study. Oxygen is a byproduct

of photosynthesis in plants. Oxygen is vital for all living things. Respiration by aquatic animals,

decomposition, and other chemical reactions consume oxygen. An example would be wastewater

contains organic materials which are decomposed, using oxygen in the process. Other sources include

runoff, and septic systems. Oxygen is measured in its dissolved form as dissolved oxygen (DO). Aquatic

animals are very sensitive to DO levels. DO is measured by in milligrams per liter. Milligrams per liter are

the amount of oxygen in a liter of water. DO is determined by the Winkler method. The Winkler method

is performed by filling a sample tube completely, no air bubbles at all. Then a series of drops are added

to the water, which then change the color in accordance to the DO level.

The climate in Virginia is variable. In the area studied, the average high for November is 59° F

and the average low is 37° F (15° C and 2.78° C respectively). The average rainfall for the area is 3.61

inches (9.17cm). There are five distinct climate regions in Virginia; the Tidewater region, the Piedmont

region, Northern Virginia, Western Mountains, and Southwestern Mountains.

Previous results indicate cold water will contain more DO than warmer waters. DO rates

fluctuate with water temperature and diurnally. If DO levels drop below unhealthy levels, the body of

water will begin the process of eutrophication, or the excessive growth of algae. The algae then dies and

DO levels drop, killing all living things in the water.

Katherine LeaverDecember 10, 2012

Research Question

Is there a correlation between dissolved oxygen levels and the water temperature?

Hypothesis

If the temperature of the water increases, then the dissolved oxygen levels will decrease.

Data Section

Independent Variable (IV): Temperature

The IV was difficult to isolate because the temperature will rise by itself, with the air

temperature.

Dependent Variable: Dissolved oxygen levels

The DV will change in accordance to the change in temperature. There will be a negative

correlation between the temperature and the DO levels.

Katherine LeaverDecember 10, 2012

Controlled Variables: Locations measured, amount of water collected, depth water is collected at, and,

how water is collected

I will do my best to control everything I can, including how deep the DO bottle is submerged,

completely fill the dissolved oxygen bottles for later testing, and the location at which the atmospheric

conditions are measured. I will submerge the DO bottle and shake it for 5 seconds to remove all air

bubbles.

Extraneous Variables: Atmospheric conditions, organisms in water, how fast the temperature rises, and,

people in the water (in boats).

These variables I cannot control. The actual weather, including temperature, humidity, wind

speed, and barometric pressure. There are organisms in the water tested, which cannot be controlled.

There are other students at the field, so I cannot control the location I am testing, for everyone can

access the pond. Also, there are private properties on the edge of the field, which all produce pollution

affecting the whole area.

Abiotic factors: Pollution and atmospheric conditions

The abiotic factors in the environment include atmospheric conditions and pollution. There is

private property located on the edge of the field. Those houses are all sources of pollution, be it heat

pollution, light pollution, and physical sources such as trash. Pollution is important, because pollution

affects organisms and photosynthetic plants, who cannot survive, then that changes the biochemical

oxygen demand.

Katherine LeaverDecember 10, 2012

Biotic factors: Organisms in the water, chemical processes, and, decomposing or decomposed matter in

the water

There are several biotic factors at the testing site. One big example are organisms in the water.

There will be humans, fish, and other organisms all producing heat in the water, which will raise the

temperature. Also, aquatic organisms will use the DO to preform cellular respiration and deplete the DO

levels, which are replaced by the photosynthetic plants (Called the BOD or biochemical oxygen demand).

The chemical processes all take DO to complete the reactions. And decomposing or decomposed matter

produce oxygen as a byproduct.

I will have 10 recorded points of where I took the water samples, and 10 recorded points on

where I recorded the atmospheric conditions on land. The land conditions will be on the chart with the

letter “a” after the trial number. The water samples will be on the chart with the letter “b” after the trial

number. I will use the DO testing kit to perform the tests after gathering the samples. I will be using a

thermometer (connected to a LabQuest), a barometer, and an anemometer.

Materials

10 labeled dissolved oxygen bottles

LabQuest with relative humidity and temperature probes.

Katherine LeaverDecember 10, 2012

Dissolved oxygen testing kit

Anemometer

Lab sheet to record all data

Pen/pencil

GPS (The one used in this experiment had a ±6 meter accuracy)

Raw Data

Land Conditions

Water Conditions and Results of the Testing

Katherine LeaverDecember 10, 2012

Pictures of the Testing

Katherine LeaverDecember 10, 2012

Map Generated on ArcView GIS

Katherine LeaverDecember 10, 2012

Standard Deviation of Test Results

±6 Meter accuracy

Katherine LeaverDecember 10, 2012

Average Temperature: 6.456°C

Variance: 0.502778

Standard Deviance: 2.0055483

Conclusion

The problem investigated in this study was the effect of temperature on dissolved oxygen levels.

My hypothesis was that the cooler water would hold more dissolved oxygen. The study was

inconclusive. I made several mistakes, and there were technological problems. I created a gap in the

data when I went to help a classmate with his project. I also dropped a DO bottle before using. And, the

GPS I used deleted a waypoint, which I couldn’t recover. If I could change the experiment, I would

change the data sheet. The format I was using got complicated. I would also not use a LabQuest. I would

use manual thermometers, psychrometers, and anemometers.

Katherine LeaverDecember 10, 2012

Sources

"5.2 Dissolved Oxygen and Biochemical Oxygen Demand." United States Environmental Protection

Agency. United States Government, 06 Mar. 2012. Web. 17 Nov. 2012.

<http://water.epa.gov/type/rsl/monitoring/vms52.cfm>.

"Monthly Weather Forecast for Stafford, VA (22556) - Weather.com." Weather.com. The Weather

Channel, 18 Nov. 2012. Web. 18 Nov. 2012.

<http://www.weather.com/weather/monthly/22556>.

"Virginia Climate." Virginia Is for Lovers. 11 Apr. 2011. Web. 10 Dec. 2012.

Hayden, Bruce P., and Patrick J. Michaels. "Virginia Climate Description." Virginia Climate Description. 20

Jan. 2000. Web. 10 Dec. 2012.

Katherine LeaverDecember 10, 2012

Perlman, Howard. "Water Properties: Dissolved Oxygen." Dissolved Oxygen, from USGS Water Science

for Schools: All about Water. 31 Oct. 2012. Web. 10 Dec. 2012.