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.