Dissolved Oxygen, Turbidity, and Gross Productivity

Presented By:Jonathan Williams

Kerian CoxBen Beha

DeAntae CooperKenderick CraigT’nachus KellyByron Williams

• How does the level of dissolved oxygen, turbidity, and pH affect the gross productivity of Lake Munson?

Research Problem

• With all the sewage once in the lake, we questioned its efficiency in sustaining life.• The purpose of our experiment was to determine the gross productivity of the lake after its restoration.

Scientific Approach

Investigate factors and properties of the water that would determine and indicate the Gross Productivity of the lake.

In this investigation, the specific variables were:

• Dissolved Oxygen levels

• Turbidity and Transparency

• pH levels

Hypothesis

• We believe that the level of dissolved oxygen will be low due to high levels of turbidity in the lake. This would lead to lower levels of gross productivity because the small amount of light penetrating the water surface of the lake would hinder the photosynthesis process, which produces oxygen. The oxygen in the lake directly affects the ability of the living organisms in the lake to survive and thrive.

Consequently, we believe that if the water at Lake Munson were to have a low turbidity level then the dissolved oxygen level will be high causing more photosynthesis to occur in the lake. As a result the overall gross productivity of the lake would increase. The pH level shows the degree of acidity of the water which affects the ability of organisms to survive, and thus the gross productivity.

Dissolved Oxygen

Definition• Dissolved Oxygen: The amount of oxygen disassociated, or

dissolved, in a given body of water at any time.

• The level of dissolved oxygen within a body of water will affect how much life is present within that ecosystem.

• It influences distribution of organisms; low levels may indicate an excess of decaying organic matter.

• Closely related to light as photosynthesis;produces oxygen.• We performed Dissolved Oxygen Test in three different areas of the lake.

What Happened

• Numerous Dissolved Oxygen tests taken around the area.

• Two different tests/methods: the manual and the DO meter.

• This gave us some certainty in our level of accuracy in our values.

• The dissolved oxygen meter was a way to really see how accurate the manual test are compared to the digital devices.

Presentation of Data

The Correlation of Turbidity, Dissolved Oxygen,

and pH of the three sites

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-5

0

5

10

15

Turbidity (JTU) DissolvedOxygen Manuel

(ppm)

pH Dissolvedoxygen meter

Site1

Site2

Site3

JTU: Jackson Turbidity Unit

Ppm: Parts per million

Turbidity/ Transparency

Definition• Turbidity: Cloudiness; Inability to transmit light. It is also the

amount of organisms that are in the water that prevent light from being able to go through to the bottom.

• Influences the depth of light penetration and subsequently photosynthesis.

• Transparency: The degree to which water allows light to penetrate.

What Happened

• We used a turbidity meter and the secci disc.

• The secci disc was again our manual test with the turbidity meter as our accuracy.

• The turbidity meter allowed us to see how accurate the manual test are compared to the digital devices.

Presentation of Data

The Correlation of Turbidity, Dissolved Oxygen,

and pH of the three sites

-10

-5

0

5

10

15

Turbidity (JTU) DissolvedOxygen Manuel

(ppm)

pH Dissolvedoxygen meter

Site1

Site2

Site3

JTU: Jackson Turbidity Unit

Ppm: Parts per million

pH and Gross Productivity

Definition• pH: (power of Hydrogen): Determines if a solution is acidic or

basic. The degree of acidity inversely impacts the ability of organisms to survive.

•

• Gross Productivity: The energy captured by a trophic level.

• Can be measured by Light Dark Bottle Method

• Productivity is a measure of the rate at which energy is accumulated.

• We performed a Dark Light Bottle test as wellas a pH test on this area of the project.

What Happened

Dark Light Bottle • This test assumes that the conditions (like the rates of respiration) in

the dark bottle are the same as in the light bottle. Not a proven certainty

• Only measures a portion of the respiration and productivity of the total community; attached algae and macrophytes, benthos, and nekton are ignored.

• Also the test requires at least 2 hours of time, so it took planning to retrieve each of the sets in the same amount of time-to control the experiment.

• The turbidity meter was used again for the pH test because of its multi function capability. It allowed us to maximize time.

Presentation of Data

The correlation of Respiration and Gross Productivity

for the three sites

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

Respiration Gross Productivity

Site1

Site2

Site3

Conclusion

• The water of Lake Munson was not low in Gross productivity as originally stated in the hypothesis. We thought that the water would be more turbid and have low levels of dissolved oxygen. The water was, in reality, not very turbid . Also, we thought the pH would be more acidic. The water was still notably acidic.  

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