Dissolved Oxygen Experiment

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Questions and Answers

What is the independent variable in the measurement of dissolved oxygen?

Light intensity

Dissolved oxygen

Primary productivity

Temperature (correct)

What is the control sample in the measurement of dissolved oxygen?

Sample at 4°C

Sample at 22°C

Sample at 32°C

Sample at room temperature (correct)

What is the dependent variable in the measurement of primary productivity?

Respiration rate

Gross productivity

Primary productivity (correct)

Light intensity

How does the percent saturation of oxygen change as temperature decreases?

It decreases Signup and view all the answers

What is the respiration rate of the sample?

4.6 mg O2/L Signup and view all the answers

What is the purpose of the 'dark' sample in the measurement of primary productivity?

To act as a control sample Signup and view all the answers

What method is used to measure dissolved oxygen in the experiment?

Winkler method Signup and view all the answers

How does dissolved oxygen change as temperature increases?

It decreases Signup and view all the answers

What is the purpose of using a nomograph in the measurement of dissolved oxygen?

To determine the percent saturation of oxygen in each sample Signup and view all the answers

What is the effect of temperature on respiration in the measurement of dissolved oxygen?

Lower temperatures increase oxygen consumption Signup and view all the answers

What is the purpose of using different light intensities in the measurement of primary productivity?

To measure the effect of light intensity on photosynthesis Signup and view all the answers

What is the Winkler method used for in the measurement of dissolved oxygen?

To determine the amount of dissolved oxygen in the samples Signup and view all the answers

How is the net productivity calculated in the measurement of primary productivity?

By subtracting the initial dissolved oxygen from the final dissolved oxygen Signup and view all the answers

What is the purpose of collecting a baseline dissolved oxygen reading from the 25˚C sample?

To serve as a reference for calculating net and gross productivity Signup and view all the answers

What is the primary factor that affects the dissolved oxygen levels in aquatic environments?

Constant replenishment from the atmosphere and photosynthesis Signup and view all the answers

What method was used to determine the dissolved oxygen in the water samples?

Winkler Method Signup and view all the answers

How does an increase in temperature affect the dissolved oxygen in an aquatic sample?

It decreases the dissolved oxygen Signup and view all the answers

What is the purpose of wrapping one sample in foil to simulate a dark sample?

To determine the respiration rate Signup and view all the answers

How does light intensity affect primary productivity in an aquatic sample?

It has a positive effect on primary productivity Signup and view all the answers

What is the percentage of oxygen in terrestrial environments compared to aquatic environments?

95% more oxygen Signup and view all the answers

Why are oxygen levels in aquatic environments vulnerable to even the slightest change?

Because they are limited in aquatic environments Signup and view all the answers

What is the purpose of calculating the net productivity in an aquatic sample?

To determine the primary productivity Signup and view all the answers

Study Notes

Measurement of Dissolved Oxygen

The purpose of the experiment was to show how temperature affects the amount of dissolved oxygen in an aquatic sample.
Water samples were collected at different temperatures (4°C, 25°C, and 30°C) and the dissolved oxygen was determined using the Winkler Method.
The percent saturation of oxygen was calculated using a nomograph.
Results indicated that as the temperature increased, the dissolved oxygen in the sample decreased.

Importance of Dissolved Oxygen

Dissolved oxygen levels are crucial in determining the quality of an aquatic environment.
Dissolved oxygen is necessary for the metabolic processes of organisms found in water.
Terrestrial environments hold over 95% more oxygen than aquatic environments.
Oxygen levels in aquatic environments are very vulnerable to even the slightest change.

Measurement of Primary Productivity

The purpose of the experiment was to demonstrate how light intensity influences primary productivity in an aquatic sample.
Water samples were collected and wrapped to simulate different light intensities (dark, 100% light, 65% light, 25% light, 10% light, and 2% light).
The dissolved oxygen of the samples was determined using the Winkler Method.
Results indicated that the greater the light, the greater the primary productivity.

Procedure and Materials

Materials used included BOD bottles, water sample, thermometer, chemicals for the Winkler method, titration vial, syringe, starch, and a nomograph.
Procedures involved collecting water samples, fixing and testing for dissolved oxygen, and calculating percent saturation of oxygen.

Data and Observations

Table 1 shows the results of the dissolved oxygen measurement experiment.
Graphs 1 and 2 display the relationships between temperature and dissolved oxygen.
Table 2 shows the results of the primary productivity experiment.
Graph 3 displays the relationship between light intensity and primary productivity.

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Description

Measuring dissolved oxygen in aquatic samples at different temperatures to analyze the effect of temperature on oxygen levels. Results show a decrease in oxygen with increasing temperature.