Explain the relationship of dissolved oxygen to primary productivity

Pearson - The Biology Place

explain the relationship of dissolved oxygen to primary productivity

measure primary productivity based on changes in dissolved oxygen in a . What is the relationship between oxygen production and assimilation of carbon? 3. What are the three ways that primary productivity can be measured? Highlight 6. What is the relationship between water temperature and dissolved oxygen?. dissolved oxygen (DO) in the dark bottle over time is a measure of the rate of . Explain. 3. What effect did light have on the primary productivity? Explain. 4.

A measure of oxygen production over time provides a means of calculating the amount of carbon that has been bound in organic compounds during that period of time.

Primary productivity can also be measured by determining the rate of carbon dioxide utilization or the rate of formation of organic compounds.

1. Explain the relationship of dissolved oxygen to primary productivity.? | Yahoo Answers

You should be able to make conversions between each of these with the following information: One method of measuring the production of oxygen is the light and dark bottle method. In this method, a culture of Chlorella is placed into a series of bottles which allow different amounts of light to reach the organism. Chlorella is a genus of single-celled green algae, belonging to the phylum Chlorophyta. Only respiration can occur in the bottle stored in the dark.

The decrease in dissolved oxygen DO in the dark bottle over time is a measure of the rate of respiration. Both photosynthesis and aerobic respiration can occur in the bottles exposed to light, however.

The difference between the amount of oxygen produced through photosynthesis and that consumed through aerobic respiration is the net productivity. The difference in dissolved oxygen over time between the bottles stored in the light and in the dark is a measure of the total amount of oxygen produced by photosynthesis. The total amount of oxygen produced is called the gross productivity. The measurement of the DO concentration of a body of water is often used to determine whether the biological activities requiring oxygen are occurring and is an important indicator of pollution.

The sodium sulfite Na2SO3 calibration solution is a skin and eye irritant. Plug the power supply into the left-hand side of the LabQuest. Turn the LabQuest on by pushing the oval button on the top left hand of the instrument. Connect a DO sensor and a temperature sensor to the LabQuest. If you have an older sensor that does not autoID, manually set up the sensor. A sensor set-up screen will appear showing all the available probe ports Fig.

Sensor set-up screen b. Meter mode screen b. Select the channel that the DO sensor is plugged into ex. CH1 for channel 1and tap the arrow to the side of the channel box. A list of compatible probes will appear in alphabetical order. Select to return to the Meter mode screen.

Prior to each use, the Dissolved Oxygen Probe must warm up for a period of 5—10 minutes as described below. If the probe is not warmed up properly, inaccurate readings will result. Perform the following steps to prepare the Dissolved Oxygen Probe. Gently remove the blue protective cap. Unscrew the membrane cap from the tip of the probe. Carefully thread the membrane cap back onto the electrode. Place the probe into a mL beaker containing distilled water and let it equilibrate for 10 min before calibration.

The probe must stay connected at all times to keep it warmed up. Your instructor will tell you which method to use for calibrating the DO sensor. If your instructor directs you to use the calibration stored in the experiment file, continue directly to the Procedure. Enter the values for the Slope and the Intercept.

Select OK and continue directly to the Procedure. Follow steps 5 and 6 to perform a manual calibration. The DO sensor will need to be calibrated. You must take into account the barometric pressure and ambient room temperature for the day of the calibration.

Calibrate the Dissolved Oxygen Probe. Zero-Oxygen Calibration Point c. Remove the probe from the water bath and place the tip of the probe into the Sodium Sulfite Calibration Solution. No air bubbles can be trapped below the tip of the probe or the probe will sense an inaccurate dissolved oxygen level. If the voltage does not rapidly decrease, tap the side of the bottle with the probe to dislodge the bubble.

The readings should be in the 0. Insert probe at Submerge probe an angle tip cm e.

  • 1. Explain the relationship of dissolved oxygen to primary productivity.?

Rinse the probe with distilled water and gently blot dry. Unscrew the lid of the calibration bottle provided with the probe. Do not touch the membrane or get it wet during this step. If you do not have the current air pressure, use Table 4 to estimate the air pressure at your altitude. Keep the probe in this position for about a minute. The readings should be above 2. When the voltage reading stabilizes, tap Keep.

Return the Dissolved Oxygen Probe to the distilled water beaker. Obtain a mL beaker. Fill it with ice and water. Place approximately mL of cold water and a couple small pieces of ice into a clean 1 L plastic container. Seal the container and vigorously shake the water for a period of 2 minutes. This will allow the air inside the container to dissolve into the water sample and give a maximum DO reading for each temperature.

Pour the water into a clean Styrofoam cup. Place the Temperature Probe in the Styrofoam cup as shown in Figure 5. Place the shaft of the Dissolved Oxygen Probe into the water and gently stir. Avoid hitting the edge of the cup with the probe. Monitor the dissolved oxygen readings displayed on the screen. Give the dissolved oxygen readings Figure 5 ample time to stabilize 90— seconds.

At colder temperatures the probe will require a greater amount of time to output stable readings seconds. Discard the cold water in the Styrofoam cup. Place the Dissolved Oxygen Probe back into the distilled water beaker. Obtain mL water that is at room temperature and pour it into the 1 L container.

explain the relationship of dissolved oxygen to primary productivity

Seal the container and shake the water vigorously for 2 minutes. Pour the water back into the Styrofoam cup. Repeat Steps 9 and After the room temperature data is recorded, pour the room temperature water out of the Styrofoam cup and place the Dissolved Oxygen Probe back into the distilled water beaker.

Repeat Steps 9 and 10 and record the data for the warm water sample. Keep one of the LabQuests and DO sensors operational after completing this part of the lab. For the other groups, when you are finished taking readings, select the File menu, then Quit. To turn the equipment off, press and hold the oval button on the top left of the LabQuest until the screen goes dark. If you plan to use the probes the following day, keep them attached to the LabQuest and store them with their tips submerged in a beaker of water.

Nomogram of Oxygen Saturation Use the nomogram of oxygen saturation in Figure 6 to determine the percent saturation of DO in your samples. Line up the edge of a ruler with the temperature of the water on the top scale and the DO on the bottom scale, then read the percent saturation from the middle scale. Record this information in Table 1 on your Data Sheet. Plot a best-fit line for your individual DO data.

Use this graph to determine the class mean DO. Once the class mean is determined for 3 different temperatures, record this information in Table 2 on your Data Sheet and plot these data on Graph 1 as well. Your instructor will provide 6 clean vials for the next part of the procedure. Each lab group will be given at least 1 vial and the appropriate number of screens or tinfoil for the vial. Each lab group will be responsible for obtaining data for the experimental condition assigned.

If you are taking just an initial and final DO reading, follow the directions in Step If data is to be taken over an approximately 24 hour period, skip to Step 21 and 22 for directions on how to set up the LabQuest and experimental samples. Fill a clean 2L beaker with approximately 1. The level of the culture in the bin should be enough to completely cover the sample vial when it is standing upright.

Take the first vial and submerge it completely in the Chlorella culture.

Net Primary Productivity with the Optical Dissolved Oxygen Sensor

Do this gently so as not to introduce too much air into the culture. Carefully stand the vial upright in the beaker. Check to see that there are no air bubbles clinging to the edges of the vial. If there are, tap the tube gently to remove them. Place the cap for the vial in the culture as well, removing any air bubble caught in the threads of the cap.

explain the relationship of dissolved oxygen to primary productivity

While the vial is still submerged, tighten the cap on securely. Remove the vial from the culture and check for air bubbles by gently turning the vial upside down.

LabBench Activity

Very small bubbles will not affect the overall reaction. Each group will repeat this procedure for the remaining 5 vials. After all the vials are filled, take the initial DO reading from the remaining Chlorella culture in the beaker. All the lab groups should record this value for the initial DO in both the individual column in the Respiration Table 3. Wrap the vial in screens or tinfoil as directed by your instructor. Wait for all the lab groups to finish assembling the vials before moving on to Step It is possible to record dissolved oxygen data for all 6 different reaction conditions over a hour period.

We are taking a sample of pond water with algae and then modeling different depths in the pond by using screening to block out successive amounts of light. Why do we take an initial reading of dissolved oxygen? What purpose does this serve in the experiment? Why does the animation show oxygen being diffusing out of the freshwater plants? What does this signify? Why does the animation show oxygen diffusing into the freshwater plants?

Why does the animation show oxygen diffusing both into and out of the freshwater plants?


Remember that plants producers perform both photosynthesis and respiration. To measure the amount of respiration that is happening in the bottle, we measure the amount of dissolved oxygen in the initial sample and then the amount of oxygen in the bottle kept in the dark.

I have added some possible measurements to help. Explain why this calculation works. Remember gross productivity is the total amount of sugars and oxygen produced by the plants in an ecosystem. The equation is correct, but it is a short cut, so it makes it more difficult to understand.

So follow me with the illustrations and the possible measurements below. So the illustration shows us there was 10mg increase in dissolved oxygen in the jar as a result of photosynthesis in the last 24 hours and there was 5mg decrease in dissolved oxygen in the jar as a result of respiration in the last 24 hours.

So the gross productivity the full photosynthetic production in this ecosystem of the algae in the bottle is the 5mg dissolved oxygen lost to respiration added back to the 10 mg dissolved oxygen accumulated in the bottle kept in the light. So what the algae really produced in the bottle was a total of 15mg dissolved oxygen, it just lost 5mg to respiration.

explain the relationship of dissolved oxygen to primary productivity

And remember, the oxygen is an indirect measurement of the sugars produced in photosynthesis and lost in respiration. Now, in your own words, explain why this calculation works. Remember net productivity is the amount of sugars and dissolved oxygen produced by the plants in an ecosystem once you subtract out what the producers have consumed in respiration. Print out the completed calculation table from Sample Problem page of the LabBench Web site, fill in your predictions on the graph as well, and attach it to this lab to show me that you have completed it.