Team+4

Team 4: Jen Molly William Kristen

Jennifer Siranosian, William Woods, Molly Travers, Kristen Towey May 5, 2012 Mrs. McLoughlin A-Block

//Algae Relations With Dissolved Oxygen//


 * Part 1: The Concentration of Dissolved Oxygen In Algal Culture at 10**°**, 20**° **and 30**°

__** Purpose: **__ To investigate the effect of temperature on dissolved oxygen concentration in algal culture.

__** Hypothesis: **__ I f the algal culture holds more dissolved oxygen at colder temperatures, then the colder algal solutions will have a higher concentration of dissolved oxygen.

__** Materials: **__ - 3 BOD bottles - manganous sulfate - starch indicator - sulfamic acid and measuring spoon - alkaline potassium iodide azide - sodium thiosulfate - 2 titration syringes - 2 20-mL sampling vials - algae culture


 * __Methods/Procedure:__** Please reference "AP Biology Laboratory 12: Dissolved Oxygen and Aquatic Primary Productivity" for Activity A procedure.

__**Data:**__

__**Table 1: Temperature and Dissolved Oxygen**__
 * = Temperature ||= Group DO ||= Group %Saturation ||
 * = 10° ||= 10 ppm ||= 90% ||
 * = 20° ||= 8 ppm ||= 90% ||
 * = 30° ||= 6.5 ppm ||= 85% ||

__**Analysis:**__ After titration, the 10° algal culture had used 1 mL of sodium thiosulfate. Each .1 mL of sodium thiosulfate used in the titration equals1 ppm DO, or 1 mg DO per L of water, so the 10° algal culture had the highest concentration of dissolved oxygen at 10 ppm. Using "Figure 1: Nomograph of Oxygen Saturation," it was found that the 10 ppm in 10° algal culture is 90% saturation. At 20°, the algal culture used .8 mL sodium thiosulfate, had 8 ppm DO, and 90% saturation. At 30°, the algal culture used .65 mL sodium thiosulfate, had 6.5 ppm DO, and 85% saturation.

__**Conclusion:**__ Since the colder algal solutions had a higher concentration of dissolved oxygen, then the algal cultures hold more dissolved oxygen at colder temperatures.


 * Part 2: The Effect of Light on Dissolved Oxygen Content In //Chorella// Algae Culture**

__**Purpose:**__ To investigate the effect of different light intensities on oxygen production of //Chorella// algae.

__**Hypothesis:**__ If the algae culture is exposed to more light, then photosynthesis will occur at a higher rate and more oxygen will be produced, increasing the concentration of dissolved oxygen in the solution.

__**Materials:**__ all of the above, and - 7 BOD bottles - 17 fiberglass screens - aluminum foil


 * __Methods/Procedure:__** Please reference "AP Biology Laboratory 12: Dissolved Oxygen and Aquatic Primary Productivity" for Activity B procedure.


 * __ Data: __**

||= || ||=  || In the data collected, it can be seen that as screens were added, the gross productivity decreased, directly affecting net productivity. The recorded baseline (initial) dissolved oxygen is 11 ppm, and the dark is 0ppm. Recorded with no screens, the net productivity is 12 ppm, as the gross productivity is 23 ppm. This shows that the total dissolved oxygen is 23 ppm. Recorded with 1 screen, the net productivity is 4 ppm, as the gross productivity is 15 ppm. This shows that the total dissolved oxgen is 15 ppm. For variables consisting of 3 screens, 5 screens, and 8 screens the results are the same, as the net productivity is -11 ppm, and the gross productivity is 0 ppm. This also means that the dissolved oxygen is 0 ppm for the three previous variables.
 * __Table 2: Group Productivity Data__**
 * = Bottle ||= DO ||= Net Productivity ||= Gross Productivity ||
 * = Baseline (Initial) ||= 11 ppm ||=
 * = Dark ||= 0 ppm ||=
 * = Light (0 screens) ||= 23 ppm ||= 12 ppm ||= 23 ppm ||
 * = 1 screen ||= 15 ppm ||= 4 ppm ||= 15 ppm ||
 * = 3 screens ||= 0 ppm ||= -11 ppm ||= 0 ppm ||
 * = 5 screens ||= 0 ppm ||= -11 ppm ||= 0 ppm ||
 * = 8 screens ||= 0 ppm ||= -11 ppm ||= 0 ppm ||
 * __Analysis:__**

__**Conclusion:**__ Since the algae in certain tests where light was exposed created more dissolved oxygen, then photosynthesis occurred at a higher rate when exposed to more light, making more oxygen, increasing the concentration of dissolved oxygen in the solution.