Holly Monroe (UR)- 5 Days Later!

Last week in the midst of all of the craziness I managed to collect samples for the Biochemical Oxygen Demand test. Even though the wind blew away most of my materials I still managed to have some dissolved oxygen tablets left to finish the test 5 days later. For this weeks discussion I decided to write my ideas and show my results. "Biochemical Oxygen Demand (BOD) is a measure of the quantity of dissolved oxygen used by bacteria as they break down organic wastes. In slow moving and polluted rivers, much of the available dissolved oxygen is consumed by bacteria, robbing other aquatic organisms of the dissolved oxygen needed to live" (Estuary and Marine Monitoring Kit). I preformed one test at Spruce Creek and one test at the Dunlawton Bridge. Below is the procedure for preforming the BOD test;

BOD Procedure:

1. Submerge a test tube into the water. carefully remove and cap the sample.
2. Wrap the sample tube with aluminum foil and keep it stored in a dark area at room temperature for 5 days.
3. Unwrap the sample tube and insert two Dissolved Oxygen TesTabs.
4. Cap the Sample making sure there are no bubbles present. invert the tube until the tablets have disintegrated.
5. After waiting 5 minutes compare the sample to the color chart for BOD.
6. "The difference in the dissolved oxygen level between the uncovered tube and the cover tube is the biochemical oxygen demand" (Estuary and Marine Monitoring Kit).

Wrapped Samples

Spruce Creek 

Dunlawton Bridge

As seen in these 3 pictures no dissolved oxygen testabs have been inserted. Therefore, both locations are demonstrating 0ppm. Now lets take a look at how they appear with the 2 dissolved oxygen testabs inserted.

Spruce Creek

I snapped a shot of myself preforming step 4 in the procedure for Spruce Creek. We can already see some change beginning to take place. I did not take a picture of Dunlawton Bridge, but the test tube remained pretty clear for most of the inverting process. However, after 5 minutes both samples appeared to be more developed, as seen below.

Spruce Creak Result

Dunlawton Bridge Result

Results Side by Side

Spruce Creek has more dissolved oxygen used by bacteria than the Dunlawton Bridge (8ppm and 4ppm, respectively). As previously stated, this means that Spruce Creek is either a slow moving body of water or polluted. Causing the bacteria to consume the available dissolved oxygen, making it more difficult for other marine organisms to survive.

Map Between Sites

I find this a little bit surprising. I hypothesized that the results between the two sites would be roughly the same. We can also see in the map photo how close the two sites are and the connecting water ways. I will have to look more into the possible dissolved oxygen impacts in the Spruce Creek area.