Monitoring Dissolved Oxygen Levels In Wolf Run Creek

[Modified Into Single PPT]By: Brandon Bell

Purpose To measure dissolved oxygen levels in Wolf

Run Creek during the course of a day, and at the same time of day for two weeks to understand the health of the creek and it’s ecosystem.

HypothesisBased on the background reading I have done and observation of my site beforehand, I think the Dissolved Oxygen levels in the creek will remain fairly consistent during the two weeks I test, affected a few days by the weather, temperature and water depth. I also think the levels will increase and decrease with the progression of the day.

Materials• LaMotte Dissolved Oxygen Kit (Model EDO)• LaMotte Wide Range pH Test Kit (Model P-5085)• Thermometer• Pipettes• Plastic Waste Container • Data Table• Pencil/Pen• Ruler• Clipboard• Gloves• Safety Glasses• Backyard rain gauge

Procedures-Choose an open, easy to access spot on the stream you are measuring. Use this same spot for all measurements.-Measure the following every day at 4:30 PM for two weeks, for the two week study. For the day studies, measure at 8 am, 2

pm, and 8 pm.-Measure Water Temperature by submerging the thermometer in the stream.-Record the Water Temperature on the table.-Measure Depth using a ruler. Place the ruler in the chosen location in the stream.-Record the depth on the table.-Measure pH using the LaMotte Wide Range pH Test Kit Model P-5085, Following the manufacturers instructions, as follows:

Rinse test tube with sample water. Fill to 5 mL line with sample water. While holding dropper bottle or pipet vertically, add 10 drops indicator solution. Cap and invert several times to mix Insert test tube into Octet Comparator. Match sample color to a color standard. Record as pH.

-Record pH on table.-Measure Dissolved Oxygen using the LaMotte Dissolved Oxygen Kit Model EDO, Following the instructions, as follows:

Remove the cap and immerse the DO [Dissolved Oxygen] bottle beneath the river’s surface. Use gloves to avoid contact with the river. Allow the water to overflow for two to three minutes. (This will ensure the elimination of air bubbles) Make sure no air bubbles are present when you take the bottle from the river. Add 8 drops Manganous Sulfate Solution and 8 drops of Alkaline Potassium Iodine Azide. Cap the bottle, making sure no air is trapped inside, and invert repeatedly to fully mix. Be very careful not to splash the chemical-laden water. Wash your hands if

you contact this water. If oxygen is present in the sample, a brownish-orange precipitate will form (floc). The first two reagents “fix” the available oxygen [Meaning time is no longer of the essence]

Allow the sample to stand until the precipitate settles halfway. When the top half of the sample turns clear, shake again, and wait for the same changes. Add 8 drops of Sulfuric Acid 1:1 Reagent. Cap and invert repeatedly until the reagent and the precipitate have dissolved. A clear yellow to brown-orange color will

develop depending on the oxygen content of the sample. Fill the titration tube to the 20 ml line with the “fixed” sample and cap. Fill the Direct Reading Titrator with Sodium Thiosulfate 0.025N Reagent. Insert the Titrator into the center hole of the titration tube cap. While gently swirling the

tube, slowly press the plunger to titrate until the yellow-brown color is reduced to a very faint yellow. Remove the cap and Titrator. Be careful not to disturb the Titrator plunger, as the titration begun in step 8 will continue in step 11. Add 8 drops of Starch Indicator

Solution. The sample should turn blue. Replace the cap and Titrator. Continue titrating until the sample changes from blue to a colorless [clear] solution. Read the test result where the plunger tip meets

the scale. Record as mg/L (ppm) dissolved oxygen

-Record the Dissolved Oxygen in ppm on the table.-Measure 24 hour rain total with a standard rain gauge.-Record notes such as current weather conditions, time, date and any other notable event or occurrence (such as added

pollution)

-Use Tap Water as Control, measure with above processes (also as shown in kits)

Trial 1- Aug 9th, 2009

Trial 2- Aug 15, 2009

Trial 3- Aug 22, 2009

Daily Changes- 4:30 Each Day Date DO pH H20 Temp Air Temp 24 Hr Rain Weather Depth

8-10-09 8.3 7.75 25 - 0 - -

8-11 8.7 7.75 24 27 1.5 12.2

8-12 8.4 7.75 23 24 1.0 - 13

8-13 9.0 7.75 25 29 0 12.5

8-14 10.0 8.0 25 29 0 11.0

8-15 10.8 8.25 26 30 0 8.5

8-16 10.0 8.25 26 29 0 7.0

8-17 10.8 8.5 27 31 0 8.0

8-18 8.8 7.5 25 28 .3 11.0

8-19 7.8 8.0 26 28 0 9.0

8-20 9.5 7.75 25 27 .3 9.5

8-21 8.6 7.75 23 26 1.2 15.5

8-22 8.8 7.75 21 24 0 13.5

ppm ⁰C ⁰C inches @ 4:30 cm

Time Date Trial DO (ppm) pH Water Temp (⁰C)

8:00 am 8-9 1 7.6 7.75 21

2:00 pm 8.0 8.0 24

4:30 pm - - -

8:00 pm 7.6 7.75 23

8:00 am 8-15 2 7.4 7.75 21

2:00 pm 10.6 8.5 24

4:30 pm 10.8 8.25 26

8:00 pm 7.8 7.75 24

8:00 am 8-22 3 7.5 7.75 20

2:00 pm 8.2 7.5 20

4:30 pm 8.8 7.75 21

8:00 pm 7.6 7.75 24

7:00 am 2-2 Control 12.4 7 16

4:30 pm 12 7 14

8:00 pm 12.4 7 13

Measurements Taken Throughout The Day

Daily MeasurementsTaken at 4:30 each day

Background Information-Wolf Run Creek runs along the western part of Lexington and through my neighborhood, flowing into the Town Branch of South Elkhorn Creek. It has been noted for its extremely high e-coli levels, in part to sewer overflows during rainstorms. -Dissolved Oxygen is one of the most important indicators for the health of a body of water. All life in the stream needs oxygen to survive. If levels become too low, the ecological system of the stream is threatened.-Oxygen is dissolved in the water from diffusion from the air. Churning water also becomes aerated. Also, photosynthesis from aquatic plants releases oxygen into the water.-Factors that affect dissolved oxygen levels:

Water Temperature-Oxygen dissolves easier in colder water

Water Movement- Moving water will have more oxygenWater Depth-Shallow water tends have more oxygen because it

is more likely to be moving, and plant life will receive more sunlight for photosynthesis.

Plant Life- Plants such as algae in the water will photosynthesize, releasing oxygen into the waterOrganic Material- Decomposers use oxygen.Pollutants- Ex.(Fertilizer to Algae to Dead Algae to Decomposers)

Dissolved Oxygen levels below 4 are considered unlivable for most aquatic animals

Discussion of Results

On the three days that I measured throughout the day, I observed that the DO level was low in the morning, that it increased by midday, and fell in the evening.During the two week observation the DO level increased when the weather was sunny and dry, and decreased when it was cloudy and rainy. Water temperature and air temperature parallel each other. Also, depth increased during and after rainy weather.

ConclusionThe major factor affecting changes in levels of dissolved oxygen in Wolf Run Creek that I observed was photosynthesis from algae. This would explain the regular pattern of the increase and decrease of DO levels from morning to evening during measurements through the day. This would also explain the relationship of high DO levels on days that are sunny. For reference, see the DO Level measurements and weather observations in the Table of Observations for the days 8-14 through 8-17. This could also explain how depth and temperature have a smaller effect than sunlight and excess nutrients in Wolf Run Creek.

Possible Future Work- Measure Dissolved Oxygen levels during different seasons

to determine if there is variation from the daily pattern found during summer with the varying conditions of the seasons.

- Repeat Experiment before and after rain storms to investigate the effects of runoff and possible sewage overflow.

Thanks To….. -Ken Cooke, Friends of Wolf Run Creek [For Providing Training with Various

Kits.]-Kentucky River Watershed Watch [For use of kits.]- The Port Royal Neighborhood Association [For encouraging the initiative.]