Transcript Monitoring Dissolved Oxygen Levels In Wolf Run Creek

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.
Hypothesis
Based 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
-Use Tap Water as Control, measure with above processes (also as shown in kits)
-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)
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
8-12
8.4
7.75
23
24
1.0
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
⁰C
⁰C
inches
ppm
12.2
-
@ 4:30
13
cm
Measurements Taken Throughout The Day
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
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
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
12.4
7
16
4:30 pm
12
7
14
8:00 pm
12.4
7
13
8:00 am
8:00 am
7:00 am
8-15
8-22
2-2
2
3
Control
Daily Measurements
Taken 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 oxygen
Water 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 water
Organic 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.
Conclusion
The 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.]