Study of Oxygen Depletion and Negative Heterograde Formation in Raystown Lake, PA Sharon Simpson...
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Transcript of Study of Oxygen Depletion and Negative Heterograde Formation in Raystown Lake, PA Sharon Simpson...
Study of Oxygen Depletion andNegative Heterograde Formation
in Raystown Lake, PA
Sharon Simpson
Juniata College
Huntingdon, Pennsylvania
Advisor - Chuck Yohn
Raystown Lake
• Reservoir created by Raystown Dam
• Located in Huntingdon and Bedford Counties
• 27 miles long, 118 miles of shoreline
• 8,300 acre surface area
Spring Oxygen and Temperature Profile
•Lake mixes completely in the spring.
•Mixing oxygenates the lower depths of the lake.
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DO
Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Dep
th (
m)
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Temp
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DO
Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Dep
th (m
)
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Temp
Typical Oxygen and Temperature Stratification
•Lake stratifies in summer
•No oxygen inputs to the lower depths of the lake.
•Respiration consumes oxygen.
•Oxygen profile measures the health of the lake.
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Temp
Typical Oxygen and Temperature Stratification
Metalimnion
Epilimnion
Hypolimnion
The Two Issues
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Negative heterogradeAnoxia
Research Questions
• What is the extent of the oxygen depletion?
• Where are the inputs of the oxygen depleting materials?
• What is the extent of the negative heterograde?
• Why is the negative heterograde forming?
Oxygen Depletion
Hypotheses
• Input of oxygen demanding materials
• From where?
1. Recreational use
2. Sediment sliding
3. Stream input
Research Design• Where are the low DO values?• Where is the highest rate of depletion?• Sampling sites
– 5 Main channel sites (sediment sliding)– 4 Sites near marinas and campgrounds (recreational sites)– 6 Sites in bays of tributaries (stream input sites)
• Sampling– Once a week, May to November– Temperature, DO, and % saturation with YSI DO meter– Readings every 1 m until the bottom or 29 m– Data collection completed within 1-3 day time span
Sampling Sites
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Dep
th (
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Temp
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DO
Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Temp
C1 Raystown DamMile 0
July 13, 1998
I1 Snyder’s RunMile 2
July 13, 1998
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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th (
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Temp
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Temp
C2Mile 6
R1 Seven Points MarinaMile 10.5
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Temp
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DO
Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Dep
th (
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Temp
R2 Seven Points MarinaMile 10.7
July 13, 1998
C3Mile 13
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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th (
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Temp
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DO
Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Dep
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Temp
I2 James CreekMile 14
July 13, 1998
I3 Trough CreekMile 14.8
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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th (
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Temp
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Dep
th (
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Temp
C4Mile 18
July 13, 1998
C5 Entriken BridgeMile 20
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Temp
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Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Temp
R4 Lake Raystown ResortMile 21.5
July 13, 1998
I5 Shy Beaver CreekMile 21.8
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DO
Temperature (°C) and Dissolved Oxygen (mg/L O2)
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Dep
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Temp
I6 Juniata RiverMile 24
July 13, 1998
Rate of Oxygen Depletion vs Distance from Dam
Distance from Dam (miles)
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Rat
e of
Dep
letio
n (a
s sl
ope)
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
0.05
r = -0.93, p <0.00
Concentration of Nitrates vs Distance from Dam
Distance from Dam (miles)
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Nitr
ates
(m
g/L
NO
3- -N
)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
r = 0.88, p < 0.00
•Nitrates used as an indicator of nutrient concentrations.
•High nutrient concentration causes oxygen depletion.
Conclusions
• The major source of oxygen depleting materials to Raystown Lake is at the input of the Juniata River.
• There was no difference in oxygen depletion among the three groups of sites.
• The oxygen depletion pattern is not uncommon for reservoirs (Cole 1990).
Negative HeterogradeMetalimnetic oxygen minimum
Possible causes studied
1. Flow pattern of river into reservoir
2. Decomposition of suspended organic matter in the metalimnion
Conductivity a marker of inflow depth
MM 24MM 27
Conductivity Profiles
Conductivity (mhos)
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Dep
th (
m)
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MM 18
Metalimnion
EpilimnionHigh conductivity values indicate depth of river inflow.
Expected Seston Valuesif hypothesis is not true
Seston Profile at Mile 6
Concentration of Seston (mg/mL)
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Dep
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Seston Profile at Mile 6
Concentration of Seston (mg/mL)
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Dep
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Depth of lowest dissolved oxygen concentration
Conclusions
• The metalimnetic oxygen minimum is caused by a collection of organic material in the metalimnion.
• The presence of a metalimnetic oxygen minimum is not uncommon in reservoirs (Cole 1990).
Acknowledgments• Raystown Field Station - Chuck Yohn
• Pfizer Corporation
• Emily Sowell, Huntingdon High School
• AJ Maurer, Juniata College
• Dr. Paula Martin, Env. Sci and Studies Dep. Juniata College
• Ken Culp, U.S. Army Corps of Engineers
• Dr. I. David Reingold, Chemistry Department, Juniata College
• Dr. Elaine Keithan, Biology Department, Bucknell University