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.

0 5 10 15 20 25

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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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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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DO

Temperature (°C) and Dissolved Oxygen (mg/L O2)

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th (

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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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Temperature (°C) and Dissolved Oxygen (mg/L O2)

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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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Temperature (°C) and Dissolved Oxygen (mg/L O2)

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C2Mile 6

R1 Seven Points MarinaMile 10.5

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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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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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Temperature (°C) and Dissolved Oxygen (mg/L O2)

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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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Temperature (°C) and Dissolved Oxygen (mg/L O2)

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th (

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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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th (

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Temperature (°C) and Dissolved Oxygen (mg/L O2)

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R4 Lake Raystown ResortMile 21.5

July 13, 1998

I5 Shy Beaver CreekMile 21.8

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Temperature (°C) and Dissolved Oxygen (mg/L O2)

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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

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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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Seston Profile at Mile 6

Concentration of Seston (mg/mL)

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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