Anoxic and Oxic Release of P from Sediments in Minnesota Lakes · 2015-04-17 · Lake TMDL 2 years continuous flow and water quality data Average inflow to Ann Lake was 49 µg/L TP

Anoxic and Oxic Release of P from Sediments in Minnesota

Lakes

Joe Bischoff Jeff Strom Wenck Associates, Inc.

Bill James University of Wisconsin-Stout

Presentation Objectives

Background on Internal P Release in Lakes

Sediment P sources

Release mechanisms

Shallow versus deep lakes

Minnesota Lakes P Release

Release rate methods

Shallow and Deep Lakes

Anoxic and oxic P release

TMDL Modeling

Estimating internal loads

What is a Total Maximum Daily Load (TMDL)?

The maximum amount of a pollutant that a water body can receive and still meet water quality standards

For lakes, focus is on the phosphorus budget External sources

Internal P recycling

Atmospheric deposition

MOSWLALALCTMDL

Drainage Areas47%

West Ann Lake2%

Atmosphere2%

Internal Load49%

Ann Lake P Budget

Sediment P Release

Sondergaard et al. 2001

Variable Extractant Recycling Potential

Loosely-bound P 1 M Ammonium Chloride Biologically labile; recycled via eH and pH reactions and

equilibrium processes

Iron-bound P 0.11 M Sodium Bicarbonate-dithionate Biologically labile; recycled via eH and pH reactions and

equilibrium processes

Labile organic P Persulfate digestion of the NaOH extraction Biologically labile; recycled via bacterial mineralization of organic

P and mobilization of polyphosphates stored in cells

Aluminum-bound P 0.1 N Sodium Hydroxide Biologically refractory

Calcium-bound P 0.5 N Hydrochloric Acid Biologically refractory

Refractory organic P Determined by subtraction of other forms

from total P Biologically refractory

Redox-sensitive P

Sediment Phosphorus Fractions

Generalized Lake Ecosystem

(Summertime Average Conditions)

Diagram not to scale

Epilimnion (Mixed Layer) warm, light water

Hypolimnion (cool, heavy water)

Thermocline (prevents mixing)

Metalimnion

0-4 meters

4-17 meters

Deep Lake Shallow Lake

Deep Lake Anoxia June July August September

Internal Loading in Deep Lakes

Internal Nutrient Cycles in Shallow Lakes

Complex oxygen cycles in shallow lakes

Increased sediment area

Shallowness makes phosphorus release readily available for algal production

Increased interaction with photic zone

Readily mixed due to lack of temperature stratification

Internal loading in clear water, submersed vegetation dominated shallow lakes poorly understood

Bottom and Surface Dissolved Phosphorous

0.0000.0100.0200.0300.0400.0500.0600.0700.080

1-May 31-May 30-Jun 30-Jul 29-Aug 28-Sep

Date

DP

(u

g/L

)

Bottom DP (mg/l)Surface DP (mg/l)

Why Laboratory Experiments?

• Controlled conditions – Temperature

– Dissolved oxygen and redox

– pH (primarily for P release under oxic conditions)

– Manipulations

• Insufficient lake data to build a P budget • Lack good watershed data

• No hypolimnetic monitoring

• Rapid results from lab estimates

• Questions about the results of a mass balance or modeling effort

Sediment Core Collection

• Upper 10 cm transferred to an incubation sleeve

• Preconditioned filtered lake water slowly siphoned onto the sediment

Core Processing

• Aerobic versus anaerobic conditions – Gas air stones with a nominal pore

size

– Gas flow rate control

– Uniformly mixes overlying water column

– Creates a diffusive boundary layer

– Oxic-anoxic conditions created by gentle purging with air or nitrogen gas

• Incubated under “summer” temperature conditions

• Temperature-controlled environmental chambers

Diffusive Phosphorus Flux

Anoxic P Release Upper Lunsten

Anoxic P Release Rate

0

0.1

0.2

0.3

0.4

0.5

0 1 2 3 4 5 6 7 8

Days

Ph

os

ph

oru

s (

mg

)

Upper Lunsten


0

1

2

0 1 2 3 4 5 6 7 8

Days

Ph

os

ph

oru

s (

mg

/L)

Lower Lunsten


0

0.1

0.2

0 5 10 15 20

Days

Ph

os

ph

oru

s (

mg

)

Lower Lunsten


0

0.1

0.2

0.3

0.4

0.5

0 5 10 15 20

DaysP

ho

sp

ho

rus

(m

g/L

)

East Auburn


0

0.05

0.1

0.15

0.2

0 1 2 3 4 5 6 7 8

Days

Ph

os

ph

oru

s (

mg

)

East Auburn


0

0.1

0.2

0.3

0.4

0.5

0 1 2 3 4 5 6 7 8

Days

Ph

os

ph

oru

s (

mg

/L)

Oxic Sediment P Release

Upper Twin


0

0.1

0.2

0.3

0 2 4 6 8 10

Days

P M

as

s,

mg

Meadow


0

0.1

0.2

0.3

0 2 4 6 8 10

Days

P M

as

s,

mg

Pike


0

0.1

0.2

0.3

0 2 4 6 8 10

Days

P M

as

s,

mg

Upper Twin

Oxic P Release Rate

0

0.02

0.04

0.06

0.08

0.1

0 2 4 6 8 10

Days

P M

as

s,

mg

Meadow

Oxic P Release Rate

0

0.1

0.2

0.3

0 2 4 6 8 10

Days

P M

as

s,

mg

Pike

Oxic P Release Rate

0

0.1

0.2

0.3

0 2 4 6 8 10

Days

P M

as

s,

mg0

0.01

0.02

0.03

0

0.05

0.10

0.15

0 10 20 30

Days

Pho

spho

rus

(mg)

(mg/

L)

Parley Lake

Oxic P Release Rate

Oxic P Release Marsh

Oxic P Release Rate

0

0.02

0.04

0.06

0.08

0.1

0 5 10 15 20 25 30 35

Days

Ph

os

ph

oru

s (

mg

)

Mud

Oxic P Release Rate

0

0.1

0.2

0 5 10 15 20 25 30 35

Days

Ph

os

ph

oru

s (

mg

)

Wasserman

Oxic P Release Rate

0

0.01

0.02

0.03

0.04

0.05

0 5 10 15 20 25 30 35

Days

Ph

os

ph

oru

s (

mg

)

Marsh

Oxic P Release Rate

0

0.02

0.04

0.06

0.08

0.1

0 5 10 15 20 25 30 35

Days

Ph

os

ph

oru

s (

mg

/L)

Mud

Oxic P Release Rate

0

0.1

0.2

0.3

0.4

0.5

0 5 10 15 20 25 30 35

Days

Ph

os

ph

oru

s (

mg

/L)

Wasserman

Oxic P Release Rate

0

0.1

0.2

0.3

0 5 10 15 20 25 30 35

Days

Ph

os

ph

oru

s (

mg

/L)

Study Lakes

61 Lakes Sampled

70 Anoxic release sites

25 Oxic release

Lakes sampled as a part of TMDL studies or other lake diagnostic studies

Majority Fall in North Central Hardwood Forest Ecoregion

Anoxic versus Oxic P Release

0.0

5.0

10.0

15.0

20.0

Oxic Release Anoxic Release

P R

ele

as

e R

ate

(m

g/m

2/d

ay

Sediment Phosphorus Release

0

5

10

15

20

25

30

Shallow Lakes Winter Shallow Lakes Summer Deep Lakes Winter Deep Lakes Summer

An

ox

ic P

Re

lea

se

(m

g/m

2/d

ay

Sediment Phosphorus Release under Anoxic Conditions

0.0

1.0

2.0

3.0

4.0

Shallow Lakes Winter Shallow Lakes Summer Deep Lakes Winter Deep Lakes Summer

Ox

ic P

Re

lea

se

(m

g/m

2/d

ay

Sediment Phosphorus Release under Oxic Conditions

0

5

10

15

20

25

30

Shallow Lakes Deep Lakes

An

ox

ic P

Re

lea

se

(m

g/m

2/d

ay

Sediment Phosphorus Release under Anoxic Conditions

Shallow Lakes with Healthy Plant Community

Lake County State Ecoregion Oxic P Release

Anoxic P Release

(mg/m2d) (mg/m2d)

Lower Lunsten Carver MN NCHF 0.3 2.2

Oneka Washington MN NCHF -- 0.2

McKusick Washington MN NCHF -- 2.4

Neill Hennepin MN NCHF -- 3.5

Schmidt - Shallow Hennepin MN NCHF -- 1.3

Marsh Carver MN NCHF <0.1 <0.1

0.0

5.0

10.0

15.0

20.0

Healthy Plant Community Turbid Water State

P R

ele

as

e R

ate

(m

g/m

2/d

ay

Shallow Lake Anoxic Phosphorus Release

Importance of Internal Loading in Lake TMDLs

Important source of phosphorus to surface waters

Often as-large or larger than external loads

Need to identify magnitude of source

Need to identify cause of internal loading

Need to establish load allocation

What is a sustainable load? Background load?

Can the lake meet water quality standards without internal load reduction?

Parley Lake Initial modeling identified

a residual load of >800 lbs/year

Initially attributed to internal loading

Evidence supported this conclusion due to high bottom water concentrations of TP

MCWD initiated a Diagnostic study to:

Confirm internal loading key driver in Parley Lake

Develop internal load control options

Parley Lake BATHTUB Model

75

66

85

76 79 79

72 77

0

10

20

30

40

50

60

70

80

90

100

110

1999 2008 2010 Average

In L

ak

e T

ota

l P

ho

sp

ho

rus

Co

nc

en

tra

tio

n [

ug

/L]

Parley Lake

Model Predicted TP [ug/L] Observed TP [ug/L]

805 265 620 563

916

235

700 617

246

228 297 257

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1999 2008 2010 Average

To

tal P

ho

sp

ho

rus

Lo

ad

[p

erc

en

t]

Parley Lake

Drainage Areas Upstream Lakes Atmosphere Internal Load1

Parley Lake Conclusions

Internal load was determined to be <20% of the total P budget

Verified by internal release rate study and good DO data

Focus of restoration shifted to upstream lakes and tributaries and biological conditions

Ann and Fish Lake TMDL

2 years continuous flow and water quality data

Average inflow to Ann Lake was 49 µg/L TP

Large model residual in Ann and Fish Lake

Internal load in Ann Lake validated by release rate study

15 mg/m2/day

Only partially explained residual in Fish Lake

Decreased settling due to depth and flushing

Ann Lake

Surface Area (acres) 773 Average Depth (ft) 6.5

Maximum Depth (ft) 17

Volume (acre-feet) 5,029 Residence Time (years) 0.18

Littoral Area (acres) 710 Littoral Area (%) 92%

Watershed (km2/acres) Mixing Depth (ft) 17

Fish Lake

Surface Area (acres) 418 Average Depth (ft) 4.8

Maximum Depth (ft) 10

Volume (acre-feet) 2,009 Residence Time (years) 0.05

Littoral Area (acres) 418 Littoral Area (%) 100%

Watershed (km2/acres) Mixing Depth (ft) 10

Fish Lake flushes almost 22 times a year Every 2 weeks

Ann Lake flushes about 6 times a year Every 2 months

Internal Load Estimate

Ann Lake

Fish Lake

year Release Rate

(mg/m2/day) AF Gross Load

(mg/m2/summer) kilograms pounds 1993 15 2 29 92 202 2008 15 6 90 282 620 2009 15 12 184 576 1,267 Oxic 0.2 NA 24 76 168

Shallow 15 52 783 2449 5,388

year Release Rate

(mg/m2/day) AF Gross Load

(mg/m2/summer) kilograms pounds

2008 5.4 16 85 144 317

2009 5.4 0 0 0 0

Oxic Release 0.3 NA 37 62 136

Shallow 5.4 64 343 581 1,277

Drainage Areas47%

West Ann Lake2%

Atmosphere2%

Internal Load49%

Ann Lake P Budget

Drainage Areas30%

Upstream Lakes57%

Atmosphere1%

Internal Load12% Fish Lake

P Budget

Conclusions

Internal P release is an important P source to lakes

Must be quantified as a part of any TMDL or diagnostic study

Laboratory P release studies provide measured estimates of internal loading

Better prediction than using model residuals

Provide reference release rates for setting TMDL allocations

Questions?

Copyright 2012 by CH2M HILL, Inc. • Company Confidential

Hypolimnetic Oxygenation in Lake Vadnais

By: Roger Scharf, John Blackstone, John Borghesi, James

Bode, Paul Gantzer, David Austin


Outline

Background Old Aeration System Hypolimnetic Oxygenation System Design New Hypolimnetic Oxygenation System Performance


Background: SPRWS

• St Paul Regional Water Services (SPRWS) – McCarrons Water Treatment Plant – Average Daily Flow = 43 MGD – Maximum Flow = 126 MGD – ~92,000 Metered Accounts – 400,000+ People Served


Background: SPRWS Supply Source Water

– Mississippi River (80-95%)

– Local Watersheds (5-20%)

AERATORS

Volume Surface

Area

Mean

Depth

Max

Depth

Hydraulic

Residence

Time

Mean

Throughput

12.1E6 m3 1.56 km2 7.7 m 17.6 m 69 days 46 MGD


Background : Lake Vadnais

Lake Vadnais – Area 385 Acres – Average depth 7.7 m – Max depth 17.6 m – HRT 69 days


control nutrients → control cyanobacteria → control taste and odor

Nutrient Release from Sediments

Blue-Green Algae

McCarrons Water Treatment Plant

Project Objectives

Taste and Odor Compounds Intake Pipe


FeO(OH):PO4

D.O. >

2 - 5 mg/L

Fe(II)

FeS

PO4

Redox management (for sediments rich in Fe)

Inject O2 or NO3 …

H2S

MeHg

to create F(III) cap … and keep

these compounds in sediment.


Historical Aeration System

Partial Lift Aeration System with Ferric Iron Injection

Installed in 1988 Required Divers for

Maintenance Aerators recycle hypolimnion

every 4 days

SOD

SCFM

Diffuser induced oxygen demand

Air Line From Shore

Aerated Water


Summer 2010 Dissolved Oxygen Performance

Lake Vadnais - Aerator Operational Pleasant Lake - Aerator NOT Operational


Summer 2010 ORP Performance

Lake Vadnais - Aerator Operational Pleasant Lake - Aerator NOT Operational


Historical Aeration System Performance

1984-1996 10 m Lake Vadnais Orthophosphate

Concentration

0

200

400

600

800

1000

Dec-8

2

Dec-8

3

Dec-8

4

Dec-8

5

Dec-8

6

Dec-8

7

Dec-8

8

Dec-8

9

Dec-9

0

Dec-9

1

Dec-9

2

Dec-9

3

Dec-9

4

Dec-9

5

Dec-9

6

Dec-9

7

Date

Ort

ho

ph

os

ph

ate

(u

g/L

)

Hypolimnetic aeration started


Hypolimnetic Oxygenation Design

Key Design Parameter is Hypolimnetic Oxygen Demand – In Situ Sediment Oxygen Demand – Ex Situ Sediment Oxygen Demand – Hypolimnion Oxygen Mass Regression Analysis


Sediment Oxygen Demand

Sediment

Isolation chamber

D.O. probe

Meter,

data

logging

Mixer

D.O. mg/L

Time, minutes


Hypolimnetic Oxygen Demand

SOD – 3.7 g-O2/m2 d

HOD = SOD x Area of Hypolimnion – 3,444 kg/d – 4,374 kg/d with Sediment and Community Oxygen Demand

HOD: Mass Regression – 700 kg/d – 2,660 kg/d with Turbulence from Diffusers Induced Demand


Linear Diffuser Layout

Supply lines

• Advantages – Wide operating range (0-200% of

design) – Experience with zebra mussels – All maintenance can be done on

shore or from a boat – Well documented project history – Minimal mechanical equipment – Minimal power use with LOX – Lowest equipment cost

Diffuser in deep holes


Oxygen Supply

•9,000 Gallon Oxygen Storage

•Twin 10,000 SCFH Vaporizers


Flow Control


Constructed On Site


Supply Lines


Diffusers Checked for Damage


Diffusers Moved Into Position


Controlled Sinking of Diffusers


Operational


control nutrients → control cyanobacteria → control taste and odor

Nutrient Release from Sediments

Blue-Green Algae

McCarrons Water Treatment Plant

Project Objectives

Taste and Odor Compounds Intake Pipe


Dissolved Oxygen Performance

2010 – Partial Lift Aerator Operational 2012 – Linear Diffuser Operational


Lake Vadnais Hypolimnion Total Iron

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

To

tal Ir

on

(m

g/L

)

New System Installed


Lake Vadnais Hypolimnion Total Phosphorus

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

0.160

0.180

To

tal P

ho

sp

ho

rus (m

g/L

)



Lake Vadnais Epilimnion Total Phosphorus

0.000

0.020

0.040

0.060

0.080

0.100

0.120

To

tal P

ho

sp

ho

rus (

mg

/L)



Questions?

Documents

Anoxic and Oxic Release of P from Sediments in Minnesota Lakes · 2015-04-17 · Lake TMDL 2 years continuous flow and water quality data Average inflow to Ann Lake was 49 µg/L TP