Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
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
Anoxic P Release Rate
0
1
2
0 1 2 3 4 5 6 7 8
Days
Ph
os
ph
oru
s (
mg
/L)
Lower Lunsten
Anoxic P Release Rate
0
0.1
0.2
0 5 10 15 20
Days
Ph
os
ph
oru
s (
mg
)
Lower Lunsten
Anoxic P Release Rate
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
Anoxic P Release Rate
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
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
/L)
Oxic Sediment P Release
Upper Twin
Anoxic P Release Rate
0
0.1
0.2
0.3
0 2 4 6 8 10
Days
P M
as
s,
mg
Meadow
Anoxic P Release Rate
0
0.1
0.2
0.3
0 2 4 6 8 10
Days
P M
as
s,
mg
Pike
Anoxic P Release Rate
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
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Outline
Background Old Aeration System Hypolimnetic Oxygenation System Design New Hypolimnetic Oxygenation System Performance
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Background : Lake Vadnais
Lake Vadnais – Area 385 Acres – Average depth 7.7 m – Max depth 17.6 m – HRT 69 days
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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.
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Summer 2010 Dissolved Oxygen Performance
Lake Vadnais - Aerator Operational Pleasant Lake - Aerator NOT Operational
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Summer 2010 ORP Performance
Lake Vadnais - Aerator Operational Pleasant Lake - Aerator NOT Operational
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Sediment Oxygen Demand
Sediment
Isolation chamber
D.O. probe
Meter,
data
logging
Mixer
D.O. mg/L
Time, minutes
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Oxygen Supply
•9,000 Gallon Oxygen Storage
•Twin 10,000 SCFH Vaporizers
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Flow Control
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Constructed On Site
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Supply Lines
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Diffusers Checked for Damage
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Diffusers Moved Into Position
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Controlled Sinking of Diffusers
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Operational
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Dissolved Oxygen Performance
2010 – Partial Lift Aerator Operational 2012 – Linear Diffuser Operational
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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
)
New System Installed
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
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)
New System Installed
Copyright 2012 by CH2M HILL, Inc. • Company Confidential
Questions?