Onondaga Lake - Tech Alive - Michigan Technological University

Report
GREGORY ALBERT E. GALICINAO
DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING
MICHIGAN TECHNOLOGICAL UNIVERSITY
STUDY SITE: ONONDAGA LAKE
-surface area: 11.7 km2
-mean depth : 12.0 m
-maximum depth: 20.5 m
-short retention time: flushes 2.5 to 4.0 times
each year
-distinguished by two depositional basins,
with a saddle region between them
-littoral zone occupies only a small area of
the lake relative to the profundal sediments
-eutrophic and dimictic
-during summer and winter, the thermallylayered Onondaga Lake also has a sulfidic
(>10 mg S·L-1) and anoxic hypolimnion
OTHER WATER QUALITY PROBLEMS
•ammonia, nitrate and phosphorus
•presence of pathogenic
microorganisms
•high levels of PCBs, calcium chloride,
mercury and other trace metals
•minimum dissolved oxygen
concentration standard (4 mg·L–1) is
frequently violated
Onondaga Lake (sign not to scale)
•Mercury.......
Testimony to the U.S. Senate has
described Onondaga Lake as one of
the most polluted in the country –
perhaps the most polluted.
Hennigan, R.D., 1990. America's Dirtiest Lake. Clearwaters 19: 813.
-Mercury: a toxic substance
found naturally or as a
contaminant introduced to
METHYLATION AND METHYLMERCURY
the environment
• elemental mercury
•Ionic mercury
•Organic mercury
-conversion of Hg to
methylmercury (MeHg)
when a methyl group
transfers from an organic
compound to a mercury
ion
-net methylation is
optimal in the absence of
oxygen
*picture courtesy of Dr. Betsy Henry, Exponents
MERCURY & METHYLMERCURY
-methylmercury:
microbiallymediated reactions
convert Hg to MeHg,
a highly toxic form
-MeHg
Bioconcentration
Factor: 104 to 107
*picture courtesy of Betsy Henry, Exponents
HISTORY OF MERCURY POLLUTION
-Industrial waste generated and discharged
to the lake by two chlor-alkali facilities
-75,000 kg from 1946-1970
-Allied Signal was ordered to reduce
external loadings from 10 kg·day-1 to 0.5
kg·day-1 in 1970
THE CHLOR-ALKALI PROCESS
Cl2
+
anode
26% NaCl
24% NaCl
Hg cathode
sodium amalgam, NaHg
-Chlor-alkali production operations halted
in 1988
-Largest sources of Hg to the lake are:
Ninemile Creek (7.1 kg.year-1), the METRO
wastewater treatment plant (3.8 kg.year-1)
and Onondaga Creek (1.8 kg.year-1) and
unquantified amount from upland sources &
resuspended sediments
H2
Hg
carbon
electrode
50% NaOH
H2O
*picture courtesy of Dr. Martin T. Auer
MERCURY IN ONONDAGA LAKE TODAY
-mercury concentrations in the lake
remain high
• water :
• sediment :
• fish :
-It still contains very high levels of
HgT at 2-25 ng·L-1 Hg and 0.3-0.7
ng·L-1 of methyl mercury (MeHg)
-Hg concentration measured in lake
fish also exceeded federal food limits
set by the US Food and Drug
Administration of 1 μg.g-1
-catch & release policy
*pictures courtesy from Dr. Betsy Henry
MERCURY IN ONONDAGA LAKE TODAY
MeHg (ng·L-1)
0
4
8
12
16
20
0
Depth (m)
5
10
15
20
....All roads lead to SEDIMENT as the possible culprit
*pictures courtesy from Dr. Betsy Henry
LAKE RESTORATION EFFORTS:
-Closure of the Allied Signal chloralkali plants
-Bottom sediments and adjacent sites
were assigned to the Federal
Superfund National Priorities List
-Clean-up of upland sites has been
completed wherein 8,500 tons of soil
were treated
-Wetland Restoration was completed
in 2007
-Groundwater Collection
System/Barrier Wall—barrier wall
construction has begun and
groundwater treatment is in progress
Innovative Soil Washing
Technology
*pictures courtesy from Dr. Betsy Henry and
http://www.cnylink.com/news_images/lrg/onondagaoutletweb.jpg
THE NEXT STEPS
•Dredging and Capping of
Contaminated Lake Sediments
-dredge 2.65 million cubic yards (SMU 1-7)
-20% of the bottom area will be covered with
clean sediment
-isolation cap over 425 acres
•Monitored Natural Recovery
-sequestration and burial will ultimately
isolate contaminant from the lake water and
reduce Hg concentrations, exposure, and
mobility
-Probable Effects Level (PEL) is set in
Onondaga Lake to be attained
Sediment Management Units (SMU)
in Onondaga Lake
*picture courtesy of Betsy Henry, Exponent
Protect the ecosystem
From MeHg flux
Long Term Recovery
What do we do
while the lake approaches
its new equilibrium?
•Electron Acceptor Amendment
-chemical-augmentation by adding
oxygen and nitrate
*pictures courtesy of Dr. Martin T. Auer
INTERIM MANAGEMENT
OF CONTAMINATED
LAKE SEDIMENTS: ELECTRON ACCEPTOR AMENDMENT
0
-2
2
4
6
8
10
Fate of mercury in the sediments:
Advection in Sediments > Diffusion
8
18
28
38
48
58
Engineered solution:
Chemical Augmentation
SULFATE REDUCTION &
METHYLATION
O
N
•Electron-donor (carbon)
•Electron acceptor (sulfate)
C
•Bioavailable species of inorganic Hg (HgS0)
2
20
8
15
6
10
4
5
2
0
0
ngMeHgL-1
mgS2-L-1
C ( H 2 O )  SO 4  H 2 S  C O 2  H 2 O
S
Hg
THE ROLE OF
in METHYLATION
-Sulfate-Reducing Bacteria-principal
methylators of mercury
SRB utilize sulfate as an electron acceptor in
metabolizing organic carbon
O2
-Hg2+ forms a neutrally-charged complex, HgS0
-Uncharged Hg-S complexes have fair lipid
solubility and are relatively nonpolar.
NO3
-Sulfate-concentration:100-200 µM
-High levels of sulfate yield high concentrations
of sulfide which has an inhibitory effect on
methylation
C(H2O)
SO4
INTERIM MANAGEMENT
OF CONTAMINATED
LAKE SEDIMENTS: ELECTRON ACCEPTOR AMENDMENT
0
-2
8
2
4
6
8
10
SINK PROCESSES:
SORPTION
DEMETHYLATION
18
28
38
48
58
It is the sink processes
that exert a major control
on the flux of methylmercury
transported to the overlying water
THE ROLE OF ELECTRON
ACCEPTORS in METHYLATION
Oxygen (mg∙L-1)
15
12
9
O2
6
3
18 m
Nitrate (mgN∙L-1)
0
2.0
1.5
NO3
1.0
0.5
18 m
MeHg (ngN∙L-1)
0
O2
Bump
6
NO3
Bump
5
4
C(H2O)
3
2
1
12-19 m
0
Apr
May
Jun
Jul
2006
Aug
Sep
SO4
Delete this page
As the sequestered mercury is
buried, it passes through a
sediment layer (sulfate
reduction) favorable for
methylmercury production with
subsequent diffusion to the
overlying water
0
2
mg S·L-1 and ng MeHg·L-1
4
6
8
10
-2
8
Depth (mm)
18
28
38
48
58
*pictures courtesy of Dr. Martin T. Auer
sulfide
MeHg
GAUGING ELECTRON ACCEPTOR AMENDMENT EFFICIENCY:
USE OF FLOW-THROUGH INCUBATION CHAMBERS
OBJECTIVE:
to demonstrate that addition of electron acceptors can inhibit MeHg flux
from the sediments
Feed
Stock
Q∙Cin
Q∙C
J
EXPERIMENTAL SET-UP
THEORY AND OPERATION: MASS BALANCE
V
dC
1.0
Flow (mL∙min -1)
dt
 Q  C in  Q  C  J  A
0.8
Q
0.6
0.4
0.2
0.0
0
J
0.3
A
 C ss
6
3
Css
0.2
0.1
2
1
0
1
2
3
0.0
4
5
6
4
5
6
Days
0
EXPERIMENTAL SET-UP
Q
Nitrate (mgN∙L-1)
J 
2
4
Days
6
12
Oxygen (mg O2.L-1)
Q∙C
MeHg (ng.L-1 )
Q∙Cin
4
Days
0.4
Feed
Stock
2
10
8
6
4
2
0
1
2
3
Days
3c
9d
0/0
10d
200
9c
9b
9a
8b
8a
7c
Low O2 + NO3
7b
7a
6b
6a
5b
A
5a
50
Q
3a
J 
3b
100
2b
High O2 + Hi NO3
1b
NO3
10c
10b
O2
10a
6d
6c
5d
5c
4c
4b
4a
2c
2a
1a
ng.m-2.d-1
A BASELINE FOR EVALUATING THE RESPONSE TO ELECTRON
ACCEPTOR AMENDMENTS
Q
150
 C ss
0
A BASELINE FOR EVALUATING THE RESPONSE TO ELECTRON
ACCEPTOR AMENDMENTS
Q
150
ng.m-2.d-1
120
90
J 
60
Q
A
 C ss
30
0
Hypolimnetic
Accumulation Rates
Porewater
Calculations
Flow-through No/No
“How much is the flux
coming out of the lake
sediments? How big is the
‘monster’? ”
ELECTRON ACCEPTOR AMENDMENT
Q
200
ng.m-2.d-1
160
120
J 
Q
A
80
 C ss
40
0
Hi O2 +
Hi NO3
Low O2
+ NO3
No/No
O2
NO3
DECREASING TREND IN MeHg RELEASE
Q
1000
ng.m-2.d-1
800
600
J 
400
Q
A
 C ss
200
0
2005
2006
2007
2008
Recent 2008 data translates to a
∽85% decrease in MeHg flux over a
four-year period
*Data provided by Upstate Freshwater Institute
ELECTRON ACCEPTOR AUGMENTATION IN A LARGER CONTEXT
0
3
6
9
12
15
0
Net demethylation
10
Q
20
30
Sulfate Reduction and Methylmercury Production
40
50
60
70
J 
Q
A
 C ss
80
90
100
Sediments serve as a repository of
the “sins of the past”-Dr. Martin T. Auer
ELECTRON ACCEPTOR BUDGET OF ONONDAGA LAKE
100%
Q
aerobic metabolism
80%
•At the onset of 2004, there was a decrease in
sulfate-reduction
60%
•Advanced Nitrification program of METRO
Q
denitrification
J 
C
40%
A
sulfate reduction
ss
20%
methanogenesis
0%
1989
1991 1993 1995 1997
* Data provided by Upstate Freshwater Institute
1999
2001
2003
2005
2007
Less organic matter means less “fuel” to
power the sulfate-reduction engine (and
consequently methlyation of mercury)
CONCLUSION
•Chemical-augmentation as an interim management procedure effectively inhibited the
release of MeHg to the water column of Onondaga Lake
•Percent reduction of MeHg release after addition of oxygen and nitrate is between Q
65-97%
FUTURE WORK
J 
Q
C
ss
•Further experimental work with nitrate additions
A is needed
•More research to characterize and identify which, between sorption or demethylation, is the
controlling MeHg sink process
ACKNOWLEDGMENT
I want to thank the following people for making this project possible:
•Dr. Hand, Dr. Urban and Dr. Bagley for agreeing to be part of my committee
Q
•Upstate Freshwater Institute , Syracuse University and Cornell University for collaborating with us in this
research project
•Honeywell Inc.
•Jesse Nordeng, Rob Fritz and Dave Perram
•Denise Heiniken and the MTU Writing Center
J 
Q
A
 C ss
•To my friends here at MTU
•To our Research Group: Brandon Ellefson and Phil Depetro and the undergraduate students, Justen Stutz,
Adam Di Pietro & Ken Windsand
•To my family and friends
•To my great adviser, Dr. Martin T. Auer
•To God
QUESTIONS?
Q
J 
Q
A
 C ss

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