GREGORY ALBERT E. GALICINAO DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING MICHIGAN TECHNOLOGICAL UNIVERSITY

STUDY SITE: ONONDAGA LAKE -surface area: 11.7 km 2 -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 thermally layered 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 • Mercury.......

Onondaga Lake (sign not to scale)

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: 8 13.

-Mercury: a toxic substance found naturally or as a contaminant introduced to METHYLATION AND METHYLMERCURY • 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, Expon ents

MERCURY & METHYLMERCURY -methylmercury: microbially mediated reactions convert Hg to MeHg, a highly toxic form -MeHg Bioconcentration Factor: 10 4 to 10 7 *picture courtesy of Betsy Henry, Exponents

THE CHLOR-ALKALI PROCESS

Cl 2

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anode 26% NaCl Hg cathode Hg 24% NaCl sodium amalgam, NaHg H 2 carbon electrode 50% NaOH H 2 O

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 -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

resuspended sediments -1 ) and unquantified amount from upland sources & *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 Hg T 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

4 8 MeHg (ng·L -1 ) 12 16 15 20 0 0 5 10 20

....All roads lead to SEDIMENT as the possible culprit *pictures courtesy from Dr. Betsy Henry

LAKE RESTORATION EFFORTS:

-Closure of the Allied Signal chlor alkali 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

Sediment Management Units (SMU) in Onondaga Lake *picture courtesy of Betsy Henry, Exponent

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

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

28 38 48 58 -2 0 2 4 6 8 10 8 18

Fate of mercury in the sediments: Advection in Sediments > Diffusion Engineered solution: Chemical Augmentation

SULFATE REDUCTION & METHYLATION

• Electron-donor (carbon) • Electron acceptor (sulfate) • Bioavailable species of inorganic Hg (HgS 0 )

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THE ROLE OF in METHYLATION

-Sulfate-Reducing Bacteria-principal methylators of mercury SRB utilize sulfate as an electron acceptor in metabolizing organic carbon -Hg 2+ forms a neutrally-charged complex, HgS 0 -Uncharged Hg-S complexes have fair lipid solubility and are relatively nonpolar. -Sulfate-concentration:100-200 µM -High levels of sulfate yield high concentrations of sulfide which has an inhibitory effect on methylation

O 2 NO 3 C(H 2 O) SO 4

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INTERIM MANAGEMENT OF CONTAMINATED LAKE SEDIMENTS: ELECTRON ACCEPTOR AMENDMENT

-2 0 2 4 6 8 10 8

SINK PROCESSES:  SORPTION  DEMETHYLATION 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

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18 m 0 2 1 0 6 5 4 3 O 2 Bump NO 3 Bump 12-19 m Apr May Jun Jul Aug Sep 2006

O 2 NO 3 C(H 2 O) SO 4

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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

-2 0 2

mg S·L -1

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and ng MeHg·L -1

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sulfide MeHg *pictures courtesy of Dr. Martin T. Auer

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∙C in Q∙C J EXPERIMENTAL SET-UP

THEORY AND OPERATION: MASS BALANCE

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A BASELINE FOR EVALUATING THE RESPONSE TO ELECTRON ACCEPTOR AMENDMENTS

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A BASELINE FOR EVALUATING THE RESPONSE TO ELECTRON ACCEPTOR AMENDMENTS

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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

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DECREASING TREND IN MeHg RELEASE

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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

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Net demethylation Q Sulfate Reduction and Methylmercury Production Sediments serve as a repository of the “sins of the past”-Dr. Martin T. Auer

ELECTRON ACCEPTOR BUDGET OF ONONDAGA LAKE

100%

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sulfate reduction

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0% 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007

• At the onset of 2004, there was a decrease in sulfate-reduction • Advanced Nitrification program of METRO * Data provided by Upstate Freshwater Institute Less organic matter means less “fuel” consequently methlyation of mercury) to power the sulfate-reduction engine (and

CONCLUSION

• Chemical-augmentation as an interim management procedure effectively inhibited the release of MeHg to the water column of Onondaga Lake • Q

FUTURE WORK

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• 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 • To my friends here at MTU

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• 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?

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