DETERMINATION OF METHYLMERCURY FLUX FROM ONONDAGA LAKE SEDIMENTS USING FLOW-THROUGH REACTORS

1. DETERMINATION OF METHYLMERCURY FLUX FROM ONONDAGA LAKE SEDIMENTS USING FLOW-THROUGH REACTORS GREGORY ALBERT E. GALICINAO DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING MICHIGAN TECHNOLOGICAL UNIVERSITY

2. 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 thermally- • layered Onondaga Lake also has a sulfidic • (>10 mg S·L-1) and anoxic hypolimnion

3. 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.

4. Mercury: a toxic substance • found naturally or as a • contaminant introduced to the environment • elemental mercury • Ionic mercury • Organic mercury METHYLATION AND METHYLMERCURY -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

5. MERCURY & METHYLMERCURY • -methylmercury: microbially-mediated reactions convert Hg to MeHg, a highly toxic form • -MeHg Bioconcentration Factor: 104 to 107 *picture courtesy of Betsy Henry, Exponents

6. 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-1to 0.5 kg·day-1 in 1970 • Chlor-alkali production operations halted in 1988 • Largest sources of Hg to the lake are: NinemileCreek (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 THE CHLOR-ALKALI PROCESS *picture courtesy of Dr. Martin T. Auer

7. 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

8. MERCURY IN ONONDAGA LAKE TODAY ....All roads lead to SEDIMENT as the possible culprit *pictures courtesy from Dr. Betsy Henry

9. 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 *pictures courtesy from Dr. Betsy Henry and http://www.cnylink.com/news_images/lrg/onondagaoutletweb.jpg

10. 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

11. 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 Sedimnt Management Units (SMU) in Onondaga Lake

12. INTERIM MANAGEMENT OF CONTAMINATED LAKE SEDIMENTS: ELECTRON ACCEPTOR AMENDMENT Fate of mercury in the sediments: Advection in Sediments > Diffusion Engineered solution: Chemical Augmentation Sedimnt Management Units (SMU) in Onondaga Lake

13. SULFATE REDUCTION & METHYLATION • Electron-donor (carbon) • Electron acceptor (sulfate) • Bioavailable species of inorganic Hg (HgS0) Sedimnt Management Units (SMU) in Onondaga Lake

14. THE ROLE OF in METHYLATION • -Sulfate-Reducing Bacteria-principal methylators of mercury • SRB utilize sulfate as an electron acceptor in metabolizing organic carbon • -Hg2+ forms a neutrally-charged complex, HgS0 • -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 Sedimnt Management Units (SMU) in Onondaga Lake

15. INTERIM MANAGEMENT OF CONTAMINATED LAKE SEDIMENTS: ELECTRON ACCEPTOR AMENDMENT • SINK PROCESSES: • SORPTION • DEMETHYLATION It is the sink processes that exert a major control on the flux of methylmercury transported to the overlying water Sedimnt Management Units (SMU) in Onondaga Lake

16. THE ROLE OF ELECTRON ACCEPTORS in METHYLATION Sedimnt Management Units (SMU) in Onondaga Lake

17. mg S·L-1 and ng MeHg·L-1 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 Delete this page Depth (mm) sulfide MeHg *pictures courtesy of Dr. Martin T. Auer Sedimnt Management Units (SMU) in Onondaga Lake

18. 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 J EXPERIMENTAL SET-UP Sedimnt Management Units (SMU) in Onondaga Lake

19. THEORY AND OPERATION: MASS BALANCE Q Css J EXPERIMENTAL SET-UP Sedimnt Management Units (SMU) in Onondaga Lake

20. A BASELINE FOR EVALUATING THE RESPONSE TO ELECTRON ACCEPTOR AMENDMENTS Q ng.m-2.d-1 Sedimnt Management Units (SMU) in Onondaga Lake

21. A BASELINE FOR EVALUATING THE RESPONSE TO ELECTRON ACCEPTOR AMENDMENTS Q ng.m-2.d-1 “How much is the flux coming out of the lake sediments? How big is the ‘monster’? ” Sedimnt Management Units (SMU) in Onondaga Lake

22. ELECTRON ACCEPTOR AMENDMENT Q ng.m-2.d-1 Hi O2 + Hi NO3 Low O2 + NO3 No/No O2 NO3 Sedimnt Management Units (SMU) in Onondaga Lake

23. DECREASING TREND IN MeHg RELEASE Q ng.m-2.d-1 Recent 2008 data translates to a ∽85% decrease in MeHg flux over a four-year period *Data provided by Upstate Freshwater Institute Sedimnt Management Units (SMU) in Onondaga Lake

24. ELECTRON ACCEPTOR AUGMENTATION IN A LARGER CONTEXT Net demethylation Q Sulfate Reduction and Methylmercury Production Sediments serve as a repository of the “sins of the past”-Dr. Martin T. Auer Sedimnt Management Units (SMU) in Onondaga Lake

25. ELECTRON ACCEPTOR BUDGET OF ONONDAGA LAKE Q aerobic metabolism • At the onset of 2004, there was a decrease in • sulfate-reduction • Advanced Nitrification program of METRO denitrification sulfate reduction methanogenesis Less organic matter means less “fuel” to power the sulfate-reduction engine (and consequently methlyation of mercury) * Data provided by Upstate Freshwater Institute Sedimnt Management Units (SMU) in Onondaga Lake

26. 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 65-97% Q FUTURE WORK • Further experimental work with nitrate additions is needed • More research to characterize and identify which, between sorption or demethylation, is the • controlling MeHg sink process Sedimnt Management Units (SMU) in Onondaga Lake

27. 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 • 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 • 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 Q Sedimnt Management Units (SMU) in Onondaga Lake

28. QUESTIONS? Q Sedimnt Management Units (SMU) in Onondaga Lake