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

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Presentation on theme: "GREGORY ALBERT E. GALICINAO DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING MICHIGAN TECHNOLOGICAL UNIVERSITY."— Presentation transcript:

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

2 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

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., America's Dirtiest Lake. Clearwaters 19:

4 METHYLATION AND METHYLMERCURY *picture courtesy of Dr. Betsy Henry, Exponents -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 elemental mercury Ionic mercury Organic mercury -Mercury: a toxic substance found naturally or as a contaminant introduced to the environment

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

6 HISTORY OF MERCURY POLLUTION -Industrial waste generated and discharged to the lake by two chlor-alkali facilities -75,000 kg from Allied Signal was ordered to reduce external loadings from 10 kg·day -1 to 0.5 kg·day -1 in Chlor-alkali production operations halted in 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 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 Hg T at 2-25 ng·L -1 Hg and 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 Groundwater Collection System/Barrier Wallbarrier wall construction has begun and groundwater treatment is in progress *pictures courtesy from Dr. Betsy Henry and

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

11 Sedimnt Management Units (SMU) in Onondaga Lake Long Term Recovery What do we do while the lake approaches its new equilibrium? *pictures courtesy of Dr. Martin T. Auer Protect the ecosystem From MeHg flux Electron Acceptor Amendment -chemical-augmentation by adding oxygen and nitrate

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

13 Sedimnt Management Units (SMU) in Onondaga Lake SULFATE REDUCTION & METHYLATION Electron-donor (carbon) Electron acceptor (sulfate) Bioavailable species of inorganic Hg (HgS 0 )

14 Sedimnt Management Units (SMU) in Onondaga Lake 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: µM -High levels of sulfate yield high concentrations of sulfide which has an inhibitory effect on methylation

15 Sedimnt Management Units (SMU) in Onondaga Lake 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

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

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

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

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

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

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

22 Sedimnt Management Units (SMU) in Onondaga Lake ELECTRON ACCEPTOR AMENDMENT Q Hi O 2 + Hi NO 3 Low O 2 + NO 3 No/NoO2O2 NO 3 ng.m -2.d -1

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

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

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

26 Sedimnt Management Units (SMU) in Onondaga Lake Q 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% 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

27 Sedimnt Management Units (SMU) in Onondaga Lake Q 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

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


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