MERCURY STATE OF THE KNOWLEDGE 29 OCTOBER Ed Swain Bruce Monson Rebecca Place Environmental Analysis & Outcomes Division

Transcription

1 MERCURY STATE OF THE KNOWLEDGE 29 OCTOBER 2013 Ed Swain Bruce Monson Rebecca Place Environmental Analysis & Outcomes Division

2 OUTLINE Loading Point Source Atmospheric Dry Deposition Sulfate Studies Recent Research local and global Fish-mercury Trend International Treaty 2

3 Point source loading has decreased Sector 2004 estimated Mercury Load (kg/yr) 2009 reported 2012 reported Waste Water Treatment Plants Coal-fired Electrical Plants Industrial Miscellaneous Taconite Processing Peat Harvesting NA NA NA Paper Mills Petroleum Refining Other Grand Total

4 Mercury deposition in precipitation (NADP/Mercury Deposition Network) 4

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6 Hg Conc. (ng/l) Ann. Precip. (in) YEAR 15 Site Lat 44.2 Lamberton 10 Lat 46.2 Camp Ripley Lat 47.5 Marcell Lat 47.9 Fernberg Ann. Precip. (in) 6

7 Dry deposition of mercury in litterfall exceeds wet deposition at many MDN monitoring sites* * Risch, MR, JF DeWild, DP Krabbenhoft, RK Kolka, and L Zhang Litterfall mercury 7 dry deposition in the eastern USA. Environmental Pollution. 161:

8 Decreased atmospheric sulfate deposition reduced methylmercury production in a Minnesota wetland* Sulfate load was not only proportional to methylmercury in water, but also to mercury in mosquito larvae. * Wasik, Mitchell, Engstrom, Swain, Monson, Balogh, Jeremiason, Branfireun, Eggert, Kolka, and Almendinger Methylmercury declines in a boreal peatland when experimental sulfate deposition decreases. Environmental Science & Technology. 46:

9 Sulfate deposition: Marcell Experimental Forest 9

10 Sulfate deposition: Fernberg (Ely) 10

11 Sulfate deposition: Camp Ripley 11

12 Sulfate deposition: Lamberton 12

13 The genes necessary for mercury methylation were identified* Two genes are required: HgcA -- codes for a protein that donates a methyl group. HgcB codes for a iron-sulfur protein that donates an electron. Sub-groups of five types of bacteria have been found with the genes, including: some sulfate reducers some iron reducers some methanogens Being able to identify methylation genes may greatly enhance our understanding of which variables control fish contamination. * Parks et al The genetic basis for bacterial mercury methylation. Science. 339:

14 DNR Sulfate Impact Studies : Tributaries, many points in the St. Louis River : Five wetlands and a lake impacted by sulfate : Sulfate source/impacts - source to estuary LCCMR : Experiments to measure sulfur cycling link to mercury cycling; load monitoring at select sites 14

15 MWRAP Future MWRAP 2012/13 Continuing studies Limited sampling to confirm/strengthen hypothesis in summer 2013 Final reports complete by Dec. 31, 2013 MWRAP 2014/15 Currently organizing Finalize plans by June 30, 2013, begin contracting. Projects conducted Jan to Dec. 31,

16 Mercury in Glacial Ridge National Wildlife Refuge A new report on mercury in wetlands at the Glacial Ridge National Wildlife Refuge was published on June 3. The largest wetland and prairie restoration in U.S. history recently was completed at the refuge. More than 3,000 acres of wetlands were restored, more than 100 miles of ditches were filled, and nearly 18,000 acres of land were reseeded with native prairie plants. Microbial conversion of inorganic mercury to the bioaccumulative methylmercury form is a particularly active process in wetlands, making wetlands important methylmercury hotspots on the landscape. Concentrations of methylmercury in the Glacial Ridge NWR wetlands are among some of the highest in the published literature, suggesting wetland restoration is a potential concern for wildlife. Cowdery, Timothy K. and Brigham, Mark E., 2013, Mercury in wetlands at the Glacial Ridge National Wildlife Refuge, northwestern Minnesota, , U.S. Geological Survey Scientific Investigations Report: , 17 pp. Available at: 16

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18 GLAD3 lakes.mxd/ BAM 11jul2013 A study of 115 northeastern Minnesota lakes could not identify factors controlling trends in fish Hg* Minnesota Wisconsin 115 Selected Lakes provinces selection states selection Miles Michigan Changes in fish mercury were not correlated with any of the environmental variables evaluated, most likely because of the multiple factors influencing fish mercury levels and the infrequency of fish Hg measurements within lakes. * Engstrom DR, BA Monson, SJ Balogh, EB Swain, and KR Parsons Resolving the cause of the recent rise of fish-mercury levels in the western Great Lakes region. Final Research Report to the 2009 Great lakes Air Deposition Program. Great lakes Commission. April 9, National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, ipc

19 Resolving the Cause of the Recent Rise of Fish-mercury Levels in the Western Great Lakes Region Atmospheric Hg inputs have not changed appreciably ( ). Changes in sediment Hg over time are likely related to increased watershed inputs. Fish-Hg concentrations correlate to DOC and mixis, but temporal change in fish-hg within lakes are not correlated with any measured lake or watershed parameters. Changes in fish-hg are likely a consequence of subtle changes in production or transport of MeHg in lake or watershed. 19

20 Some researchers* assume that mercury used in mining was emitted to atmosphere But sediment cores from northern Minnesota** and elsewhere do not support that assumption: * Streets et al All-time releases of mercury to the atmosphere from human activities. Environmental Science & Technology. 45: * Amos et al Legacy impacts of all-time anthropogenic emissions on the global mercury cycle. Global Biogeochemical Cycle s. 27:1-12. ** Engstrom, DR, Balogh, SJ, and Swain, EB History of mercury inputs to Minnesota lakes: Influences of watershed dis turbance 20 and localized atmospheric deposition. Limnology and Oceanography. 52(6):

21 Mercury effects on fish (Sandheinrich & Wiener 2011) We conclude that the principal effects of methylmercury on fish populations at existing exposure levels in North American freshwaters would be sublethal damage to tissues and depressed reproduction. 21

22 Hg (ppb) Trend of mercury in standardized northern pike and walleye, adjusted for fish length and latitude Hg (ppb) : Model spfhg.1 Linear Trend Annual Means Smooth of Annual Means (31 yr) 1,105 Lakes 2,748 cases (lake-species-yr) Linear Trend: - 0.7% /yr Year 22

23 SUMMARY 1. Mercury loading from point sources has decreased; while atmospheric deposition shows large variations and recent increases. 2. Mercury deposition in leaves (litterfall) exceeds wet deposition at many monitoring sites. 3. DNR s sulfate impact studies in St. Louis River will have final reports due Dec. 31, 2013, but will continue with research and a conference in Methylmercury and total mercury concentrations in water from Glacial Ridge National Wildlife Refuge were high in the unrestored wetlands. 5. Decreasing atmospheric sulfate deposition to a northern Minnesota wetland decreased the production of methylmercury; sulfate deposition is declining. 23

24 SUMMARY (continued) 6. Scientists identified the genes necessary for bacterial mercury methylation. 7. Changes in fish-mercury concentrations were not explained by changes in total mercury deposition or watershed characteristics in NE Minnesota lakes. 8. It has been erroneously assumed that mercury historically used in gold and silver mining was emitted to the atmosphere. 9. Mercury shown to have direct toxic effects on fish at ambient levels. 10. Fish-mercury concentrations in northern pike and walleye are trending downward 0.7% per year despite decadal shifts in the trend. 24

25 Minamata Convention

26 Minamata Convention With the signing of the Minamata Convention on Mercury we will be going a long way in protecting the world forever from the devastating health consequences from Mercury - World Health Organization Director General Dr. Margaret Chan

27 Minamata Convention 140 countries and territories 5 years January 2013 Geneva, Switzerland Presented for adoption and signature October 2013.

28 Minamata Convention The global legally binding instrument on mercury must be ratified 50 countries - up to 5 years

29 Minamata Convention Supply: mercury mining Artisanal mining Emissions from point source Phase out mercury by 2018 or 2025 Products/Processes Cease manufacturing, import and export of nine product categories by 2020.

30 t Minamata Convention Summary Platform for continued cooperation Limited but has potential Benefits to global communication

31 t For more information Ed Swain: , Bruce Monson: , Rebecca Place: , B