Ed Swain

Bruce Monson

Rebecca Place

Environmental Analysis & Outcomes Division

MERCURY STATE OF THE KNOWLEDGE

29 OCTOBER 2013

OUTLINE

• Loading

• Point Source

• Atmospheric

• Dry Deposition

• Sulfate Studies

• Recent Research – local and global

• Fish-mercury Trend

• International Treaty

2

Point source loading has decreased

Sector

Mercury Load (kg/yr)

2004

estimated

2009

reported

2012

reported

Waste Water Treatment Plants 8.04 3.51 3.02

Coal-fired Electrical Plants 0.42 0.34 0.33

Industrial – Miscellaneous 0.39 0.31 0.31

Taconite Processing 0.28 0.30 0.29

Peat Harvesting NA NA NA

Paper Mills 0.03 0.07 0.07

Petroleum Refining 0.06 0.10 0.04

Other 0.19 0.20 0.15

Grand Total 9.41 4.83 4.21

3

Mercury deposition in precipitation

(NADP/Mercury Deposition Network)

4

Figure 3 Mercury annual deposition (top panel), concentration (bottom panel) at four sites in Minnesota; includes smoother curve for each site to show shifts over the 17 years of monitoring (1996-2012)

5

1995 2000 2005 2010 2015

YEAR

0

10

20

30

40

An

n. P

reci

p. (

in)

Lat 47.9 Fernberg

Lat 47.5 Marcell

Lat 46.2 Camp Ripley

Lat 44.2 Lamberton

Site

0 10 20 30 40

Ann. Precip. (in)

5

10

15

20

Hg

Co

nc.

(n

g/L)

6

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. 2012. Litterfall mercury

dry deposition in the eastern USA. Environmental Pollution. 161:284-290. 7

Decreased atmospheric sulfate deposition reduced

methylmercury production in a Minnesota wetland*

• * Wasik, Mitchell, Engstrom, Swain, Monson, Balogh, Jeremiason, Branfireun, Eggert, Kolka,

and Almendinger. 2012. Methylmercury declines in a boreal peatland when experimental sulfate

deposition decreases. Environmental Science & Technology. 46:6663-6671.

Sulfate load was not only proportional to

methylmercury in water, but also to mercury in

mosquito larvae.

8

Sulfate deposition: Marcell Experimental Forest

9

Sulfate deposition: Fernberg (Ely)

10

Sulfate deposition: Camp Ripley

11

Sulfate deposition: Lamberton

12

The genes necessary for

mercury methylation were identified*

• * Parks et al. 2013. The genetic basis for bacterial mercury methylation. Science.

339:1332-1335.

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.

13

DNR Sulfate Impact Studies

14

2007-2009: Tributaries, many points in the St. Louis River

2010-2011: Five wetlands and a lake impacted by sulfate

2011-2012: Sulfate source/impacts - source to estuary – LCCMR

2012-2013: Experiments to measure sulfur cycling link to mercury

cycling; load monitoring at select sites

http://www.dnr.state.mn.us/lands_minerals/dnr_so4_research.html

MWRAP Future

15

• 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. 2014 to Dec. 31, 2015

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, 2007-9, U.S. Geological Survey Scientific Investigations Report: 2013-5068, 17 pp. Available at: http://pubs.er.usgs.gov/publication/sir20135068

16

17

A study of 115 northeastern Minnesota lakes could

not identify factors controlling trends in fish Hg*

• * Engstrom DR, BA Monson, SJ Balogh, EB Swain, and KR Parsons. 2012. 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, 2012.

18

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.

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Minnesota

Wisconsin Michigan

Resolving the Cause of the Recent Rise of Fish-mercury Levels

in the Western Great Lakes Region

• Atmospheric Hg inputs have not changed appreciably (1980 – 2010).

• 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

Some researchers* assume that mercury used in

mining was emitted to atmosphere

• * Streets et al. 2013. All-time releases of mercury to the atmosphere from human activities. Environmental Science & Technology. 45:10485-

10491.

• * Amos et al. 2013. Legacy impacts of all-time anthropogenic emissions on the global mercury cycle. Global Biogeochemical Cycles. 27:1-12.

• ** Engstrom, DR, Balogh, SJ, and Swain, EB. 2007. History of mercury inputs to Minnesota lakes: Influences of watershed dis turbance and

localized atmospheric deposition. Limnology and Oceanography. 52(6):2467-2483.

But sediment cores from northern Minnesota**

and elsewhere do not support that assumption:

20

Mercury effects on fish (Sandheinrich & Wiener 2011)

21

“ 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.”

Trend of mercury in standardized northern pike and

walleye, adjusted for fish length and latitude

1985 1990 1995 2000 2005 2010

10

01

50

20

02

50

30

03

50

40

0Hg (ppb) 1982-2012: Model spfhg.1

Year

Hg

(p

pb

)

Linear TrendAnnual MeansSmooth of Annual Means

22

1982-2012 (31 yr)

1,105 Lakes

2,748 cases

(lake-species-yr)

Linear Trend: - 0.7% /yr

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 2014.

4. 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

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

Minamata Convention

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

Minamata Convention

• 140 countries and territories

• 5 years

• January 2013 Geneva, Switzerland

• Presented for adoption and signature October 2013.

Minamata Convention

• The global legally binding instrument on mercury must be

ratified 50 countries

- up to 5 years

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.

Minamata Convention

t

Summary

• Platform for continued cooperation

• Limited but has potential

• Benefits to global communication

For more information t

Ed Swain: 651-757-2772, edward.swain@state.mn.us Bruce Monson: 651-757-2579, bruce.monson@state.mn.us Rebecca Place: 651-757-2807, rebecca.place@state.mn.us B