2004 Mercury Workshop

1. 2004 Mercury Workshop Moderators Summary

2. Overview of Mercury Research and Relations to DOI Resource Management • Mercury is a problem at a global and a local scale. • Atmospheric deposition is a major pathway and man’s sources of emissions continue to make a major global and local contribution. • “Where” mercury is deposited also plays a critical role – some major drivers on the landscape are pH, wetlands, wetting/drying cycles, sulfur, carbon. • “New” loading of mercury matters – bioavailability. • Disturbances (fire, dredging, global warming) and land management (wetland restoration & construction, reservoir construction, erosion, mining, mine restoration, fire, land-use changes) profoundly influence the mercury problem.

3. Overview of Mercury Research and Relations to DOI Resource Management • Power utilities, municipal, and medical waste incinerators are major sources of emissions. • Two important regulatory measures are: MACT Standards and Clean Air Interstate Rule (CAIR ) • USEPA estimates the costs of controls in the billions $ and the benefits in the tens of billions $. • DOI agencies and Native Americans have lands that are both vast in size (land and sea) and highly decentralized. • Agencies need to better understand sources, transport, and fate of mercury. • Effects on individual biological species and ecosystems

4. Overview of Mercury Research and Relations to DOI Resource Management • DOI agencies need research on the specific ecosystem characteristics and processes that influence the rate at which Hg methylates and demethylates. • DOI agencies need research on the specific physical, chemical, and biological factors that influence the rate at which Hg methylates and demethylates. • DOI agencies need research on management techniques for lessening methylation rates. • We need to emphasize the role of long-term monitoring and trend analysis in all media. • DOI agencies need a variety of decision support tools – maps, models, databases. • We need to consider the role of DOI lands as locations for monitoring and research.

5. Overview of Mercury Research and Relations to DOI Resource Management • We need to understand the connection between the marine and the terrestrial environment. • We need to increase the level and clarity of the information that we provide. • People who do subsistence fishing have a much greater exposure to mercury through their consumption, 180 lb/year. • We need to understand the movement of mercury through the food chain. • We need to understand reproductive and developmental impacts to biota. • Need to look at synergistic effects w/ other constituents

6. Case Studies on DOI Lands and Effects of Land Management on Mercury • Understanding environmental influences on methylmercury levels in aquatic systems • looking across gradients in environmental factors • Common correlations with [MeHg] across case studies: • sulphate, DOC, pH, (different ranges?), wet/dry cycles • sometimes linear relationships (pH), some not (sulphate) • Other factors were more case-specific: • local land-use issues • importance of local emission sources • lakes vs. wetlands

7. Case Studies on DOI Lands and Effects of Land Management on Mercury • Value of integrated studies • need to consider deposition/inputs, methylation and food webs • Value of long-term studies • associating reductions in abiotic and biotic [MeHg] in Everglades with local emission reductions • Value of combining field and experimental studies • cause-effect linkages confirmed by lab/mesocosm/whole ecosystem experiments

8. Case Studies on DOI Lands and Effects of Land Management on Mercury Challenges • How can we integrate findings from many case studies to provide better understanding? • To what extent can new insights from one area be reliably applied to others? (eg. inputs of “new” vs. “old” mercury, etc.) • How can we better use the findings from case studies to help land/resource managers, pollution regulators, industry, etc. make better decisions? • How are mercury issues affected by other management concerns? (eg. acidic deposition, climate change, etc.)

9. Biological effects • For birds, embryonic stage most sensitive to Hg. • Mallards in the lab: embryotoxic threshold = 0.8-1.0 ppm in egg. • Egg injection studies to simulate field exposure of Hg. • Piscivorous species are more sensitive to Hg. • To produce 0.8-1.0 ppm in egg, food = ~0.1 ppm. • If Hg criterion (0.1 ppm) is protective for wildlife, should be protective for humans.

10. Biological effects • For humans, mercury in blood is methylmercury and primary source is fish. • Toxicity depends on dose and developmental period. • Fetal neurotoxicity: 1/5 – 1/10 exposure that adversely affects adults • Reference Hg dose, 35 ug/L; about 600,000 newborns above this dose. • Other possible mercury risks: • Cardiovascular • Reproductive and endocrine • Persistent and delayed neurotoxicity

11. Biological effects • In the lab, fathead minnows fed methylmercury had reduced reproductive success and altered reproductive behavior and hormone levels. • Northern pike from the field from VNP analyzed for Hg and hormones • Testosterone suppressed by melthylmercury • Unknown population effects

12. Biological effects • Proposed avian indicator species for mercury contamination • High correlation between fish prey Hg & loon blood. • High correlation between Hg in loon blood & eggs. • Increase in Hg in bird blood from marine to estuarine to river to lake. • Trend to higher Hg in adult than in young birds • Trend to higher Hg in the larger sex of each species • Common loon proposed for national indicator program • There is an ecological impact to individual loons and likely population effects from Hg

13. Tools for Accessing Data, Models, and Ancillary Information • A huge volume of data on Hg in fish and other biota have been collected over time. • These data are beginning to become available to other investigators through development of large databases that collect data for numerous projects. • Making these data available and modeling the data can serve users by reducing the costs of projects by reducing the need to collect new data.

14. Tools for Accessing Data, Models, and Ancillary Information • One problem to further collecting/aggregating data is incompatibility in data formats and/or mis-entered or missing meta data. • Fish tissue; the “Wente” National dataset. Contains 45K records of fish tissue, with potential for up to 100K records. • EMMMA@usgs,gov

15. Tools for Accessing Data, Models, and Ancillary Information • NADP –MDN data – Weekly monitoring of wet Hg (plus occasionally dry). There is the need to expand MDN coverage. Nonetheless, these MDN measurements are collectively indicating a general decrease in wet Hg deposition. This monitoring needs to continue. GOOGLE: Mercury Deposition Network • 17K record dataset (3.2 Hg records) for contaminants in wildlife. WWW.PWRC.USGS.gov/contaminants-online

16. Tools for Accessing Data, Models, and Ancillary Information • Other datasets are available to compliment these data collections. A strong recommendation would be to allocate $ to make these large datasets more complete. • New data should be collected in such a way as to promote data consistency at Regional/National scales.

17. Hg0 RGM PgM Geo_M (Wet + Dry) RM So42- Doc Mercury Sources: Summary • Local sources MATTER • Weight of evidence so far suggests that local and continental atmospheric sources DRIVE supply of reactive Hg (RM) • Caveats • Global atmospheric sources are becoming more important • Hgº half life is key modeling factor, but measurements to date support a longer Dep at pristine sites are likely half global; half N. American • New Hg 8x more “available than old • MANY PATHWAYS • Wet Dep • Dry Dep • Geological • Mining • Weathering/natural • Geothermal AXIS OF Methylation Relative importance of a given pathway depends on LOCATION (That means MAPS) Relative Importance of Hg sources to methylation depends other factors on the ground (That means more MAPS)

18. Mercury Sources: a management perspective • Think like a manager: • $20-50k (if you are lucky!) • Need to focus money on most important, or the best guess as to what’s most important • Long-term sensitive indicator (often, no “s” at park funding levels) of Hg risk • Get to know your NPS region’s Inventory & Monitoring coordinators! • Approaches: What to measure/monitor? • Birds, Fishes (i.e., Hearn descriptive maps)? • Axis of “Methylation” (i.e., process-based) • SO42-, DOC, etc are the other factors besides Hg availability that contribute to MeHg • Both have been applied in GIS/Map-based frameworks • Hearn and Wente--maps descriptive/empirical • Booth et al--processes/axis of Meth.. (see poster) • DATA QUALITY ACT • Uncertainty has to be quantified and identified • LOCATION, LOCATION, LOCATION--MAPS

19. Mercury Sources: Which is important where?

20. Mercury Sources: How to communicate with Managers Seigneur, C., K. Vijayaraghavan, K. Lohman, P. Karamchandani and C. Scott, 2004. Global source attribution for mercury deposition in the United States. Environmental Science & Technology 38(2), 555-569. (Maps and map tools are better than just papers for busy managers-synthesis)

21. Influence of Ecosystem Setting on Mercury and Mercury Management • DOC/S/Hg Triad - Controls Hg dynamics mainly by influencing microbial community structure • Many ecosystem factors control the DOC/S/Hg Triad - landscape dynamics (pH, eutrophication, water level,fire) - ecosystem type (e.g. SW marsh vs. FW marsh) - food-web dynamics - elevation

22. Influence of Ecosystem Setting on Mercury and Mercury Management • Coordination of existing programs may be sufficient to help us assess ecosystem response to emission reductions (instead of a large federally funded program) • Ecosystems are complex, no one factor drives Hg bioavailability • What information is most useful to ecosystem managers?