Michael Murray, Ph.D. National Wildlife Federation

and 12 co-authors

National Water Quality Monitoring ConferenceSan Jose, CAMay 10, 2006

A Framework for Monitoring the Response to Changing Mercury Releases

Developed through workshop organized by Society of Environmental Toxicology and

Chemistry, September 2003

Fish Consumption Advisories for Mercury

NOTE: This map depicts the presence and type of fish advisories issued by the states for mercury as of December 2004. Because only selected waterbodies are monitored, this map does not reflect the full extent of chemical contamination of fish tissues in each state or province.

Source: U.S. EPA, National Listing of Fish Advisories

Source: EPA, Controlling Power Plant Emissions: Emissions Progress (EPA Web site)

September 2003 Workshop

• Organized by Society of Environmental Toxicology and Chemistry, involving 33 mercury researchers, and funded by U.S. Environmental Protection Agency, Electric Power Research Institute and others

• Rationale:– Voluntary and regulatory Hg programs continue to be

implemented– No systematic, integrated national monitoring done to

assess trends in Hg in various environmental compartments

– Need for more information on environmental impact of specific programs (e.g. rule affecting U.S. coal-fired power plants)

Workshop ParticipantsGovernment

• David P. Krabbenhoft, USGS/WRD

• Tamara Saltman, EPA Clean Air Markets Div.

• Michael L. Abbott, Idaho National Engineering and Env. Laboratory

• Robert B. Ambrose, US EPA/ORD

• Thomas D. Atkeson, FL Dept. Environ. Protection

• Drew Bodaly, Freshwater Institute, Canada

• O. Russell Bullock, Jr., US EPA/ORD

• Dan R. Engstrom, St. Croix Watershed Res. Station

• Richard A. Haeuber, US EPA Headquarters

• Steven E. Lindberg, Oak Ridge National Laboratory (ret.)

• John Munthe, Swedish Environ. Res. Institute

• Mark Nilles, USGS• Edward Swain, Minnesota

Pollution Control Agency

Academia• Robert P. Mason,

UMCES, CBL• Michael Newman, VIMS• William W. Bowerman,

Clemson University• Joanna Burger, Rutgers

University• Charles Driscoll, Syracuse

University• Cynthia C. Gilmour,

Smithsonian Environmental Research Center

• James P. Hurley, University of Wisconsin

• Marc Lucotte, Univ. Quebec, Montreal

• Nicola Pirrone, CNR-Institute for Atmospheric Pollution, Italy

• James G. Wiener, University of Wisconsin-La Crosse

• Marti F. Wolfe, California State University-Chico

Industry/NGO/Other• Reed C. Harris, Tetra

Tech, Inc.• Michael Murray, National

Wildlife Federation• Robin J. Reash, American

Electric Power• Steven S. Brown, Rohm &

Haas Company• David C. Evers,

BioDiversity Research Inst.• John J. Jansen, Southern

Company Services, Inc.• Dennis Leonard, Detroit

Edison• Leonard Levin, Electric

Power Research Institute• Donald B. Porcella,

Environ. Science and Management

• Edward J. Zillioux, Florida Power and Light Company 

(Bold indicates co-authors on presentation)

September 2003 Workshop – Approach

• Format: plenary discussions and deliberation/drafting within four work groups (airsheds and watersheds, sediments/water, aquatic biota, wildlife)

• General approach:– Establish criteria for Hg indicators– Use criteria to identify indicators of Hg contamination in

various environmental matrices– Using indicators, develop framework that can form basis

of national/continental monitoring network to assess responses to changes in Hg releases

Products

• Overview paper in Environmental Science and Technology (Mason et al., 2005, 39(1):14A-22A)

• Presentations (ICMGP, 2004; EUEC, 2005, EPA/USGS Hg Roundtable, 2005) and Congressional briefings

• Book to be published by SETAC/Taylor & Francis (2006)

Mercury Cycling is Complex

Source: Harris et al. 2006

Factors to Consider in Developing Hg Monitoring Network• Magnitude (or potential) of changes in Hg releases and

deposition• Larger-scale spatial variability (e.g. local vs. regional vs.

global sources)• Temporal variability

– Source strength and its changes (e.g., different magnitude of changes in regional sources vs. global)

– Differences in response time of systems (e.g., watershed soil vs. water column vs. phytoplankton vs. forage fish tissue Hg)

• Factors affecting formation of methylmercury (e.g., organic carbon, redox potential, sulfate, bacterial populations), and additional factors that can alter bioaccumulation and biomagnification in aquatic food webs and exposure in wildlife

Criteria Used in Developing Hg Indicators

• Ideal indicator characteristics:– Relevant to human health endpoints– Responsive to changes in Hg loadings– Quality historical data available– Adequate data collection infrastructure in place– Sampling and analysis is feasible– Able to adjust for confounding factors– Easily related to other components of ecosystem– Widely applicable (have broad geographic distribution)– For fauna:

• Involve fauna with well known life history• Able to be measured non-invasively, or otherwise not

significantly impact populations

  Cluster Intensive# Sites/ecoregion

Approx. 15-20 Approx. 1

Selection basis

Similar broad ecological characteristics but different site conditions

Include sites where changing loads are expected

Parameters measured

Primary Hg indicators Generally primary Hg indicators + additional parameters

Purpose Identify general trends Address mechanistic questions (e.g. extent of biota MeHg change associated with changes in Hg deposition)

• Envision sampling within each of approx. 10 ecoregions in U.S. (or North America)

• Sampling scheme would involve cluster and intensive sites:

Monitoring Network Structure

Source: EPA, Regulatory Impact Analysis for Clean Air Mercury Rule, 2005

 Compartment Indicator SitesAir and watersheds

Total weekly wet Hg deposition ClusterSpeciated atmospheric measurements IntensiveSnowpack sampling ClusterWatershed yield IntensiveEvasion flux (aquatic and terrestrial) Intensive

Water and sediments (Hg characterization)

Total Hg and MeHg in surface water Cluster/intensiveTotal Hg, MeHg, and % MeHg in surface sediments

Cluster/intensive

Total Hg accumulation in sediments Cluster/intensiveInstantaneous methylation/demethylation rates

Intensive

Types of Hg Indicators – Airsheds, Watersheds, and Characterization in Water and Sediments

Sampling frequency would range from quarterly (e.g., sediment sampling at intensive sites) to every 5-10 years (total Hg accumulation in sediments).

Compartment Indicator SitesAquatic biota* Yearling forage fish Cluster/intensive

Piscivorous fish Cluster/intensiveEstuarine benthic invertebrates Cluster/intensive

Wildlife** Raccoon ClusterMink IntensiveCommon loon Cluster/intensiveHerring gull ClusterHarbor porpoise & Leach’s storm petrel

Cluster

Bicknell’s thrush ClusterBelted kingfisher Cluster/intensive

Types of Hg Indicators – Aquatic Biota and Wildlife

*: Could analyze plankton to assist with mechanistic interpretations.**: Sampling tissues – generally blood, egg, fur or feathers, as appropriate; annual schedule (with sensitivity to seasonal variability).

Other Aspects of Monitoring Program• Need to measure relevant ancillary parameters:

– Hydrological parameters, watershed characteristics– Water, sediment chemistry – Biota characteristics (e.g. age, length/weight, sex,

condition)• Should take advantage of existing programs,

databases to extent practical (e.g., NADP/MDN network, LTER sites, fish tissue monitoring programs)

• Coupling measured data with modeling will be essential in fully understanding responses, in particular addressing mechanistic questions; also need to consider statistical issues in trend detection

Source: NADP/MDN Web site

Mercury Cycling in D-MCM

Inflow/Runoff

Outflow

Settling/Resusp Diffusion

Wet and dry Deposition

MeHg

Hg(0)

Hg(II)

Volatilization

Hg(II) MeHg

Bioaccumulation

BurialBurial

Settling/Resusp Diffusion

Mercury Concentrations in Florida Everglades Largemouth Bass

From: Atkeson et al., 2003, Integrating Atmospheric Mercury Deposition with Aquatic Cycling in South Florida

From: Atkeson et al., 2003, Integrating Atmospheric Mercury Deposition with Aquatic Cycling in South Florida

Everglades: Model Projections of Impact of Load Reductions on Fish Mercury Levels

Summary

• Mercury cycling is complex, and a monitoring network must consider the many factors that affect Hg from source to receptor, with indicators chosen appropriately

• A network that includes both primary monitoring data (cluster sites) and use of additional indicators (intensive sites) offers best hope of detecting responses and understanding reasons for them

• Network should build on existing efforts, be started as soon as practical, and be in place for at least 15-20 years to fully capture environmental response to changes in Hg releases