Reconnaissance Survey of Mercury in Water, Sediment, and Fish from U.S. Streams

1. Reconnaissance Survey of Mercury in Water, Sediment, and Fish from U.S. Streams By Barbara Scudder, Lia Chasar, Nancy Bauch, Dennis Wentz, Mark Brigham, David Krabbenhoft, Patrick Moran, William Brumbaugh, and Michelle Lutz U.S. Department of the Interior U.S. Geological Survey

2. Fish Consumption Advisories – 2004 (source: USEPA National Listing of Fish Advisories)

3. Percentage of Lake Acres / River Miles with Mercury Advisories (source: USEPA National Listing of Fish Advisories, 2004)

4. USGS Mercury Studies in Rivers • Reconnaissance Survey of Mercury • 1998 Pilot: 106 sites • Krabbenhoft and others (1999) • Brumbaugh and others (2001) • 1999-2002: 113 sites • 2004-5: 60 sites • Detailed Studies of Mercury Cycling and Bioaccumulation • 2003-4: 8 sites • 2006-7: 5 sites

5. Reconnaissance Survey Objectives • Assess total mercury (THg) and methylmercury (MeHg) in water and streambed sediment, and THg in fish • Span regional and national gradients in mercury source strength (deposition, mining) and factors that govern mercury cycling • Identify ecosystem characteristics that favor the production and bioaccumulation of MeHg • Explore environmental factors that may drive regional and national variations in fish mercury concentrations

6. Study Design – 1998 Pilot • Sites selected based on factors thought to be important in bioavailability of mercury, in priority: • wetland density in basin • pH, sulfate, organic carbon • Suspected or known mercury loading • Samples collected June through October 1998

7. Study Design: > 1998 • Expand on site coverage from 1998 • Base site network on: • Targeted settings • Reference/noncultivated • Cultivated agriculture • Urban • Mining (current or abandoned) • Factors thought to affect mercury methylation • Wetland density in watershed • Water chemistry (pH, sulfate, DOC) • Mercury loading – suspected or known

8. 100 80 60 40 20 0 Land Cover/ Land Use of All U.S. Stream Basins (n=62,000) in Blue and USGS Mercury Reconnaissance Basins (n=219) in Green Percent Land Cover/Land Use Ag Urban Forest Range

9. Methods • Surface-water • Single grab sample – center of stream flow • Filtered and particulate MeHg, THg (unfiltered in 1998) • pH, temperature, DO, DOC, sulfate • Streambed sediment • Single composite sample • Bulk (unsieved) – surface, depositional areas • MeHg and THg • Particle size, dry weight • Acid volatile sulfide • Loss on ignition (surrogate for organic carbon)

10. Methods (continued) • Sampled Predator Fish • Electrofishing • THg • Target: 3-4 year old Largemouth bass • Single-species composites (3-5 fish) • Skin-off fillets • Length, weight, age • Modeled fish (Wente, 2004) • Accounts for variability among sample events and sample characteristics • Based on THg and length of sampled fish from sites • 35.5 cm (14 in) largemouth bass and rainbow trout

18. Due to bioaccumulation and biomagnification, mercury in sampled fish was several orders of magnitude higher than the river water

19. Mercury in sampled fish increased with methylmercury in water

20. Mercury in sampled fish increased with methylmercury in water

21. Relation stronger for Hg in sampled largemouth bass and water

22. Conclusions • Total mercury concentrations in fish increased with increasing methylmercury concentrations in whole (unfiltered) water • Weak correlation between fish mercury and sediment methylmercury • Fish mercury concentrations exceeding the 0.3 ppm criterion were widespread, and particularly common in SE US streams and western mining-impacted streams.

23. State and Tribal personnel USGS personnel - Technical assistance NAWQA study unit personnel George Aiken, USGS-WRD, Boulder, CO Amanda Bell, USGS-WRD, Middleton, WI Rod DeWeese, USGS-BRD, Denver, CO Kerie Hitt, USGS-WRD, Reston, VA Steve Wente, USGS-WRD, Mounds View, MN Acknowledgments Contact info: Barb Scudder (bscudder@usgs.gov) US Geological Survey, 8505 Research Way, Middleton, WI 53711