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Mercury Sources in Local Watersheds: Speciation, Release to Stormwater, and Remaining Questions

8. Mercury Sources in Local Watersheds: Speciation, Release to Stormwater, and Remaining Questions. Lester McKee RMP Sources Pathways and Loadings Work Group Chair San Francisco Estuary Institute lester@sfei.org Feb 19 th 2008. 8. RMP Hg Strategy.

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Mercury Sources in Local Watersheds: Speciation, Release to Stormwater, and Remaining Questions

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  1. 8 Mercury Sources in Local Watersheds:Speciation, Release to Stormwater, and Remaining Questions Lester McKee RMP Sources Pathways and Loadings Work Group Chair San Francisco Estuary Institute lester@sfei.org Feb 19th 2008

  2. 8 RMP Hg Strategy “…it may be possible to identify specific fractions of total mercury entering the Bay…that contribute disproportionately to accumulation in species of concern…” Q2. Which processes, sources, and pathways contribute disproportionately to food web accumulation? • Implies we need to understand: • Mass loads – essential for TMDLs • Speciation (availability) of different inputs • Temporal dynamics (within years and between years) • Spatial patterns (Local impacts)

  3. 8 Outline • Review sources, loads, speciation, and temporal dynamics in Bay Area: • Mining runoff • Urban runoff • Non-urban runoff • First order estimate of methyl-Hg entering the Bay from watersheds. Not ready to do reactive-Hg loads.

  4. 8 Mining Sources - “True Sources” draining to SF Bay • CEP report (Abu-Saba, 2003) • High Priority (documented discharges, high connectivity to the Bay, obvious habitat threats): • Marsh Creek, Mt Diablo • La Joya, Napa R. • Bella Oaks, Napa R. • Borges, American Canyon Ck. • New Almaden Mines, Guadalupe R.

  5. 8 Mining Sources(New Almaden, Guadalupe R.)Total Hg Loads Estimated Long Term Average (1975-2006) = 129 kg * Year-to-date Estimated *

  6. 8 Mining Sources(New Almaden, Guadalupe R.)Wet Season Speciation * Weighted concentration () = authors preference

  7. 8 Mining Sources(New Almaden, Guadalupe R.)Temporal dynamics (within years) HgD(%) 15% MeHgT(%) 2%

  8. 8 Industrial, railway lines and auto wreckers Urban Sources Land fills, recycling facilities and transport of recyclable goods Ongoing uses (dental, batteries, laboratory, PDAs, other) Watershed surface and channel sediment erosion (natural background) Gasoline and diesel Paint Watershed surface and channel sediment erosion (atmospherically derived) Atmospheric deposition (on going)

  9. 8 Urban Sources Estimate 45% of the urban Hg budget is either derived from historic atmospheric loading or ongoing atmospheric loading Watershed surface and channel sediment erosion (atmospherically derived) Atmospheric deposition (on going)

  10. 8 Urban Loads (estimates)

  11. 8 Urban Speciation * Weighted concentration () = authors preference

  12. 8 Urban Temporal dynamics (within years) (San Pedro, Storm Drain (San Jose) HgD(%) 65% MeHgT(%) 1%

  13. 8 Urban Temporal dynamics (within years) (Z4LA, Storm Drain (Hayward) 36% HgD(%) MeHgT(%) 4%

  14. Natural Background (0.08 mg/kg) Atmospheric Deposition (downwind of urban) Agriculture uses (pesticides and dairy) Rural home uses 8 Non-urban Sources Watershed surface and channel sediment erosion (natural background) Watershed surface and channel sediment erosion (atmospherically derived)

  15. 8 Non-urban Sources • Atmospheric Deposition (downwind of urban) Watershed surface and channel sediment erosion (atmospherically derived)

  16. 8 Non-urban Loads

  17. 8 Non-urban Speciation * Dependant on amount of wetland () = authors preference

  18. 8 Non-urban Temporal dynamics (within years) • No information locally • Review by Mason and Dean (2007) summarizes much of the recent literature: • Higher % HgD associated with low SSC streams and summer base flow • Seasonality of % MeHgT less clear but can correlate with flow, SSC, and HgT in some systems. Influenced by %wetland and DOC in some systems

  19. 8 First Order Estimate of MeHgT loads *Biggest uncertainty

  20. 8 Summary • A picture of total and methyl mercury variation in Bay Area watersheds is emerging • Loads Speciation Seasonality New Q2 • Non-urban runoff is potentially a large source of MeHg and Hg-R in both wet and dry weather flow • No local data(Suggest Napa, Walnut, Alameda, or Coyote) • Urban dry weather flows high in MeHg and Hg-R as a % of HgT, but no loads data to determine impact • Will sampleZ4LA this early summer (n = 9 samples) • Bay Hg Basin Plan Amendment and MRP call for monitoring

  21. 8 References Mason R., and Dean, D., 2007. WERF’s bioavailability project: Research update. The Claremont Resort & Spa, Berkeley, California, December 4-5, 2007. McKee, L., Leatherbarrow, J., Eads, R., and Freeman, L., 2004. Concentrations and loads of PCBs, OC pesticides, and mercury associated with suspended sediments in the lower Guadalupe River, San Jose, California. A Technical Report of the Regional Watershed Program: SFEI Contribution #86. San Francisco Estuary Institute, Oakland, CA. 79pp.

  22. 8 Acknowledgements • SFEI field and data management staff • Sources Pathways and Loading Work Group • Funding from: • RMP • CEP • SCVWD, SCVURPPP, USACE • Water Board • Moss Landing Marine Laboratories

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