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SF Bay Region Atmospheric Mercury Monitoring

Explore atmospheric mercury monitoring study from RMP and USEPA in SF Bay Region, with data on wet deposition and ambient concentrations. Management implications for urban pollution. Detailed analysis and implications for future mercury monitoring protocols.

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SF Bay Region Atmospheric Mercury Monitoring

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  1. SF Bay Region Atmospheric Mercury Monitoring Funded by: RMP, USEPA w/ services by: NADP/MDN, Contra Costa, San Francisco, San Jose

  2. Relevant Management Questions • Are current estimates about loading to San Francisco Bay from watersheds, wastewater treatment facilities, and atmosphere valid? • What is the contribution of atmospheric deposition to urban storm water?

  3. SF Region Atmospheric Hg • RMP Pilot Study • 1999-2000, wet deposition + dry ambient concentration, 3 sites • Mercury Deposition Network (MDN) • wet deposition continued 2000-2006 @ RMP pilot study South Bay site (NASA Ames) • Guadalupe & NASA Ambient Hg • ambient concentration @NASA, Calero, Fall 2005

  4. RMP Pilot Study Sites • Away from sources as practicable • Located North (Martinez), Central (Treasure Island), South (NASA Ames) Bay • NASA Ames becomes MDN site

  5. NASA Ames • MDN CA72 “San Jose” site

  6. Calero Reservoir

  7. RMP Pilot Study/MDN • Aerochem (wet deposition) collector

  8. Guadalupe/NASA Ambient • EPA Region IX Mobile Hg Lab

  9. Mobile Hg Lab (Interior) • Tekran automated Hg analyzer w/ particulate and reactive speciation modules. • 2537 • 1135 • 1130

  10. 2006 California MDN Sites San Jose Sequoia NP

  11. Results: RMP Pilot Study • Wet deposition & rainfall concentrations

  12. Results: MDN • RMP Pilot S Bay: Conc < 10ng/L, rainfall < .5m/yr

  13. Results: RMP Pilot Study • Atmospheric Concentrations (pg/m3) • No speciation measured (pg/m3)

  14. Results: Calero • Daily afternoon Hg max (all species) • Reactive + particulate ~0.3% of elemental

  15. Results: NASA • Daily morning Hg (elemental) max • Reactive + particulate ~0.2% of elemental

  16. Summary: • Atmospheric conc and annual wet dep similar to previous RMP Pilot Study (Bayside & watershed sites similar magnitude) • Direct wet dep flux to Bay ~4 µg/m2·yr (load ~5 kg/yr) • Reactive + particulate ~0.2-0.3% of elemental Hg (~20x lower than previous RMP Pilot Study estimate of ~5% from literature) • Direct dry dep flux to Bay ~2.5 µg/m2·yr (~3 kg/yr load, w/ 2 kg elemental, 1 kg reactive+particulate)

  17. Management Implications: (with a bit of handwaving) • Reactive+particulate= ionic dry dep ~ 1 kg/yr • Ionic wet dep unknown, possibly ~.015 kg/yr (0.3% of total) to 5 kg/yr (100%) • New ionic mercury most readily available for methylation (METAALICUS, 6% of applied 202Hg(II) converted to Me202Hg within 1 day) • 0.4 to 2 pg/L·day ionic Hg available from air dep for methylation (1% to 5% of ambient MeHg conc) • Need speciation for wet dep and other Hg loads to the Bay (which <1% of tot Hg becomes MeHg?)

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