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SF Bay Region Atmospheric Mercury Monitoring

SF Bay Region Atmospheric Mercury Monitoring. Funded by: RMP, USEPA w/ services by: NADP/MDN, Contra Costa, San Francisco, San Jose. Relevant Management Questions. Are current estimates about loading to San Francisco Bay from watersheds, wastewater treatment facilities, and atmosphere valid?

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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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