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 Sequoia NP San Jose

11. Results: RMP Pilot Study Wet deposition & rainfall concentrations South Bay Central Bay North Bay Region Area (km 2 )4852144341133 Rainfall (cm/yr)36685853 Hg Conc (ng/L)9.76.67.48.0 Wet Dep (µg/m 2 ·yr)3.54.54.34.2 Loading (kg/yr)1.70.961.84.8

12. Results: MDN RMP Pilot S Bay: Conc < 10ng/L, rainfall <.5m/yr San JoseSequoia 2 nd half 2003 2.04 µg/m 2.115 m precip 17.7 ng/L (3.60 µg/m 2 13.4 ng/L all year) 2.56 µg/m 2.526 m precip 4.87 ng/L 20042.02 µg/m 2.257 m precip 7.88 ng/L 1.74 µg/m 2.412 m precip 4.22 ng/L 20053.56 µg/m 2.431m precip 8.26 ng/L 6.42 µg/m 2 1.29 m precip 4.98 ng/L

13. Results: RMP Pilot Study Atmospheric Concentrations (pg/m 3 ) No speciation measured South Bay Central Bay North Bay Entire Estuary Average2.201.902.302.10 Stdev.66.33.59.57 (pg/m 3 )

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/m 2 ·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/m 2 ·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 202 Hg(II) converted to Me 202 Hg 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?)