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Mercury Flux in an Urban Watershed System

Mercury Flux in an Urban Watershed System. Joseph T. Bushey 1 , Peter M. Groffman 2 , Charles T. Driscoll 1 , Gary T. Fisher 3 1 Syracuse University Dept. of Civil & Environmental Engineering 2 Institute of Ecosystem Studies, 3 US Geological Survey October 19, 2006. Overview. Background

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Mercury Flux in an Urban Watershed System

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  1. Mercury Flux in an Urban Watershed System Joseph T. Bushey1, Peter M. Groffman2, Charles T. Driscoll1, Gary T. Fisher3 1Syracuse University Dept. of Civil & Environmental Engineering 2Institute of Ecosystem Studies, 3US Geological Survey October 19, 2006

  2. Overview • Background • Objectives • Results • Urbanization • Storm Events • Conclusions

  3. (Cartoon from: www.grinningplanet.com) • Why? • Neurotoxin • Bioaccumulation potential • What? • Gaseous Hgo • Hg2+ (RGM, ionic, particulate) • Methyl Hg – BAD GUY, bioaccumulates • Where? • Paints, pesticides, scientific/medical, electrical • Manufacturing (e.g. chlorine) • Utilities/fossil fuels → atmospheric deposition

  4. Why Urban? • Added exposure • Increased anthropogenic inputs • Altered ecosystem processes

  5. Objectives • Quantify the effect on Hg species flux with respect to: • Urbanization/Land use changes • Elevated discharge events • Assess the impact of ecosystem alterations on Hg transport and transformation processes • 11 Sites associated with Gwynns Falls LTER • Mercury: THg, MeHg, filtered vs. unfiltered • Ancillary chemistry: e.g. DOC, TSS, SO42-, DO

  6. Main Branch Forest Suburban Suburban Boundary Urban

  7. Main Stem Chemical Flux (Units: THg, MeHg – mg m-2 yr-1; DOC, TSS – g m-2 yr-1)

  8. What are effects of urbanization?- Hg mobility - • THg ↑ with urbanization WRT • DOC • TSS • Effect of runoff • Particulate Hg important for flux

  9. What are effects of urbanization?- Methylation potential - • Methylation • De-coupling of Hg-DOC • Decreased effect of biotic activity on Hg mobility • Anthropogenic DOC source? Oxic conditions?

  10. Urban Forest Suburban Base What are effects of elevated events?

  11. Conclusions • Urbanization alters Hg-DOC relationship and effects on Hg mobility • THg and MeHg flux ↓ under base flow conditions for developed ecosystems • Importance of particulate and high flow events on THg flux

  12. Future Work • Examine link between urban DOC and Hg mobility • Study the effect of the short-circuiting of ecosystem processes on Hg mobility • Investigate the interaction between the urban canopy cover and Hg loading • Explore the potential for diurnal variations

  13. Acknowledgements • Funding: • The Dreyfus Foundation • US Environmental Protection Agency • National Science Foundation (LTER Program) • Support: • Baltimore Co. Dept. of Envir. Protection & Mgmt. • USGS Cooperative Water Program • City of Baltimore Dept. of Public Works • Dan Dillon, Tara Krebs (IES) • M. Montesdeoca, J. Flagg, J. Hanley, M. Bushey (SU)

  14. “Every Cloud has a Quicksilver Lining”

  15. Land Use Chemical Flux (Units: THg, MeHg – mg m-2 yr-1; DOC, TSS – g m-2 yr-1)

  16. Effect of High Flow on Flux (Units: THg, MeHg – mg m-2 yr-1; DOC, TSS – g m-2 yr-1)

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