1. 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

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

3. Why? Why? Neurotoxin Neurotoxin Bioaccumulation potential Bioaccumulation potential What? What? Gaseous Hg o Gaseous Hg o Hg 2+ (RGM, ionic, particulate) Hg 2+ (RGM, ionic, particulate) Methyl Hg – BAD GUY, bioaccumulates Methyl Hg – BAD GUY, bioaccumulates Where? Where? Paints, pesticides, scientific/medical, electrical Paints, pesticides, scientific/medical, electrical Manufacturing (e.g. chlorine) Manufacturing (e.g. chlorine) Utilities/fossil fuels → atmospheric deposition Utilities/fossil fuels → atmospheric deposition (Cartoon from: www.grinningplanet.com)

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

5. Objectives Quantify the effect on Hg species flux with respect to: Quantify the effect on Hg species flux with respect to: Urbanization/Land use changes Urbanization/Land use changes Elevated discharge events Elevated discharge events Assess the impact of ecosystem alterations on Hg transport and transformation processes Assess the impact of ecosystem alterations on Hg transport and transformation processes 11 Sites associated with Gwynns Falls LTER 11 Sites associated with Gwynns Falls LTER Mercury: THg, MeHg, filtered vs. unfiltered Mercury: THg, MeHg, filtered vs. unfiltered Ancillary chemistry: e.g. DOC, TSS, SO 4 2-, DO Ancillary chemistry: e.g. DOC, TSS, SO 4 2-, DO

6. Main Branch Forest Suburban Urban Suburban Boundary

7. PBGBVNCP Forest Reference Suburban Headwater Suburban Boundary Urban Outlet THg 1.100.500.730.85 MeHg 0.0450.0110.0190.020 DOC 0.700.660.881.39 TSS 2.231.212.041.73 Main Stem Chemical Flux (Units: THg, MeHg –  g m -2 yr -1 ; DOC, TSS – g m -2 yr -1 )

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

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

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

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

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

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

14. “Every Cloud has a Quicksilver Lining”

15. PBGLMDRH ForestSuburbanAgUrban THg 1.100.460.332.02 MeHg 0.0450.0130.0170.028 DOC 0.700.820.362.07 TSS 2.232.050.713.36 Land Use Chemical Flux (Units: THg, MeHg –  g m -2 yr -1 ; DOC, TSS – g m -2 yr -1 )

16. PB GLMD RHRH-SC ForestSuburbanAgUrban Storm THg 1.10 0.460.33 2.026.72 MeHg 0.045 0.0130.017 0.0280.108 DOC 0.70 0.820.36 2.072.40 TSS 2.23 2.050.71 3.3614.6 Effect of High Flow on Flux (Units: THg, MeHg –  g m -2 yr -1 ; DOC, TSS – g m -2 yr -1 )