Mercury Flux in an Urban Watershed System

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

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(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

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Why Urban?

• Increased anthropogenic inputs
• Altered ecosystem processes

• Added
• exposure

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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

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Main Branch
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Main Stem Chemical Flux
(Units THg, MeHg mg m-2 yr-1 DOC, TSS g
m-2 yr-1)
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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?

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What are effects of elevated events?
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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

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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)

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Every Cloud has a Quicksilver Lining
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Land Use Chemical Flux
(Units THg, MeHg mg m-2 yr-1 DOC, TSS g
m-2 yr-1)
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Effect of High Flow on Flux
(Units THg, MeHg mg m-2 yr-1 DOC, TSS g
m-2 yr-1)