1	The Role of Benthic Macrofauna in Influencing Fluxes and Speciation of Dissolved Zinc and Copper in Estuarine Sediments Ken MacGillivray Committee Members: Dr. Stephen A. Skrabal Dr. Robert J. Kieber Dr. Robert Whitehead University of North Carolina at Wilmington 5 September, 2002
2	Why Study Copper and Zinc? Can be toxic to biota Non-toxic at low conc.’s Ubiquitous Numerous anthropogenic sources Toxicity, bioavailability controlled by speciation
3	Why study the estuary? Mixing zone between ocean and river Interface between fresh and saline systems Unique chemistry
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5	Speciation of Cu and Zn Cu in the estuary: >99.9% occurs as Cu-L Zn in the estuary: 1-95% occurs as Zn-L Therefore, characterization of ligands crucial to understanding chemistry of Cu and Zn
6	Benthic Fluxes “Benthic” = bottom of estuary Sediments can be important sources or sinks for ligands, metals “Flux” = rate at which concentration of substance increases or decreases across sediment-water interface per m² Flux: measured in nmol m²d
7	Benthic Fluxes
8	Might benthic organisms influence fluxes in the CFE? Streblospio benedicti: a polychaete that is common in the CFE
9	S. benedicti
10	S. benedicti
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12	S. benedicti: Burrowing animal Can quickly rearrange sediment surfaces Hearty, opportunistic organism Normal density: 2,000 individuals per m²
13	Goals of this study: Determine TDCu, TDZn, and their fluxes Determine Speciation of Cu, Zn and ligand fluxes Characterize ligands (Find K’, classes) Effect of bioturbation on fluxes Significance of benthic fluxes to overlying water of estuary
14	Methods SAMPLING Collect with box corer (APRIL and JUNE, 2001) Transfer to core tubes Sample, Incubate 48-60 hours, Sample ANALYTICAL Electrochemical Analysis Total Dissolved Cu and T.D. Zn – Std. Additions Speciation: CLE-CSV
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