SS4.06 Speciation, Bioavailability, and Impacts of Atmospheric Trace Metals in Aquatic Systems
Date: Wednesday, June 12, 2002
Location: Poster Session - VCC
 
ZvalarenSD, University of North Carolina at Wilmington, Wilmington, USA, zvalarens@uncwil.edu
Willey, J, D, University of North Carolina at Wilmington, Wilmington, USA, willeyj@uncwil.edu
Kieber, R, J, University of North Carolina at Wilmington, Wilmington, USA, kieberr@uncwil.edu
 
CHROMIUM SPECIATION IN COASTAL RAINWATER
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Chromium exists in two oxidation states in natural waters, Cr(III) and Cr(VI). The toxicity and solubility of chromium are dependent on its oxidation state. Hexavalent chromium is a toxic soluble anion, while trivalent chromium is a less toxic, particle reactive cation. Chromium is released into the atmosphere by natural and anthropogenic sources. Rainwater is thought to be an important removal mechanism for atmospheric chromium. The concentration and speciation of chromium were determined in rainwater samples from Wilmington North Carolina, a coastal community, from October 1999 to December 2001. Volume weighted average concentrations of Cr(total), Cr(III) and Cr(VI) in rainwater were 4.8nM, 0.9nM and 1.5nM respectively. Hexavalent and trivalent chromium were present in all seasons. Cr(VI) concentrations were higher in the summer, and Cr(III) concentrations were higher in the winter. No evidence of photochemical reaction was observed for Cr(III) or Cr(VI). Cr(III) and Cr(VI) concentrations did not correlate with each other, or with other rainwater parameters including Cr(total), Fe(II), Fe(III), hydrogen ion, chloride, nitrate and dissolved organic carbon concentrations.