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Interactions between dissolved organic matter and mercury in the Florida Everglades

January 1, 2003

Experiments were conducted using organic matter isolated from various surface waters in the Florida Everglades to study the interactions between dissolved organic matter (DOM) and Hg (II). Conditional distribution coefficients ( ), obtained using an equilibriurn dialysis ligand exchange method, were strongly affected by the Hg/DOM concentration ratio. Very strong interactions (  = 10  L kg -1), indicative of Hg-thiol bonds, were observed at Hg/DOM ratios below approximately 1 g Hg per mg DOM. Above approximately 10 g Hg per mg DOM much lower  values (  L kg -1) were obtained. DOM-Hg interactions were also studied by HgS (log K ) dissolution and precipitation experiments. In the dissolution experiments, a significant amount of Hg was released from cinnabar in the presence of DOM, suggesting strong interactions. Conversely, precipitation of HgS was strongly inhibited in the presence of low concentrations ( 3 mg C/L) of DOM. In both the dissolution and precipitation experiments, organic matter rich in aromatic moities was more reactive with HgS than less aromatic fractions and sulfur-containing model compounds. These results suggest that DOM can influence the geochemistry of inorganic complexes of Hg in the Everglades, especially HgS, by strong Hg-DOM binding and colloidal stabilization.

Publication Year 2003
Title Interactions between dissolved organic matter and mercury in the Florida Everglades
DOI 10.1051/jp4:20030235
Authors G. Aiken, M. Haitzer, J. N. Ryan, K. Nagy, George Aiken
Publication Type Article
Publication Subtype Journal Article
Series Title Journal De Physique. IV : JP
Index ID 70025745
Record Source USGS Publications Warehouse
USGS Organization Toxic Substances Hydrology Program