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Results for “Journal De Physique. IV : JP”

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2 recordsLinked to original sources
USGS1997

XAFS studies of Pb(II)-chloro and Hg(II)-chloro ternary complexes on goethite

EXAFS spectroscopy was used to study Pb(II) and Hg(II) adsorption complexes on goethite (α-FeOOH) in the presence of Cl - . At pH 7, the dominant Pb(II) species are bonded to edges of FeO 6 octahedra and are similar to complexes that occur in the absence of Cl - . At pH≤6, Pb(II)-chloro ternary complexes pedominate and are bonded to corners of FeO 6 octahedra. At pH 6.5, linear Hg(OH)Cl ternary complexes predominate that are bonded to goethite through surface oxygens in a bent Hg-O-Fe geometry. In the absence of Cl - , the Hg(II) surface complexes retain this basic geometry, but an OH group replaces the chloride ion in the first coordination shell.

Journal De Physique. IV : JP↗
USGS2003

Interactions between dissolved organic matter and mercury in the Florida Everglades

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.

Florida↗