Mercury(II) sorption to two Florida Everglades peat: Evidence for strong and weak binding and competition by dissolved organic matter released from the peat

Environmental Science & Technology
By: , and 

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Abstract

The binding of mercury(II) to two peats from Florida Everglades sites with different rates of mercury methylation was measured at pH 6.0 and 0.01 M ionic strength. The mercury(II) sorption isotherms, measured over a total mercury(II) range of 10-7.4 to 10-3.7 M, showed the competition for mercury(II) between the peat and dissolved organic matter released from the peat and the existence of strong and weak binding sites for mercury(II). Binding was portrayed by a model accounting for strong and weak sites on both the peat and the released DOM. The conditional binding constants (for which the ligand concentration was set as the concentration of reduced sulfur in the organic matter as measured by X-ray absorption near-edge structure spectroscopy) determined for the strong sites on the two peats were similar (Kpeat,s = 1021.8±0.1and 1022.0±0.1 M-1), but less than those determined for the DOM strong sites (Kdom,s = 1022.8±0.1and 1023.2±0.1 M-1), resulting in mercury(II) binding by the DOM at low mercury(II) concentrations. The magnitude of the strong site binding constant is indicative of mercury(II) interaction with organic thiol functional groups. The conditional binding constants determined for the weak peat sites (Kpeat,w = 1011.5±0.1 and 1011.8±0.1 M-1) and weak DOM sites (Kdom,w = 108.7±3.0 and 107.3±4.5 M-1) were indicative of mercury(II) interaction with carboxyl and phenol functional groups.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Mercury(II) sorption to two Florida Everglades peat: Evidence for strong and weak binding and competition by dissolved organic matter released from the peat
Series title Environmental Science & Technology
DOI 10.1021/es0114005
Volume 36
Issue 19
Year Published 2002
Language English
Publisher American Chemical Society
Contributing office(s) Toxic Substances Hydrology Program
Description 7 p.
First page 4058
Last page 4064
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