Skip to main content
U.S. flag

An official website of the United States government

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

January 1, 2002

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.

Citation Information

Publication Year 2002
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
DOI 10.1021/es0114005
Authors R. Todd Drexel, Markus Haitzer, Joseph N. Ryan, George R. Aiken, Kathryn L. Nagy
Publication Type Article
Publication Subtype Journal Article
Series Title Environmental Science & Technology
Series Number
Index ID 70185139
Record Source USGS Publications Warehouse
USGS Organization Toxic Substances Hydrology Program

Related Content