Binding of mercury(II) to aquatic humic substances: Influence of pH and source of humic substances

Haitzer, M.; Aiken, G. R.; Ryan, J. N.

Abstract:

Conditional distribution coefficients (KDOM???) for Hg(II) binding to seven dissolved organic matter (DOM) isolates were measured at environmentally relevant ratios of Hg(II) to DOM. The results show that KDOM??? values for different types of samples (humic acids, fulvic acids, hydrophobic acids) isolated from diverse aquatic environments were all within 1 order of magnitude (1022.5??1.0-1023.5??1.0 L kg-1), suggesting similar Hg(II) binding environments, presumably involving thiol groups, for the different isolates. KDOM??? values decreased at low pHs (4) compared to values at pH 7, indicating proton competition for the strong Hg(II) binding sites. Chemical modeling of Hg(II)-DOM binding at different pH values was consistent with bidentate binding of Hg(II) by one thiol group (pKa = 10.3) and one other group (pKa = 6.3) in the DOM, which is in agreement with recent results on the structure of Hg(II)-DOM bonds obtained by extended X-ray absorption fine structure spectroscopy (EXAFS).

Genre:

Article

ProdID:

70025408

Citation Author:

Haitzer, M.; Aiken, G. R.; Ryan, J. N.

Citation Contributing Office:

Citation Datum:

Citation Day:

Citation Edition:

Citation Editor:

Citation End Page:

2441

Citation Issue:

Citation Keywords:

Citation Language:

English

Citation Larger Work Title:

Environmental Science and Technology

Citation LatN:

Citation LatS:

Citation LonE:

Citation LonW:

Citation Month:

Citation No Pagination:

Citation Number Of Pages:

Citation Online Only Flag:

Citation Phsyical Description:

Citation Projection:

Citation Public Comments:

Citation Publisher:

Citation Series:

Citation Series Code:

Citation Series Number:

Citation Search Results Text:

Binding of mercury(II) to aquatic humic substances: Influence of pH and source of humic substances; 2003; Article; Journal; Environmental Science and Technology; Haitzer, M.; Aiken, G. R.; Ryan, J. N.