Kinetic controls on the complexation between mercury and dissolved organic matter in a contaminated environment
- ORNL
The interaction of mercury (Hg) with dissolved natural organic matter (NOM) under equilibrium conditions is the focus of many studies but the kinetic controls on Hg-NOM complexation in aquatic systems has often been overlooked. We examined the rate of Hg-NOM complexation using reactive Hg (HgR) measurements and C18 solid phase extraction in Upper East Fork Poplar Creek (UEFPC) in Oak Ridge, Tennessee, and in controlled laboratory experiments using a reference NOM isolate. Greater than 90% of the dissolved Hg at the headwaters of UEFPC was present as HgR and this fraction decreased downstream but remained >25% of the dissolved Hg at all sites. Equilibrium calculations indicate that Hg-NOM complexes should dominate throughout UEFPC, but the presence of HgR suggests that equilibrium conditions are not established. Rate constants for Hg-NOM complexation varied between 0.05 and 0.29 hr-1 in laboratory experiments. This study demonstrates the need to consider Hg-NOM complexation kinetics on processes such as Hg methylation and solid phase partitioning.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 985273
- Journal Information:
- Environmental Science & Technology, Vol. 43, Issue 22; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- English
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