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Title: Why dissolved organic matter (DOM) enhances photodegradation of methylmercury

Methylmercury (MeHg) is known to degrade photochemically, but it remains unclear what roles naturally dissolved organic matter (DOM) and complexing organic ligands play in MeHg photodegradation. Here we investigate the rates and mechanisms of MeHg photodegradation using DOM samples with varying oxidation states and origins as well as organic ligands with known molecular structures. All DOM and organic ligands increased MeHg photodegradation under solar irradiation, but the first-order rate constants varied depending on the oxidation state of DOM and the type and concentration of the ligands. Compounds containing both thiols and aromatics (e.g., thiosalicylate and reduced DOM) increased MeHg degradation rates far greater than those containing only aromatic or thiol functional groups (e.g., salicylate or glutathione). Our results suggest that, among other factors, the synergistic effects of thiolate and aromatic moieties in DOM greatly enhance MeHg photodegradation.
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  1. ORNL
Publication Date:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Science and Technology Letters; Journal Volume: 1; Journal Issue: 10
Research Org:
Oak Ridge National Laboratory (ORNL)
Sponsoring Org:
SC USDOE - Office of Science (SC)
Country of Publication:
United States
methylmercury; demethylation; photodegradation; mercury