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Title: Kinetics of Methylmercury Production Revisited

Journal Article · · Environmental Science and Technology
 [1];  [1];  [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division
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Laboratory measurements of the biologically mediated methylation of mercury (Hg) to the neurotoxin monomethylmercury (MMHg) often exhibit kinetics that are inconsistent with first-order kinetic models. Using time-resolved measurements of filter passing Hg and MMHg during methylation/demethylation assays, a multisite kinetic sorption model, and reanalyses of previous assays, we show in this paper that competing kinetic sorption reactions can lead to time-varying availability and apparent non-first-order kinetics in Hg methylation and MMHg demethylation. The new model employing a multisite kinetic sorption model for Hg and MMHg can describe the range of behaviors for time-resolved methylation/demethylation data reported in the literature including those that exhibit non-first-order kinetics. Additionally, we show that neglecting competing sorption processes can confound analyses of methylation/demethylation assays, resulting in rate constant estimates that are systematically biased low. Finally, simulations of MMHg production and transport in a hypothetical periphyton biofilm bed illustrate the implications of our new model and demonstrate that methylmercury production may be significantly different than projected by single-rate first-order models.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Biological and Environmental Research (BER)
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1423042
Journal Information:
Environmental Science and Technology, Vol. 52, Issue 4; ISSN 0013-936X
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 13 works
Citation information provided by
Web of Science

Figures / Tables (6)

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES