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Title: Periphyton biofilms influence net methylmercury production in an industrially contaminated system

Abstract

Mercury (Hg) methylation and methylmercury (MMHg) demethylation activity of periphyton biofilms from East Fork Poplar Creek, Tennessee, USA (EFPC) were measured during 2014-2015 using stable Hg isotopic rate assays. 201Hg II and MM 202Hg were added to intact periphyton samples and the formation of MM 201Hg and loss of MM 202Hg were monitored over time and used to calculate first-order rate constants for methylation and demethylation, respectively. The influence of location, temperature/season, light exposure and biofilm structure on methylation and demethylation were examined. Between-site differences in net methylation for samples collected from an upstream versus downstream location were driven by differences in the demethylation rate constant (k d). In contrast, the within-site seasonal difference in net methylation was driven by changes in the methylation rate constant (k m). Samples incubated in the dark had lower net methylation due to km values that were 60% less than those incubated in the light. Disrupting the biofilm structure decreased km by 50% and resulted in net demethylating conditions. Overall, the measured rates resulted in a net excess of MMHg generated which could account for 27-85% of the MMHg flux in EFPC and suggests intact, actively photosynthesizing periphyton biofilms harbor zones of MMHg production.

Authors:
 [1];  [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1326487
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Environmental Science and Technology
Additional Journal Information:
Journal Name: Environmental Science and Technology; Journal ID: ISSN 0013-936X
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 54 ENVIRONMENTAL SCIENCES; mercury; East Fork Poplar Creek; methylmercury; periphyton

Citation Formats

Olsen, Todd Andrew, Brandt, Craig C., and Brooks, Scott C. Periphyton biofilms influence net methylmercury production in an industrially contaminated system. United States: N. p., 2016. Web. doi:10.1021/acs.est.6b01538.
Olsen, Todd Andrew, Brandt, Craig C., & Brooks, Scott C. Periphyton biofilms influence net methylmercury production in an industrially contaminated system. United States. doi:10.1021/acs.est.6b01538.
Olsen, Todd Andrew, Brandt, Craig C., and Brooks, Scott C. Mon . "Periphyton biofilms influence net methylmercury production in an industrially contaminated system". United States. doi:10.1021/acs.est.6b01538. https://www.osti.gov/servlets/purl/1326487.
@article{osti_1326487,
title = {Periphyton biofilms influence net methylmercury production in an industrially contaminated system},
author = {Olsen, Todd Andrew and Brandt, Craig C. and Brooks, Scott C.},
abstractNote = {Mercury (Hg) methylation and methylmercury (MMHg) demethylation activity of periphyton biofilms from East Fork Poplar Creek, Tennessee, USA (EFPC) were measured during 2014-2015 using stable Hg isotopic rate assays. 201HgII and MM202Hg were added to intact periphyton samples and the formation of MM201Hg and loss of MM202Hg were monitored over time and used to calculate first-order rate constants for methylation and demethylation, respectively. The influence of location, temperature/season, light exposure and biofilm structure on methylation and demethylation were examined. Between-site differences in net methylation for samples collected from an upstream versus downstream location were driven by differences in the demethylation rate constant (kd). In contrast, the within-site seasonal difference in net methylation was driven by changes in the methylation rate constant (km). Samples incubated in the dark had lower net methylation due to km values that were 60% less than those incubated in the light. Disrupting the biofilm structure decreased km by 50% and resulted in net demethylating conditions. Overall, the measured rates resulted in a net excess of MMHg generated which could account for 27-85% of the MMHg flux in EFPC and suggests intact, actively photosynthesizing periphyton biofilms harbor zones of MMHg production.},
doi = {10.1021/acs.est.6b01538},
journal = {Environmental Science and Technology},
number = ,
volume = ,
place = {United States},
year = {Mon Sep 12 00:00:00 EDT 2016},
month = {Mon Sep 12 00:00:00 EDT 2016}
}

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