Sources of Methylmercury to Snowpacks of the Alberta Oil Sands

Dec 3, 2017 - Snowpacks in the Alberta Oil Sands Region (AOSR) of Canada contain elevated loadings of methylmercury (MeHg; a neurotoxin that ...
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Sources of methylmercury to snowpacks of the Alberta Oil Sands Region: A study of in situ methylation and particulates Chelsea E. Willis, Jane L. Kirk, Vincent L. St.Louis, Igor Lehnherr, Parisa A Ariya, and Rodrigo Benjamin Rangel-Alvarado Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.7b04096 • Publication Date (Web): 03 Dec 2017 Downloaded from http://pubs.acs.org on December 4, 2017

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Environmental Science & Technology

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Sources of methylmercury to snowpacks of the Alberta Oil Sands

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Region: A study of in situ methylation and particulates

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Chelsea E. Willis†, Jane L. Kirk*,‡, Vincent L. St. Louis†, , Igor Lehnherr§, Parisa A. Ariyaǁ,

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Rodrigo Benjamin Rangel-Alvarado¤

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Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada

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Aquatic Contaminants Research Division, Environment and Climate Change Canada,

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Burlington, Ontario L7S 1A1, Canada

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§

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Canada

Department of Geography, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6,

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ǁ

Department of Atmospheric & Oceanic Sciences and ¤Department of Chemistry, McGill

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University, Montréal, Québec H3A 2K6, Canada

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Methylmercury, snow, Alberta Oil Sands Region, mercury methylation, mercury stable isotopes,

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particle-bound methylmercury

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*

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ABSTRACT: Snowpacks in the Alberta Oil Sands Region (AOSR) of Canada contain

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elevated loadings of methylmercury (MeHg; a neurotoxin that biomagnifies through foodwebs)

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due to oil sands related activities. At sites ranging from 0-134 km from the major AOSR

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upgrading facilities, we examined sources of MeHg by quantifying potential rates of MeHg

email: [email protected]

ACS Paragon Plus Environment

Environmental Science & Technology

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production in snowpacks and melted snow using mercury stable isotope tracer experiments, as

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well as quantifying concentrations of MeHg on particles in snowpacks (pMeHg). At four sites,

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methylation rate constants were low in snowpacks (km=0.001–0.004 d-1) and non-detectable in

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melted snow, except at one site (km=0.0007 d-1). The ratio of methylation to demethylation varied

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between 0.3-1.5, suggesting that the two processes are in balance and that in situ production is

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unlikely an important net source of MeHg to AOSR snowpacks. pMeHg concentrations

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increased linearly with distance from the upgraders (R2=0.71, p