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Higher mass-independent isotope fractionation of methylmercury in the pelagic food web of Lake Baikal (Russia).
MedLine Citation:
PMID:  22545798     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Mercury undergoes several transformations that influence its stable isotope composition during a number of environmental and biological processes. Measurements of Hg isotopic mass-dependent (MDF) and mass-independent fractionation (MIF) in food webs may therefore help to identify major sources and processes leading to significant bioaccumulation of methylmercury (MeHg). In this work, δ13C, δ15N, concentration of Hg species (MeHg, Inorg. Hg), and stable isotopic composition of Hg were determined at different trophic levels of the remote and pristine Lake Baikal ecosystem. Muscle of seals and different fish as well as amphipods, zooplankton and phytoplankton were specifically investigated. MDF during trophic transfer of MeHg leading to enrichment of heavier isotopes in the predators was clearly established by δ202Hg measurements in the pelagic prey-predator system (carnivorous sculpins and top-predator seals). Despite the low concentrations of Hg in the ecosystem, the pelagic food web reveals very high MIF Δ199Hg (3.15 to 6.65‰) in comparison to coastal fish (0.26 to 1.65‰) and most previous studies in aquatic organisms. Trophic transfer does not influence MIF signature since similar Δ199Hg was observed in sculpins (4.59  0.55‰) and seal muscles (4.62  0.60‰). The MIF is suggested to be mainly controlled by specific physical and biogeochemical characteristics of the water column. The higher level of MIF in pelagic fish of Lake Baikal is mainly due to the bioaccumulation of residual MeHg that is efficiently turned over and photodemethylated in deep oligotrophic and stationary (i.e. long residence time) freshwater columns.
Authors:
Vincent Perrot; Mikhail Pastukhov; Vladimir N Epov; Søren Husted; Olivier F X Donard; David Amouroux
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-4-30
Journal Detail:
Title:  Environmental science & technology     Volume:  -     ISSN:  1520-5851     ISO Abbreviation:  -     Publication Date:  2012 Apr 
Date Detail:
Created Date:  2012-5-1     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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