(Supplementary Table 1) Mercury isotope values for common and thick-billed murre (Uria aalge, Uria lomvia) eggs from Alaska

Atmospheric deposition of mercury to remote areas has increased threefold since pre-industrial times. Mercury deposition is particularly pronounced in the Arctic. Following deposition to surface oceans and sea ice, mercury can be converted into methylmercury, a biologically accessible form of the to...

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Bibliographic Details
Main Authors: Point, David, Sonke, Jeroen E, Day, R D, Roseneau, D G, Hobson, Keith A, Vander Pol, S S, Moors, A J, Pugh, R S, Donard, Olivier F X, Becker, P R
Format: Dataset
Language:English
Published: PANGAEA 2011
Subjects:
Area/locality
Bering Sea
Biological sample
BIOS
Bogoslof_Is
CapeLisburne
Chukchi Sea
DATE/TIME
E-Amatuli_Is
Event label
Gulf of Alaska
International Polar Year (2007-2008)
IPY
Latitude of event
Longitude of event
Sample ID
Sample type
Species
common name
StGeorge_Is
StLawrence_Is
StLazaria_Is
Δ199Hg
Δ201Hg
δ200Hg
δ202Hg
Arctic
Arctic Ocean
Pacific
Chukchi
International Polar Year
Sea ice
thick-billed murre
Uria aalge
Uria lomvia
Alaska
uria
Online Access:https://doi.pangaea.de/10.1594/PANGAEA.818266
https://doi.org/10.1594/PANGAEA.818266
Description
Summary:Atmospheric deposition of mercury to remote areas has increased threefold since pre-industrial times. Mercury deposition is particularly pronounced in the Arctic. Following deposition to surface oceans and sea ice, mercury can be converted into methylmercury, a biologically accessible form of the toxin, which biomagnifies along the marine food chain. Mass-independent fractionation of mercury isotopes accompanies the photochemical breakdown of methylmercury to less bioavailable forms in surface waters. Here we examine the isotopic composition of mercury in seabird eggs collected from colonies in the North Pacific Ocean, the Bering Sea and the western Arctic Ocean, to determine geographical variations in methylmercury breakdown at northern latitudes. We find evidence for mass-independent fractionation of mercury isotopes. The degree of mass-independent fractionation declines with latitude. Foraging behaviour and geographic variations in mercury sources and solar radiation fluxes were unable to explain the latitudinal gradient. However, mass-independent fractionation was negatively correlated with sea-ice cover. We conclude that sea-ice cover impedes the photochemical breakdown of methylmercury in surface waters, and suggest that further loss of Arctic sea ice this century will accelerate sunlight-induced breakdown of methylmercury in northern surface waters.

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