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  • 1
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    Total mercury and total methylmercury during the POLARSTERN cruise ARK-XXVI/3 (TransArc) (2015)
    PANGAEA
    In:  Supplement to: Heimbürger, Lars-Eric; Sonke, Jeroen E; Cossa, Daniel; Point, David; Lagane, Christelle; Laffont, Laure; Galfond, Benjamin T; Nicolaus, Marcel; Rabe, Benjamin; Rutgers van der Loeff, Michiel M (2015): Shallow methylmercury production in the marginal sea ice zone of the central Arctic Ocean. Scientific Reports, https://doi.org/10.1038/srep10318
    Details
    Publication Date: 2023-06-17
    Description: Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (〈79°N). Here we present the first central Arctic Ocean (79-90°N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81-85°N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150-200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production.
    Keywords: Arctic Ocean; ARK-XXVI/3; Bottle number; CTD/Rosette; CTD-RO; Date/Time of event; DEPTH, water; Elevation of event; Event label; GEOTRACES; Global marine biogeochemical cycles of trace elements and their isotopes; Laptev Sea; Latitude of event; Longitude of event; Mercury; Methylmercury; Polarstern; Pressure, water; PS78/218-2; PS78/245-2; PS78/273-2; PS78/280-1; PS78 TransArc; see comment
    Type: Dataset
    Format: text/tab-separated-values, 334 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 2
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    (Supplementary Table 1) Mercury isotope values for common and thick-billed murre (Uria aalge, Uria lomvia) eggs from Alaska (2011)
    PANGAEA
    In:  Supplement to: 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 (2011): Methylmercury photodegradation influenced by sea-ice cover in Arctic marine ecosystems. Nature Geoscience, 4(3), 188-194, https://doi.org/10.1038/ngeo1049
    Details
    Publication Date: 2023-12-13
    Description: 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.
    Keywords: 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; Species, common name; StGeorge_Is; StLawrence_Is; StLazaria_Is; Δ199Hg; Δ201Hg; δ199Hg; δ200Hg; δ201Hg; δ202Hg
    Type: Dataset
    Format: text/tab-separated-values, 473 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 3
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    Trends in tuna carbon isotopes suggest global changes in pelagic phytoplankton communities (2020)
    Wiley
    Details
    Publication Date: 2023-02-08
    Description: Considerable uncertainty remains over how increasing atmospheric CO2 and anthropogenic climate changes are affecting open‐ocean marine ecosystems from phytoplankton to top predators. Biological time series data are thus urgently needed for the world's oceans. Here, we use the carbon stable isotope composition of tuna to provide a first insight into the existence of global trends in complex ecosystem dynamics and changes in the oceanic carbon cycle. From 2000 to 2015, considerable declines in δ13C values of 0.8‰–2.5‰ were observed across three tuna species sampled globally, with more substantial changes in the Pacific Ocean compared to the Atlantic and Indian Oceans. Tuna recorded not only the Suess effect, that is, fossil fuel‐derived and isotopically light carbon being incorporated into marine ecosystems, but also recorded profound changes at the base of marine food webs. We suggest a global shift in phytoplankton community structure, for example, a reduction in 13C‐rich phytoplankton such as diatoms, and/or a change in phytoplankton physiology during this period, although this does not rule out other concomitant changes at higher levels in the food webs. Our study establishes tuna δ13C values as a candidate essential ocean variable to assess complex ecosystem responses to climate change at regional to global scales and over decadal timescales. Finally, this time series will be invaluable in calibrating and validating global earth system models to project changes in marine biota.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Stable mercury concentrations of tropical tuna in the south western Pacific ocean: An 18-year monitoring study (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: Global anthropogenic mercury (Hg) emissions to the atmosphere since industrialization are widely considered to be responsible for a significant increase in surface ocean Hg concentrations. Still unclear is how those inputs are converted into toxic methylmercury (MeHg) then transferred and biomagnified in oceanic food webs. We used a unique long-term and continuous dataset to explore the temporal Hg trend and variability of three tropical tuna species (yellowfin, bigeye, and skipjack) from the southwestern Pacific Ocean between 2001 and 2018 (n = 590). Temporal trends of muscle nitrogen (δ15N) and carbon (δ13C) stable isotope ratios, amino acid (AA) δ15N values and oceanographic variables were also investigated to examine the potential influence of trophic, biogeochemical and physical processes on the temporal variability of tuna Hg concentrations. For the three species, we detected significant inter-annual variability but no significant long-term trend for Hg concentrations. Inter-annual variability was related to the variability in tuna sampled lengths among years and to tuna muscle δ15N and δ13C values. Complementary AA- and model-estimated phytoplankton δ15N values suggested the influence of baseline processes with enhanced tuna Hg concentrations observed when dinitrogen fixers prevail, possibly fuelling baseline Hg methylation and/or MeHg bioavailability at the base of the food web. Our results show that MeHg trends in top predators do not necessary capture the increasing Hg concentrations in surface waters suspected at the global oceanic scale due to the complex and variable processes governing Hg deposition, methylation, bioavailability and biomagnification. This illustrates the need for long-term standardized monitoring programs of marine biota worldwide.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Shallow methylmercury production in the marginal sea ice zone of the central Arctic Ocean (2015)
    Nature Publishing Group
    In:  EPIC3Scientific Reports, Nature Publishing Group, 5(10318), ISSN: (online): 2045-2322
    Details
    Publication Date: 2016-11-29
    Description: Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (〈79°N). Here we present the first central Arctic Ocean (79–90°N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81–85°N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150–200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
    Location Call Number Limitation Availability
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    PAPER (OA)
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