Overview
Dietz et al. (2025) present Hg stable isotope data for key aquatic predatory species sampled across Greenland between 1983 and 2024, including Arctic char (Salvelinus alpinus), shorthorn sculpin (Myoxocephalus scorpius), ringed seal (Pusa hispida), glaucous gull, and polar bear. The study found that total Hg concentrations in muscle tissue are lowest in sculpins, ringed seals, and polar bears (medians 0.09–0.36 µg/g wet weight) and highest in Arctic char and glaucous gull (medians 0.61–0.66 µg/g ww). Isotope analysis demonstrates that ocean currents carrying legacy Hg — not atmospheric deposition — are the dominant pathway driving Hg uptake in Arctic marine and coastal areas, explaining the paradox of decreasing atmospheric Hg emissions but increasing Hg loads in many Arctic species.
Key numbers
Total Hg concentrations in muscle tissue (µg/g wet weight):
- Shorthorn sculpin (Myoxocephalus scorpius): median 0.09 µg/g ww (Central West Greenland, lower); significantly lower in Central West vs. Northwest and Central East Greenland
- Ringed seal (Pusa hispida): median approximately 0.10–0.36 µg/g ww range across regions; lower in Central West Greenland
- Glaucous gull (Larus hyperboreus): median 0.61 µg/g ww
- Land-locked Arctic char (Salvelinus alpinus): median 0.66 µg/g ww (highest among study species)
- Polar bear (Ursus maritimus): median within 0.09–0.36 µg/g ww range
Regional pattern: Central West Greenland (Atlantic Ocean-influenced) has significantly lower total Hg and higher δ²⁰²Hg than Northwest and Central East Greenland (Arctic Ocean-influenced); difference of ~0.46–0.63‰ in δ²⁰²Hg across species and peat matrices.
Temporal trend: Significant increases in total Hg and δ²⁰²Hg for several species and sites over the past 40 years, suggesting increased legacy Hg loading from the ocean rather than recent atmospheric emissions.
Atmospheric deposition pathway: 60–97% as Hg(0) (elemental), 3–40% as Hg(II) wet/dry deposition, based on Δ²⁰⁰Hg signatures.
Methods (brief)
Hg stable isotope analysis (δ²⁰²Hg, Δ¹⁹⁹Hg, Δ²⁰⁰Hg, Δ²⁰¹Hg) of muscle tissue and peat profiles. Total Hg concentrations measured alongside isotopes. Arctic Monitoring and Assessment Programme (AMAP) samples collected 1983–2024. Trophic level assessed via stable nitrogen isotopes. Statistical comparison of regional differences using IQR/median methods.
Note: This paper reports tHg in food-relevant Arctic species (Arctic char, ringed seal are human foods for Arctic communities); speciation into MeHg vs. inorganic Hg is inferred from isotope signatures rather than directly measured as MeHg fraction in food matrices.
Implications
Certification: Arctic char and ringed seal carry tHg at 0.61–0.66 µg/g ww — approaching or exceeding FDA action levels for Hg in fish (1.0 µg/g) depending on species and region. Ocean legacy Hg is increasing, not decreasing with emissions reductions.
Courses: Critical case study for explaining why atmospheric Hg reduction policy (Minamata Convention) may not translate to rapid fish tissue Hg improvements. Legacy oceanic Hg is the dominant driver for marine and freshwater Arctic species.
App: Arctic fish (especially freshwater wild char) carry elevated tHg flags; regional provenance matters (Atlantic-influenced Greenland is somewhat lower than Arctic Ocean-influenced regions).
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Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Change | Description |
|---|---|---|---|
| a8052bb | 2026-08-09 | major | 6 sections added; narrative text revised |