Legacy Mercury Pollution in Oceans Threatens Arctic Wildlife and Ecosystems

Despite significant global efforts to reduce mercury emissions, scientists report a persistent increase in mercury concentrations in Arctic wildlife, creating long-term risks for both ecosystems and human health. A study published in *Nature Communications* by researchers from Aarhus University and the University of Copenhagen highlights that ocean currents are actively transporting historical mercury pollution to the Arctic region, exacerbating the existing environmental crisis.

The lead researcher, Professor Rune Dietz from Aarhus University, stated, "We've monitored mercury in Arctic animals for over 40 years. Despite declining global emissions since the 1970s, we see no corresponding decrease in Arctic concentrations—on the contrary" (Dietz, 2025). This finding is particularly alarming given that mercury, a potent neurotoxin, has been found at levels in top Arctic predators such as polar bears and toothed whales that are 20 to 30 times higher than pre-industrial levels.

The study emphasizes that mercury released into the atmosphere can remain airborne for about a year, but once deposited into the ocean, it can persist for over 300 years. This long residence time indicates that even with current emission reductions, the Arctic may continue to experience elevated mercury levels for centuries. This poses serious health risks not only to wildlife but also to Indigenous communities that rely on marine mammals for sustenance (Sonne, 2025).

The team analyzed over 700 environmental samples—including tissues from polar bears, seals, fish, and peat—from across Greenland, collected over the past four decades. They examined the composition of six common mercury isotopes to identify distinct regional differences that correlate with ocean current patterns. Senior Researcher Jens Søndergaard elaborated, "These isotope signatures act like fingerprints, revealing the sources and transport pathways of mercury" (Søndergaard, 2025).

For instance, central West Greenland is influenced by Atlantic inflow via the Irminger Current, whereas other regions are dominated by Arctic Ocean currents. The isotopic analysis has allowed researchers to trace the origins of mercury pollution back to major sources, including industrial activities in countries such as China. According to Dietz, "Transport of mercury from major sources to Greenland via ocean currents can take up to 150 years. This helps explain the lack of decline in Arctic mercury levels" (Dietz, 2025).

The implications of this research are critical for global mercury regulation efforts, particularly in light of the UN's Minamata Convention on Mercury, which aims to mitigate global mercury pollution. The findings underscore the necessity for continued action at both national and international levels to address the legacy of mercury contamination.

As the Arctic environment continues to change, the research team is committed to further investigating mercury isotopes across the Arctic through the "GreenPath" project. The isotopic analyses also contribute to international initiatives such as WhaleAdapt and ArcSolutions, which seek to enhance understanding and mitigation of mercury pollution in these vulnerable ecosystems.

In conclusion, the ongoing rise in mercury concentrations in Arctic wildlife highlights the urgent need for comprehensive and sustained efforts to address both historical and current sources of mercury pollution. Future research and policy actions will be vital in protecting Arctic ecosystems and the health of communities dependent on these critical resources. The long-term threat posed by legacy pollution necessitates a proactive approach to ensure the survival of both wildlife and human populations in the Arctic region.