Revealing the Reality of Mercury Accumulation in Glaciers from Arctic to Antarctic: Mercury Concentration 'Hotspots' in Dark Glacial Deposits

An international research team including Professor Nozomu Takeuchi of the Center for Environmental Remote Sensing at Chiba University (with members from Poland, the UK, Canada, and Italy) surveyed mercury concentrations in 'cryoconite,' dark sediment found on the surface of glaciers worldwide. The results revealed that cryoconite functions as a reservoir for highly concentrated mercury, reaching severe pollution levels in some regions. This discovery demonstrates that glacial melting caused by global warming may introduce a new risk of mercury contamination in downstream areas, raising the need for comprehensive watershed monitoring.

This research was published in the international environmental science journal 'Journal of Hazardous Materials' on May 9, 2026.

Background Mercury is one of the most toxic elements, causing severe damage to nervous and immune systems. With glaciers around the world currently melting rapidly due to global warming, there have been many uncertainties regarding the amount of mercury held by glaciers and future release volumes. The research team focused on cryoconite, which has the property of efficiently adsorbing pollutants from the atmosphere, and conducted a global-scale study.

Key Findings The team analyzed 48 glaciers in total, combining 130 samples collected from 39 glaciers in both hemispheres with existing data, and revealed the following:

- **High-Concentration Accumulation in Cryoconite**: Mercury was detected in all 48 glaciers surveyed. Mercury concentrations in cryoconite were more than 10% higher than in surrounding soil or river sediments, indicating it functions as a powerful 'pollutant trap' in glacial ecosystems. - **Significant Differences Between Hemispheres**: Glaciers in the Northern Hemisphere showed higher average pollution levels than those in the Southern Hemisphere. Particularly high values were recorded at Nigardsbreen in Norway (up to approx. 0.96 ppm), as well as in Alaska and the European Alps. This is thought to reflect past and current industrial activities (coal combustion, mining, etc.) in the Northern Hemisphere. - **Accumulation in Ice Microbes and Environmental Risks**: In Greenlandic glaciers, mercury was detected at levels comparable to cryoconite in 'snow algae' that turn snow red. This is the first demonstration that mercury is being integrated into microbes proliferating on glaciers. As melting progresses, there is a risk that mercury accumulated in these microbes and cryoconite will flow downstream, potentially impacting regional ecosystems and human health in the future.

Outlook This study proves that 'cryoconite,' which has been overlooked, plays an extremely important role in the global mercury cycle. As warming accelerates glacial melt, high concentrations of mercury accumulated in these hotspots risk being released rapidly into downstream rivers and oceans, potentially impacting human health through fish and other sources. This emphasizes the importance of international mercury management based on the Minamata Convention and provides a new perspective for monitoring rapidly changing polar and alpine environments.