Ice-to-ocean method tracks mercury mobilization and export from Greenland ice sheet

A new study paints a high-resolution picture of how mercury moves from Greenland’s icy interior to the surrounding ocean—an environmental pathway that can influence ecosystems far beyond the ice sheet itself. Writing in Communications Earth & Environment, researchers report an “ice-to-ocean” framework designed to track mercury mobilization, transport, and eventual export, bridging a gap between glaciology and geochemistry.

Mercury is a potent neurotoxicant, and even small shifts in its cycling can alter atmospheric deposition patterns, ocean chemistry, and food-web contamination. Yet mercury export from ice sheets has been notoriously difficult to quantify because the relevant processes occur across harsh terrain, variable temperatures, and strongly coupled hydrological pathways.

The team combined field- and model-informed logic to simulate how mercury embedded or deposited on ice can become chemically available during melting and runoff events. When surface snow and ice warm, meltwater can reorganize the chemical environment, changing how mercury partitions between solid phases and dissolved forms. In particular, the study emphasizes mobilization mechanisms driven by meltwater flushing and reaction pathways that occur as water flows toward marine margins.

A central result is that episodic melt conditions can act as short, efficient “delivery windows,” during which mobilized mercury is transported rapidly from land-ice surfaces into coastal waters. This timing matters: the ocean does not simply receive a steady trickle, but likely receives pulses that can enhance downstream bioavailability.

The researchers also address export efficiency—the fraction of mobilized mercury that survives transport without being strongly re-sorbed or transformed before reaching the sea. By coupling hydrological transport assumptions with mercury chemistry, the framework estimates how much mercury could reach ocean settings where it may be transformed further.

Although the work focuses on Greenland, the implications extend to other cryospheric regions where warming increases meltwater production and alters drainage networks. As Arctic temperatures rise, the balance between storage in ice and release to oceans may shift, potentially affecting mercury exposure risk in marine food chains.

Finally, the study provides a roadmap for linking ice-sheet dynamics to contaminant fate, offering a tool for future projections under different melt scenarios. If mercury export accelerates, the Arctic could become a more active source of contamination to the global ocean—an outcome with measurable consequences.