Mercury Export from Arctic Great Rivers

Area of Science:

• Environmental Science
• Geochemistry
• Arctic Research

Background:

• The Arctic Ocean receives substantial global river discharge, yet mercury (Hg) export estimates are limited.
• Understanding land-ocean linkages is crucial in the rapidly changing Arctic.

Purpose of the Study:

• To establish a contemporary benchmark for riverine total mercury (THg) export from major Arctic rivers.
• To quantify pan-Arctic THg flux and identify key drivers of mercury mobilization and transport.

Main Methods:

• Coordinated, year-round sampling of six major Arctic rivers from 2012-2017.
• Measurement of total mercury (THg) concentrations and fluxes.
• Analysis of hydrological and sediment data to model THg export.

Main Results:

• The six major Arctic rivers exported an average of 20,000 kg/year of THg.
• Pan-Arctic THg flux was estimated at 37,000 kg/year, with over 90% during spring/summer discharge.
• Higher THg yields correlated with increased watershed denudation.

Conclusions:

• Established a contemporary benchmark for Arctic riverine mercury export.
• Highlighted the critical role of seasonal discharge and watershed characteristics in mercury transport.
• Emphasized the potential acceleration of mercury cycling due to Arctic warming and permafrost thaw.