Arctic rivers dump carbon into the sea

Despite the massive impact of climate change on the world's Arctic regions, there is a scarcity of data on exactly how the Arctic regions are changing. In particular, there is little understanding of how thawing permafrost is impacting the global carbon cycle.

The EU-funded 'Terrestrial organic matter characterization in Arctic River through molecular and isotopic analyses' (TOMCAR-PERMAFROST) project is studying the Great Whale River in Canada to understand the effects of thawing permafrost.

Researchers used geographic information systems and biochemical analysis to reveal how much carbon is transferred into the oceans by Arctic rivers. They are particularly interested in organic matter, as this has a huge effect on carbon cycles.

The project team found that the Great Whale River transported between 200 and 700 tonnes of dissolved organic carbon (DOC) per day during the spring flooding season. This is both old and new DOC, and the composition is influenced by whether there is fresh snow cover in the watershed area.

TOMCAR-PERMAFROST also noted that mercury concentration in the River increased dramatically during the flood period. During the project, scientists recorded the highest-ever concentration of mercury in an Arctic river.

The findings of this project are alarming, because such large influxes of DOC into the world's oceans will intensify the effects of global warming. However, the information is valuable to researchers trying to model the long-term effects of climate change.