What is it about?

Particulate organic matter in Arctic rivers has previously thought to be mostly from vulnerable northern high-latitude soils like permafrost. Here, using eight years of data from the six biggest Arctic rivers, we show that instead much of that organic matter comes from aquatic biomass produced in the river systems themselves. Organic matter from aquatic biomass is more likely to fuel food webs than organic matter than soils, so Arctic Ocean food webs may be benefiting from this previously unrecognized export.

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Why is it important?

Frozen Arctic permafrost soils currently store twice as much carbon as is presently in the atmosphere. Since the Arctic is warming twice as fast as the rest of the planet, that carbon is being released as soils thaw. To prepare for how that released carbon will impact greenhouse gas emissions and climate change it is critical to understand what happens to that carbon after release. It has previously been believed that most particles of carbon transported in Arctic rivers came from warming soils, but here we show that the contribution of recently produced aquatic biomass has been underestimated. This large contribution of in situ riverine production suggests a need to reevaluate how much soil carbon reaches rivers, the fate of Arctic riverine carbon, and its role in global carbon cycling.


The Arctic is a challenging, remote region in which to work, and yet it is of utmost importance to humanity. Projects like this one that tackle questions on a pan-Arctic scale rely on strong international collaborations, and are now more important than ever. It has been an honor working with a diverse group of co-authors from Russia, Switzerland, Canada, Alaska, and the contiguous United States to undertake work than no one group of us could have done alone. I hope that this article reinforces the need for continued long term international collaboration to better understand our changing world.

Megan Behnke
University of Alaska Southeast

Read the Original

This page is a summary of: Aquatic biomass is a major source to particulate organic matter export in large Arctic rivers, Proceedings of the National Academy of Sciences, March 2023, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2209883120.
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