Particulate organic matter (POM) transported in Arctic rivers has previously been viewed as originating primarily from vulnerable northern high-latitude soils. Here, we present results from 8 y of POM sampling from the six largest Arctic rivers, a unique set of mixing models, and endmember data to show that aquatic biomass, a previously overlooked endmember, may contribute 39 to 60% of the average annual 4,391 Gg/y pan-Arctic POM flux. Because of compositional differences, soil-derived POM (like ancient permafrost) has previously appeared to be preferentially preserved in sediments while autochthonous POM (like aquatic biomass) preferentially fuels food webs; this major contribution of in situ riverine production thus suggests a need to reevaluate Arctic riverine POM fate and role in global carbon cycling.
Megan I. Behnke, Suzanne E. Tank, James W. McClellan, Robert M. Holmes, Negar Haghipour, Timothy I. Eglinton, Peter A. Raymond, Anya Suslova, Alexander V. Zhulidov, Tatiana Gurtovaya, Nikita Zimov, Sergey Zimov, Edda A. Mutter, Edwin Amos, Robert G. M. Sp. 2023. Aquatic biomass is a major source to particulate organic matter export in large Arctic rivers. Proceedings of the National Academy of Sciences. Volume 120, No. 12: https://doi.org/10.1073/pnas.2209883120. DOI: https://doi.org/10.1073/pnas.2209883120.