This study analyzed seasonal and annual fluxes of nutrients and organic matter from major Arctic rivers into the Arctic Ocean and surrounding seas. The researchers found that the six largest Arctic rivers, Ob, Yenisey, Lena, Kolyma, Yukon, and Mackenzie, account for over 80% of the freshwater and constituent fluxes into the Arctic Ocean. Nutrient fluxes, particularly dissolved inorganic nitrogen and phosphorus, varied seasonally with spring snowmelt contributing the largest amounts. The standardized sampling techniques used across the pan-Arctic region produced reliable data that can be used to model how rapid warming may impact marine and freshwater ecosystems through changes in fluvial dynamics and nutrient delivery over time.