Arctic river dissolved and biogenic silicon exports - current conditions and future changes with warming

Silicon (Si) exports from terrestrial to marine systems can dictate phytoplankton species composition in Arctic coastal waters. Diatoms are often the dominant autotroph in Arctic waters, making Si an important control on Arctic marine primary productivity. Yet, even as Arctic regions are among the fastest warming on Earth, we lack baseline knowledge on the magnitudes and controls of Arctic river Si exports. To address uncertainties in current and future Si behavior, we used a combination of field data and modeling to quantify daily yields of dissolved Si (DSi) and biogenic Si (BSi) from a 400 km space‐for‐time latitudinal gradient of seven basins across the boreal‐Arctic transition in Alaska (USA) over the course of two years (2015‐2016). Mean annual DSi concentrations (33‐149 μM) and yields (13‐49 kmol km‐2 yr‐1) were significantly and positively correlated with mean basin active layer depth, indicating that permafrost thaw will likely increase DSi fluxes to Arctic coastal waters. Conv...