The silica cycle is intimately coupled with marine food-web dynamics, biogeochemical transformations, and the efficiency of the biological carbon pump (BCP). To elucidate the factors controlling biogenic silica (bSiO2) flux and its role in carbon export, we conducted a year-long (August 2008-September 2009) sediment trap deployment on the Northwind Ridge in the western Arctic Ocean. BSiO2 fluxes exhibited a pronounced seasonal signal, closely paralleling those of particulate organic carbon (POC) and diatoms, with mean fluxes in 2009 tripling those of 2008. This interannual disparity was primarily driven by the interplay of seasonal sea-ice retreat, oligotrophic Beaufort Gyre influence, and nutrient-rich Pacific Water Inflow. Heavily silicified Chaetoceros resting spores (CRS) dominated the temporal variability of both bSiO₂ and POC fluxes, with CRS flux correlated significantly with each flux- highlighting their role as a primary conduit for POC export to the deep ocean. The mean bSiO2 flux (119.9 mmol Si m-2 yr-1) approximated the global average but substantially exceeded those of the Atlantic and Pacific warm pools, while remaining lower than in the Southern Ocean or Bering Sea. Molar Si/Cinorg and Corg/Cinorg ratios consistently exceeded unity, classifying the Chukchi Sea as a Silica Ocean, wherein diatom-dominated export-facilitated by bSiO2 ballasting-exerts primary control on deep-ocean carbon sequestration. These findings provide critical baseline constraints for projecting how ongoing Arctic warming and shifting circulation may reshape regional biogeochemistry and carbon cycling.
🌊
