Concentrations, ratios, and sinking fluxes of major bioelements at Ocean Station Papa

Fluxes of major bioelements associated with sinking particles were quantified in late summer 2018 as part the EXport Processes Ocean from RemoTe Sensing (EXPORTS) field campaign near Station Papa subarctic northeast Pacific. The thorium-234 method was used conjunction size-fractionated (1–5, 5–51, and >51 μm) concentrations particulate nitrogen (PN), total phosphorus (TPP), biogenic silica (bSi), inorganic carbon (PIC) collected using large volume filtration via situ pumps. We build upon recent work quantifying POC fluxes during EXPORTS. Similar remineralization length scales observed for both PN across all particle size classes depths 50–500 m. Unlike bSi PIC, soft tissue–associated POC, PN, TPP strongly attenuated 50 m to base euphotic zone (approximately 120 m). Cruise-average thorium-234-derived (mmol m–2 d–1) at 1.7 ± 0.6 0.22 0.07 0.019 0.007 TPP, 0.69 0.26 bSi, 0.055 0.022 PIC. These bioelement similar previous observations this site, exception which 1 2 orders magnitude lower. Transfer efficiencies within upper twilight (flux 220 m/flux m) highest PIC (84%) (79%), followed by (61%), (58%), (49%). differences indicate preferential relative or larger losses tissue biominerals below zone. Comprehensive characterization obtained here will support future efforts linking phytoplankton community composition food-web dynamics composition, magnitude, attenuation material that sinks deeper waters.