Recent studies have reported that the C:N:P stoichiometry of marine particles is quite variable and flexible. Understanding how much carbon is transported per unit of phosphorus by sinking particles via the biological carbon pump (BCP) would provide insights for predicting the efficiency of the carbon pump in future oligotrophic environments. In this study, we investigated the relationship between particulate phosphorus and the BCP by analyzing 21 sinking particle samples collected at each depth of 900 m and 4100 m at station KE08 (33°41.8′N, 156°39.7′E; bottom depth: 5,330 m) in the northwestern Pacific, influenced by the Kuroshio Extension. The samples were collected at 10- or 30-day intervals from August 2018 to August 2019. We analyzed the organic carbon and nitrogen content. In particular, we determined P content of five species (Total P, Organic P, Inorganic P, HCl-P, and NaOH-P) following the SMT (Standards, Measurements and Testing programme) protocol to assess temporal changes in P speciation and fluxes. We examined the content of CaCO₃, Al, and opal to investigate the factors that regulate flux variations of particulate phosphorus and particulate organic carbon. The relationship between changes in particulate organic carbon flux over depth and time, and the C:N:P ratio will be discussed.

biological carbon pump, marine sinking particles, stoichiometric ratio, particulate phosphorus, sediment trap, organic carbon