Temperature effects on carbon-specific respiration rate and sinking velocity of diatom aggregates – potential implications for deep ocean export processes

[摘要] Most deep ocean carbon flux profiles show low and almost constant fluxes ofparticulate organic carbon (POC) in the deep ocean. However, the reason forthe non-changing POC fluxes at depths is unknown. This study presents directmeasurements of formation, degradation, and sinking velocity of diatomaggregates from laboratory studies performed at 15 °C and4 °C during a three-week experiment. The average carbon-specificrespiration rate during the experiment was 0.12 ± 0.03 at15 °C, and decreased 3.5-fold when the temperature was lowered to4 °C. No direct influence of temperature on aggregate sinking speedwas observed. Using the remineralisation rate measured at 4 °C and anaverage particle sinking speed of 150 m d⁻¹, calculated carbon fluxeswere similar to those collected in deep ocean sediment traps from a globaldata set, indicating that temperature plays a major role for deep oceanfluxes of POC.

[学科分类] 地球化学与岩石