Respiration of new and old carbon in the surface ocean: Implications for estimates of global oceanic gross primary productivity

摘要

New respiration (R-new, of freshly fixated carbon) and old respiration (R-old, of storage carbon) were estimated for different regions of the global surface ocean using published data on simultaneous measurements of the following: (1) primary productivity using C-14 ((PP)-P-14); (2) gross primary productivity (GPP) based on O-18 or O-2; and (3) net community productivity (NCP) using O-2. The ratio R-new/GPP in 24h incubations was typically between 0.1 and 0.3 regardless of depth and geographical area, demonstrating that values were almost constant regardless of large variations in temperature (0 to 27 degrees C), irradiance (surface to similar to 100m deep), nutrients (nutrient-rich and nutrient-poor waters), and community composition (diatoms, flagellates, etc,). As such, between 10 and 30% of primary production in the surface ocean is respired in less than 24 h, and most respiration (between 55 and 75%) was of older carbon. R-new was most likely associated with autotrophs, with minor contribution from heterotrophic bacteria. Patterns were less clear for R-old. Short C-14 incubations are less affected by respiratory losses. Global oceanic GPP is estimated to be between 70 and 145 Gt C yr(-1).