Falkowski PG, Barber RT, Smetacek V
P. G. Falkowski is at the Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901-8521, USA. R. T. Barber is in the Division of Earth and Ocean Sciences, Duke University, Beaufort, NC 28516, USA. V. Smetacek is at the Alfred Wegener Institute for Polar and Marine Research, Bremerhaven D-27570, Germany.
Science. 1998 Jul 10;281(5374):200-7. doi: 10.1126/science.281.5374.200.
Changes in oceanic primary production, linked to changes in the network of global biogeochemical cycles, have profoundly influenced the geochemistry of Earth for over 3 billion years. In the contemporary ocean, photosynthetic carbon fixation by marine phytoplankton leads to formation of approximately 45 gigatons of organic carbon per annum, of which 16 gigatons are exported to the ocean interior. Changes in the magnitude of total and export production can strongly influence atmospheric CO2 levels (and hence climate) on geological time scales, as well as set upper bounds for sustainable fisheries harvest. The two fluxes are critically dependent on geophysical processes that determine mixed-layer depth, nutrient fluxes to and within the ocean, and food-web structure. Because the average turnover time of phytoplankton carbon in the ocean is on the order of a week or less, total and export production are extremely sensitive to external forcing and consequently are seldom in steady state. Elucidating the biogeochemical controls and feedbacks on primary production is essential to understanding how oceanic biota responded to and affected natural climatic variability in the geological past, and will respond to anthropogenically influenced changes in coming decades. One of the most crucial feedbacks results from changes in radiative forcing on the hydrological cycle, which influences the aeolian iron flux and, in turn, affects nitrogen fixation and primary production in the oceans.
与全球生物地球化学循环网络变化相关的海洋初级生产力变化，在超过30亿年的时间里对地球的地球化学产生了深远影响。在当代海洋中，海洋浮游植物的光合固碳作用每年导致约45亿吨有机碳的形成，其中16亿吨被输出到海洋内部。总生产力和输出生产力的变化幅度在地质时间尺度上会强烈影响大气二氧化碳水平（进而影响气候），同时也为可持续渔业捕捞设定上限。这两种通量严重依赖于决定混合层深度、海洋内外营养物质通量以及食物网结构的地球物理过程。由于海洋中浮游植物碳的平均周转时间约为一周或更短，总生产力和输出生产力对外部强迫极为敏感，因此很少处于稳定状态。阐明生物地球化学对初级生产力的控制和反馈，对于理解海洋生物群落在地质历史时期如何响应并影响自然气候变率，以及在未来几十年将如何响应人为影响的变化至关重要。最关键的反馈之一源于水文循环辐射强迫的变化，它影响风尘铁通量，进而影响海洋中的固氮作用和初级生产力。
