Upper Ocean Carbon Export and the Biological Pump SPECIAL ISSUE - JGOFS

coastal and open Pacific Ocean. They also demonstrated that the flux of particles out of the surface layer, as measured by sediment traps, generally approximated the large-scale rate of new production. In 1967, Richard Dugdale and John Goering had defined new production as the fraction of the overall net primary production that was supported by external, or “new” inputs of nutrients. They focused on nitrate in deep ocean water supplied to the euphotic zone by vertical mixing and upwelling as the principal new nutrient, but they did explicitly identify N2 fixation as a potential source of new nitrogen (see Michaels et al., this issue). They also highlighted sinking particles as the major pathway for export in the oceanic nitrogen budget. But it was Eppley and Peterson (1979) who articulated the paradigm that came to govern ocean flux studies over the coming decades: We estimate the sinking flux of POC [Particulate Organic Carbon] in the deep ocean by assuming that new production, as defined by Dugdale and Goering, is quantitatively equivalent to the organic matter that can be exported from the total production in the euphotic zone without the production system running down (Eppley and Peterson, 1979, p. 679). Eppley and Peterson also defined the ratio of new to total production as the f-ratio and showed that f was an asymptotic function of the magnitude of total production. This relationship provided an explicit link between remotely-sensed primary production rates and the ocean carbon cycle. If total production could be estimated from remotely-sensed properties, one could apply the Eppley-Peterson algorithm and calculate the export rates as functions of time and space. The f-ratio thus provided both a means to define the efficiency of the biological pump quantitatively and a step toward quantifying the functioning of the pump on a global scale. Upper Ocean Carbon Export and the Biological Pump SPECIAL ISSUE – JGOFS