Estimation of Global Rates and Fluxes

The basie mechanism inducing microbial activity is the supply of organie matter to the seafloor and this is generally eoupled to surfaee water produe-tivity. Most of the highly produetive areas in the global ocean are adjaeent to the eontinents, so 

Fluxes of oxygen and nitrate, therefore, vary over several orders of magnitude between oligo-trophic open oeean areas and continental shelf and slope areas. This is about 50 to 6,000 mmol m yr for oxygen and -600 to 380 mmol m yr for nitrate (e g. Devol and Christensen 1993 Glud et al. 1994 Berelson et al. 1994 Hanunond et al. 1996 Luther et al. 1997 Hensen et al. 1998 Wenzhofer and Glud 

2-10 mol N yr have been estimated more recently by Codispoti et al. (2001) who explained this npward correction mainly by the need of balancing the isotopic nitrate pool at 5 N of abont 5%o (Sigman et al. 1999, 2000). 

---