Concentrations and uptake of nitrate and ammonium in the Atlantic Ocean between 60∘N and 50∘S

摘要: Abstract The uptake rates and concentrations of nitrate ammonium were determined during three research cruises in the Atlantic Ocean: At 20 ∘ W between 60 N 37 June July 1996, UK Falkland Islands ( 48 – 50 S ) September October 1997, South Africa 33 May 1998. Euphotic zone NO 3 - varied 0.005 μ mol l 1 northern southern gyres to a maximum within Benguela upwelling system. 70% stations occupied oligotrophic conditions (nominally defined as where 0.05 ), surface elevations attributed photoinhibition mechanisms. NH 4 + much less variable 0.109 ± 0.150 than , showed same general trend minima concentration (of 5.2 microbial was significantly correlated chlorophyll concentrations, whilst dependent on no association with other environmental variables. Variability nitrogen uptake:concentration ratio oceanographic provinces associated physical including mixed-layer depth rate diapycnal mixing; therefore, cannot be predicted simply from nutrient concentration. In contrast, relationship f-ratio (where source is undefined, may have both new regenerated components) robustly, so that can (within 95%) by either or integrated .