Euphotic zone nitrification in the NE subarctic Pacific: Implications for measurements of new production

摘要: Abstract Ammonium (NH4+) oxidation rates, nitrate (NO3−) uptake rates and dissolved nutrient concentrations were measured throughout the euphotic zone along Line P oceanographic transect in NE subarctic Pacific, on three cruises (winter, spring late-summer) 2009. NH4+ was found to proceed ranged from undetectable 97 nmol L− 1 d− 1. Evidence suggest that both light played a role regulating with increasing as decreased increased. The observation ubiquitous process demonstrates not all NO3− present this region of water column should be considered new nitrogen, has important implications for estimates production Pacific. Depth-integrated 0.65 6.0 mmol m− 2 d− 1, we could have supported between 3 100% phytoplankton demands P. Taking potential regeneration into account resulted being reduced by an average ~ 50%. During late-summer, degree which reduced, when taken consideration, tightly anti-correlated total rates. This indicates nitrification are greatest less productive regions oceans.