Indian Ocean denitrification

Interpretation of the N distribution in the Pacific and Indian oceans is more difficult because of the existence of strong denitrification sites adjacent to the places where one expects to find the N2 fixation signals. In the subtropical North Pacific, where N2 fixation is well documented (Karl et al., 1997), the N maximum exists just near the surface and does not extend into the thermocline as is the case in the subtropical North Atlantic. This is likely a result of the eroding effect by waters that obtain extremely low N values in the eastern Pacific and are then advected westwards in the main thermocline (Fig. 1.12). 

The authors found strong stabtiizing feedbacks in the northern Indian Ocean and in the North Atlantic that act to minimize changes in the marine N inventory over relatively short timescales ( 30—200 years) and concluded that rates of N2 fixation are tightly linked to N P ratios in surface waters and thus denitrification, locally for the Indian Ocean and more remotely for the Atlantic Ocean. ITowever, the strength of these stabilizing feedbacks was weaker in other regions mainly due to Fe... 

Naqvi, S.W.A., Kumar, M.D., Narvekar, P.V., de Sousa, S.N., George, M.D. and D Silva, C. (1993) An intermediate nepheloid layer associated with high microbial metabolic rates and denitrification in the Northwest Indian ocean. Journal of Geophysical Research, 98, 16469-16479. 

---