The hydrographic record at Station S in the Sargasso Sea shows the development of a subsurface oxygen maximum within the euphotic zone which must be of photosynthetic origin. Consideration of insolation, heat budgets and available 3He/3H data yields an estimate of the order of 5 M m−2 y−1 for the vertically integrated oxygen production rate. Gas exchange calculations reveal a similar oxygen flux leaving the surface, and examination of respiration cycles below the euphotic zone yields consistent results. Such results point to new production of the order of 50 g C m−2 y−1. By using a more realistic mixed layer-thermocline model (Klein and Coste, 1984) it appears that the flux of nutrients into the euphotic zone is sufficient to support such a production. The pulse-like nature of nutrient injection implied by this model raises the possibility of a spatially variable efficiency of recycling which may account for the disparity between the above observations and the level of new production inferred from 14C and 12N incubation techniques.
Jenkins, W. J., and J. C. Goldman. 1985. "Seasonal oxygen cycling and primary production in the Sargasso Sea." Journal of Marine Research 43, (2). https://elischolar.library.yale.edu/journal_of_marine_research/1783