F. Louanchi et Rg. Najjar, Annual cycles of nutrients and oxygen in the upper layers of the North Atlantic Ocean, DEEP-SEA II, 48(10), 2001, pp. 2155-2171
Citations number
48
Categorie Soggetti
Aquatic Sciences","Earth Sciences
Journal title
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY
Monthly climatologies of nutrients and oxygen in the upper North Atlantic O
cean are analyzed and used to estimate the rates of spring-summer new produ
ction and remineralization. The annual cycle of surface nutrients is charac
terized by a spring-summer biological drawdown and a fall-winter increase d
ue to vertical mixing. The drawdown is accompanied by maximum oxygen supers
aturations. In the subsurface layer (100-200 m), the decrease of oxygen con
centrations during the spring-summer period reflects the remineralization o
f organic matter. The spring-summer drawdown of surface nutrients implies n
ew production rates that are high in the high latitudes (around 40 g C/m(2)
on average), and low in the low and temperate latitudes (about 15 g C/m(2)
on average). In the subsurface layer, respiration rates are computed from
the oxygen concentration decrease during the spring-summer period. Results
show that most of the new production in the low latitudes, and half or less
of it in the high latitudes, is remineralized above 200 m. The spring-summ
er new production in the North Atlantic Ocean is estimated to be 1.3 Pg C.
Considering that the spring-summer production that is not mineralized in th
e top 200 m of the ocean is mainly composed of particulate organic matter t
he spring-summer export at 200 m is estimated to be between 0.4 and 0.6 Pg
C for the whole North Atlantic Ocean. (C) 2001 Elsevier Science Ltd. All ri
ghts reserved.