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Summertime Evolution of Net Community Production and CO 2 Flux in the Western Arctic Ocean
Author(s) -
Ouyang Zhangxian,
Qi Di,
Zhong Wenli,
Chen Liqi,
Gao Zhongyong,
Lin Hongmei,
Sun Heng,
Li Tao,
Cai WeiJun
Publication year - 2021
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2020gb006651
Subject(s) - arctic , flux (metallurgy) , oceanography , sea ice , new production , environmental science , saturation (graph theory) , arctic ice pack , atmospheric sciences , nutrient , climatology , chemistry , geology , phytoplankton , mathematics , organic chemistry , combinatorics
To examine seasonal and regional variabilities in metabolic status and the coupling of net community production (NCP) and air‐sea CO 2 fluxes in the western Arctic Ocean, we collected underway measurements of surface O 2 /Ar and partial pressure of CO 2 ( p CO 2 ) in the summers of 2016 and 2018. With a box‐model, we demonstrate that accounting for local sea ice history (in addition to wind history) is important in estimating NCP from biological oxygen saturation (Δ(O 2 /Ar)) in polar regions. Incorporating this sea ice history correction, we found that most of the western Arctic exhibited positive Δ(O 2 /Ar) and negative p CO 2 saturation, Δ( p CO 2 ), indicative of net autotrophy but with the relationship between the two parameters varying regionally. In the heavy ice‐covered areas, where air‐sea gas exchange was suppressed, even minor NCP resulted in relatively high Δ(O 2 /Ar) and low p CO 2 in water due to limited gas exchange. Within the marginal ice zone, NCP and CO 2 flux magnitudes were strongly inversely correlated, suggesting an air to sea CO 2 flux induced primarily by biological CO 2 removal from surface waters. Within ice‐free waters, the coupling of NCP and CO 2 flux varied according to nutrient supply. In the oligotrophic Canada Basin, NCP and CO 2 flux were both small, controlled mainly by air‐sea gas exchange. On the nutrient‐rich Chukchi Shelf, NCP was strong, resulting in great O 2 release and CO 2 uptake. This regional overview of NCP and CO 2 flux in the western Arctic Ocean, in its various stages of ice‐melt and nutrient status, provides useful insight into the possible biogeochemical evolution of rapidly changing polar oceans.