The role of net community production in air‐sea carbon fluxes at the North Pacific subarctic‐subtropical boundary region

• Published in: Limnology and Oceanography
• Main Authors: Howard, Evan, Emerson, Steven, Bushinsky, Seth, Stump, Charles
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2010
• Subjects: Aquatic Science; Oceanography; Pacific; Subarctic
• Online Access: http://dx.doi.org/10.4319/lo.2010.55.6.2585; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.4319%2Flo.2010.55.6.2585; https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2010.55.6.2585

The North Pacific subarctic‐subtropical boundary region is an important sink for atmospheric CO 2 , with high annual influx relative to surrounding waters and large seasonal variability. The location of the subarctic‐subtropical gyre boundary is relatively stable, but there is a large seasonal migration of the North Pacific Chlorophyll Front, between ~30°N and ~45°N. To determine the role of biological productivity on the seasonal CO 2 flux, we measured sections of oxygen‐argon gas ratios on cruises across the transition zone in November 1997 (autumn) and September 2008 (summer). A simple upper ocean model was used with the O 2 :Ar data to estimate the net community production (NCP) in the euphotic zone. On both cruises the NCP was highest at the chlorophyll front with average values from 30°N to 45°N of 3.4 ± 2.0 and 8.1 ± 2.7 mmol C m −2 d −1 in autumn and summer, respectively. These values are sufficient to make biologically induced carbon export an important component of the CO 2 drawdown in this region. Processes that control the relatively high NCP at this boundary are not certain, but it has been demonstrated that horizontal convergence of nitrate plays some role.