TY - JOUR
T1 - Biological production in the NE Pacific and its influence on air-sea CO2 flux
T2 - Evidence from dissolved oxygen isotopes and O 2/Ar
AU - Juranek, L. W.
AU - Quay, P. D.
AU - Feely, R. A.
AU - Lockwood, D.
AU - Karl, D. M.
AU - Church, M. J.
PY - 2012
Y1 - 2012
N2 - We determine rates of gross photosynthetic O2 production (GOP) and net community O2 production (NCP) using the triple oxygen isotope and O2/Ar approach on two spring and two late summer meridional transects of the NE Pacific. Observed GOP and NCP in the subtropical (89±9 and 8.3±1.3 mmol O2 m-2 d -1, respectively) and subarctic (193±16 and 16.3±3.8 mmol O2 m-2 d-1) were in agreement with rates previously determined at time series stations in each region, validating the regional representativeness of these sites. At the transition zone chlorophyll front (TZCF), which migrates seasonally from 32N in spring to 40°N in summer, GOP and NCP were elevated by 2-4× compared to adjacent areas. Coincident with the TZCF, increases in surface nitrate concentration and extensive changes in phytoplankton community composition were observed. HPLC pigment data indicated substantial increases in a prymnesiophyte (e.g., coccolithophore) biomarker at the TZCF on a spring and summer cruise, and a diatom biomarker on the spring cruise. Increases in remotely sensed surface particulate inorganic carbon concentration were also observed at the TZCF on all four cruises, indicating that coccolithophore production may contribute to increased productivity at the TZCF. Meridional trends in observed air-sea CO2 flux on each cruise resembled those of the biologically induced CO2 flux (NCP), but with an overprinting of the response of air-sea CO2 exchange to summer warming. A simple carbon budget based on regional CO2 flux climatology demonstrates the importance of NCP for net annual air-sea CO2 uptake, although slow air-sea equilibration and seasonal solubility effects obscure this term.
AB - We determine rates of gross photosynthetic O2 production (GOP) and net community O2 production (NCP) using the triple oxygen isotope and O2/Ar approach on two spring and two late summer meridional transects of the NE Pacific. Observed GOP and NCP in the subtropical (89±9 and 8.3±1.3 mmol O2 m-2 d -1, respectively) and subarctic (193±16 and 16.3±3.8 mmol O2 m-2 d-1) were in agreement with rates previously determined at time series stations in each region, validating the regional representativeness of these sites. At the transition zone chlorophyll front (TZCF), which migrates seasonally from 32N in spring to 40°N in summer, GOP and NCP were elevated by 2-4× compared to adjacent areas. Coincident with the TZCF, increases in surface nitrate concentration and extensive changes in phytoplankton community composition were observed. HPLC pigment data indicated substantial increases in a prymnesiophyte (e.g., coccolithophore) biomarker at the TZCF on a spring and summer cruise, and a diatom biomarker on the spring cruise. Increases in remotely sensed surface particulate inorganic carbon concentration were also observed at the TZCF on all four cruises, indicating that coccolithophore production may contribute to increased productivity at the TZCF. Meridional trends in observed air-sea CO2 flux on each cruise resembled those of the biologically induced CO2 flux (NCP), but with an overprinting of the response of air-sea CO2 exchange to summer warming. A simple carbon budget based on regional CO2 flux climatology demonstrates the importance of NCP for net annual air-sea CO2 uptake, although slow air-sea equilibration and seasonal solubility effects obscure this term.
UR - http://www.scopus.com/inward/record.url?scp=84861172239&partnerID=8YFLogxK
U2 - 10.1029/2011JC007450
DO - 10.1029/2011JC007450
M3 - Article
AN - SCOPUS:84861172239
SN - 2169-9291
VL - 117
JO - Journal of Geophysical Research: Oceans
JF - Journal of Geophysical Research: Oceans
IS - 5
M1 - C05022
ER -