The biological pump plays a key role in the global carbon cycle by transporting photosynthetically fixed organic carbon into the deep ocean, where it can be sequestered from the atmosphere over annual or longer time scales if exported below the winter ventilation depth. In the subpolar North Atlantic, carbon sequestration via the biological pump is influenced by two competing forces: a spring diatom bloom that features large, fast-sinking biogenic particles, and deep winter mixing that requires particles to sink much further than in other ocean regions to escape winter ventilation. We synthesize biogeochemical sensor data from the first two years of operations at the Ocean Observatories Initiative Irminger Sea Array of moorings and gliders (September 2014–July 2016), providing the first simultaneous year-round observations of biological carbon cycling processes in both the surface ocean and the seasonal thermocline in this critical but previously undersampled region. These data show significant mixed layer net autotrophy during the spring bloom and significant respiration in the seasonal thermocline during the stratified season (~5.9 mol C m–2 remineralized between 200 m and 1,000 m). This respired carbon is subsequently ventilated during winter convective mixing (>1,000 m), a significant reduction in potential carbon sequestration. This highlights the importance of year-round observations to accurately constrain the biological pump in the subpolar North Atlantic, as well as other high-latitude regions that experience deep winter mixing.
Palevsky, H.I., and D.P. Nicholson. 2018. The North Atlantic biological pump: Insights from the Ocean Observatories Initiative Irminger Sea Array. Oceanography 31(1):42–49, https://doi.org/10.5670/oceanog.2018.108.
Antia, N., R. Peinert, D. Hebbeln, U. Bathmann, U. Fehner, and B. Zeitzschel. 2001. Basin-wide particulate carbon flux in the Atlantic Ocean: Regional export patterns and potential for atmospheric CO2 sequestration. Global Biogeochemical Cycles 15(4):845–862, https://doi.org/10.1029/2000gb001376.
Behrenfeld, M.J., and E.S. Boss. 2014. Resurrecting the ecological underpinnings of ocean plankton blooms. Annual Review of Marine Science 6(1):167–194, https://doi.org/10.1146/annurev-marine-052913-021325.
Bittig, H.C., and A. Körtzinger. 2015. Tackling oxygen optode drift: Near-surface and in-air oxygen optode measurements on a float provide an accurate in situ reference. Journal of Atmospheric and Oceanic Technology 32(8):1,536–1,543, https://doi.org/10.1175/JTECH-D-14-00162.1.
Bittig, H.C., and A. Körtzinger. 2017. Technical note: Update on response times, in-air measurements, and in situ drift for oxygen optodes on profiling platforms. Ocean Science 13(1):1–11, https://doi.org/10.5194/os-13-1-2017.
Briggs, N., M.J. Perry, I. Cetinić, C. Lee, E. D’Asaro, A.M. Gray, and E. Rehm. 2011. High-resolution observations of aggregate flux during a sub-polar North Atlantic spring bloom. Deep Sea Research Part I 58(10):1,031–1,039, https://doi.org/10.1016/j.dsr.2011.07.007.
Buesseler, K.O., P. Michael, H.D. Livingston, and K. Cochrant. 1992. Carbon and nitrogen export during the JGOFS North Atlantic Bloom Experiment estimated from 234Th:238U disequilibria. Deep Sea Research 39(7–8):1,115–1,137, https://doi.org/10.1016/0198-0149(92)90060-7.
Bushinsky, S.M., S.R. Emerson, S.C. Riser, and D.D. Swift. 2016. Accurate oxygen measurements on modified Argo floats using in situ air calibrations. Limnology and Oceanography: Methods 14:491–505, https://doi.org/10.1002/lom3.10107.
Church, M.J., M.W. Lomas, and F. Muller-Karger. 2013. Sea change: Charting the course for biogeochemical ocean time-series research in a new millennium. Deep Sea Research Part II 93:2–15, https://doi.org/10.1016/j.dsr2.2013.01.035.
Ciais, P., C. Sabine, G. Bala, L. Bopp, V. Brovkin, J. Canadell, A. Chhabra, R. DeFries, J. Galloway, M. Heimann, and others. 2013. Carbon and other biogeochemical cycles. Pp. 465–570. In Climate Change 2013 - The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. T.F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, and V. Bex, eds, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, https://doi.org/10.1017/CBO9781107415324.015.
D’Asaro, E.A., and C. McNeil. 2013. Calibration and stability of oxygen sensors on autonomous floats. Journal of Atmospheric and Oceanic Technology 30:1,896–1,906, https://doi.org/10.1175/JTECH-D-12-00222.1.
Dall’Olmo, G., J. Dingle, L. Polimene, R.J.W. Brewin, and H. Claustre. 2016. Substantial energy input to the mesopelagic ecosystem from the seasonal mixed-layer pump. Nature Geoscience 9:820–823, https://doi.org/10.1038/ngeo2818.
de Boyer Montégut, C., G. Madec, A.S. Fischer, A. Lazar, and D. Iudicone. 2004. Mixed layer depth over the global ocean: An examination of profile data and a profile-based climatology. Journal of Geophysical Research 109, C12003, https://doi.org/10.1029/2004JC002378.
de Jong, M.F., and L. de Steur. 2016. Strong winter cooling over the Irminger Sea in winter 2014–2015, exceptional deep convection, and the emergence of anomalously low SST. Geophysical Research Letters 43(13):7,106–7,113, https://doi.org/10.1002/2016GL069596.
de Jong, M.F., M. Oltmanns, J. Karstensen, and L. de Steur. 2018. Deep convection in the Irminger Sea observed with a dense mooring array. Oceanography 31(1):50–59, https://doi.org/10.5670/oceanog.2018.109.
de Jong, M.F., H.M. Van Aken, K. Våge, and R.S. Pickart. 2012. Convective mixing in the central Irminger Sea: 2002–2010. Deep Sea Research Part I 63:36–51, https://doi.org/10.1016/j.dsr.2012.01.003.
DeVries, T., F. Primeau, and C. Deutsch. 2012. The sequestration efficiency of the biological pump. Geophysical Research Letters 39, L13601, https://doi.org/10.1029/2012GL051963.
Emerson, S. 2014. Annual net community production and the biological carbon flux in the ocean. Global Biogeochemical Cycles 28:14–28, https://doi.org/10.1002/2013GB004680.
Emerson, S., and S. Bushinsky. 2014. Oxygen concentrations and biological fluxes in the open ocean. Oceanography 27(1):168–171, https://doi.org/10.5670/oceanog.2014.20.
Field, C.B., M.J. Behrenfeld, J.T. Randerson, and P. Falkowski. 1998. Primary production of the biosphere: Integrating terrestrial and oceanic components. Science 281(5374):237–240, https://doi.org/10.1126/science.281.5374.237.
Garcia, H.E., and L.I. Gordon. 1992. Oxygen solubility in seawater: Better fitting solubility equations. Limnology and Oceanography 37(6):1,307–1,312, https://doi.org/10.4319/lo.19126.96.36.1997.
Hennon, T.D., S.C. Riser, and S. Mecking. 2016. Profiling float-based observations of net respiration beneath the mixed layer. Global Biogeochemical Cycles 30:920–932, https://doi.org/10.1002/2016GB005380.
Henson, S.A., C. Beaulieu, and R. Lampitt. 2016. Observing climate change trends in ocean biogeochemistry: When and where. Global Change Biology 22:1,561–1,571, https://doi.org/10.1111/gcb.13152.
Henson, S.A., J.P. Dunne, and J.L. Sarmiento. 2009. Decadal variability in North Atlantic phytoplankton blooms. Journal of Geophysical Research 114(4):1–11, https://doi.org/10.1029/2008JC005139.
Henson, S.A., I. Robinson, J.T. Allen, and J.J. Waniek. 2006. Effect of meteorological conditions on interannual variability in timing and magnitude of the spring bloom in the Irminger Basin, North Atlantic. Deep Sea Research Part I 53:1,601–1,615, https://doi.org/10.1016/j.dsr.2006.07.009.
Johnson, K.S., and H. Claustre. 2016. Bringing Biogeochemistry into the Argo Age. Eos 97, https://doi.org/10.1029/2016EO062427.
Johnson, K.S., J.N. Plant, S.C. Riser, and D. Gilbert. 2015. Air oxygen calibration of oxygen optodes on a profiling float array. Journal of Atmospheric and Oceanic Technology 32(11):2,160–2,172, https://doi.org/10.1175/JTECH-D-15-0101.1.
Khatiwala, S., F. Primeau, and T. Hall. 2009. Reconstruction of the history of anthropogenic CO2 concentrations in the ocean. Nature 462(7271):346–349, https://doi.org/10.1038/nature08526.
Körtzinger, A., U. Send, R.S. Lampitt, S. Hartman, D.W.R. Wallace, J. Karstensen, M.G. Villagarcia, O. Llinás, and M.D. DeGrandpre. 2008. The seasonal pCO2 cycle at 49°N/16.5°W in the northeastern Atlantic Ocean and what it tells us about biological productivity. Journal of Geophysical Research 113, C04020, https://doi.org/10.1029/2007JC004347.
Laws, E.A. 1991. Photosynthetic quotients, new production and net community production in the open ocean. Deep Sea Research 38(1):143–167, https://doi.org/10.1016/0198-0149(91)90059-O.
Laws, E.A., E. D’Sa, and P. Naik. 2011. Simple equations to estimate ratios of new or export production to total production from satellite-derived estimates of sea surface temperature and primary production. Limnology and Oceanography: Methods 9:593–601, https://doi.org/10.4319/lom.2011.9.593.
Le Quéré, C., R.M. Andrew, J.G. Canadell, S. Sitch, J.I. Korsbakken, G.P. Peters, A.C. Manning, T.A. Boden, P.P. Tans, R.A. Houghton, and others. 2016. Global carbon budget 2016. Earth System Science Data 8:605–649, https://doi.org/10.5194/essd-8-605-2016.
Martin, J.M., G.A. Knauer, D.M. Karl, and W.W. Broenkow. 1987. VERTEX: Carbon cycling in the Northeast Pacific. Deep Sea Research 34(2):267–285, https://doi.org/10.1016/0198-0149(87)90086-0.
Martin, P., R.S. Lampitt, M.J. Perry, R. Sanders, C. Lee, and E. D’Asaro. 2011. Export and mesopelagic particle flux during a North Atlantic spring diatom bloom. Deep Sea Research Part I 58:338–349, https://doi.org/10.1016/j.dsr.2011.01.006.
Martz, T.R., K.S. Johnson, and S.C. Riser. 2008. Ocean metabolism observed with oxygen sensors on profiling floats in the South Pacific. Limnology and Oceanography 53(5, part 2):2,094–2,111, https://doi.org/10.4319/lo.2008.53.5_part_2.2094.
Nicholson, D.P., and M.L. Feen. 2017. Air calibration of an oxygen optode on an underwater glider. Limnology and Oceanography: Methods 15:495–502, https://doi.org/10.1002/lom3.10177.
Oschlies, A., and P. Kahler. 2004. Biotic contribution to air-sea fluxes of CO2 and O2 and its relation to new production, export production, and net community production. Global Biogeochemical Cycles 18, GB1015, https://doi.org/10.1029/2003GB002094.
Palevsky, H.I., P.D. Quay, D.E. Lockwood, and D.P. Nicholson. 2016a. The annual cycle of gross primary production, net community production, and export efficiency across the North Pacific Ocean. Global Biogeochemical Cycles 30:361–380, https://doi.org/10.1002/2015GB005318.
Palevsky, H.I., P.D. Quay, and D.P. Nicholson. 2016b. Discrepant estimates of primary and export production from satellite algorithms, a biogeochemical model and geochemical tracer measurements in the North Pacific Ocean. Geophysical Research Letters 43:8,645–8,653, https://doi.org/10.1002/2016GL070226.
Pickart, R.S., M.A. Spall, M.H. Ribergaard, G.W.K. Moore, and R.F. Milliff. 2003. Deep convection in the Irminger Sea forced by the Greenland tip jet. Nature 424(6945):152–156, https://doi.org/10.1038/nature01729.
Quay, P., J. Stutsman, and T. Steinhoff. 2012. Primary production and carbon export rates across the subpolar N. Atlantic Ocean basin based on triple oxygen isotope and dissolved O2 and Ar gas measurements. Global Biogeochemical Cycles 26, GB2003, https://doi.org/10.1029/2010GB004003.
Sabine, C.L., R.A. Feely, N. Gruber, R.M. Key, K. Lee, J.L. Bullister, R. Wanninkhof, C. Wong, D.W.R. Wallace, B. Tilbrook, and others. 2004. The oceanic sink for anthropogenic CO2. Science 305:367–371, https://doi.org/10.1126/science.1097403.
Sabine, C.L., and T. Tanhua. 2010. Estimation of anthropogenic CO2 inventories in the ocean. Annual Review of Marine Science 2:175–198, https://doi.org/10.1146/annurev-marine-120308-080947.
Sanders, R., S.A. Henson, M. Koski, C.L. De La Rocha, S.C. Painter, A.J. Poulton, J. Riley, B. Salihoglu, A. Visser, A. Yool, and others. 2014. The biological carbon pump in the North Atlantic. Progress in Oceanography 129:200–218, https://doi.org/10.1016/j.pocean.2014.05.005.
Sarmiento, J.L., and N. Gruber. 2006. Ocean Biogeochemical Dynamics. Princeton University Press, Princeton, NJ, 526 pp.
Siegel, D.A., K.O. Buesseler, S.C. Doney, S.F. Sailley, M.J. Behrenfeld, and P.W. Boyd. 2014. Global assessment of ocean carbon export by combining satellite observations and food-web models. Global Biogeochemical Cycles 28:181–196, https://doi.org/10.1002/2013GB004743.
Stukel, M.R., M. Kahru, C.R. Benitez-Nelson, M. Decima, R. Goericke, M.R. Landry, and M.D. Ohman. 2015. Using Lagrangian-based process studies to test satellite algorithms of vertical carbon flux in the eastern North Pacific Ocean. Journal of Geophysical Research 120:7,208–7,222, https://doi.org/10.1002/2015JC011264.
Takeshita, Y., T.R. Martz, K.S. Johnson, J.N. Plant, D. Gilbert, S.C. Riser, C. Neill, and B. Tilbrook. 2013. A climatology-based quality control procedure for profiling float oxygen data. Journal of Geophysical Research 118:5,640–5,650, https://doi.org/10.1002/jgrc.20399.
Volk, T., and M.I. Hoffert. 1985. Ocean carbon pumps: Analysis of relative strengths and efficiencies in ocean-driven atmospheric CO2 changes. Pp. 99–110 in The Carbon Cycle and Atmospheric CO2 Natural Variations Archean to Present. E.T. Sundquist and W.S. Broecker, eds, Geophysical Monograph Series, vol. 32, American Geophysical Union, Washington, DC.
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