%ABöttjer, Daniela [Department of Oceanography, School of Ocean and Earth Science and Technology University of Hawai'i at Mānoa Honolulu Hawai'i, Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa Honolulu Hawai'i]%ABöttjer, Daniela [Department of Oceanography, School of Ocean and Earth Science and Technology; University of Hawai'i at Mānoa; Honolulu Hawai'i; Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa; Honolulu Hawai'i]%ADore, John [Department of Land Resources and Environmental Sciences Montana State University Bozeman Montana]%ADore, John [Department of Land Resources and Environmental Sciences; Montana State University; Bozeman Montana]%AKarl, David [Department of Oceanography, School of Ocean and Earth Science and Technology University of Hawai'i at Mānoa Honolulu Hawai'i, Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa Honolulu Hawai'i]%AKarl, David [Department of Oceanography, School of Ocean and Earth Science and Technology; University of Hawai'i at Mānoa; Honolulu Hawai'i; Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa; Honolulu Hawai'i]%ALetelier, Ricardo [Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa Honolulu Hawai'i, College of Earth, Ocean, and Atmospheric Sciences Oregon State University Corvallis Oregon]%ALetelier, Ricardo [Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa; Honolulu Hawai'i; College of Earth, Ocean, and Atmospheric Sciences; Oregon State University; Corvallis Oregon]%AMahaffey, Claire [Department of Earth, Ocean, and Ecological Sciences, School of Environmental Sciences University of Liverpool Liverpool United Kingdom]%AMahaffey, Claire [Department of Earth, Ocean, and Ecological Sciences, School of Environmental Sciences; University of Liverpool; Liverpool United Kingdom]%AWilson, Samuel [Department of Oceanography, School of Ocean and Earth Science and Technology University of Hawai'i at Mānoa Honolulu Hawai'i, Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa Honolulu Hawai'i]%AWilson, Samuel [Department of Oceanography, School of Ocean and Earth Science and Technology; University of Hawai'i at Mānoa; Honolulu Hawai'i; Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa; Honolulu Hawai'i]%AZehr, Jonathan [Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa; Honolulu Hawai'i; Ocean Sciences Department; University of California; Santa Cruz California]%AZehr, Jonathan [Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa Honolulu Hawai'i, Ocean Sciences Department University of California Santa Cruz California]%AChurch, Matthew [Department of Oceanography, School of Ocean and Earth Science and Technology University of Hawai'i at Mānoa Honolulu Hawai'i, Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa Honolulu Hawai'i]%AChurch, Matthew [Department of Oceanography, School of Ocean and Earth Science and Technology; University of Hawai'i at Mānoa; Honolulu Hawai'i; Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa; Honolulu Hawai'i]%BJournal Name: Limnology and Oceanography; Journal Volume: 62; Journal Issue: 1; Related Information: CHORUS Timestamp: 2023-09-17 20:43:47 %D2016%IWiley Blackwell (John Wiley & Sons) %JJournal Name: Limnology and Oceanography; Journal Volume: 62; Journal Issue: 1; Related Information: CHORUS Timestamp: 2023-09-17 20:43:47 %K %MOSTI ID: 10018859 %PMedium: X %TTemporal variability of nitrogen fixation and particulate nitrogen export at Station ALOHA %XAbstract

We present nearly 9 yrs (June 2005–December 2013) of measurements of upper‐ocean (0 m to 125 m) dinitrogen (N2) fixation rates, coupled with particulate nitrogen (PN) export at 150 m, from Station ALOHA (22° 45′N, 158°W) in the North Pacific Subtropical Gyre. Between June 2005 and June 2012, N2fixation rates were measured based on adding the15N2tracer as a gas bubble. Beginning in August 2012,15N2was first dissolved into filtered seawater and the15N2‐enriched water was subsequently added to N2fixation incubations. Direct comparisons between methodologies revealed a robust relationship, with the addition of15N2‐enriched seawater resulting in twofold greater depth‐integrated rates than those derived from adding a15N2gas bubble. Based on this relationship, we corrected the initial period of measurements, and the resulting rates of N2fixation averaged 230 ± 136 μmol N m−2d−1for the full time series (n = 71). Analysis of the15N isotopic composition of sinking PN, together with an isotope mass balance model, revealed that N2fixation supported 26–47% of PN export during calendar years 2006–2013. The N export derived from these fractional contributions and measured N2fixation rates ranged between 502 and 919 μmol N m−2 d−1, which are equivalent to rates of net community production (NCP) of 1.5 to 2.7 mol C m−2 yr−1, consistent with previous independent estimates of NCP at this site.

%0Journal Article