Global oceanic diazotroph database version 2 and elevated estimate of global oceanic N 2 fixation

• Published in: Earth System Science Data
• Main Authors: Z. Shao, Y. Xu, H. Wang, W. Luo, L. Wang, Y. Huang, N. S. R. Agawin, A. Ahmed, M. Benavides, M. Bentzon-Tilia, I. Berman-Frank, H. Berthelot, I. C. Biegala, M. B. Bif, A. Bode, S. Bonnet, D. A. Bronk, M. V. Brown, L. Campbell, D. G. Capone, E. J. Carpenter, N. Cassar, B. X. Chang, D. Chappell, Y.-L. Chen, M. J. Church, F. M. Cornejo-Castillo, A. M. S. Detoni, S. C. Doney, C. Dupouy, M. Estrada, C. Fernandez, B. Fernández-Castro, D. Fonseca-Batista, R. A. Foster, K. Furuya, N. Garcia, K. Goto, J. Gago, M. R. Gradoville, M. R. Hamersley, B. A. Henke, C. Hörstmann, A. Jayakumar, Z. Jiang, S.-J. Kao, D. M. Karl, L. R. Kittu, A. N. Knapp, S. Kumar, J. LaRoche, H. Liu, J. Liu, C. Lory, C. R. Löscher, E. Marañón, L. F. Messer, M. M. Mills, W. Mohr, P. H. Moisander, C. Mahaffey, R. Moore, B. Mouriño-Carballido, M. R. Mulholland, S. Nakaoka, J. A. Needoba, E. J. Raes, E. Rahav, T. Ramírez-Cárdenas, C. F. Reeder, L. Riemann, V. Riou, J. C. Robidart, V. V. S. S. Sarma, T. Sato, H. Saxena, C. Selden, J. R. Seymour, D. Shi, T. Shiozaki, A. Singh, R. E. Sipler, J. Sun, K. Suzuki, K. Takahashi, Y. Tan, W. Tang, J.-É. Tremblay, K. Turk-Kubo, Z. Wen, A. E. White, S. T. Wilson, T. Yoshida, J. P. Zehr, R. Zhang, Y. Zhang, Y.-W. Luo
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2023
• Subjects: Environmental sciences; GE1-350; Geology; QE1-996.5; Indian; Pacific; North Atlantic
• Online Access: https://doi.org/10.5194/essd-15-3673-2023; https://doaj.org/article/1237611228b24f379a945a880ff82d90

Marine diazotrophs convert dinitrogen ( N 2 ) gas into bioavailable nitrogen (N), supporting life in the global ocean. In 2012, the first version of the global oceanic diazotroph database (version 1) was published. Here, we present an updated version of the database (version 2), significantly increasing the number of in situ diazotrophic measurements from 13 565 to 55 286. Data points for N 2 fixation rates, diazotrophic cell abundance, and nifH gene copy abundance have increased by 184 %, 86 %, and 809 %, respectively. Version 2 includes two new data sheets for the nifH gene copy abundance of non-cyanobacterial diazotrophs and cell-specific N 2 fixation rates. The measurements of N 2 fixation rates approximately follow a log-normal distribution in both version 1 and version 2. However, version 2 considerably extends both the left and right tails of the distribution. Consequently, when estimating global oceanic N 2 fixation rates using the geometric means of different ocean basins, version 1 and version 2 yield similar rates (43–57 versus 45–63 Tg N yr −1 ranges based on one geometric standard error). In contrast, when using arithmetic means, version 2 suggests a significantly higher rate of 223±30 Tg N yr −1 (mean ± standard error; same hereafter) compared to version 1 ( 74±7 Tg N yr −1 ). Specifically, substantial rate increases are estimated for the South Pacific Ocean ( 88±23 versus 20±2 Tg N yr −1 ), primarily driven by measurements in the southwestern subtropics, and for the North Atlantic Ocean ( 40±9 versus 10±2 Tg N yr −1 ). Moreover, version 2 estimates the N 2 fixation rate in the Indian Ocean to be 35±14 Tg N yr −1 , which could not be estimated using version 1 due to limited data availability. Furthermore, a comparison of N 2 fixation rates obtained through different measurement methods at the same months, locations, and depths reveals that the conventional 15 N 2 bubble method yields lower rates in 69 % cases compared to the new 15 N 2 dissolution method. This updated version of the database can ...