Gorbunov Maxim Y.

No Thumbnail Available
Last Name
Gorbunov
First Name
Maxim Y.
ORCID

Filters

1 1 1
2005 - 2009 1 2010 - 2020 1
2
2
Reset filters

Settings

Search Results

Now showing 1 - 2 of 2
  • Article
    Synthesis of iron fertilization experiments : from the Iron Age in the Age of Enlightenment
    (American Geophysical Union, 2005-09-28) Baar, Hein J. W. de ; Boyd, Philip W. ; Coale, Kenneth H. ; Landry, Michael R. ; Tsuda, Atsushi ; Assmy, Philipp ; Bakker, Dorothee C. E. ; Bozec, Yann ; Barber, Richard T. ; Brzezinski, Mark A. ; Buesseler, Ken O. ; Boye, Marie ; Croot, Peter L. ; Gervais, Frank ; Gorbunov, Maxim Y. ; Harrison, Paul J. ; Hiscock, William T. ; Laan, Patrick ; Lancelot, Christiane ; Law, Cliff S. ; Levasseur, Maurice ; Marchetti, Adrian ; Millero, Frank J. ; Nishioka, Jun ; Nojiri, Yukihiro ; van Oijen, Tim ; Riebesell, Ulf ; Rijkenberg, Micha J. A. ; Saito, Hiroaki ; Takeda, Shigenobu ; Timmermans, Klaas R. ; Veldhuis, Marcel J. W. ; Waite, Anya M. ; Wong, Chi-Shing
    Comparison of eight iron experiments shows that maximum Chl a, the maximum DIC removal, and the overall DIC/Fe efficiency all scale inversely with depth of the wind mixed layer (WML) defining the light environment. Moreover, lateral patch dilution, sea surface irradiance, temperature, and grazing play additional roles. The Southern Ocean experiments were most influenced by very deep WMLs. In contrast, light conditions were most favorable during SEEDS and SERIES as well as during IronEx-2. The two extreme experiments, EisenEx and SEEDS, can be linked via EisenEx bottle incubations with shallower simulated WML depth. Large diatoms always benefit the most from Fe addition, where a remarkably small group of thriving diatom species is dominated by universal response of Pseudo-nitzschia spp. Significant response of these moderate (10–30 μm), medium (30–60 μm), and large (>60 μm) diatoms is consistent with growth physiology determined for single species in natural seawater. The minimum level of “dissolved” Fe (filtrate < 0.2 μm) maintained during an experiment determines the dominant diatom size class. However, this is further complicated by continuous transfer of original truly dissolved reduced Fe(II) into the colloidal pool, which may constitute some 75% of the “dissolved” pool. Depth integration of carbon inventory changes partly compensates the adverse effects of a deep WML due to its greater integration depths, decreasing the differences in responses between the eight experiments. About half of depth-integrated overall primary productivity is reflected in a decrease of DIC. The overall C/Fe efficiency of DIC uptake is DIC/Fe ∼ 5600 for all eight experiments. The increase of particulate organic carbon is about a quarter of the primary production, suggesting food web losses for the other three quarters. Replenishment of DIC by air/sea exchange tends to be a minor few percent of primary CO2 fixation but will continue well after observations have stopped. Export of carbon into deeper waters is difficult to assess and is until now firmly proven and quite modest in only two experiments.
  • Article
    FIReglider: mapping in situ chlorophyll variable fluorescence with autonomous underwater gliders
    (Association for the Sciences of Limnology and Oceanography, 2020-07-16) Carvalho, Filipa ; Gorbunov, Maxim Y. ; Oliver, Matthew J. ; Haskins, Christina ; Aragon, David ; Kohut, Josh ; Schofield, Oscar M. E.
    Nutrient and light availability regulate phytoplankton physiology and photosynthesis in the ocean. These physiological processes are difficult to sample in time and space over physiologically and ecologically relevant scales using traditional shipboard techniques. Gliders are changing the nature of data collection, by allowing a sustained presence at sea over regional scales, collecting data at resolution not possible using traditional techniques. The integration of a fluorescence induction and relaxation (FIRe) sensor in a Slocum glider allows autonomous high‐resolution and vertically‐resolved measurements of photosynthetic physiological variables together with oceanographic data. In situ measurements of variable fluorescence under ambient light allows a better understanding of the physical controls of primary production (PP). We demonstrate this capability in a laboratory setting and with several glider deployments in the Southern Ocean. Development of these approaches will allow for the in situ evaluation of phytoplankton light stress and photoacclimation mechanisms, as well as the role of vertical mixing in phytoplankton dynamics and the underlying physiology, especially in remote locations and for prolonged duration.