Spatial coupling of nitrogen inputs and losses in the ocean

  title={Spatial coupling of nitrogen inputs and losses in the ocean},
  author={Curtis A. Deutsch and Jorge L. Sarmiento and Daniel M. Sigman and Nicolas Gruber and John P. Dunne},
Nitrogen fixation is crucial for maintaining biological productivity in the oceans, because it replaces the biologically available nitrogen that is lost through denitrification. But, owing to its temporal and spatial variability, the global distribution of marine nitrogen fixation is difficult to determine from direct shipboard measurements. This uncertainty limits our understanding of the factors that influence nitrogen fixation, which may include iron, nitrogen-to-phosphorus ratios, and… 
Convergent estimates of marine nitrogen fixation
It is suggested that biological carbon export in the ocean is higher than expected and that stabilizing nitrogen-cycle feedbacks are weaker than previously thought, and a role for top-down zooplankton grazing control is proposed in shaping the global patterns of nitrogen fixation.
Large-scale distribution of Atlantic nitrogen fixation controlled by iron availability
Oceanic fixed-nitrogen concentrations are controlled by the balance between nitrogen fixation and denitrification1, 2, 3, 4. A number of factors, including iron limitation5, 6, 7, can restrict
Changes in North Atlantic nitrogen fixation controlled by ocean circulation
Recovering changes in North Atlantic nitrogen fixation over the past 160,000 years from the shell-bound nitrogen isotope ratio of planktonic foraminifera in Caribbean Sea sediments suggests that excess phosphorus is the master variable in the North Atlantic Ocean and indicates that the variations in its supply over the most recent glacial cycle were dominated by the response of regional ocean circulation to the orbital cycles.
Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean
Abstract. The overarching goal of this study is to simulate subsurface N* (sensu, Gruber and Sarmiento, 1997; GS97) anomaly patterns in the North Atlantic Ocean and determine the basin wide rates of
Mechanistic models of oceanic nitrogen fixation
Oceanic nitrogen fixation and biogeochemical interactions between the nitrogen, phosphorus and iron cycles have important implications for the control of primary production and carbon storage in the
The marine nitrogen cycle: recent discoveries, uncertainties and the potential relevance of climate change
A nitrogen budget for the coastal and open ocean, where inputs and outputs match rather well, is presented and predicted climate change will impact the expansion of the oceans' oxygen minimum zones, the productivity of surface waters and presumably other microbial processes, with unpredictable consequences for the cycling of nitrogen.
Elusive marine nitrogen fixation
  • N. Gruber
  • Environmental Science
    Proceedings of the National Academy of Sciences
  • 2016
Knapp et al. (9) report on the results from their journey to one of these major denitrification regions, aimed at finding the purported high levels of N in N2 fixation in these regions.
Iron availability limits the ocean nitrogen inventory stabilizing feedbacks between marine denitrification and nitrogen fixation
It is suggested that iron is the ultimate limiting nutrient leading to nitrogen being the proximate limiting nutrient over wide regions today, leading to a higher marine N inventory, increased export production, and perhaps widespread phosphorus limitation of the phytoplankton community.
Distribution and rates of nitrogen fixation in the western tropical South Pacific Ocean constrained by nitrogen isotope budgets
Abstract. Constraining the rates and spatial distribution of dinitrogen (N 2) fixation fluxes to the ocean informs our understanding of the environmental sensitivities of N 2 fixation as well as the
The Global Nitrogen Cycle
The geobiology of nitrogen is dominated by large inert reservoirs and small biological fluxes. The largest reservoirs are nitrogen gas (in the atmosphere and dissolved in the ocean) and sedimentary


Denitrification and N2 fixation in the Pacific Ocean
We establish the fixed nitrogen budget of the Pacific Ocean based on nutrient fields from the recently completed World Ocean Circulation Experiment (WOCE). The budget includes denitrification in the
The oceanic fixed nitrogen and nitrous oxide budgets: Moving targets as we enter the anthropocene?*
New data force us to raise previous estimates of oceanic denitrification. Our revised estimate of ~ 450 Tg N yr -1 (Tg = 10 12 g) produces an oceanic fixed N budget with a large deficit (~ 200 Tg N
Evolution of the nitrogen cycle and its influence on the biological sequestration of CO2 in the ocean
Over geological time, photosynthetic carbon fixation in the oceans has exceeded respiratory oxidation of organic carbon. The imbalance between the two processes has resulted in the simultaneous
Global patterns of marine nitrogen fixation and denitrification
A new quasi‐conservative tracer N*, defined as a linear combination of nitrate and phosphate, is proposed to investigate the distribution of nitrogen fixation and denitrification in the world oceans.
A global marine‐fixed nitrogen isotopic budget: Implications for Holocene nitrogen cycling
A nitrogen stable isotopic model was constructed in order to constrain the Holocene marine‐fixed nitrogen budget. The primary sources and sinks considered were riverine and atmospheric sources,
Unicellular cyanobacteria fix N2 in the subtropical North Pacific Ocean
It is shown that there are unicellular cyanobacteria in the open ocean that are expressing nitrogenase, and are abundant enough to potentially have a significant role in N dynamics.
Phosphate depletion in the western North Atlantic Ocean.
It is hypothesized that nitrogen versus phosphorus limitation of primary production in the present-day ocean may be closely linked to iron supply through control of dinitrogen (N2) fixation, an iron-intensive metabolic process.
Isotopic constraints on glacial/interglacial changes in the oceanic nitrogen budget
We investigate the response of the 15N/14N of oceanic nitrate to glacial/interglacial changes in the N budget, using a geochemical box model of the oceanic N cycle that includes N2 fixation and
The role of nitrogen fixation in biogeochemical cycling in the subtropical North Pacific Ocean
Seven years of time-series observations of biogeochemical processes in the subtropical North Pacific Ocean gyre have revealed dramatic changes in the microbial community structure and in the