High sensitivity of ultra‐oligotrophic marine ecosystems to atmospheric nitrogen deposition

Mouriño‐Carballido, Beatriz; Pahlow, Markus; Oschlies, Andreas

doi:10.1029/2011gl050606

Cited by 11 publications

(12 citation statements)

References 33 publications

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“…The higher C : N ratio computed for ESTOC was consistent with the carbon rich organic matter observed in the mixed layer (Koeve, 2006) and the sinking organic matter in the region, and with close to Redfield ratios observed in the sinking organic matter at BATS (Schnetzer and Steinberg, 2002). Moreover, ecological models employed to study the sensitivity of carbon export to atmospheric nitrogen inputs in NASW and NASE showed higher C : N values in the sinking organic matter in NASE (Mouriño-Carballido et al, 2012).…”

Section: Remineralization Ratessupporting

confidence: 83%

“…Another source of new nitrogen that could explain the observed differences in carbon export between the two stations is biological nitrogen fixation. Recent studies indicate that this process supplies a significative contribution to total new nitrogen inputs in oligotrophic waters (Capone et al, 2005;Mouriño-Carballido et al, 2011;Bonnet et al, 2011). Biogeochemical estimates suggest a lower contribution of nitrogen fixation at ESTOC compared with BATS (Neuer et al, 2002a).…”

Section: Introductionmentioning

confidence: 99%

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Regional differences in modelled net production and shallow remineralization in the North Atlantic subtropical gyre

et al. 2012

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Abstract. We used 5-yr concomitant data of tracer distribution from the BATS (Bermuda Time-series Study) and ES-TOC (European Station for Time-Series in the Ocean, Canary Islands) sites to build a 1-D tracer model conservation including horizontal advection, and then compute net production and shallow remineralization rates for both sites. Our main goal was to verify if differences in these rates are consistent with the lower export rates of particulate organic carbon observed at ESTOC. Net production rates computed below the mixed layer to 110 m from April to December for oxygen, dissolved inorganic carbon and nitrate at BATS (1.34 ± 0.79 mol O 2 m −2 , −1.73 ± 0.52 mol C m −2 and −125±36 mmol N m −2 ) were slightly higher for oxygen and carbon compared to ESTOC (1.03 ± 0.62 mol O 2 m −2 , −1.42 ± 0.30 mol C m −2 and −213 ± 56 mmol N m −2 ), although the differences were not statistically significant. Shallow remineralization rates between 110 and 250 m computed at ESTOC (−3.9 ± 1.0 mol O 2 m −2 , 1.53 ± 0.43 mol C m −2 and 38 ± 155 mmol N m −2 ) were statistically higher for oxygen compared to BATS (−1.81 ± 0.37 mol O 2 m −2 , 1.52 ± 0.30 mol C m −2 and 147 ± 43 mmol N m −2 ). The lateral advective flux divergence of tracers, which was more significant at ESTOC, was responsible for the differences in estimated oxygen remineralization rates between both stations. According to these results, the differences in net production and shallow remineralization cannot fully explain the differences in the flux of sinking organic matter observed between both stations, suggesting an additional consumption of nonsinking organic matter at ESTOC.

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Section: Remineralization Ratessupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Regional differences in modelled net production and shallow remineralization in the North Atlantic subtropical gyre

et al. 2012

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“…Had we considered variable stoichiometry there, the very low N:C ratio of phytoplankton would cause a much higher NPP response compared to what we simulated with our fixed stoichiometry model. Mouriño‐Carballido et al [] showed that this effect can lead to an up to fivefold higher response of NPP, but only where nitrate is more or less permanently low. Such a larger fertilization would induce a stronger thermocline deoxygenation and hence a stronger response of the stabilizing feedback via denitrification.…”

Section: Caveatsmentioning

confidence: 99%

The anthropogenic perturbation of the marine nitrogen cycle by atmospheric deposition: Nitrogen cycle feedbacks and the ¹⁵N Haber‐Bosch effect

Yang

Gruber

2016

Global Biogeochemical Cycles

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Over the last 100 years, anthropogenic emissions have led to a strong increase of atmospheric nitrogen deposition over the ocean, yet the resulting impacts and feedbacks are neither well understood nor quantified. To this end, we run a suite of simulations with the ocean component of the Community Earth System Model v1.2 forced with five scenarios of nitrogen deposition over the period from 1850 through 2100, while keeping all other forcings unchanged. Even though global oceanic net primary production increases little in response to this fertilization, the higher export and the resulting expansion of the oxygen minimum zones cause an increase in pelagic and benthic denitrification and burial by about 5%. In addition, the enhanced availability of fixed nitrogen in the surface ocean reduces global ocean N2 fixation by more than 10%. Despite the compensating effects through these negative feedbacks that eliminate by the year 2000 about 60% of the deposited nitrogen, the anthropogenic nitrogen input forced the upper ocean N budget into an imbalance of between 9 and 22 Tg N yr−1 depending on the deposition scenario. The excess nitrogen accumulates to highly detectable levels and causes in most areas a distinct negative trend in the δ15N of the oceanic fixed nitrogen pools—a trend we refer to as the 15N Haber‐Bosch effect. Changes in surface nitrate utilization and the nitrogen feedbacks induce further changes in the δ15N of NO3−, making it a good but complex recorder of the overall impact of the changes in atmospheric deposition.

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“…In this work, the abilities of the ACCMIP MMM (Lamarque et al, 2013a) and the TM4-ECPL model, hereafter TM4 (Kanakidou et al, 2016;Myriokefalitakis et al, 2015), to estimate atmospheric N dry deposition to the ocean are evaluated. The evaluation was done by comparison to a substantial database of aerosol N observations collected during ships' voyages over all the major ocean basins.…”

Section: Introductionmentioning

confidence: 99%

Observation- and model-based estimates of particulate dry nitrogen deposition to the oceans

et al. 2017

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Anthropogenic nitrogen (N) emissions to the atmosphere have increased significantly the deposition of nitrate (NO) and ammonium (NH) to the surface waters of the open ocean, with potential impacts on marine productivity and the global carbon cycle. Global-scale understanding of the impacts of N deposition to the oceans is reliant on our ability to produce and validate models of nitrogen emission, atmospheric chemistry, transport and deposition. In this work, ~2900 observations of aerosol NO and NH concentrations, acquired from sampling aboard ships in the period 1995 - 2012, are used to assess the performance of modelled N concentration and deposition fields over the remote ocean. Three ocean regions (the eastern tropical North Atlantic, the northern Indian Ocean and northwest Pacific) were selected, in which the density and distribution of observational data were considered sufficient to provide effective comparison to model products. All of these study regions are affected by transport and deposition of mineral dust, which alters the deposition of N, due to uptake of nitrogen oxides (NO) on mineral surfaces. Assessment of the impacts of atmospheric N deposition on the ocean requires atmospheric chemical transport models to report deposition fluxes, however these fluxes cannot be measured over the ocean. Modelling studies such as the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), which only report deposition flux are therefore very difficult to validate for dry deposition. Here the available observational data were averaged over a 5° × 5° grid and compared to ACCMIP dry deposition fluxes (ModDep) of oxidised N (NO) and reduced N (NH) and to the following parameters from the TM4-ECPL (TM4) model: ModDep for NO, NH and particulate NO and NH, and surface-level particulate NO and NH concentrations. As a model ensemble, ACCMIP can be expected to be more robust than TM4, while TM4 gives access to speciated parameters (NO and NH) that are more relevant to the observed parameters and which are not available in ACCMIP. Dry deposition fluxes (CalDep) were calculated from the observed concentrations using estimates of dry deposition velocities. Model - observation ratios, weighted by grid-cell area and numbers of observations, (R) were used to assess the performance of the models. Comparison in the three study regions suggests that TM4 over-estimates NO concentrations (R = 1.4 - 2.9) and under-estimates NH concentrations (R = 0.5 - 0.7), with spatial distributions in the tropical Atlantic and northern Indian Ocean not being reproduced by the model. In the case of NH in the Indian Ocean, this discrepancy was probably due to seasonal biases in the sampling. Similar patterns were observed in the various comparisons of CalDep to ModDep (R = 0.6 - 2.6 for NO, 0.6 - 3.1 for NH). Values of R for NH CalDep - ModDep comparisons were approximately double the corresponding values for NH CalDep - ModDep comparisons due to the significant fraction of gas-phase NH deposition incorporated in the TM4 and ACCMIP ...

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High sensitivity of ultra‐oligotrophic marine ecosystems to atmospheric nitrogen deposition

Cited by 11 publications

References 33 publications

Regional differences in modelled net production and shallow remineralization in the North Atlantic subtropical gyre

Regional differences in modelled net production and shallow remineralization in the North Atlantic subtropical gyre

The anthropogenic perturbation of the marine nitrogen cycle by atmospheric deposition: Nitrogen cycle feedbacks and the ¹⁵N Haber‐Bosch effect

Observation- and model-based estimates of particulate dry nitrogen deposition to the oceans

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High sensitivity of ultra‐oligotrophic marine ecosystems to atmospheric nitrogen deposition

Cited by 11 publications

References 33 publications

Regional differences in modelled net production and shallow remineralization in the North Atlantic subtropical gyre

Regional differences in modelled net production and shallow remineralization in the North Atlantic subtropical gyre

The anthropogenic perturbation of the marine nitrogen cycle by atmospheric deposition: Nitrogen cycle feedbacks and the 15N Haber‐Bosch effect

Observation- and model-based estimates of particulate dry nitrogen deposition to the oceans

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The anthropogenic perturbation of the marine nitrogen cycle by atmospheric deposition: Nitrogen cycle feedbacks and the ¹⁵N Haber‐Bosch effect