The marine nitrogen cycle: recent discoveries, uncertainties and the potential relevance of climate change

Voß, Maren; Bange, Hermann W.; Dippner, Joachim W.; Middelburg, Jack J.; Montoya, Joseph P.; Ward, Bettie

doi:10.1098/rstb.2013.0121

Cited by 261 publications

(209 citation statements)

References 112 publications

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“…Even the opposite, brine generation by evaporation may, induce stratification (Friedrich et al, 2008). Stratification blocks the oxygen transfer through the water column and triggers the formation of oxygen-depleted zones (Voss et al, 2013) that also emit nitrous oxide (N 2 O), a potent greenhouse gas (GHG) and a powerful ozone-depleting agent.…”

Section: Introductionmentioning

confidence: 99%

Climate engineering by mimicking natural dust climate control: the iron salt aerosol method

et al. 2017

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Abstract. Power stations, ships and air traffic are among the most potent greenhouse gas emitters and are primarily responsible for global warming. Iron salt aerosols (ISAs), composed partly of iron and chloride, exert a cooling effect on climate in several ways. This article aims firstly to examine all direct and indirect natural climate cooling mechanisms driven by ISA tropospheric aerosol particles, showing their cooperation and interaction within the different environmental compartments. Secondly, it looks at a proposal to enhance the cooling effects of ISA in order to reach the optimistic target of the Paris climate agreement to limit the global temperature increase between 1.5 and 2 • C.Mineral dust played an important role during the glacial periods; by using mineral dust as a natural analogue tool and by mimicking the same method used in nature, the proposed ISA method might be able to reduce and stop climate warming. The first estimations made in this article show that by doubling the current natural iron emissions by ISA into the troposphere, i.e., by about 0.3 Tg Fe yr −1 , artificial ISA would enable the prevention or even reversal of global warming. The ISA method proposed integrates technical and economically feasible tools.

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Section: Introductionmentioning

confidence: 99%

Climate engineering by mimicking natural dust climate control: the iron salt aerosol method

et al. 2017

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“…Diazotrophs possess nitrogenase, the enzyme that catalyzes this process, which reduces atmospheric N 2 to bioavailable ammonium (NH + 4 ). With an estimated global flux of ∼140-177 Tg N year −1 , BNF is the main mechanism that supplies new N to the ocean, fueling phytoplanktonic photosynthesis and the subsequent export of organic matter into the deep waters through the "biological carbon pump" (Voss et al, 2013). The limited number of studies simultaneously quantifying BNF vs. the transport of nitrate into the euphotic zone through turbulent mixing indicate that BNF can equal or even exceed nitrate diffusion in some regions of the subtropical gyres Mouriño-Carballido et al, 2011;Painter et al, 2013;Fernández-Castro et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Biological N2 Fixation in the Upwelling Region off NW Iberia: Magnitude, Relevance, and Players

et al. 2017

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The classical paradigm about marine N 2 fixation establishes that this process is mainly constrained to nitrogen-poor tropical and subtropical regions, and sustained by the colonial cyanobacterium Trichodesmium spp. and diatom-diazotroph symbiosis. However, the application of molecular techniques allowed determining a high phylogenic diversity and wide distribution of marine diazotrophs, which extends the range of ocean environments where biological N 2 fixation may be relevant. Between February 2014 and December 2015, we carried out 10 one-day samplings in the upwelling system off NW Iberia in order to: (1) investigate the seasonal variability in the magnitude of N 2 fixation, (2) determine its biogeochemical role as a mechanism of new nitrogen supply, and (3) quantify the main diazotrophs in the region under contrasting hydrographic regimes. Our results indicate that the magnitude of N 2 fixation in this region was relatively low (0.001 ± 0.002 -0.095 ± 0.024 µmol N m −3 d −1 ), comparable to the lower-end of rates described for the subtropical NE Atlantic. Maximum rates were observed at the surface during both upwelling and relaxation conditions. The comparison with nitrate diffusive fluxes revealed the minor role of N 2 fixation (<2%) as a mechanism of new nitrogen supply into the euphotic layer. Small diazotrophs (<10 µm) were responsible for all N 2 fixation activity detected in the region. Quantitative PCR targeting the nifH gene revealed the highest abundances of two sublineages of Candidatus Atelocyanobacterium thalassa or UCYN-A (UCYN-A1 and UCYN-A2), mainly at surface waters during upwelling and relaxation conditions, and of Gammaproteobacteria γ-24774A11 at deep waters during downwelling. Maximum abundance for the three groups were up to 6.7 × 10 2 , 1.5 × 10 3 , and 2.4 × 10 4 nifH copies L −1 , respectively. Our findings demonstrate measurable N 2 fixation activity and presence of diazotrophs throughout the year in a nitrogen-rich temperate region.

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“…Our study highlights the importance of understanding the response of multiple ecosystem components over the longer term if we are to provide ecosystem-relevant evidence to underpin decisions that aim to secure the protection of natural capital (Pittman and Armitage, 2016), and ensure the sustainable management of coastal and shelf sea ecosystem services (Voss et al 2013).…”

Section: Discussionmentioning

confidence: 99%

Mediation of nitrogen by post-disturbance shelf communities experiencing organic matter enrichment

et al. 2017

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Microbes and benthic macro-invertebrates interact in sediments to play a major role in the biogeochemical cycling of organic matter, but the extent to which their contributions are modified following natural and anthropogenic changes has received little attention. Here, we investigate how nitrogen transformations, ascertained from changes in archaeal and bacterial N-cycling microbes and water macronutrient concentrations ([NH 4 -N], [NO 2 -N], [NO 3 -N]), in sand and sandy mud sediments differ when macrofaunal communities that have previously experienced contrasting levels of chronic fishing disturbance are exposed to organic matter enrichment.We find that differences in macrofaunal community structure related to differences in fishing activity affect the capacity of the macrofauna to mediate microbial nitrogen cycling in sand, but not in sandy mud environments. Whilst we found no evidence for a change in ammonia oxidiser community structure, we did find an increase in archaeal and bacterial denitrifier (AnirKa, nirS) and anammox (hzo) transcripts in macrofaunal communities characterized by higher ratios of suspension to deposit feeders, and a lower density but higher biomass of sediment-reworking fauna. Our findings suggest that nitrogen transformation in shelf sandy sediments is dependent on the stimulation of specific nitrogen cycling pathways that are associated with differences in the composition and context-dependent expression of the functional traits that belong to the resident bioturbating macrofauna community.

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The marine nitrogen cycle: recent discoveries, uncertainties and the potential relevance of climate change

Cited by 261 publications

References 112 publications

Climate engineering by mimicking natural dust climate control: the iron salt aerosol method

Climate engineering by mimicking natural dust climate control: the iron salt aerosol method

Biological N2 Fixation in the Upwelling Region off NW Iberia: Magnitude, Relevance, and Players

Mediation of nitrogen by post-disturbance shelf communities experiencing organic matter enrichment

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