Transatlantic equatorial distribution of nitrous oxide and methane

Oudot, Claude; Jean‐Baptiste, Philippe; Fourré, Élise; Mormiche, Claire; Guevel, Michael; Ternon, Jean-François; Corre, Pierre Le

doi:10.1016/s0967-0637(02)00019-5

Cited by 49 publications

(70 citation statements)

References 52 publications

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“…During the "Meteor 55" cruise, a plume of Amazon Water had been identified in the western basin of the tropical North Atlantic (Körtzinger, 2003). In contrast to Oudot et al (2002), who reported enhanced values in the plume of the Amazon River, we found no influence on N 2 O concentrations (Walter et al, 2004).…”

Section: N 2 O Distribution Along Isopycnal Levelscontrasting

confidence: 86%

“…We assume the AAIW transports N 2 O from the south to the cold-temperate North Atlantic. At depths shallower (Oudot et al, 2002) and a previous study in the Guinea Dome area (Oudot et al, 1990). Although the overall pattern is the same, we observed generally lower N 2 O concentrations than Oudot et al (2002).…”

Section: N 2 O In the Surface Layer Of The North Atlanticsupporting

confidence: 70%

“…At depths shallower (Oudot et al, 2002) and a previous study in the Guinea Dome area (Oudot et al, 1990). Although the overall pattern is the same, we observed generally lower N 2 O concentrations than Oudot et al (2002). This might be a result of a calibration disagreement, supported by measured atmospheric N 2 O values of 316 ppb in 1993.…”

Section: N 2 O In the Surface Layer Of The North Atlanticsupporting

confidence: 67%

“…• 30 N were reported by Oudot et al (2002). In this paper we present a comprehensive set of 73 vertical profiles of nitrous oxide from three trans-Atlantic cruises, covering the cold-temperate North Atlantic, the subtropical and the tropical North Atlantic.…”

mentioning

confidence: 99%

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Nitrous oxide in the North Atlantic Ocean

et al. 2006

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Section: N 2 O Distribution Along Isopycnal Levelscontrasting

confidence: 86%

Section: N 2 O In the Surface Layer Of The North Atlanticsupporting

confidence: 70%

Section: N 2 O In the Surface Layer Of The North Atlanticsupporting

confidence: 67%

mentioning

confidence: 99%

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Nitrous oxide in the North Atlantic Ocean

et al. 2006

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“…CH 4 fluxes were higher at stations located at the PF and A3, where phytoplanktonic blooms were observed (see Table 2), but the tendency was the reverse for N 2 O, with an influx into the aforementioned stations. CH 4 emission rates during this study were higher than previously measured (Table 2), with a range of 0.1 to 3.0 µmol m −2 d −1 for the Pacific Ocean (Bates et al, 1996;Holmes et al, 2000;Sansone et al, 2001) and 0.5 to 9.7 µmol m −2 d −1 for the Atlantic Ocean (Oudot et al, 2002;Forster et al, 2009). In the South Pacific ocean (10 • -64 • S, 140 • E), crossing the PF, Yoshida et al (2011) reported CH 4 fluxes ranging from 2.4 to 4.9 µmol m −2 d −1 .…”

Section: Ch 4 and N 2 O Emission In The Southern Oceancontrasting

confidence: 58%

Dissolved greenhouse gases (nitrous oxide and methane) associated with the naturally iron-fertilized Kerguelen region (KEOPS 2 cruise) in the Southern Ocean

et al. 2015

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Abstract. The concentrations of greenhouse gases (GHGs), such as nitrous oxide (N 2 O) and methane (CH 4 ), were measured in the Kerguelen Plateau region (KPR). The KPR is affected by an annual microalgal bloom caused by natural iron fertilization, and this may stimulate the microbes involved in GHG cycling. This study was carried out during the KEOPS 2 cruise during the austral spring of 2011. Oceanographic variables, including N 2 O and CH 4 , were sampled (from the surface to 500 m depth) in two transects along and across the KRP, the north-south (TNS) transect (46 • -51 • S, ∼ 72 • E) and the east-west (TEW) transect (66 • -75 • E, ∼ 48.3 • S), both associated with the presence of a plateau, polar front (PF) and other mesoscale features. The TEW presented N 2 O levels ranging from equilibrium (105 %) to slightly supersaturated (120 %) with respect to the atmosphere, whereas CH 4 levels fluctuated dramatically, being highly supersaturated (120-970 %) in areas close to the coastal waters of the Kerguelen Islands and in the PF. The TNS showed a more homogenous distribution for both gases, with N 2 O and CH 4 levels ranging from 88 to 171 % and 45 to 666 % saturation, respectively. Surface CH 4 peaked at southeastern stations of the KPR (A3 stations), where a phytoplankton bloom was observed. Both gases responded significantly, but in contrasting ways (CH 4 accumulation and N 2 O depletion), to the patchy distribution of chlorophyll a. This seems to be associated to the supply of iron from various sources. Air-sea fluxes for N 2 O (from −10.5 to 8.65, mean 1.25 ± 4.04 µmol m −2 d −1 ) and for CH 4 (from 0.32 to 38.1, mean 10.01 ± 9.97 µmol −2 d −1 ) indicated that the KPR is both a sink and a source for N 2 O, as well as a considerable and variable source of CH 4 . This appears to be associated with biological factors, as well as the transport of water masses enriched with Fe and CH 4 from the coastal area of the Kerguelen Islands. These previously unreported results for the Southern Ocean suggest an intense microbial CH 4 production in the study area.

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Ventilation versus biology: What is the controlling mechanism of nitrous oxide distribution in the North Atlantic?

Paz

García-Ibáñez

Steinfeldt

et al. 2017

Global Biogeochemical Cycles

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The extent to which water mass mixing and ocean ventilation contribute to nitrous oxide (N2O) distribution at the scale of oceanic basins is poorly constrained. We used novel N2O and chlorofluorocarbon measurements along with multiparameter water mass analysis to evaluate the impact of water mass mixing and Atlantic Meridional Overturning Circulation (AMOC) on N2O distribution along the Observatoire de la variabilité interannuelle et décennale en Atlantique Nord (OVIDE) section, extending from Portugal to Greenland. The biological N2O production has a stronger impact on the observed N2O concentrations in the water masses traveling northward in the upper limb of the AMOC than those in recently ventilated cold water masses in the lower limb, where N2O concentrations reflect the colder temperatures. The high N2O tongue, with concentrations as high as 16 nmol kg−1, propagates above the isopycnal surface delimiting the upper and lower AMOC limbs, which extends from the eastern North Atlantic Basin to the Iceland Basin and coincides with the maximum N2O production rates. Water mixing and basin‐scale remineralization account for 72% of variation in the observed distribution of N2O. The mixing‐corrected stoichiometric ratio N2O:O2 for the North Atlantic Basin of 0.06 nmol/μmol is in agreement with ratios of N2O:O2 for local N2O anomalies, suggesting than up to 28% of N2O production occurs in the temperate and subpolar Atlantic, an overlooked region for N2O cycling. Overall, our results highlight the importance of taking into account mixing, O2 undersaturation when water masses are formed and the increasing atmospheric N2O concentrations when parameterizing N2O:O2 and biological N2O production in the global oceans.

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Transatlantic equatorial distribution of nitrous oxide and methane

Cited by 49 publications

References 52 publications

Nitrous oxide in the North Atlantic Ocean

Nitrous oxide in the North Atlantic Ocean

Dissolved greenhouse gases (nitrous oxide and methane) associated with the naturally iron-fertilized Kerguelen region (KEOPS 2 cruise) in the Southern Ocean

Ventilation versus biology: What is the controlling mechanism of nitrous oxide distribution in the North Atlantic?

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