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

Florez-Leiva, Lennin; Besoain, V.; Sarthou, Géraldine; Fernández, Camila

doi:10.5194/bg-12-1925-2015

Cited by 17 publications

(17 citation statements)

References 82 publications

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“…This was not observed. There were no indications of significant N 2 O production in the mixed layer over the southeast Kerguelen Plateau at the onset of the bloom [ Farias et al ., ], with estimated atmosphere‐ocean N 2 O fluxes ranging from −10.5 to 5.1 µmol m −2 d −1 (with positive values representing fluxes from the ocean to the atmosphere). Nitrification is thought to dominate N 2 O production in oxic water columns [ Bange , ].…”

Section: Resultsmentioning

confidence: 99%

Significant mixed layer nitrification in a natural iron‐fertilized bloom of the Southern Ocean

Fripiat

Elskens

Trull

et al. 2015

Global Biogeochemical Cycles

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Nitrification, the microbially mediated oxidation of ammonium into nitrate, is generally expected to be low in the Southern Ocean mixed layer. This paradigm assumes that nitrate is mainly provided through vertical mixing and assimilated during the vegetative season, supporting the concept that nitrate uptake is equivalent to the new primary production (i.e., primary production which is potentially available for export). Here we show that nitrification is significant (~40-80% of the seasonal nitrate uptake) in the naturally iron-fertilized bloom over the southeast Kerguelen Plateau. Hence, a large fraction of the nitrate-based primary production is regenerated, instead of being exported. It appears that nitrate assimilation (light dependent) and nitrification (partly light inhibited) are spatially separated between the upper and lower parts, respectively, of the deep surface mixed layers. These deep mixed layers, extending well below the euphotic layer, allow nitrifiers to compete with phytoplankton for the assimilation of ammonium. The high contributions of nitrification to nitrate uptake are in agreement with both low export efficiency (i.e., the percentage of primary production that is exported) and low seasonal nitrate drawdown despite high nitrate assimilation.

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Section: Resultsmentioning

confidence: 99%

Significant mixed layer nitrification in a natural iron‐fertilized bloom of the Southern Ocean

Fripiat

Elskens

Trull

et al. 2015

Global Biogeochemical Cycles

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“…This pattern has been previously reported in the Arctic Ocean (Kitidis et al, 2010;Randall et al, 2012), and is subsequently affected by mixing processes and water mass circulation. Under-saturation of N 2 O has also been described in the Bering Sea and the Indian Sector of the Southern Ocean (Chen et al, 2014;Farías et al, 2015). However, physical processes are probably not the only processes producing those very under-saturated levels.…”

Section: Pml and Haloclinementioning

confidence: 95%

Climate relevant trace gases (N2O and CH4) in the Eurasian Basin (Arctic Ocean)

Verdugo

Damm

Snoeijs

et al. 2016

Deep Sea Research Part I: Oceanographic Research Papers

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A B S T R A C TThe concentration of greenhouse gases, including nitrous oxide (N 2 O), methane (CH 4 ), and compounds such as total dimethylsulfoniopropionate (DMSP t ), along with other oceanographic variables were measured in the icecovered Arctic Ocean within the Eurasian Basin (EAB). The EAB is affected by the perennial ice-pack and has seasonal microalgal blooms, which in turn may stimulate microbes involved in trace gas cycling. Data collection was carried out on board the LOMROG III cruise during the boreal summer of 2012. Water samples were collected from the surface to the bottom layer (reaching 4300 m depth) along a South-North transect (SNT), from 82.19°N, 8.75°E to 89.26°N, 58.84°W, crossing the EAB through the Nansen and Amundsen Basins. The Polar Mixed Layer and halocline waters along the SNT showed a heterogeneous distribution of N 2 O, CH 4 and DMSP t , fluctuating between 42-111 and 27-649% saturation for N 2 O and CH 4, respectively; and from 3.5 to 58.9 nmol L −1 for DMSP t . Spatial patterns revealed that while CH 4 and DMSP t peaked in the Nansen Basin, N 2 O was higher in the Amundsen Basin. In the Atlantic Intermediate Water and Arctic Deep Water N 2 O and CH 4 distributions were also heterogeneous with saturations between 52% and 106% and 28% and 340%, respectively. Remarkably, the Amundsen Basin contained less CH 4 than the Nansen Basin and while both basins were mostly under-saturated in N 2 O. We propose that part of the CH 4 and N 2 O may be microbiologically consumed via methanotrophy, denitrification, or even diazotrophy, as intermediate and deep waters move throughout EAB associated with the overturning water mass circulation. This study contributes to baseline information on gas distribution in a region that is increasingly subject to rapid environmental changes, and that has an important role on global ocean circulation and climate regulation.

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“…The interaction occurs between the roots and soil microorganisms. The number and community structure of microorganisms affect the generation and emission of GHGs [42].…”

Section: Influence Factors Of Ghg Emissionmentioning

confidence: 99%

Emission Laws and Influence Factors of Greenhouse Gases in Saline-Alkali Paddy Fields

Tang

Liang

et al. 2016

Sustainability

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Abstract:The study of greenhouse gas emissions has become a global focus, but few studies have considered saline-alkali paddy fields. Gas samples and saline-alkali soil samples were collected during the green, tillering, booting, heading and grain filling stages. The emission fluxes of CO 2 , CH 4 , and N 2 O as well as the pH, soil soluble salt, available nitrogen, and soil organic carbon contents were detected to reveal the greenhouse gas (GHG) emission laws and influence factors in saline-alkali paddy fields. Overall, GHG emissions of paddy soil during the growing season increased, then decreased, and then increased again and peaked at booting stage. The emission fluxes of CO 2 and CH 4 were observed as having two peaks and a single peak, respectively. Both the total amount of GHG emission and its different components of CO 2 , CH 4 , and N 2 O increased with the increasing reclamation period of paddy fields. A positive correlation was found between the respective emission fluxes of CO 2 , CH 4 , and N 2 O and the available nitrogen and SOC, whereas a negative correlation was revealed between the fluxes of CO 2 , CH 4 , and N 2 O and soil pH and soil conductivity. The study is beneficial to assessing the impact of paddy reclamation on regional greenhouse gas emissions and is relevant to illustrating the mechanisms concerning the carbon cycle in paddy soils.

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

Cited by 17 publications

References 82 publications

Significant mixed layer nitrification in a natural iron‐fertilized bloom of the Southern Ocean

Significant mixed layer nitrification in a natural iron‐fertilized bloom of the Southern Ocean

Climate relevant trace gases (N2O and CH4) in the Eurasian Basin (Arctic Ocean)

Emission Laws and Influence Factors of Greenhouse Gases in Saline-Alkali Paddy Fields

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