New insights on the mineralization of dissolved organic matter in central, intermediate, and deep water masses of the northeast North Atlantic

Álvarez‐Salgado, Xosé Antón; Nieto‐Cid, Mar; Álvarez, Marta; Pérez, Fíz F.; Morin, Pascal; Mercier, Herlé

doi:10.4319/lo.2013.58.2.0681

Cited by 43 publications

(57 citation statements)

References 53 publications

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“…The nutrient transports across the southern boundary of the eSPNA were calculated by combining volume transports derived from an inverse model applied to hydrographic measurements (Lherminier et al, 2007) and nutrient concentration measurements (Álvarez-Salgado et al, 2013) along the OVIDE 2002 section. The net production rate (J BG N ) was diagnosed from the balance of oceanic, riverine, and atmospheric fluxes by assuming steady state ( N∕ t = 0).…”

Section: Nutrient Budgets In the Espnamentioning

confidence: 99%

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Dissolved Organic Nitrogen Production and Export by Meridional Overturning in the Eastern Subpolar North Atlantic

Fernández-Castro

Álvarez

Nieto‐Cid

et al. 2019

Geophysical Research Letters

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Dissolved organic matter (DOM) is produced in the surface and exported towards the deep ocean, adding ∼2 PgC/year to the global carbon export. Due to its central role in the Meridional Overturning Circulation, the eastern subpolar North Atlantic (eSPNA) contributes largely to this export. Here we quantify the transport and budget of dissolved organic nitrogen (DON) in the eSPNA, in a box delimited by the OVIDE 2002 section and the Greenland‐Iceland‐Scotland sills. The Meridional Overturning Circulation exports >15.9 TgN/year of DON downward and, contrary to the extended view that these are materials of subtropical origin, up to 33% of the vertical flux derives from a net local DON production of 7.1 ± 2.6 TgN/year. The low C:N molar ratio of DOM production (7.4 ± 4.1) and the relatively short transit times in the eSPNA (3 ± 1 year) suggest that local biogeochemical transformations result in the injection of fresh bioavailable DOM to the deep ocean.

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Section: Nutrient Budgets In the Espnamentioning

confidence: 99%

“…A detailed description of the instruments and calibrations associated with the physical and chemical parameters are presented elsewhere (Lherminier et al, 2007;Álvarez-Salgado et al, 2013). Ninety-one full-depth hydrographic stations were occupied, from the continental shelf off Greenland to Lisbon.…”

Section: Nutrient Transports Across the Ovide 2002 Sectionmentioning

confidence: 99%

Dissolved Organic Nitrogen Production and Export by Meridional Overturning in the Eastern Subpolar North Atlantic

Fernández-Castro

Álvarez

Nieto‐Cid

et al. 2019

Geophysical Research Letters

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“…While the hydrographic parameters that describe a set of source water types (SWTs) used for the eOMP analysis are assumed to be time independent, the concentrations within each water mass of species such as DIC or C ant vary over time and can therefore only be resolved by evoking the concept of water mass mixing-weighted average concentration, i.e. archetypal concentration (Álvarez-Salgado et al, 2013) (see Sect. 4.2).…”

Section: Methodsmentioning

confidence: 99%

“…In order to determine SWT concentrations of time-varying species such as DIC, DIC nat and C ant , the mixing-weighted concentration or archetypal concentration, C i , of these species was calculated for each SWT, i (Álvarez-Salgado et al, 2013):…”

Section: Extended Optimum Multiparameter Analysis (Eomp)mentioning

confidence: 99%

Inorganic carbon and water masses in the Irminger Sea since 1991

et al. 2018

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Abstract. The subpolar region in the North Atlantic is a major sink for anthropogenic carbon. While the storage rates show large interannual variability related to atmospheric forcing, less is known about variability in the natural dissolved inorganic carbon (DIC) and the combined impact of variations in the two components on the total DIC inventories. Here, data from 15 cruises in the Irminger Sea covering the 24-year period between 1991 and 2015 were used to determine changes in total DIC and its natural and anthropogenic components. Based on the results of an extended optimum multiparameter analysis (eOMP), the inventory changes are discussed in relation to the distribution and evolution of the main water masses. The inventory of DIC increased by 1.43 ± 0.17 mol m −2 yr −1 over the period, mainly driven by the increase in anthropogenic carbon (1.84 ± 0.16 mol m −2 yr −1 ) but partially offset by a loss of natural DIC (−0.57 ± 0.22 mol m −2 yr −1 ). Changes in the carbon storage rate can be driven by concentration changes in the water column, for example due to the ageing of water masses, or by changes in the distribution of water masses with different concentrations either by local formation or advection. A decomposition of the trends into their main drivers showed that variations in natural DIC inventories are mainly driven by changes in the layer thickness of the main water masses, while anthropogenic carbon is most affected by concentration changes. The storage rates of anthropogenic carbon are sensitive to data selection, while changes in DIC inventory show a robust signal on short timescales associated with the strength of convection.

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“…One simple approach is to assume that the water parcel results from the linear mixing of two or more source water types (SWT; called end-members) in a conservative u-S space, a physical process that should equally transform the conservative and nonconservative properties. In particular, since any water sample in the conservative u-S space can be expressed as the linear combination of three (u, S) end-members, the corresponding biogeochemical concentration should emerge from a multiple linear correlation with S and u (e.g., Álvarez-Salgado et al 2013). The linear mixing approach has been extensively used for determining the distribution of water masses in the World Ocean, either using the classical method of mixing triangles when only temperature and salinity are involved (Mamayev 1975) or employing different varieties of the optimum multiparameter method when other properties are also considered (e.g., Mackas et al 1987;Llanillo et al 2012Llanillo et al , 2013.…”

Section: Introductionmentioning

confidence: 99%

A Simple Nonlinear and End-Member-Free Approach for Obtaining Ocean Remineralization Patterns

Fuente

Pelegrí

Canepa

et al. 2017

Journal of Atmospheric and Oceanic Technology

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The variability of a biogeochemical property in the ocean is the outcome of both nonconservative (such as respiration and photosynthesis) and conservative (mixing of water masses with distinct concentrations at origin) processes. One method to separate both contributions is based on a multiple regression of the biogeochemical property in terms of temperature u and salinity S as conservative proxies of water masses. This regression delivers the variability related to the conservative fraction and hence allows for identifying the residual as the biogeochemical anomaly. Here, the standard multiple linear regression (MLR) method, which assumes that water masses mix locally and linearly, is compared with a nonlinear polynomial regression (PR) over the entire (u, S) space. The PR method has two important advantages over MLR: allows for simultaneous nonlinear mixing of all water masses and does not require knowing the end-member water types. Both approaches are applied to data along 7.58N in the equatorial Atlantic Ocean, and the biogeochemical anomalies are calculated for humic-like fluorescent dissolved organic matter, apparent oxygen utilization, and nitrate-all of them related through in situ remineralization processes. The goodness of both approaches is assessed by analyzing the linear dependence and the coefficient of correlation between the anomalies. The results show that the PR method can be applied over the entire water column and yet retains the local variability associated with nonconservative processes. The potential of the PR approach is also illustrated by calculating the oxygen-nitrate stoichiometric ratio for the entire 7.58N transatlantic section.

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New insights on the mineralization of dissolved organic matter in central, intermediate, and deep water masses of the northeast North Atlantic

Cited by 43 publications

References 53 publications

Dissolved Organic Nitrogen Production and Export by Meridional Overturning in the Eastern Subpolar North Atlantic

Dissolved Organic Nitrogen Production and Export by Meridional Overturning in the Eastern Subpolar North Atlantic

Inorganic carbon and water masses in the Irminger Sea since 1991

A Simple Nonlinear and End-Member-Free Approach for Obtaining Ocean Remineralization Patterns

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