Atmospheric fluxes of soluble organic C, N, and P to the Mediterranean Sea: Potential biogeochemical implications in the surface layer

Djaoudi, Kahina; Wambeke, F. Van; Barani, Aude; Hélias-Nunige, Sandra; Sempéré, Richard; Pulido-Villena, Elvira

doi:10.1016/j.pocean.2017.07.008

Cited by 29 publications

(38 citation statements)

References 74 publications

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“…The relationship between monthly precipitation rates and DOC fluxes confirmed the high efficiency in DOM atmospheric deposition of DOC via rain events in the Med Sea, as recently reported by Djaoudi et al (2018).…”

Section: Doc Input From the Atmospheresupporting

confidence: 88%

“…In addition, the Sahara desert is an intermittent source of mineral dust, that can transport nutrients and organic carbon to the Basin (Goudie and Middleton, 2001;Prospero et al, 2005;Vincent et al, 2016). Atmospheric deposition of nutrients (N and P) strongly influences the marine biogeochemical cycles of the Med Sea, it has therefore received attention in the last 30 years (Migon et al, 1989;Herut et al, 2002;Ridame and Guieu, 2002;Markaki et al, 2003Markaki et al, , 2010Pulido-Villena et al, 2008;Djaoudi et al, 2018). Compared to inorganic nutrients, there is still very few data on the atmospheric deposition of Dissolved Organic Carbon (DOC) to the surface ocean, both at the global and local scale.…”

Section: Introductionmentioning

confidence: 99%

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Atmospheric deposition of organic matter at a remote site in the Central Mediterranean Sea: implications for marine ecosystem

Galletti¹,

Becagli²,

Sarra³

et al. 2020

Preprint

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Abstract. Atmospheric fluxes of dissolved organic matter (DOM) were studied for the first time at the Island of Lampedusa, a remote site in the Central Mediterranean Sea (Med Sea), close to the Sahara desert, between 19 March 2015 and 1 April 2017. The main goals of this work are: to quantify total atmospheric deposition of DOM in this area and to evaluate the impact of dust deposition on DOM dynamics in the surface waters of the Mediterranean Sea. Our data show high variability in DOM deposition rates without a clear seasonality and allow to estimate a dissolved organic carbon (DOC) input from the atmosphere of 120.7 mmol DOC m−2 yr−1. Over the entire time-series, the average dissolved organic phosphorous (DOP) and dissolved organic nitrogen (DON) contributions to the total dissolved pools were 40 % and 26 %, respectively. The data on atmospheric elemental ratios also show that each deposition event is characterized by a specific elemental ratio, suggesting a high variability in DOM composition and the presence of multiple sources. This study indicates that the organic substances transported by Saharan dust at Lampedusa site mainly have natural origin, especially from sea spray and that Saharan dust can be an important carrier of organic substances, even if the load of DOC associated with dust is highly variable. Our estimates suggest that atmospheric input has an impact to the Med Sea larger than to the global ocean and that DOC fluxes from the atmosphere to the Med Sea can be up to 6-fold larger than river input. Longer time series, combined with a modelling effort, are therefore mandatory in order to investigate the response of DOM dynamics in the Med Sea to the change in aerosol deposition pattern due to the effect of climate change.

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Section: Doc Input From the Atmospheresupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Atmospheric deposition of organic matter at a remote site in the Central Mediterranean Sea: implications for marine ecosystem

Galletti¹,

Becagli²,

Sarra³

et al. 2020

Preprint

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“…In the Mediterranean Sea, the existent dataset of nM measurements of DIP at both spatial and temporal scales is severely scarce. The few reported nM concentrations of DIP are limited to two cross-basin cruises (PROSOPE cruise in 1999, Moutin et al, 2002: 7 (Djaoudi et al, 2017). By reporting an important amount of vertical profiles along a longitudinal gradient, the present study is the first to extensively address the distribution of nM DIP in the P-depleted Mediterranean surface waters.…”

Section: Discussionmentioning

confidence: 75%

“…To date, lack of DIP data above this phosphacline has precluded resolving vertical variability in this key layer as has led to the traditional view of an entirely depleted and invariant dissolved phosphate surface pool. Few studies, however, by using sensitive determination of DIP, have reported low but detectable increases in nanomolar DIP concentration above the phosphacline adding evidence against this traditional view Krom et al, 2005;Djaoudi et al, 2017). Nevertheless, the scarcity and the sparse nature of available nM DIP data in the Mediterranean Sea still precludes a complete assessment of DIP dynamics in the upper waters at the basin scale.…”

Section: Introductionmentioning

confidence: 99%

“…As for DIP, a critical gap in accurate DOP data (i.e., based on nanomolar DIP measurements) persists in the upper waters of the Mediterranean Sea Pujo-Pay et al, 2011). Indeed, only two studies have reported nanomolar DIP and DOP data simultaneously Djaoudi et al, 2017). In the Mediterranean Sea, when DIP is exhausted, DOP becomes a possible alternative source of P as confirmed by high activities of alkaline phosphatase suggesting an active utilization of the DOP pool in upper waters , 2009.…”

Section: Introductionmentioning

confidence: 99%

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Sensitive Determination of the Dissolved Phosphate Pool for an Improved Resolution of Its Vertical Variability in the Surface Layer: New Views in the P-Depleted Mediterranean Sea

et al. 2018

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An accurate understanding of the biogeochemistry of dissolved phosphate pool in the upper waters of P-depleted oceanic regions is constrained by the low sensitivity of routine phosphate measurements. In this study, by using the sensitive Liquid Waveguide Capillary Cell method, we report the first extensive cross-basin survey of nanomolar dissolved inorganic phosphate (DIP) and dissolved organic phosphate (DOP) concentration in P-depleted surface waters of the Mediterranean Sea during the stratification period. In the north western Mediterranean Sea (NWMS), DIP above the mixed layer depth (MLD) ranged between 4.9 and 26.5 nM. Along an E-W transect crossing Ionian and Tyrrhenian Seas (E-W transect), DIP above the MLD was lower, ranging between 0.9 and 11.4 nM. Contrarily to the traditional view of a depleted and invariant surface dissolved phosphate pool, a significant vertical variability of DIP and DOP was revealed in upper waters. A positive gradient of DIP was observed above the phosphacline, between the MLD and the deep chlorophyll maximum (DCM) depth, suggesting a potential diffusion of new phosphate to near-surface waters, even under stratified conditions. Interestingly, despite this apparent DIP availability, a significant negative gradient of DOP concentration was observed in the same layer. Finally, the positive gradient in DIP coincided with a significant increase in N:P ratio, suggesting a higher rate of increase of N than of P. The results obtained in this study indicate that acquiring nanomolar DIP data is a sine qua non condition for the comprehension and prediction of the biogeochemical functioning of P-depleted oceanic regions, such as the Mediterranean Sea.

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Dissolved Organic Carbon Dynamics in the Ligurian Sea

Santinelli¹

2020

The Mediterranean Sea in the Era of Global Change 2

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Atmospheric fluxes of soluble organic C, N, and P to the Mediterranean Sea: Potential biogeochemical implications in the surface layer

Abstract: International audienc

Cited by 29 publications

References 74 publications

Atmospheric deposition of organic matter at a remote site in the Central Mediterranean Sea: implications for marine ecosystem

Atmospheric deposition of organic matter at a remote site in the Central Mediterranean Sea: implications for marine ecosystem

Sensitive Determination of the Dissolved Phosphate Pool for an Improved Resolution of Its Vertical Variability in the Surface Layer: New Views in the P-Depleted Mediterranean Sea

Dissolved Organic Carbon Dynamics in the Ligurian Sea

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