Longitudinal variability of the biogeochemical role of Mediterranean aerosols in the Mediterranean Sea

Abstract. The Mediterranean Sea is a semi-enclosed basin characterized by a strong thermal stratification during summer during which the atmosphere is the main source of new nutrients to the nutrient-depleted surface layer. From aerosol sampling and microcosm experiments performed during the TransMed BOUM cruise (June–July 2008) we showed that: (i) the Mediterranean atmosphere composition (Al, Fe, P) was homogeneous over ~28° of longitude and was a mixture with a constant proportion of anthropogenic contribution and a variable but modest contribution of crustal aerosols. This quite stable composition over a one month period and a long transect (~2500 km) allowed to define the Mediterranean atmospheric "background" that characterizes the summer season in the absence of major Saharan event and forest fires, (ii) primary production significantly increased at all tested stations after aerosols addition collected on-board and after Saharan dust analog addition, indicating that both additions relieved on-going (co)-limitations. Although both additions significantly increased the N2 fixation rates at the western station, diazotrophic activity remained very low (~0.2 nmol N L−1 d−1), (iii) due to the presence of anthropogenic particles, the probable higher solubility of nutrients associated with mixed aerosols (crustal + anthropogenic contribution), conferred a higher fertilizing potential to on-board collected aerosol as compared to Saharan dust analog. Finally, those experiments showed that atmospheric inputs from a mixed atmospheric event ("summer rain" type) or from a high-intensity Saharan event would induce comparable response by the biota in the stratified Mediterranean SML, during summer.

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Wet deposition in the remote western and central Mediterranean as a source of trace metals to surface seawater

10.5194/acp-2021-624 ◽

2021 ◽

Author(s):

Karine Desboeufs ◽

Franck Fu ◽

Matthieu Bressac ◽

Antonio Tovar-Sánchez ◽

Sylvain Triquet ◽

...

Keyword(s):

Trace Metals ◽

Mediterranean Sea ◽

Wet Deposition ◽

Saharan Dust ◽

Surface Microlayer ◽

Dust Deposition ◽

Central Mediterranean ◽

Order Of Magnitude ◽

The Mediterranean ◽

Atmospheric Inputs

Abstract. This study reports the only recent characterisation of two contrasted wet deposition events collected during the PEACETIME cruise in the Mediterranean open seawater, and their impact on trace metals (TMS) marine stocks. Rain samples were analysed for Al, 12 trace metals (TMs hereafter, including Co, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V and Zn) and nutrients (N, P, DOC) concentrations. The first rain sample collected in the Ionian Sea (rain ION) was a wet typical regional background deposition event whereas the second rain collected in the Algerian Basin (rain FAST) was a Saharan dust wet deposition. The concentrations of TMs in the two rain samples were significantly lower compared to concentrations in rains collected at coastal sites reported in the literature, suggesting either less anthropogenic influence in the remote Mediterranean environment, or decreased emissions during the last decades in the Mediterranean Sea. The TMs inventories in the surface microlayer and mixed layer (0–20 m) at ION and FAST stations before and after the events, compared to atmospheric fluxes, showed that the atmospheric inputs were a significant source of particulate TMs for both layers. At the scale of the western and central Mediterranean, the atmospheric inputs were of the same order of magnitude as marine stocks within the ML for dissolved Fe, Co and Zn, underlining the role of the atmosphere in their biogeochemical cycle in the stratified Mediterranean Sea. In case of intense wet dust deposition event, the contribution of atmospheric inputs could be critical for dissolved stocks of the majority of TMs.

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Introduction to the project DUNE, a DUst experiment in a low Nutrient, low chlorophyll Ecosystem

Biogeosciences Discussions ◽

10.5194/bgd-10-12491-2013 ◽

2013 ◽

Vol 10 (7) ◽

pp. 12491-12527 ◽

Cited By ~ 10

Author(s):

C. Guieu ◽

F. Dulac ◽

C. Ridame ◽

P. Pondaven

Keyword(s):

Trace Elements ◽

Atmospheric Deposition ◽

Mediterranean Sea ◽

Surface Waters ◽

Carbon Pump ◽

Mesocosm Experiments ◽

The Mediterranean ◽

Atmospheric Inputs ◽

Oligotrophic Ecosystem ◽

The Impact

Abstract. The main goal of the project DUNE was to estimate the impact of atmospheric deposition on an oligotrophic ecosystem based on mesocosm experiments simulating strong atmospheric inputs of Aeolian dust. Atmospheric deposition is now recognized as a significant source of macro- and micro-nutrients for the surface ocean, but the quantification of its role on the biological carbon pump is still poorly determined. We proposed in DUNE to investigate the role of atmospheric inputs on the functioning of an oligotrophic system particularly well adapted to this kind of study: the Mediterranean Sea. The Mediterranean Sea – etymologically, sea surrounded by land – is submitted to atmospheric inputs that are very variable both in frequency and intensity. During the thermal stratification period, only atmospheric deposition is prone to fertilize Mediterranean surface waters which has become very oligotrophic due to the nutrient depletion (after the spring bloom). This paper describes the objectives of DUNE and the implementation plan of a series of mesocosms experiments during which either wet or dry and a succession of two wet deposition fluxes of 10 g m−2 of Saharan dust have been simulated. After the presentation of the main biogeochemical initial conditions of the site at the time of each experiment, a general overview of the papers published in this special issue is presented, including laboratory results on the solubility of trace elements in erodible soils in addition to results from the mesocosm experiments. Our mesocosm experiments aimed at being representative of real atmospheric deposition events onto the surface of oligotrophic marine waters and were an original attempt to consider the vertical dimension in the study of the fate of atmospheric deposition within surface waters. Results obtained can be more easily extrapolated to quantify budgets and parameterize processes such as particle migration through a "captured water column". The strong simulated dust deposition events were found to impact the dissolved concentrations of inorganic dissolved phosphorus, nitrogen, iron and other trace elements. In the case of Fe, adsorption on sinking particles yields a decrease in dissolved concentration unless binding ligands were produced following a former deposition input and associated fertilization. For the first time, a quantification of the C export induced by the aerosol addition was possible. Description and parameterization of biotic (heterotrophs and autotrophs, including diazotrophs) and abiotic processes (ballast effect due to lithogenic particles) after dust addition in sea surface water, result in a net particulate organic carbon export in part controlled by the "lithogenic carbon pump".

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Recent increase of Saharan dust transport over the Mediterranean Sea, as revealed from ocean color satellite (SeaWiFS) observations

Journal of Geophysical Research Atmospheres ◽

10.1029/2005jd006795 ◽

2006 ◽

Vol 111 (D12) ◽

Cited By ~ 68

Author(s):

D. Antoine ◽

D. Nobileau

Keyword(s):

Mediterranean Sea ◽

Ocean Color ◽

Saharan Dust ◽

Dust Transport ◽

Recent Increase ◽

The Mediterranean

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Zooplankton of a stressed area in the Damietta coast of the Mediterranean Sea

Acta Adriatica ◽

10.32582/aa.58.2.5 ◽

2017 ◽

Vol 58 (2) ◽

pp. 245-260 ◽

Cited By ~ 2

Author(s):

Wael S. Eltohamy ◽

Ahmad Alzeny ◽

Yasmine A. M. Azab

Keyword(s):

Community Structure ◽

Mediterranean Sea ◽

Ballast Water ◽

Environmental Variables ◽

Species Invasions ◽

The Mediterranean ◽

June July ◽

Zooplankton Communities ◽

The Impact ◽

Univariate Analyses

The spatial pattern of zooplankton communities at Damietta coast, southeastern Mediterranean was studied to assess the impact of human activities on the abundance and community structure. Twenty-five stations from five different stressed sites were sampled in June-July 2014. Thirty-four zooplankton taxa were recorded, in addition to the larvae of copepods and meroplankton. Copepoda was the most abundant group among which, Oithona nana, Euterpina acutifrons, and Parvocalanus cirrostratus were the most frequent. The calanoid copepod Pseudodiaptomus trihamatus is a new record for the Mediterranean Sea that may have been introduced via ballast water. Multivariate/Univariate analyses demonstrated that 1) the environmental variables and zooplankton communities represented significant differences among five sites; 2) the spatial variations of community structure were undoubtedly due to land-based effluents; and 3) among all environmental variables, salinity and phytoplankton biomass had the major determining effects on the spatial patterns of zooplankton categories. The results indicates that not only the discharged water makes the Damietta coast at risk, but also the ballast water is not less dangerous. Hence, we emphasize the need for activation of the ballast water management to reduce the risk of future species invasions.

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Predominant transport paths of Saharan dust over the Mediterranean Sea to Europe

Journal of Geophysical Research Atmospheres ◽

10.1029/2011jd016482 ◽

2012 ◽

Vol 117 (D2) ◽

pp. n/a-n/a ◽

Cited By ~ 93

Author(s):

P. Israelevich ◽

E. Ganor ◽

P. Alpert ◽

P. Kishcha ◽

A. Stupp

Keyword(s):

Mediterranean Sea ◽

Saharan Dust ◽

The Mediterranean

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Saharan Dust Deposition May Affect Phytoplankton Growth in the Mediterranean Sea at Ecological Time Scales

PLoS ONE ◽

10.1371/journal.pone.0110762 ◽

2014 ◽

Vol 9 (10) ◽

pp. e110762 ◽

Cited By ~ 44

Author(s):

Rachele Gallisai ◽

Francesc Peters ◽

Gianluca Volpe ◽

Sara Basart ◽

José Maria Baldasano

Keyword(s):

Mediterranean Sea ◽

Time Scales ◽

Phytoplankton Growth ◽

Saharan Dust ◽

Dust Deposition ◽

The Mediterranean

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Large Saharan dust storms: Implications for chlorophyll dynamics in the Mediterranean Sea

Global Biogeochemical Cycles ◽

10.1002/2016gb005404 ◽

2016 ◽

Vol 30 (11) ◽

pp. 1725-1737 ◽

Cited By ~ 7

Author(s):

Rachele Gallisai ◽

Gianluca Volpe ◽

Francesc Peters

Keyword(s):

Mediterranean Sea ◽

Dust Storms ◽

Saharan Dust ◽

The Mediterranean

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Assessing the role of dust deposition on phytoplankton ecophysiology and succession in a low-nutrient low-chlorophyll ecosystem: a mesocosm experiment in the Mediterranean Sea

Biogeosciences Discussions ◽

10.5194/bgd-9-19199-2012 ◽

2012 ◽

Vol 9 (12) ◽

pp. 19199-19243 ◽

Cited By ~ 1

Author(s):

V. Giovagnetti ◽

C. Brunet ◽

F. Conversano ◽

F. Tramontano ◽

I. Obernosterer ◽

...

Keyword(s):

Mediterranean Sea ◽

Phytoplankton Community ◽

Phytoplankton Bloom ◽

Community Response ◽

Mesocosm Experiment ◽

Saharan Dust ◽

Dust Deposition ◽

Layer System ◽

Pigment Analysis ◽

The Mediterranean

Abstract. In this study, we investigate the phytoplankton community response, with emphasis on ecophysiology and succession, after two experimental additions of Saharan dust in the surface layer of a low-nutrient low-chlorophyll ecosystem in the Mediterranean Sea. Three mesocosms were amended with evapocondensed dust to simulate realistic Saharan dust events while three additional mesocosms were kept unamended and served as controls. Experiments consisted in two consecutive dust additions and samples were daily collected at different depths (−0.1, −5 and −10 m) during one week, starting before each addition occurred. Data concerning HPLC pigment analysis on two size classes (< 3 and > 3 µm), electron transport rate (ETR) versus irradiance curves, non-photochemical fluorescence quenching (NPQ) and phytoplankton cell abundance (measured by flow cytometry), are presented and discussed in this paper. Results show that picophytoplankton mainly respond to the first dust addition, while the second addition leads to an increase of both pico- and nano-/microphytoplankton. Ecophysiological changes in the phytoplankton community are revealed, and an increase in NPQ development, as well as in pigment concentration per cell, follows the dust additions. ETR does not show large variations between dust-amended and control conditions, while biomass increases in response to the dust additions. Furthermore, the biomass increase observed during this mesocosm experiment allows us to attempt a quantitative assessment and parameterization of the onset of a phytoplankton bloom in a nutrient-limited ecosystem. These results are discussed focusing on the adaptation of picophytoplankton to such a nutrient-limited mixed layer system, as well as on size-dependent competition ability in phytoplankton.

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