Sediment dynamics in the Gulf of Lion (NW Mediterranean Sea) during two autumn–winter periods with contrasting meteorological conditions

Estournel, Claude; Mikolajczak, Guillaume; Ulses, Caroline; Bourrin, François; Canals, Miquel; Charmasson, Sabine; Doxaran, David; Duhaut, Thomas; Madron, Xavier Durrieu de; Marsaleix, Patrick; Palanqués, Albert; Puig, Pere; Radakovitch, Olivier; Sánchez-Vidal, Anna; Verney, Romaric

doi:10.1016/j.pocean.2022.102942

Cited by 9 publications

(4 citation statements)

References 73 publications

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“…In their study (see Figure 14 of [52]), the export of sediment from the shelf during the winter 2012 deep cascading event was estimated to about 1 Mt, which corresponds to about 15% of the total particulate load exported by rivers; the major part originating from the Rhône River (99%). Metal river fluxes recorded in 2012 are consistent with those previously reported by [18], who described two contrasting years (2001)(2002) in terms of the water and particle discharge of the Rhône River (Table 1).…”

Section: Impact On the Fate Of Metallic Elements In The Basinmentioning

confidence: 97%

“…The atmospheric deposition considers the monthly measurements at the Cap Béar site extrapolated to the whole continental shelf of about 12,000 km 2 (from the coastline to the shelf break at 120 m deep). The fluxes exported from the continental shelf, delimited by the 100 m isobath, were based on estimates obtained by sediment transport modeling for the same period [52] and the mean January-March 2012 PTM concentrations measured at 1000 m deep in the Lacaze-Duthiers and Cap de Creus Canyons (Table 2). [22,[24][25][26]) are indicated by black stars and deep convection events (after [43,45,46,51]) are indicated by grey bands.…”

Section: Impact On the Fate Of Metallic Elements In The Basinmentioning

confidence: 99%

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Impact of Dense Water Formation on the Transfer of Particles and Trace Metals from the Coast to the Deep in the Northwestern Mediterranean

Madron

Aubert

Charrìère

et al. 2023

Water

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This study aimed to describe the interannual variability of dense shelf water cascading and open ocean convection in the Gulf of Lions (NW Mediterranean) based on long-term temperature and current records and its impact on particle fluxes and associated metals. These observations highlight the predominant role of the rare intense events of dense shelf water cascading (1999/2000, 2005/2006, 2012/2013) in the basinward export of particles, which are mainly brought by rivers. Measurements of particulate trace metals in 2012 indicate that the monitored intense cascading event may be responsible for a significant fraction (~15%) of the annual input to the shelf. To this first process is added the effect of somehow more recurrent deep convection events (2005, 2009–2013) that remobilize the deep sediments, receptacle of coastal inputs, and disperse them rapidly at the scale of the northern Mediterranean basin, and gradually over the entire western basin. Coastal and oceanic dense water formations are key physical processes in the Mediterranean margins, whose reduction in intensity and recurrence has already been observed and also anticipate in climate scenarios that will likely change the dispersion pathways of chemical particles in this region.

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Section: Impact On the Fate Of Metallic Elements In The Basinmentioning

confidence: 97%

Section: Impact On the Fate Of Metallic Elements In The Basinmentioning

confidence: 99%

Impact of Dense Water Formation on the Transfer of Particles and Trace Metals from the Coast to the Deep in the Northwestern Mediterranean

Madron

Aubert

Charrìère

et al. 2023

Water

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“…The Gulf of Lion is a microtidal, wave -dominated 100 system, with a tidal range of 30 to 50 cm. Due to salt induced flocculation (Thill et al 2001), most suspended particulate matters (SPM) carried out by the Rhône River settle in front of the mouth, on the prodelta (Maillet et al 2006;Estournel et al 2023). The study site (station Z, water depth 20 m, Fig.…”

Section: Study Site 95mentioning

confidence: 99%

Characterization of the benthic biogeochemical dynamics after flood events in the Rhône River prodelta: A data-model approach

Ferreira,

Nmor,

Viollier

et al. 2023

Preprint

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Abstract. At the land-sea interface, the benthic carbon cycle is strongly influenced by the export of terrigenous particulate material across the river-ocean continuum. Episodic flood events delivering massive sedimentary materials can occur, but their short-term impact on carbon cycling is poorly understood. In this paper, we use a coupled data-model approach to estimate the temporal variations of sediment-water fluxes, biogeochemical pathways and their reaction rates during these abrupt phenomena. We studied one episodic depositional event in the vicinity of the Rhône River mouth (NW Mediterranean Sea) during the fall-winter of 2021–2022. The distribution of dissolved inorganic carbon (DIC), sulfate (SO42−) and methane (CH4) were measured in sediment porewater collected every 2 weeks before and after the deposition of a 25 cm sediment layer during the main winter flood event. Significant changes in the distribution of DIC, SO42− and CH4, concentrations were observed in the sediment porewaters. The use of an early diagenetic model (FESDIA) to calculate biogeochemical reaction rates and fluxes revealed that this type of flooding event can increase the total organic carbon mineralization rate in the sediment by 75 % a few days after deposition, essentially by increasing the sulfate reduction contribution to total mineralization relative to non-flood depositional period. It predicts a short-term decrease of the DIC flux out of the sediment from 100 to 55 mmol m−2 d−1 after the deposition of the new sediment layer with a longer-term increase by 4 %, therefore implying an initial internal storage of DIC in the newly deposited layer and a slow release over relaxation of the system. Furthermore, examination of the stoichiometric ratios of DIC and SO42− as well as model output over this five-months window shows a decoupling between the two modes of sulfate reduction following the deposition – organoclastic sulfate reduction (OSR) intensified in the newly deposited layer below the sediment surface, whereas anaerobic oxidation of methane (AOM) intensified at depth below the former buried surface. This depth-wise bifurcation of both pathways of sulfate reduction in the sediment column is clearly related to the deepening of the sulfate-methane transition zone (SMTZ) by 25 cm after the flood deposition. Our findings highlight the significance of short-term transient biogeochemical processes at the seafloor and provide new insights on the benthic carbon cycle in the coastal ocean.

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“…Mudbanks are one of the major coastal morphological features that have a direct influence and close impact on dynamics in the coastal area (Lefebvre et al, 2004;Parvathy et al, 2015;de Vries et al, 2022;van Bijsterveldt et al, 2023). The river mouth shows the influence of the dynamics of sediments deposition and the processes organising the deposits (Cai et al, 2022;Gardel et al, 2022;Moyano-Paz et al, 2022;Estournel et al, 2023). The morphology of these environments is dynamic and responds to variations in transportation, erosional and depositional of sediments both in space and time (Oyedotun and Burningham, 2019;Turki et al, 2021;Afentoulis et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

River mouth morphodynamics and deflection over the short term: effects on spit growth and mangrove dynamics

Oyedotun

Nedd

2023

Front. Environ. Sci.

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The river mouth shows the influence of the dynamics of sediment deposition and the processes organising the deposits. The river mouths of the Guyana coast, as with other coastal systems in the Guianas, are influenced by the deposition of mud banks from the Amazon River and other rivers. This study analysed and probed the influence of the riverine and marine influences on small river mouth morphological developments. In this study, the morphological dynamics of the system were carried out from satellite images through the comparison of the inter-annual morphodynamics of the river mouths, complemented by data from hydrodynamic processes among others. This study demonstrates that the recent advancement and availability of Synthetic Aperture Radar (SAR), remotely sensed data, allow for the classification of migrating river mouth action and processes; effective monitoring of mudflats development and spit formation; and, the exhibition of river mouth transitioning and infilling. Sentinel-1 images of the Mahaica-Mahaicony river mouth in Guyana were processed and analysed using Google Earth Engine (GEE) and ArcGIS to observe the mud dynamics and its effects on deflecting the river mouth, influencing the development of spit and mangrove dynamics. The results of the analyses show that the dynamics of the mud shoal and river mouth are governed by feedback from various estuarine and hydrodynamic processes resulting from the interactions between the river and ocean. The results have not only highlighted the importance of mud infilling and sediment build-up for spit development and river-mouth deflection but the impact of the sediment morphological dynamics on the ecosystem (mangrove) associated with the river mouth.

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Sediment dynamics in the Gulf of Lion (NW Mediterranean Sea) during two autumn–winter periods with contrasting meteorological conditions

Cited by 9 publications

References 73 publications

Impact of Dense Water Formation on the Transfer of Particles and Trace Metals from the Coast to the Deep in the Northwestern Mediterranean

Impact of Dense Water Formation on the Transfer of Particles and Trace Metals from the Coast to the Deep in the Northwestern Mediterranean

Characterization of the benthic biogeochemical dynamics after flood events in the Rhône River prodelta: A data-model approach

River mouth morphodynamics and deflection over the short term: effects on spit growth and mangrove dynamics

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