River Discharge and Wind Influence Upon Particulate Transfer at the Land–Ocean Interaction: Case Study of the Rhone River Plume

Naudin, Jean-Jacques; Cauwet, Gustave; Chrétiennot‐Dinet, Marie‐Josèphe; Deniaux, Brigitte; Devenon, Jean‐Luc; Pauc, Henri

doi:10.1006/ecss.1996.0190

Cited by 72 publications

(51 citation statements)

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“…These markers made relatively low contributions to the fatty acids in the sediments, which is consistent with previous studies highlighting the limited exchanges between the water column and the benthic boundary layer in this part of the Gulf of Lions (Naudin et al, 1997). At the uppermost distal station (F), sediments were enriched in lipids compared to the other stations, suggesting a contribution from a fresh marine source (Fig.…”

Section: Organic Matter Sources Inferred From Biomarkerssupporting

confidence: 91%

Biogeochemistry of fatty acids in a river-dominated Mediterranean ecosystem (Rhône River prodelta, Gulf of Lions, France): Origins and diagenesis

Pruski

Buscail

Bourgeois

et al. 2015

Organic Geochemistry

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Major rivers transfer high loads of continental particulate organic matter to deltaic environments, where the impact on the biogeochemistry and productivity of coastal sediments depends on the sources and lability of these inputs. Our aims are to provide new insights into the reactivity of riverine inputs in coastal environments and to delineate the parameters controlling their fate in these dynamic systems. Sediment cores were collected from a Mediterranean deltaic system (the Rhône prodelta and its adjacent shelf) during a period of moderate river discharge (Spring 2007) and analyzed for their fatty acid composition. Sediment properties were also described using biochemical bulk analyses (organic carbon and lipids), granulometry and profiles of redox potential. Based on the bulk compositional changes and hierarchical clustering of the fatty acid biomarkers, we determined the principal sources of organic matter and their spatial distribution.Fatty acids were primarily of continental origin in the prodelta, shifting to a higher contribution from marine sources in the shelf area. Fatty acids derived from both continental and marine sources were efficiently degraded in the sediments by microbial decay processes in the upper oxic layer. Degradation rate constants calculated from the down-core decreases in concentrations indicate that fatty acid degradation was enhanced in sediments influenced by the Rhône River.The most important parameters affecting fatty acid preservation were the inherent stability of individual molecular components and their physical association with mineral matrices, the source and freshness of the inputs, and the depositional environment (redox condition, accumulation rates).3

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Section: Organic Matter Sources Inferred From Biomarkerssupporting

confidence: 91%

Biogeochemistry of fatty acids in a river-dominated Mediterranean ecosystem (Rhône River prodelta, Gulf of Lions, France): Origins and diagenesis

Pruski

Buscail

Bourgeois

et al. 2015

Organic Geochemistry

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“…1). For this experiment, a drifter (Naudin et al 1997) was launched 1 nautical mile (1.8 km) south of the Rhone river mouth (Roustan buoy) to follow the mixing of the river plume with the marine underlying water. The drifter was tracked by the oceanographic RV 'Téthys II', on which continuous conductivity-temperature-depth (CTD) measurements were performed to select stations for sampling of water with different salinity.…”

Section: Methodsmentioning

confidence: 99%

Bacterial activity and genetic richness along an estuarine gradient (Rhone River plume, France)

Troussellier¹,

Schäfer²,

Batailler³

et al. 2002

Aquat. Microb. Ecol.

120

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Bacterial diversity and activity were simultaneously investigated by microbial ecological and molecular biological methods along an estuarine gradient from the Rhone River to the Mediterranean Sea. Following a Lagrangian strategy, we sampled plume, frontal and marine layers. The sampled estuarine gradient exhibited large changes both in physico-chemical and in microbiological characteristics. Bacterial abundances and activities showed a more drastic decrease in the low salinity range of the gradient than expected from simple dilution models, indicating that an important fraction of freshwater bacteria disappeared in the mixing area. High specific activities, in particular for leucine, in the marine end-part of the gradient suggested important bacterial protein synthesis, which may be a sign of an active survival strategy for bacterial communities subjected to oligotrophic conditions. Bacterial genetic diversity of the sampled estuarine area, as estimated by the number of DNA-derived denaturing gradient gel electrophoresis (DGGE) bands, was high (13 to 55 bands) compared to that reported in other aquatic ecosystems. This high diversity may be the consequence of the interface position of estuaries. The proportion of active populations was estimated using the ratio of DGGE bands derived from RNA and DNA. This ratio was lower in Rhone water than in marine water, indicating that only a part of the constitutive populations were active, while the activity was distributed within a larger fraction of populations in the marine assemblage. Very few DGGE bands detected in freshwater samples were also detected in the marine end-part of the gradient, suggesting that a very limited number of freshwater bacteria could survive under marine conditions. Detection of these freshwater populations from RNA might indicate that these bacteria were able to synthesize different stress proteins as the result of a survival strategy or that these bacteria were able to maintain metabolic activity under marine conditions. The structure of marine communities was strongly affected by decreasing salinity. However, it seems that the decrease of DNAderived bands may simply have been the consequence of the mixing of marine and freshwater. No obvious relationship between genetic richness and activity changes was observed. This lack of a relationship may be the consequence of a very short residence time of water in the mixing area studied.

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“…The sediment accumulation rate varies from 20 to 50 cm yr −1 at the present Roustan mouth of the Rhône River and strongly decreases with the distance from the river. Sediment is exported seaward by several turbid layers: the surface nepheloid layer, related to river plume; an intermediate nepheloid layer that forms during periods of water-column stratification; and a persistent bottom nepheloid layer, whose influence decreases from the river mouth to the outer shelf (Calmet and Fernandez, 1990;Naudin et al, 1997). The surficial plume is typically a few meters thick close to the mouth but rapidly thins seaward to a few centimeters (Millot, 1990); it is deflected southwestward by the surface water circulation on the GoL shelf.…”

Section: The Gulf Of Lions Geological and Oceanographic Settingsmentioning

confidence: 99%

Holocene hydrological changes in the Rhône River (NW Mediterranean) as recorded in the marine mud belt

et al. 2016

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Abstract. Expanded marine Holocene archives are relatively scarce in the Mediterranean Sea because most of the sediments were trapped in catchment areas during this period. Mud belts are the most suitable targets to access expanded Holocene records. These sedimentary bodies represent excellent archives for the study of sea-land interactions and notably the impact of the hydrological activity on sediment accumulation. We retrieved a 7.2 m long sediment core from the Rhône mud belt in the Gulf of Lions in an area where the average accumulation rate is ca. 0.70 m 1000 yr −1 . This core thus provides a continuous and high-resolution record of the last 10 ka cal BP. A multiproxy dataset (XRF core scan, 14 C dates, grain size and organic-matter analysis) combined with seismic stratigraphic analysis was used to document decadal to centennial changes in the Rhône hydrological activity. Our results show that (1) the early Holocene was characterized by high sediment delivery likely indicative of local intense (but short-duration) rainfall events, (2) important sediment delivery around 7 ka cal BP presumably related to increased river flux, (3) a progressive increase in continental/marine input during the mid-Holocene despite increased distance from river outlets due to sea-level rise possibly related to higher atmospheric humidity caused by the southward migration of the storm tracks in the North Atlantic, (4) multidecadal to centennial humid events took place in the late Holocene. Some of these events correspond to the cold periods identified in the North Atlantic (Little Ice Age, LIA; Dark Ages Cold Period) and also coincide with time intervals of major floods in the northern Alps. Other humid events are also observed during relatively warm periods (Roman Humid Period and Medieval Climate Anomaly).

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River Discharge and Wind Influence Upon Particulate Transfer at the Land–Ocean Interaction: Case Study of the Rhone River Plume

Cited by 72 publications

References 0 publications

Biogeochemistry of fatty acids in a river-dominated Mediterranean ecosystem (Rhône River prodelta, Gulf of Lions, France): Origins and diagenesis

Biogeochemistry of fatty acids in a river-dominated Mediterranean ecosystem (Rhône River prodelta, Gulf of Lions, France): Origins and diagenesis

Bacterial activity and genetic richness along an estuarine gradient (Rhone River plume, France)

Holocene hydrological changes in the Rhône River (NW Mediterranean) as recorded in the marine mud belt

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