The Holocene sedimentation on the Gulf of Lions margin: a quantitative approach

Got, H.; Aloïsi, Jean-Claude

doi:10.1016/0278-4343(90)90062-q

Cited by 65 publications

(34 citation statements)

References 14 publications

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“…In the NW Mediterranean margin and deep-sea floor, sedimentation processes, by way of trap deposition and/or sediment accumulation, were studied at different time-scales: the Holocene scale (10,000 years) by Got and Aloisi (1990) and the annual/seasonal scale by Monaco et al (1990) and Puig and Palanques (1998). Radionuclides, mainly 210 Pb fluxes, have been successfully used by Heussner et al (1990), and recently by Zuo et al (1997), who give revised rates and a spatial distribution of these annual sedimentation rates corresponding to the present study area (Zuo et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Phytodetritus at the sediment-water interface, NW Mediterranean Basin: spatial repartition, living cells signatures, meiofaunal relationships

Riaux-Gobin¹,

Dinet²,

Dugué³

et al. 2004

Sci. Mar.

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SUMMARY: The deep-sea phytodetritus at the sediment-water interface was investigated in the continental margin, canyons and interfluves from 260 to 2070 m depth in the northwestern Mediterranean in June 1995. Overlying phytoplankton biomass, hydrodynamics and relationships with meiofauna densities were also evaluated. The phytoplankton biomass was low (< 0.2 µg Chl a l -1 ), with the lowest standing stocks on the eastern part of the Balearic Basin. Two sedimentary entities were identified: 1) the west coast where pigment concentrations were higher, with an average of 0.38 µg Chl a g -1 dry weight and 4.60 Phaeo a g -1 dw on the first half cm of sediments; and 2) the eastern part of the North Balearic basin where pigment concentrations were significantly lower (0.15 µg Chl a g -1 dw). A north to south gradient was observed, with higher pigment amounts on the Rhodanian slope. Differences were found in the different parts of the studied canyons, with a slight increase in the Axis sites. The vertical pigment repartition was a gradual decrease in the Interfluve sites, whereas concentrations decreased sharply below the first cm in the Axis sites, attesting differences in sedimentation, grazing or bioturbation within the different canyon parts. The north to south gradient in the phytoplankton Chl a/Chl b ratio and sedimented phytodetritus attest geographical differences within phytoplankton assemblages (i.e. diatoms are absent in the south). The epifluorescence tests from the interface revealed the presence of living microphytes at the northern sites, associated with aggregates and faeces. No consistent fluff was evidenced anywhere. The revival tests also agree with a north to south trend. The Meiofaunal density was positively related to the quality of the sedimented layer. A PCA, within the major parameters and factors, illustrates these relationships. All results allow two distinct geographical sectors to be discriminated around the frontal zone: the NW and E sides of the NW Mediterranean Basin, following in particular their contrasted hydrodynamics. The results indicated the relationships within phytoplankton input, underlying phytodetritic layer and meiofauna. They confirm the well-documented statement that demonstrates the deep-sea floor chloropigment concentration to be a good proxy for the overlying primary productivity, but also that some pigment ratios representative of plankton assemblages are preserved on surficial deep sediments, even after sedimentation and grazing.Key-words: deep-sea phytodetritus, meiofauna, phytoplankton, NW Mediterranean Basin. RESUMEN: FITODETRITOS EN LA INTERFASE SEDIMENTO-AGUA, CUENCA MEDITERRÁNEA NORDOCCIDENTAL: DISTRIBUCIÓN ESPACIAL, SEÑALES DE CÉLULAS VIVAS, RELACIONES CON LA MEIOFAUNA. -Se investigó el detrito de agua profunda en la interface sedimento-agua en el margen continental, caniones y interfluves entre 260 y 2070 m de profundidad en el mar Mediterráneo Noroccidental en junio de 1995. La biomasa de fitoplancton flotante, la hidrodinámica, y las relaciones con las densida...

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Section: Introductionmentioning

confidence: 99%

Phytodetritus at the sediment-water interface, NW Mediterranean Basin: spatial repartition, living cells signatures, meiofaunal relationships

Riaux-Gobin¹,

Dinet²,

Dugué³

et al. 2004

Sci. Mar.

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“…At the SWI, the DIC gradients were stronger than the TA gradients for all stations. Despite the spatial heterogeneity in the sediments, the three major areas defined by Got and Aloisi, 1990) in this region display different biogeochemical gradients. Accordingly, stations from each group will be reported and discussed separately.…”

Section: The Oxic Layermentioning

confidence: 99%

“…Got and Aloisi (1990) defined three major domains: the proximal domain, in a radius of 2 km from the river outlet with water depth ranging from 10 to 30 m; the prodelta domain, between 2 and 5 km from the river mouth with depth ranging from 30 to 70 m; and the distal domain, with depth between 70 and 80 m, which passed 5 km from the river mouth. Annual sedimentation rates reach up to 30-48 cm yr −1 close to the river mouth (Charmasson et al, 1998) and rapidly decrease below 0.1 cm yr −1 on the continental shelf (Miralles et al, 2005).…”

Section: The Rhône River Deltamentioning

confidence: 99%

Carbonate chemistry in sediment porewaters of the Rhône River delta driven by early diagenesis (northwestern Mediterranean)

et al. 2016

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Abstract. The Rhône River is the largest source of terrestrial organic and inorganic carbon for the Mediterranean Sea. A large fraction of this terrestrial carbon is either buried or mineralized in the sediments close to the river mouth. This mineralization follows aerobic and anaerobic pathways, with a range of impacts on calcium carbonate precipitation and dissolution in the sediment near the sediment-water interface. This study focuses on the production of dissolved inorganic carbon (DIC) and total alkalinity (TA) by early diagenesis, consequential pH variations and the effect on calcium carbonate precipitation or dissolution. The sediment porewater chemistry was investigated along a transect from the Rhône River outlet to the continental shelf. TA and concentrations of DIC, SO 2− 4 and Ca 2+ were analyzed on bottom waters and extracted sediment porewaters, whereas pH and oxygen concentrations were measured in situ using microelectrodes. The average oxygen penetration depth into the sediment was 1.7 ± 0.4 mm close to the river mouth and 8.2 ± 2.6 mm in the continental shelf sediments, indicating intense respiration rates. Diffusive oxygen fluxes through the sediment-water interface ranged between 3 and 13 mmol O 2 m −2 d −1 . In the first 30 cm of the sediment, TA and DIC porewater concentrations increased with depth up to 48 mmol L −1 near the river outlet and up to 7 mmol L −1 on the shelf as a result of aerobic and anaerobic mineralization processes. Due to aerobic processes, at all stations pH decreased by 0.6 pH units in the oxic layer of the sediment accompanied by a decrease of the saturation state regarding calcium carbonate. In the anoxic layer of the sediments, sulfate reduction was the dominant mineralization process and was associated with an increase of porewater saturation state regarding calcium carbonate.Ultimately anoxic mineralization of organic matter caused calcium carbonate precipitation demonstrated by a large decrease in Ca 2+ concentration with depth in the sediment. Carbonate precipitation decreased in the offshore direction, together with the carbon turnover and sulfate consumption in the sediments. The large production of porewater alkalinity characterizes these sediments as an alkalinity source to the water column, which may increase the CO 2 buffering capacity of these coastal waters. Estuarine sediments should therefore receive more attention in future estimations of global carbon fluxes.

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“…The transition between sands and muds is outlined by a distinct regional step in the sea-floor morphology, that can reach up to 20-25 m of height and can be tracked all along the shelf edge (Berné et al, 2002). The sands are characterized by high carbonate content (25-50%), mainly due to a significant biogenic component (Got and Aloïsi, 1990);…”

mentioning

confidence: 99%

Sand bodies at the shelf edge in the Gulf of Lions (Western Mediterranean): Deglacial history and modern processes

et al. 2006

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The Holocene sedimentation on the Gulf of Lions margin: a quantitative approach

Cited by 65 publications

References 14 publications

Phytodetritus at the sediment-water interface, NW Mediterranean Basin: spatial repartition, living cells signatures, meiofaunal relationships

Phytodetritus at the sediment-water interface, NW Mediterranean Basin: spatial repartition, living cells signatures, meiofaunal relationships

Carbonate chemistry in sediment porewaters of the Rhône River delta driven by early diagenesis (northwestern Mediterranean)

Sand bodies at the shelf edge in the Gulf of Lions (Western Mediterranean): Deglacial history and modern processes

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