Provenance of organic matter and nutrient conditions on a river- and upwelling influenced shelf: A case study from the Portuguese Margin

Alt-Epping, Ulrich; Mil-Homens, Mário; Hebbeln, Dierk; Abrantes, Fatima F; Schneider, Robert

doi:10.1016/j.margeo.2007.04.016

Cited by 45 publications

(24 citation statements)

References 29 publications

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“…BIT index) showed that terrestrial organic matter decreases seawards. Furthermore, a study off the Douro River (Alt- Epping et al, 2007) established that δ 13 C TOC could be used as an indicator of the source (marine vs. terrestrial) of organic matter in this zone. δ 13 C TOC at 100 m water depth has values around −24‰, showing that organic matter is a mixture of terrestrial and marine sources.…”

Section: Tablementioning

confidence: 99%

Lateral and vertical distributions of living benthic foraminifera off the Douro River (western Iberian margin): Impact of the organic matter quality

Dessandier

Bonnin

Kim

et al. 2015

Marine Micropaleontology

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Section: Tablementioning

confidence: 99%

Lateral and vertical distributions of living benthic foraminifera off the Douro River (western Iberian margin): Impact of the organic matter quality

Dessandier

Bonnin

Kim

et al. 2015

Marine Micropaleontology

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“…Our δ 13 C OC data from the marine surface sediments indicate that the majority of the OC on the Portuguese shelf is of marine origin. Even in the estuary, only 50 to 65 % of OC content is estimated to be of terrestrial origin (Alt-Epping et al, 2007). The Tagus River acts mainly as a supplier of terrigenous lithogenic particles to the coastal ocean, while the majority of the terrestrial organic matter is retained inside the estuary (Jouanneau et al, 1998).…”

Section: Characteristics Of the Bulk Organic Mattermentioning

confidence: 99%

Transport of branched tetraether lipids from the Tagus River basin to the coastal ocean of the Portuguese margin: consequences for the interpretation of the MBT'/CBT paleothermometer

Zell

Kim

Balsinha³

et al. 2014

Biogeosciences

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Abstract. Branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are thought to be transported from soil to marine sediment by rivers, have been used to reconstruct the mean annual air temperature (MAAT) and soil pH of the drainage basin using the methylation index of branched tetraethers (MBT, recently refined as MBT') and cyclization index of branched tetraethers (CBT) from coastal marine sediment records. In this study, we trace the brGDGTs from source to sink in the Tagus River basin, the longest river system on the Iberian Peninsula, by determining their concentration and distribution in soils, river suspended particulate matter (SPM), riverbank sediments, marine SPM, and marine surface sediments. The concentrations of brGDGTs in river SPM were substantially higher and their distributions were different compared to those of the drainage basin soils. This indicates that brGDGTs are mainly produced in the river itself. In the marine environment, the brGDGT concentrations rapidly decreased with increasing distance from the Tagus estuary. At the same time, the brGDGT distributions in marine sediments also changed, indicating that marine in situ production also takes place. These results show that there are various problems that complicate the use of the MBT'/CBT for paleoreconstructions using coastal marine sediments in the vicinity of a river. However, if the majority of brGDGTs are produced in the river, it might be possible to reconstruct the environmental (temperature and pH) conditions of the river water using appropriate aquatic calibrations, provided that marine core locations are chosen in such a way that the brGDGTs in their sediments are predominantly derived from riverine in situ production.

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“…Besides internal tides that operate more vigorously at the proximal sections of the canyon at time scales of hours (upper section) to weeks (middle section), sediment gravity flows may occur on a yearly or longer timescales and turbidity currents strong enough to transport sand down the canyon take place on a centennial timescale (de Stigter et al, 2007). The material captured in the canyon consists predominantly of terrigenous silt and clay (Alt-Epping et al, 2007;de Stigter et al, 2007;Arzola et al, 2008) and several studies point to chlorophyll-a and organic carbon concentrations that are significantly higher in the canyon than in the adjacent open slope sediments (García et al, 2008;Ingels et al, 2009;Pusceddu et al, 2010).…”

Section: Study Areamentioning

confidence: 99%

“…Further increased concentrations observed in the Nazaré and Cascais canyons (Garcia and Thomsen, 2008;Ingels et al, 2009;Pusceddu et al, 2010) are likely to result from their effectiveness to capture sediment from lateral transport along the shelf. The Nazaré Canyon is very active and captures predominantly material of terrigenous origin (Alt-Epping et al, 2007;de Stigter et al, 2007;Arzola et al, 2008). This refractory carbon is of very limited nutrient value but, although the higher C:N values reflect the relative poor quality of the organic matter, macrofauna density and both TN and TOC concentrations were higher than in the Setú bal and Cascais canyons.…”

Section: Environmental Influences On Abundance and Biomassmentioning

confidence: 99%

Biodiversity of macrofaunal assemblages from three Portuguese submarine canyons (NE Atlantic)

Cunha

Paterson

Amaro

et al. 2011

Deep Sea Research Part II: Topical Studies in Oceanography

101

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a b s t r a c tThe macrofaunal assemblages from three Portuguese submarine canyons, Nazaré , Cascais and Setú bal were studied from samples collected at their upper (900-1000 m), middle (3200-3500 m) and lower sections (4200-4500 m) and at the adjacent open slopes ( $ 1000 m), during the HERMES cruises D297 (R.R.S. Discovery, 2005) CD179 (R.R.S. Charles Darwin, 2006) and 64PE252 (R.V. Pelagia, 2006). The taxonomic composition and patterns in biodiversity, abundance and community structure of the benthic macrofauna were described. Annelida (42.1% of total abundance; 137 species) and Arthropoda (20.6%; 162 species) were, respectively, the most abundant and the most species-rich Phyla among the 342 taxa identified during this study. Multivariate analyses showed significant differences between and within canyons and between canyons and open slope assemblages. At their upper section, canyons supported higher macrofauna abundance but slightly lower biodiversity than the adjacent slopes at similar depth. In all canyons abundance reached the highest value in the middle section and the lowest in the upper section, with marked fluctuations in Nazaré (474-4599 ind. m

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Provenance of organic matter and nutrient conditions on a river- and upwelling influenced shelf: A case study from the Portuguese Margin

Cited by 45 publications

References 29 publications

Lateral and vertical distributions of living benthic foraminifera off the Douro River (western Iberian margin): Impact of the organic matter quality

Lateral and vertical distributions of living benthic foraminifera off the Douro River (western Iberian margin): Impact of the organic matter quality

Transport of branched tetraether lipids from the Tagus River basin to the coastal ocean of the Portuguese margin: consequences for the interpretation of the MBT'/CBT paleothermometer

Biodiversity of macrofaunal assemblages from three Portuguese submarine canyons (NE Atlantic)

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