Long-term monitoring (1960–2008) of the river-sediment transport in the Red River Watershed (Vietnam): Temporal variability and dam-reservoir impact
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(Science of the Total Environment. vol. 2010, n° 0048-9697, pp. 4654-4664, 31/07/2010)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, Bioemco, ENS-PSL, PSL, IRD, INRA, UPMC, CNRS, IWMI-SEA, IWMI, CGIAR, SFRI, VAAS
Metal fluxes to the sediments of the Moulay Bousselham lagoon, Morocco.
The metal content in surface sediments (0-2 cm, 26 samples), in a sediment core (120, 1 cm slices), taken from Moulay Bousselham (Morocco) was investigated. Concentrations of Al, Fe, Mn, Pb, Zn, Cu, Ni, Cr, Cd, As, and Hg were evaluated in surface and cored sediments of Moulay Bousselham lagoon. Significantly high concentrations in lg g-1 dw of Pb (31.7-6.2), Zn (758.9-167), Cu (310.7- 22), Ni (96-10.5), Cr (113-18.9), Cd (0.84-0.02), As (1-0.1), and Hg (0.61-0.02) were found in sediment samples from Moulay Bousselham lagoon. Calculated enrichment factors [EFMe = (Me/Al)sample/(Me/Al)background], using Al as a normalizer, and correlation matrices showed that metal pollution in Merja Zerga of Moulay Bousselham lagoon was the product of anthropogenic sources, while the metal content in Merja Kehla was of natural origins. The results suggest that a major change in the sedimentary regime of the lagoon, associated with internal trapping and re-distribution of heavy metal, has been occurring in the past few decades. The cause would appear to be the construction of a Nador Canal at the lagoon. Probable effects concentrations (PEC) were often exceeded for heavy metals in the lagoon sediments, especially for Zn, Cu, Ni, and Cr, and four stations, stations MZ-11, MZ-12, MZ-13, MZ-14, MZ-16, and MZ-17, had multiple metals at presumptively toxic levels. These comparisons suggest that sediment metal levels in the river are clearly high and probably pose an environmental risk at some stations. The levels of most of the metals were not greatly enriched, a consideration that is of the utmost importance when contamination issues are at stake. Metal concentrations found in Moulay Bousselham lagoon were comparable to aquatic systems classified as contaminated from other regions of the world.
(Environmental Earth Sciences. vol. 61, n° 1866-6280, pp. 275-286, 01/07/2010)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LETG - Nantes, UNICAEN, NU, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN
Contrasting paleoceanographic conditions off Morocco during Heinrich events (1 and 2) and the Last Glacial Maximum
(Quaternary Science Reviews. vol. 29, n° 0277-3791, pp. 1923-1939, 01/07/2010)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, IIQAB-CSIC, CSIC
Modélisation couplée vagues-courant : développement avec MARS 3D et WAVEWATCH-III
(pp. 17-24, 20/06/2010)
M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER
Pliocene and Lower Pleistocene vegetation and climate changes at the European scale: Long pollen records and climatostratigraphy
The biostratigraphically calibrated long pollen record at DSDP Site 380 (southwestern Black Sea) displays a high-resolution continuous and contrasted evolution of the vegetation in the region for the entire Pliocene and Lower Pleistocene. An accurate correlation is established with the reference global oxygen isotopic curve and with the Northwestern European climatostratigraphy. Climatostratigraphic relationships are evident at the latitudinal and longitudinal scale of Europe, confirming the extensive strength of pollen analysis as a tool for correlations over large distances.
(Quaternary International. vol. 219, n° 1040-6182, pp. 152-167, 17/06/2010)
LDO, INSU - CNRS, UBO EPE, CNRS, AYBE, ITÜ, ITÜ, PEPS, UCBL, INSU - CNRS, CNRS, GeoEcoMar, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS
Large scale Vorticity generation due to dissipating waves in the surf zone.
In this paper, we investigate the mechanisms which control the generation of wave-induced mean current vorticity in the surf zone. From the vertically-integrated and time-averaged momentum equations given recently by Smith [21], we obtain a vorticity forcing term related to differential broken-wave energy dissipation. Then, we derive a new equation for the mean current vorticity, from the nonlinear shallow water shock-wave theory. Both approaches are consistent, under the shallow water assumption, but the later gives explicitly the generation term of vorticity, without any ad-hoc parametrization of the broken-wave energy dissipation.
(Discrete and Continuous Dynamical Systems - Series B. vol. 13, n° 1531-3492, pp. 729--738, 16/06/2010)
I3M, UM2, UM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM
The Crotone series: A synthesis and new data
The Crotone series is undoubtedly the best-studied Early Pleistocene succession in the world. Its matchless location and sedimentary conditions contribute to optimal achievements in biostratigraphy, magnetostratigraphy, cyclostratigraphy, and finally chronology. Robust stratigraphic correlations are established between the Semaforo and Vrica areas thanks to field surveys, a cored borehole, and ash mineralogy and geochemistry. The Crotone series covers the time-interval from 2.47 to 1.21 Ma and displays 30 complete glacial–interglacial cycles, from MIS 97 to MIS 37. Insolation cycles are recorded from i-236 to i-116 by combining lithology (sapropels) and palynology (amorphous organic matter and abundance in pollen grains of riparian trees, two indices of anoxic condition development and runoff intensity, respectively). The understanding of Early Pleistocene glacial–interglacial pollen records is clarified as the response of vegetation to the strong interaction between precession and obliquity has been analysed along several successive climatic cycles. Modern pollen records from the Rhône mouth shed light on the conditions of deposition of the sapropels, contributing to specify their intensity and duration.
(Quaternary International. vol. 219, n° 1040-6182, pp. 121-133, 10/06/2010)
PEPS, UCBL, INSU - CNRS, CNRS, LDO, INSU - CNRS, UBO EPE, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, UCL, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, IAMC-CNR
Climate-driven changes in coastal marine systems of western Europe
Coastal marine systems, the interface between the ocean and terrestrial realms, are among the most important systems on the planet both ecologically and economically because of their crucial role in earth system functioning. Although direct impacts of human activities on physical, chemical and biological components of these systems have been widely documented, the potential influence of climate variability is less well known. Here, we used data from Service d'Observation en Milieu Littoral (SOMLIT), a marine monitoring programme that has since 1997 collected samples at 12 sites located along the French coasts from 42° to 51°N. Applying standardised principal component analysis (PCA), we documented the year-to-year fluctuations in these coastal systems and evaluated the potential influence of climate variability using data on atmospheric circulation (wind intensity and direction), precipitation and temperature. Our study revealed a pronounced sensitivity of these systems to climate variability. As the impact of climate change may become more prominent in the next decades, this study suggests that climate might strongly influence the marine coastal environment and act in synergism with other anthropogenic pressures to alter the state and functioning of biological and ecological systems and the services they provide.
(Marine Ecology Progress Series. vol. 408, n° 0171-8630, pp. 129-148, 03/06/2010)
LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, AD2M, SBR, UPMC, CNRS, UPMC, CNRS
The Orinoco turbidite system: Tectonic controls on sea-floor morphology and sedimentation
Because of its location in an active margin context, the sand-rich Orinoco turbidite system is controlled morphologically and tectonically by the compressional structures of the Barbados prism, and as a consequence, the sedimentation system does not exhibit a classic fan geometry. The sea-floor geometry between the slope of the front of the Barbados prism and the slope of the Guyana margin induces the convergence of the turbidite channels toward the abyssal plain at the front of the Barbados accretionary prism. Also, whereas in most passive margins the turbidite systems are commonly organized upstream to downstream as canyon, then channel levee, then lobes, here, because of the control by active tectonics, the sedimentary system is organized as channel levee, then canyons, then channelized lobes. In shallow water, landward of the prism, the system has multiple sources with several distributaries, and progressively downward, the channel courses are more complex with frequent convergences or divergences that are emphasized by the effects of the undulating sea-floor morphologies. Erosional processes are almost absent in the upper part of the turbidite system shallower than 1500 m (4921 ft). Erosion along channels develops mostly between 2000 and 4000 m (6562 and 13,123 ft) of water depth, above the compressional structures of the Barbados prism. Incisions show irregular meandering and sinuous courses in the low-relief segments and less sinuous courses where channels incise the structures. Larger incisions (canyons) are 3 km (1.9 mi) wide and 300 m (984 ft) deep. The occurrence of different phases of successive incisions is responsible for the development of morphologically correlative terraces in both flanks of the canyons. This might be the consequence of two mechanisms: the tectonic activity of the deformation front characterized by progressive uplift and thrusting of recent sediments, and the superimposition of the cycles of the Orinoco turbidite system. Piston-core surveys have demonstrated that turbidite sediments moving through the channel and canyon system and deposited in the abyssal plain are mostly coarse sandy deposits covered by recent pelagic planktonic-rich sedimentation, which indicates that sand deposition slowed down during the postglacial sea level rise.
(AAPG Bulletin. vol. 94, n° 0149-1423, pp. 869-887, 01/06/2010)
IFPEN, BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LGCA, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, CNRS, GEOSCIENCES, PSL