Predicting the impact of land use on the major element and nutrient fluxes in coastal Mediterranean rivers: The case of the Teˆt River (Southern France)

This study presents a detailed discrimination between the natural and anthropogenic sources of dissolved major elements in the Teˆt River, a typical small coastal river in the south of France. The main objectives were to quantify the materials that were released by human activities in the basin, and to determine the specific element inputs for the major land use forms. The dissolved material fluxes were estimated by weekly monitoring over a hydrological year (2000–2001) along the major water gauging stations, and the flux relationships were examined in the context of anthropogenic and natural basin characteristics as determined by a Geographical Information System (GIS). Intensive agricultural land use in the form of fruit tree cultures and vineyards has a strong control on the dissolved element fluxes in the river. Area specific element releases for these cultures are greatest for SO4, with an estimated average of about 430 ± 18 keq km2 a1. This is P11 times the natural SO4 release by rock weathering. Also for K, NO3, PO4 and Mg, the specific releases were P6 times the natural weathering rates (respectively about 44, 60, 4 and 265 keq km2 a1). Waste-waters are the other major source of anthropogenic elements in the river. They have an important role for the fluxes of inorganic P and N, but they are also a considerable source of Cl and Na to the river. For example, the average annual release of Cl is around 150 moles/inhabitant in the rural basin parts. Further downstream, however, where population density strongly increases, industrial effluents can enhance this value (>300 moles/inhabitant). The waste-waters contribute more than 70% of the dissolved inorganic N export to the sea, although their contribution to the average DOC export is almost negligible (3%)

Model-Based Feedforward Optimal Control applied to a Turbulent Separated Flow

International audienceThe paper presents a model-based optimal feedforward control methodology applied to the control of a separated flow. A model is first identified as a delayed bilinear model from experimental data using a special identification procedure, for which the precision is compared to other existing results. Then, using the identified model, the optimal feedforward control problem is formulated and solved for the case of a periodic relay control. The theoretical control results are supported with numerical simulations

Sliding Mode Control for Turbulent Flows

International audienceThe control of turbulent flows is a growing field with major interest, such as in aeronautical industries. This paper deals with the control of a flow separation. The dynamical model of the flow is identified based on experimental data using a specific identification procedure. A setpoint tracking problem is solved by means of Sliding Mode Control methodology. The theoretical results are supported with numerical simulations

Lipoxygenase-induced autoxidative degradation of terrestrial particulate organic matter in estuaries: A widespread process enhanced at high and low latitude

International audienceThere exists a substantial amount of research on abiotic (e.g. photochemical) degradation pertaining to organic matter (OM) in the marine realm. While recent research has shown its importance in the degradation of terrestrial particulate OM (TPOM), the mechanisms involved in the induction of autoxidation in estuaries remain unclear. In this study, we propose for the first time the involvement of lipoxygenase (LOX) activity in the induction of autoxidation in mixed waters. The observation of unusual profiles of palmitoleic acid oxidation products and the presence of jasmonic acid in suspended particulate matter (SPM) collected close to the Rhône River, as well as in samples from the Mackenzie and Amazon rivers, is attributed to strong LOX activity. We show the role played by salinity in the induction of this LOX activity and provide an explanation for the differences in estuarine autoxidation level. At high latitude, lower temperatures and irradiance favor photooxidative damage to higher plant debris and, consequently, hydroperoxide production. High hydroperoxide content strongly contributes to LOX activation in mixed waters. The high resulting LOX activity enhances alkoxyl radical production and thus autoxidation. On the contrary, at low latitude, photooxidative effects are limited, and riverine autoxidation is favored. The higher hydroperoxide content of TPOM may, as a consequence, thereby also contribute to a high level of LOX activity and autoxidation in estuaries. In temperate zones, land and riverine photooxidative and autoxidative damage is limited, unlike estuaries where we observed significant LOX-induced and autox-idative damage.

Reproduction patterns of the bloody cockle Senilia senilis (Linnaeus 1758) in the Sine-Saloum inverse estuary

Understanding the reproductive biology of a species is an important means of determining the renewal capacity of natural stocks, especially in the case of heavily exploited species. It is a fundamental element in supporting the implementation of management measures. Here, we studied the bloody cockle (S. senilis) in the Sine-Saloum, with the aim of describing its seasonal and spatial reproductive cycle. S. senilis reproduction was studied over an annual cycle at two sites chosen for their contrasting situations along the upstream-downstream gradient. The reproductive cycle was studied by histological analysis of a pool of individuals maintained in-situ and sampled throughout the year. Our results showed that gamete maturation is asynchronous within and between individuals. Gametogenesis mostly occurred in October. The maturation stage showed a seasonal pattern with continuous reproduction throughout the year, with two preferred periods between May and July and December and February. The reproductive cycle is highly dependent on temperature and salinity variations, resulting in a seasonal cycle and spatial heterogeneity. The temperature induces gametogenesis and salinity synchronizes the spawning periods

Monique Goullet, Michel Parisse, Apprendre le latin médiéval. Manuel pour grands commençants

Kerhervé Jean, Kerhervé Annie. Monique Goullet, Michel Parisse, Apprendre le latin médiéval. Manuel pour grands commençants. In: Annales de Bretagne et des pays de l'Ouest. Tome 104, numéro 2, 1997. pp. 132-134

Monique Goullet, Michel Parisse, Apprendre le latin médiéval. Manuel pour grands commençants

Kerhervé Jean, Kerhervé Annie. Monique Goullet, Michel Parisse, Apprendre le latin médiéval. Manuel pour grands commençants. In: Annales de Bretagne et des pays de l'Ouest. Tome 104, numéro 2, 1997. pp. 132-134

Arthur de Richemont, connétable et duc. Entre guerre et politique dans la France du XVe siècle

International audienc

La Bretagne finistérienne des ducs, 1213-1532

Y. Le GalloInternational audienc