Abundance and biomass of macrobenthos in the western part of the Black Sea during Mare Nigrum cruise S-RO2

Dataset containing macrobenthos data for samples collected during September 2008 in the North-West Black Sea (between 44°46' - 43°45' N latitude and 30° 11' - 29°35' E longitude). Macrobenthos sampling was done in 4 stations using a 0.14 m**2 Van Veen grab. Washing of the sample through two sieves - 1 mm and 0.25 mm mesh size; the material retained by the two sieves was examined at the binocular microscope; all animals were extracted, using fine tweezers and the species or group of species were identified and counted (in order to determine the density of populations); the larger organisms were measured and weighed (structure and biomass); for smaller organisms, the average wet weights inscribed in standard tables were used to calculate the biomass. Taxonomic identification was done at the GeoEcoMar by A. Teaca and T. Begun using the relevant taxonomic literature ( "Key-book for the identification of the Black Sea and Sea of Azov Fauna, 1968 -1972, Kiev - in Russian, V 1-4; BACESCU, M.C., MÜLLER, G. I., GOMOIU, M.-T., 1971). BACESCU, M.C., MÜLLER, G. I., GOMOIU, M.-T., 1971-Benthic ecological research to Black Sea. Comparative quantitative and qualitative analyse of pontic benthic fauna. Marine Ecology, 4, 1-357 (in Romanian). Key-book for the identification of the Black Sea and Sea of Azov Fauna, 1968 -1972, Kiev, V. 1-4 (in Russian).

Models for Lateral Dynamic Interaction of High-Speed Trains and Bridges

In this work a methodology for analysing the lateral coupled behavior of large viaducts and high-speed trains is proposed. The finite element method is used for the structure, multibody techniques are applied for vehicles and the interaction between them is established introducing wheel-rail nonlinear contact forces. This methodology is applied for the analysis of the railway viaduct of the R´ıo Barbantino, which is a very long and tall bridge in the north-west spanish high-speed line.

Reduction of Nutrient Losses with Eroded Sediments by Post-Fire Soil Stabilisation Techniques

After an experimental fire in steep shrub land in a temperate–humid region (north-west Spain), the effects of two post-fire stabilisation treatments (grass seeding and straw mulching) on the chemical properties of eroded sediments,and the amount of nutrients lost with them, we reevaluated relative to control burnt soil, over a period of 13 months. Total C and N concentrations, and d 13 C, indicated that sediments were mainly contributed by charred plant and litter material. The highest concentrations of extractable base cations in the sediments occurred during the first 3 months following fire, especially for Na and K. As treatments had little or no effect on nutrient concentration in sediments, differences in nutrient losses were due to the 10-fold lower sediment production in mulching compared with other treatments. In control and seeding treatments, the accumulated amounts of nutrients lost with sediments were 989–1028kgha 1 (C), 77kgha 1 (N), 1.9–2.4kgha 1 (Ca), 0.9–1.1kgha 1 (Mg), 0.48–0.55kgha 1 (NH 4 þ –N), 0.39–0.56kgha 1 (K), 0.19–0.34kgha 1 (Na) and , 0.1kgha 1 (P and NO 3 –N) . These values accounted for 22–25% (total C and N) and 5–12% (NH 4 þ –N, Ca, P and Mg) of available nutrients in ash, and 1.0–2.4% of those in ash þ topsoil. As nutrient and sediment losses were strongly correlated, the reduction of the latter by mulching application leads to an effective decrease of post-fire nutrient losses.

Biochemical evolution II: Origin of life in tubular microstructures on weathered feldspar surfaces

Mineral surfaces were important during the emergence of life on Earth because the assembly of the necessary complex biomolecules by random collisions in dilute aqueous solutions is implausible. Most silicate mineral surfaces are hydrophilic and organophobic and unsuitable for catalytic reactions, but some silica-rich surfaces of partly dealuminated feldspars and zeolites are organophilic and potentially catalytic. Weathered alkali feldspar crystals from granitic rocks at Shap, north west England, contain abundant tubular etch pits, typically 0.4–0.6 μm wide, forming an orthogonal honeycomb network in a surface zone 50 μm thick, with 2–3 × 106 intersections per mm2 of crystal surface. Surviving metamorphic rocks demonstrate that granites and acidic surface water were present on the Earth’s surface by ∼3.8 Ga. By analogy with Shap granite, honeycombed feldspar has considerable potential as a natural catalytic surface for the start of biochemical evolution. Biomolecules should have become available by catalysis of amino acids, etc. The honeycomb would have provided access to various mineral inclusions in the feldspar, particularly apatite and oxides, which contain phosphorus and transition metals necessary for energetic life. The organized environment would have protected complex molecules from dispersion into dilute solutions, from hydrolysis, and from UV radiation. Sub-micrometer tubes in the honeycomb might have acted as rudimentary cell walls for proto-organisms, which ultimately evolved a lipid lid giving further shelter from the hostile outside environment. A lid would finally have become a complete cell wall permitting detachment and flotation in primordial “soup.” Etch features on weathered alkali feldspar from Shap match the shape of overlying soil bacteria.

Contribution à l’étude de la thérophytisation des matorrals des versants sud des monts de Tlemcen (Algérie occidentale)

La zone sur laquelle porte notre contribution est localisée dans le Nord-Ouest Algérien. Cette étude est consacrée à l’analyse de la diversité biologique et la dynamique des formations végétales des matorrals des versants sud des monts de Tlemcen. L’utilisation de la méthode aire-espèce de Braun Blanquet nous a permis de dégager une liste de 149 espèces à partir de 150 relevés fl oristiques effectués sur l’ensemble des stations d’étude. 4,69 % des espèces appartiennent aux for mations forestières et pré-forestières, avec une hauteur n’excédant pas 2 mètres; 13,42 % aux matorrals et 81,87 % aux pelouses. La conjugaison des facteurs de dégradation a entrainé une perturbation des écosystèmes locaux accompagnée d’une régression des aires de répartition de nombreux taxons. Deux facteurs majeurs peuvent être évoqués : – amplifi cation de l’impact humain lié à l’utilisation anarchique des écosystèmes (défrichement; coupe; surpâturages; bois de chauffe), – péjorations climatiques. L’analyse statistique des spectres biologiques nous a permis de mettre en évidence les modifications de la flore le long d’un gradient dynamique: forêt – pré forêt – matorral – pelouse. Plus des 3/4 des espèces recensées dans la zone d’étude appartiennent aux thérophytes et aux hemicryptophytes.