Search

10 pages, 6 figures, 1 table, [EN] Aeolian inputs of organic and inorganic nutrients to the ocean are important as they can enhance biological production in surface waters, especially in oligotrophic areas like the Mediterranean. The Mediterranean littoral is particularly exposed to both anthropogenic and Saharan aerosol depositions on a more or less regular basis. During the last few decades experimental studies have been devoted to examining the effect of inorganic nutrient inputs from dust on microbial activity. In this study, we performed experiments at two different locations of the NW Mediterranean, where we evaluated the changes in the quality and quantity of dissolved organic matter due to atmospheric inputs of different origin (Saharan and anthropogenic) and its subsequent transformations mediated by microbial activities. In both experiments the humic-like and protein-like substances, and the fluorescence quantum yield increased after addition. In general, these changes in the quality of dissolved organic matter did not significantly affect the prokaryotes. The recalcitrant character of the fluorescent dissolved organic matter (FDOM) associated with aerosols was confirmed, as we found negligible utilization of chromophoric compounds over the experimental period. We framed these experiments within a two-year time series data set of atmospheric deposition and coastal surface water analyses. These observations showed that both Saharan and anthropogenic inputs induced changes in the quality of organic matter, increasing the proportion of FDOM substances. This increase was larger during Saharan dust events than in the absence of Saharan influence, [ES] Los aportes atmosféricos de nutrientes orgánicos e inorgánicos al océano son importantes ya que pueden aumentar la producción biológica en aguas superficiales, especialmente en las zonas oligotróficas como el Mediterráneo. El litoral del Mediterráneo está particularmente expuesto a aportes de origen antropogénico y a deposiciones de polvo sahariano de forma más o menos regular. Durante las últimas décadas los estudios experimentales se han dedicado, sobre todo, a examinar el efecto de la entrada de nutrientes inorgánicos atmosféricos sobre la actividad microbiana. En este estudio, se realizaron experimentos con comunidades microbianas procedentes de dos zonas del Mediterráneo noroccidental. Se evaluaron los cambios en la calidad y cantidad de la materia orgánica disuelta debido a aportes atmosféricos de distinto origen y sus posteriores transformaciones mediadas por actividades microbianas. En ambos experimentos las sustancias orgánicas fluorescentes y el rendimiento cuántico de fluorescencia aumentaron después de la adición de material atmosférico. En general, estos cambios en la calidad de la materia orgánica no afectaron significativamente a los organismos procariotas. El carácter recalcitrante de la materia orgánica disuelta fluorescente (FDOM) contenida en los aerosoles se confirmó ya que la utilización de compuestos cromóforos durante el período experimental fue insignificante. Los resultados obtenidos se contextualizan en relación con una serie temporal de dos años de datos adquiridos de deposición atmosférica y análisis de agua superficial costera. La variabilidad temporal de estas dos variables mostró que tanto los aportes saharianos como antropogénicos provocaron cambios en la calidad de la materia orgánica disuelta en aguas superficiales, incrementando la fracción fluorescente. Éste aumento resultó ser mayor durante eventos de polvo sahariano que en ausencia de ellos, This study was supported by the projects 1179-1198. ADEPT (CTM2011-23458), DOREMI (CTM2012-342949) and ANIMA (CTM2015-65720-R MINECO/FEDER, UE). E.D. Sánchez-Pérez would like to thank the Consejo Nacional de Ciencia y Tecnologia (CONACyT) for their financial support through a PhD fellowship. I. Marín thanks the FPI Spanish scholarship programme for its support (BES 2012-052976)

Aluminium-based coatings are potential candidates for a sacrificial protection of steel. Such coatings, elaborated by magnetron sputtering, offer a good corrosion protection but often present poor tribological properties [1,2]. Cathodic arc evaporation PVD process has outstanding potential to deposit corrosion-resistant coatings with relatively dense structure. Moreover, adherent coatings and large scale production can be obtained. Aluminium, titanium and multilayer titanium/aluminium coatings have been deposited on steel substrates. The coating uniformity and homogeneity analysis were performed by optical and scanning electron microscopy while energy dispersive X-ray microanalyses were carried out to check the coating composition. The corrosion behaviours of smooth and threaded coated samples were analysed from 5% salt spray exposures and electrochemically characterized with voltamperometric measurements. Titanium/aluminium multilayers on low carbon steel lead to better corrosion resistance than monolayer coatings. Vacuum coating tests, carried out on small parts by means of a barrel coater, led us to consider the process to be a possible alternative to the actual anti-corrosion treatments of steel substrates, especially as a substitute for cadmium coatings.

Diamond-like carbon was physically vapour deposited on various substrates using an enhanced cathodic are plasma in Ar, H2 and/or CH4. The enhanced evaporator allows diamond-like coating deposition with a better surface finish than a conventional vacuum arc system does; the size of the macroparticles did not exceed 0.3 μm. Emphasis is put on the evaporator design and its capabilities. The plasma species were identified by optical emission spectroscopy while carbon coatings were characterized by scanning electron microscopy, Raman spectroscopy and electron spectroscopy for chemical analysis.