peer reviewed | Monoterpenes are compounds naturally emitted by wooden materials. A preliminary study had demonstrated the occurrence of some monoterpenes in the timber frame constructions. Contrary to the active sampling, the passive sampling with Radiello® device simplifies the sampling step that is an interest in indoor environment. However, the knowledge of the sampling rate is necessary for quantification via the passive samplers Radiello®. Radiello® sampler with Tenax TA cartridge was evaluated for the 4-h concentration measurements of nine monoterpenes (α-pinene, β-pinene, d-limonene, Δ3-carene, camphene, carvone, 1,8-cineole, linalool and p-cymene). The performance parameters of the method (calibration curve, trueness, repeatability, blank level, stability of samples) were estimated. The sampling rates were first evaluated under the standard conditions in an exposure chamber. The influences of three environmental factors (temperature (T), relative humidity (RH) and concentration level (C)) on the sampling rates were also evaluated following a full factorial design at two factor levels (low and high). The monoterpenes concentrations in the exposure chamber were followed by an active sampling on tube Tenax TA. For both sampling devices, analyses were realized by TD-GC-MS. The results of this study demonstrated that the Radiello® device is suitable for the measurement of 5 of 9 studied monoterpenes. The sampling rates were defined by an equation including two factors, temperature and relative humidity. Temperature is found to be the most important factor leading to variability of the all monoterpene sampling rates. An equation allowing to estimate the sampling rate was established for every studied compound. Measurements of monoterpenes with the Radiello® device were then carried out on new wooden houses and compared with measurements obtained by active sampling on Tenax TA tubes.

Revisamos las consecuencias ecológicas de la deposición de N en las cinco regiones mediterráneas del mundo. La estacionalidad de las precipitaciones y los incendios regulan el ciclo del N en estos ecosistemas con escasez de agua, donde domina la deposición seca de N. La acumulación de nitrógeno en los suelos y en las superficies de las plantas produce picos de disponibilidad con las primeras lluvias invernales. El desacoplamiento entre los flujos de N y la demanda de la planta promueve pérdidas por lixiviación y emisiones de gases. Las diferencias en la disponibilidad de P pueden controlar la respuesta a los aportes de N y la susceptibilidad a la invasión de plantas exóticas. Los pastos invasores se acumulan como combustible durante la estación seca, alterando los regímenes de incendios. California y la cuenca mediterránea son las más amenazadas por la deposición de N; sin embargo, existe evidencia limitada de los impactos de la deposición de N fuera de California. En consecuencia, se necesita más investigación para determinar las cargas críticas para cada región y tipo de vegetación en función de los elementos más sensibles, como los cambios en la composición de las especies de líquenes y el ciclo del N.

International audience | Phytoplankton diversity, primary and bacterial production, nutrients and metallic contaminants were measured during the wet season (July) and dry season (March) in the Bach Dang Estuary, a sub-estuary of the Red River system, Northern Vietnam. Using canonical correspondence analysis we show that phytoplankton community structure is potentially influenced by both organometallic species (Hg and Sn) and inorganic metal (Hg) concentrations. During March, dissolved methylmercury and inorganic mercury were important factors for determining phytoplankton community composition at most of the stations. In contrast, during July, low salinity phytoplankton community composition was associated with particulate methylmercury concentrations, whereas phytoplankton community composition in the higher salinity stations was more related to dissolved inorganic mercury and dissolved mono and tributyltin concentrations. These results highlight the importance of taking into account factors other than light and nutrients, such as eco-toxic heavy metals, in understanding phytoplankton diversity and activity in estuarine ecosystems.

International audience | Phytoplankton diversity, primary and bacterial production, nutrients and metallic contaminants were measured during the wet season (July) and dry season (March) in the Bach Dang Estuary, a sub-estuary of the Red River system, Northern Vietnam. Using canonical correspondence analysis we show that phytoplankton community structure is potentially influenced by both organometallic species (Hg and Sn) and inorganic metal (Hg) concentrations. During March, dissolved methylmercury and inorganic mercury were important factors for determining phytoplankton community composition at most of the stations. In contrast, during July, low salinity phytoplankton community composition was associated with particulate methylmercury concentrations, whereas phytoplankton community composition in the higher salinity stations was more related to dissolved inorganic mercury and dissolved mono and tributyltin concentrations. These results highlight the importance of taking into account factors other than light and nutrients, such as eco-toxic heavy metals, in understanding phytoplankton diversity and activity in estuarine ecosystems.