No abstract

A methodology is proposed for modeling the diffusion of fragrances released from a moving source. First, we started with a one‐dimensional model considering molecular diffusion of α‐pinene in air as the only mass transport mechanism. The validation was performed in a diffusion tube, and a system was developed to move the scented source along the axial direction. Results showed that experimental data fitted well with the numerical simulation, suggesting this model as a valid tool to describe the trail of a fragrance released from a moving source for low Re of the order of 10. In the case of a person walking at the speed of 1.34 m/s in a room or corridor inside a building, three‐dimensional models are required and mass transport of the perfume to the surrounding air will be dominated by turbulent diffusion or eddy diffusion Dt which is two orders of magnitude higher than molecular diffusion. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2890–2897, 2018

In the present study, a theoretical model based on Fick's second law for radial diffusion is proposed for modelling the radial diffusion of fragrances. For that, three fragrance systems were studied containing α‐pinene and limonene as pure components, or a mixture of α‐pinene, limonene, linalool, and geranyl acetate. This model combines the UNIFAC group contribution method for the vapour‐liquid equilibrium with the Fickian radial diffusion model. The experimental gas concentrations of the odorant components were measured in a diffusion tube (1D axial diffusion) and quantified using gas chromatography with a flame ionization detector. The numerical solutions were obtained using the general Process Modelling Systems (gPROMS) software version 4.2.0. An equivalence relation between the 1D axial diffusion model and 1D radial diffusion model was developed. Finally, the odour intensity and character of the studied fragrance systems were assessed using Stevens’ power law and the strongest component model, respectively. The obtained results showed good agreement between the numerical simulation and the experimental gas concentration data, suggesting the proposed methodology as an efficient tool to assess the radial diffusion of fragrance systems over time and distance.

Climate change has been increasing at an unprecedented rate in the last decades. Global warming has been causing a variety of impacts in marine ecosystems, including shifts in the geographical ranges of species. The north-western Iberian Peninsula coast is particularly interesting to study distribution shifts as it features a strong latitude thermal gradient, establishing a biogeographical transitional region where several cold- and warm-adapted species have their equatorward or poleward distributions. In the early 2000s, it appeared that, while warm-water species were already responding to warming, cold-water species did not display a coherent response. It is now necessary to gather up-to-date data on the distribution of the same group of species to understand if current patterns of change confirm or deny those observed back then, which may give us important clues about the mechanisms setting species limits in the area. This study provides a fine-scale description of the occurrence of intertidal macroalgae species in the rocky shores of the north-western Iberian coast. Specifically, the spatial distribution and semi-quantitative abundance of 34 native and invasive species were assessed at 70 wave-exposed locations. This included 19 species of cold-water affinity, 10 species of warm-water affinity and five neutral species. When contrasted with historical observations, these new data can be used to quantify and map biodiversity change in the region, as well as help understanding the mechanisms constraining species distributions.

Climate change has been increasing at an unprecedented rate in the last decades. Warming has been causing a variety of impacts in marine ecosystems, including shifts in the geographical ranges of species. The North-western Iberian Peninsula coast is particularly interesting to study distribution shifts as it features a strong latitude thermal gradient, establishing a biogeographical transitional region where several cold- and warm-adapted species have their equatorward or poleward distributions. In the early 2000s, it appeared that while warm-water species were already responding to warming, cold-water species did not display a coherent response. It is now necessary to gather fresh data on the distribution of the same group of species to understand if current patterns of change confirm or deny those observed back then, which may give us important clues about the mechanisms setting species limits in the area. This study aims at providing a fine-scale description of the occurrence of intertidal macroalgae species in the rocky shores of the North-western Iberian coast. Specifically, the spatial distribution and semi-quantitative abundance of 34 native and invasive species were assessed at 70 wave-exposed locations. This included 19 species of cold-water affinity, 10 species of warm-water affinity and 5 neutral species. When contrasted with historical observations, these new data can be used to quantify and map biodiversity change in the region, as well as help understanding the mechanisms constraining species distributions.