Microplastic contamination of intertidal sediments of Scapa Flow, Orkney: A first assessment.

The concentration of microplastic particles and fibres was determined in the intertidal sediments at selected sites in Scapa Flow, Orkney, using a super-saturated NaCl flotation technique to extract the plastic and FT-IR spectroscopy to determine the polymer types. Mean concentrations were 730 and 2300kg sediment (DW), respectively. Detailed spatial and quantitative analysis revealed that their distribution was a function of proximity to populated areas and associated wastewater effluent, industrial installations, degree of shore exposure and complex tidal flow patterns.

Development and evaluation of an experimental protocol for 3-D visualization and characterization of the structure of bacterial biofilms in porous media using laboratory X-ray tomography.

The development of a reliable model allowing accurate predictions of biofilm growth in porous media relies on a good knowledge of the temporal evolution of biofilm structure within the porous network. Since little is known about the real 3-D structure of biofilms in porous media, this work was aimed at developing a new experimental protocol to visualize the 3-D microstructure of the inside of a porous medium using laboratory X-ray microtomography. A reliable and reproducible methodology is proposed for (1) growing a biofilm inside a porous medium, and (2) X-ray tomography-based characterization of the temporal development of the biofilm at the inlet of the biofilter.

Influence of hydrodynamics on the growth kinetics of glass-adhering Pseudomonas putida cells through a parallel plate flow chamber.

The objective of this work was to investigate the influence of hydrodynamics on the growth kinetics of surface-adhering Pseudomonas putida cells. The results showed in particular that under non substrate-limiting conditions, the early step of bacterial apparent growth rate is lower than those measured with suspended cells. Contrary to previously cited authors which explain this behavior to the different adhesive properties of the "daughter"-cells (which makes more probable the detachment of these daughter-cells), in our experimental conditions, that explanation does not hold and we show a clear dependence of growth kinetics with flow conditions, due to the formation of boundary layer concentration at low Reynolds number.

Application of synchrotron X-ray microtomography for visualizing bacterial biofilms 3D microstructure in porous media.

The development of reliable models to accurately predict biofilm growth in porous media relies on a good knowledge of the temporal evolution of biofilms structure within the porous network. Since little is known on the true 3D structure of biofilms developed in porous media, this work aimed at developing a new experimental protocol to visualize the 3D microstructure of bacterial biofilms in porous media. The main originality of the proposed procedure lies on the combination of the more recent advances in synchrotron microtomography (Paganin mode) and of a new contrast agent (1-chloronaphtalene) that has never been applied to biofilm visualization.

Induced agitation in homogeneous bubbly flows at moderate particle Reynolds number.

We investigated the agitation induced in a liquid by quasimonodispersed spherical bubbles. For Re(p) about 10 and for void fractions ranging from 0.002 to 0.