Influence of environmental and anthropogenic factors on the composition, concentration and spatial distribution of microplastics: A case study of the Bay of Brest (Brittany, France).

The concentration and spatial distribution of microplastics in the Bay of Brest (Brittany, France) was investigated in two surveys. Surface water and sediment were sampled at nine locations in areas characterized by contrasting anthropic pressures, riverine influences or water mixing. Microplastics were categorized by their polymer type and size class. Microplastic contamination in surface water and sediment was dominated by polyethylene fragments (PE, 53-67%) followed by polypropylene (PP, 16-30%) and polystyrene (PS, 16-17%) microparticles. The presence of buoyant microplastics (PE, PP and PS) in sediment suggests the existence of physical and/or biological processes leading to vertical transfer of lightweight microplastics in the bay. In sediment (upper 5 cm), the percentage of particles identified by Raman micro-spectroscopy was lower (41%) than in surface water (79%) and may explain the apparent low concentration observed in this matrix (0.97 ± 2.08 MP kg-1 dry sediment). Mean microplastic concentration was 0.24 ± 0.35 MP m-3 in surface water. We suggest that the observed spatial MP distribution is related to proximity to urbanized areas and to hydrodynamics in the bay. A particle dispersal model was used to study the influence of hydrodynamics on surface microplastic distribution. The outputs of the model showed the presence of a transitional convergence zone in the centre of the bay during flood tide, where floating debris coming from the northern and southern parts of the bay tends to accumulate before being expelled from the bay. Further modelling work and observations integrating (i) the complex vertical motion of microplastics, and (ii) their point sources is required to better understand the fate of microplastics in such a complex coastal ecosystem.

Bronchial carcinoids.

Seventy-four bronchial carcinoids were observed over a period of 20 years, representing 69.7% of so-called "benign" tumors and 3.8% of all bronchial tumors resected during the same period of time. The tumors were centrally located in 59 cases and peripheral in 14 cases. From 54 biopsies, the preoperative diagnosis was accurate for 27, presumed for 15, doubtful for 15 and erroneous for 7 patients. Surgery was performed on 73 patients: 7 bronchotomies, 3 enucleations, 2 wedge resections, 5 segmentectomies, 35 lobectomies, 4 lobectomies with sleeve resections, 11 bilobectomies and 6 pneumonectomies. One patient died postoperatively. All the tumors were considered as carcinoids on initial microscopical examination. There were 4 cases of associated tumors. Six patients developed recurrence and 9 patients died from another cause. A pathology review changed the diagnosis into neuroendocrine carcinoma in 2 cases. Carcinoids should be considered and resected as carcinomas in the majority of cases, because of possible errors in diagnosis, of the effect of obstruction, of tumoral associations and of lymphatic involvement. Recurrences are possible.