Littérature scientifique sur le sujet « Biocolonisation »

Polymer-modified mortars are cementitious materials that integrate polymers from 5 to 20 wt.%. Those materials are widely used for protecting and/or repairing concrete surfaces among which building facades, civil engineering structures, or sewage networks. In this context, polymer-modified mortars are applied into thin layers of about 1–3 cm. However, previous studies performed regarding such materials were carried out on massive pieces and did not consider the interactions between polymer-modified mortars and microorganisms. Nevertheless, such interactions can lead to undesired aesthetical or structural modifications of those materials. As a result, the main objective of this paper is to evaluate the resistance to biocolonisation of polymer-modified mortars applied into thin layers in environmental conditions that are representative of the on-site applications. Two formulations of polymer-modified mortars and a polymer-free mortar are characterised in the hardened state. Then, the resistance of those mortars to biocolonisation is tested by means of two laboratory accelerated tests. The first experiment is performed in order to recreate biofouling at the surface of the specimens, while the second one exposes the materials to biodeterioration. The results and analyses show that in the presence of polymer, both porosity and capillary absorption of mortars are reduced, but this does not allow preventing or slowing down biocolonisation. In addition, this study suggests that the nature of the polymer has an influence on bioreceptivity of polymer-modified mortars. Finally, our results suggest that in the presence of polymer, the global material may have an improved inner cohesion.

Les ingénieurs spécialisés en génie civil doivent intégrer dans leur design des mesures de protection de la biodiversité marine de qui autorise le concept d’écoconception d’infrastructures marines respectueuses de l’environnement. Les matériaux cimentaires sont privilégiés pour concevoir les infrastructures marines et interagissent avec le milieu marin. Ces structures seront colonisées par des micro-organismes et macroorganismes marins. Dans un premier temps, les organismes forment un biofilm à la surface du béton en fonction des facteurs environnementaux et des propriétés physico-chimiques du matériau. Dans cette étude, il a été démontré que la pré-carbonatation des matériaux cimentaires accélère la croissance des micro-organismes formant le biofilm à leur surface en abaissant le pH de la surface. Il a été démontré en laboratoire que la colonisation de la surface par des micro-organismes augmente également l’hydrophobicité de la surface et pourrait ainsi améliorer la durabilité du matériau en diminuant l’absorption d’eau de mer contenant des agents agressifs.

Hypogenic caves represent unique environments for the development of specific microbial communities that need to be studied. Caves with rock art pose an additional challenge due to the fragility of the paintings and engravings and to microbial colonization which may induce chemical, mechanical and aesthetic alterations. Therefore, it is essential to understand the communities that thrive in these environments and to monitor the activity and effects on the host rock in order to better preserve and safeguard these ancestral artforms. This study aims at investigating the Palaeolithic representations found in the Escoural Cave (Alentejo, Portugal) and their decay features. These prehistoric artworks, dating back up to 50,000 B.P., are altered due to environmental conditions and microbial activity inside the cave. Microbial cultivation methods combined with culture-independent techniques, biomarkers’ viability assays and host rock analysis allowed us to better understand the microbial biodiversity and biodeteriogenic activity within the hypogenic environment of this important cave site. This study is part of a long-term monitoring program envisaged to understand the effect of this biocolonisation and to understand the population dynamics that thrive in this hypogean environment.

Afin de limiter le changement climatique lié à l’utilisation d’énergies fossiles, certaines nations se tournent vers l’utilisation de sources d’énergies renouvelables notamment d'origine éolienne. Bénéficiant des acquis et technologies de l’industrie pétrolière offshore, l’industrie éolienne a pu s’étendre vers la haute mer. Toutefois, avec des enjeux environnementaux et sociétaux, ce déplacement vers le large n’est pas sans impacts. En effet, les éoliennes en mer peuvent engendrer des effets indésirables sur la vie marine. La littérature montre également une colonisation rapide des structures immergées par des communautés benthiques sessiles. Cette biocolonisation peut impacter ce secteur en plein essor en modifiant les paramètres des composants immergés de façon significative. Dans ce manuscrit ce point a été étudié via l’analyse de médias sous-marins de lignes d'ancrages d’une éolienne flottante française. En parallèle, les perceptions et inquiétudes de communautés côtières du Nord-Est des États- Unis et de I ‘Ouest de la France ont été recueillies. Ceci a permis de mettre en évidence les préoccupations récurrentes sur les impacts sur la biodiversité marine ou la pêche locale. Ces résultats ont par la suite permis de développer un concept de — structure d'atténuation des effets environnementaux pour éolienne flottante. Le concept, exposé auprès de communautés littorales américaines et françaises, a permis de quantifier la volonté de payer pour son application dans les futurs parcs éoliens flottants. Enfin, ce concept de structure a été le sujet de tests à échelle réduite au large des Sables d’ Olonne
In order to limit climate change linked to the use of fossil fuels, some nations are turning to the use of renewable energy sources, particularly wind power. Benefiting from the experience and technologies of the offshore oil industry, the wind energy industry has been able to expand into the open sea. However, with environmental and societal issues at stake, this move offshore is not without its impacts. Offshore wind turbines can have undesirable effects on marine life. The literature also shows the rapid colonization of submerged structures by sessile benthic communities. This biocolonization can impact this booming sector by significantly altering the parameters of submerged components. In this manuscript, this point was investigated via underwater media analysis of French floating wind turbine anchor lines. In parallel, the perceptions and concerns of coastal communities in the Northeastern USA and Westem France were collected. This highlighted recurring concerns about impacts on marine biodiversity or local fisheries. These results were subsequently used to develop a concept for an environmental mitigation structure for floating wind turbines. The concept, presented to coastal communities in the USA and France, quantified the willingness to pay for its application in future floating wind farms. Finally, the concept was tested on a reduced scale off the coast of Les Sables d’Olonne