"Plastisphere - the holistic approach and numerical description of microplastics surfaces"

The aim of this research is to discuss the current state-of-art, basic data and the methodology for the quantitative and qualitative physical and chemical characterisation of the marine microplastics (MMs; polymer debris < 5 mm) and the Plastisphere. In particular, the surface of synthetic materials is crucial as determines the type of biofilm which growths on the substrate. The main hypothesis of this paper, based on the preliminary research, is that the Plastisphere is not one biotope but the variety of diversified ecological niches. As the amount of MMs growths constantly and rapidly in the environment, the understanding of their behaviour and ecological impact is one of the main challenges of the Anthropocene Era. It is crucial to perform the basic research of a Plastisphere from the point of view of its chemical and physical properties. The qualitative and quantitative characterization of the surface will be presented. This is an entirely new and important area of research combining the biological, chemical and physical approach. Although the Plastisphere is already extensively studied by microbiologist observing the biofilm and by material scientists interested in the weathering of polymer materials, there is no correlation between those approaches. The aim of this project is to construct the bridge between the physical and chemical description of the Plastisphere and its microbiological and ecological significance. Various algorithms, based on the profilometry and SEM pictures analysis, will be proposed to describe in detail the morphology of naturally weathered polymers. This holistic approach is necessary to better understand the eighth continent and its variety of niches. Finally, one can underline the importance of this emerging research area considering for instance the amount of antibiotic-resistant bacteria already found on a Plastisphere. The variety of samples measured includes: MMs filtered from pelagial waters, sea birds casts, primary sources materials, weathered fragments of litoral wastes, ghost nets, to name just a few. The results from those techniques: IR spectroscopy in ATR and reflectance mode, Raman spectroscopy (line 532 nm or one in the range 400-700 nm if needed), SEM-EDX, profilometry have been numerically modelled basing on the image analysis. Thanks to the spectra characterisation, the risk of overestimation due to the inorganic debris visible in optical microscopy and erroneously classified as MMs, is limited and some preliminary qualitative description of weathering proposed. All in all, this approach addresses the interdisciplinary global problem of marine microplastics pollution providing the advanced physical and chemical characterisation tools for the description of biological samples. The project addresses the current and globally important problem of plastics in the environment and tackle it from the unique and needed perspective - basic studies of physical and chemical properties.