Sviluppo di un metodo termoanalitico per la quantificazione di microplastiche in matrici complesse

Microplastics (MPs) are highly debated emerging contaminants that are widespread on Earth. Nowadays, assessment of the risk that MPs pose on human health and environment were not developed yet, and standardized analytical methods for their quantification in complex matrices do not exist. Therefore, the formulation of standards which regulating MPs emission in the environment is not possible. The purpose of this study was to develop and apply a method for the analysis of MPs in sewage sludges and water from a wastewater treatment plant (WWTP), due to the relevance of those matrices as important pathway for MPs to enter the environment. Seven polymers were selected, because of their relevance on market production and their frequency of occurrence in such plants: polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyvinyl chloride (PVC), and nylon 6 (PA-6). In the study, a pre-treatment procedure was optimised using Fenton’s reagent and analyses carried out by combining thermochemolysis with Py-GC-MS after sample filtration on quartz (0.3 µm). Polymer quantification was performed with solid polymer mixture in silica and good correlations were obtained with internal calibration. As main results, Fenton's reagent negatively affected the recovery of some polymers (PP, PE, PS, PA-6) and a possible matrix interference was noticed, especially for PET and PVC. The WWTP allowed a good abatement of PS, PE, PP and PVC (on average 90 %) and comparable results were hypothesised for the other polymers. Polymer concentrations is sewage sludges ranged between < 2 μg/gdry and 3.5 mg/ gdry, for PC and PVC, respectively. Possible overestimations for PET and PVC, due to matrix interreferences, were taken into account and discussed.

Bioactivity of extracts from extremophile microalgae Coccomyxa sp. on chloride cells in operculum tissue of Fundulus heteroclitus

Microalgae have been studied because of their great potential as a source of new compounds with important value for biotechnology and to understand their strategies of survival in extreme environments. The microalgae Coccomyxa sp., studied in this thesis, is a poly-extremophile witch was isolated from the acid mine drainage of S. Domingos mine. This environment is characterized by low pH (<3) and high concentration of metals, such as copper and iron. The main purpose of the present work was to evaluate the potential bioactivity in an ex-vivo animal model (Fundulus heteroclitus), and expression on selected genes, of cellular extracts obtained from cultures of Coccomyxa sp. at pH 7 without or with exposure to copper (0.6mM Cu²+). The extracts of Coccomyxa sp. cultured at pH 7 exposed to copper show a great potential to be used as epithelial NKCC inhibitors, revealing their potential use as diuretics, but did not show significant effects on gene expression. Coccomyxa sp. could be a good source of cellular extracts with a great potential to be used in pharmaceutical and biotechnology industries.