| Popis: |
Everyday life conveniences and activities such as washing clothing made of synthetic fibers, tire wear, and plastic packaging break down in the environment may serve as an abundant source of microplastic (MP). There is plenty of evidence that microplastic is a problem due to its shape, size, and concentration and the fact that it can easily enter the food chain which causes negative impacts on human health and the environment. An important aspect of this problem is also the fact that microplastic and other contaminants of emerging concern (CEC) present in water can interact, in terms of the adsorption of CEC onto the MP surface. The adverse effect of MP in water is therefore influenced by factors affecting adsorption capacity: particle size, specific surface area, hydrophobicity, and polarity of MP as well as CEC. The aim of this study was to investigate the aquatic toxicity of pristine and photooxidative (UV) aged microplastics and pesticide atrazine samples after the sorption. For that purpose, we investigated the impact of UV aging on polyethylene terephthalate (PET) bottles and correlated it with surface properties. Polyethylene terephthalate was inspected for morphology changes using Scanning Electron Microscopy and Fourier Transformation Infrared Spectroscopy. The specific surface was investigated by using Brunauer-Emmet-Teller Analyzer to determine the adsorption capacity of MP. The fragmentation of PET bottles into microplastic particles has also been investigated. In adsorption tests, using pristine and aged PET MP, the concentration of atrazine in the aqueous phase was monitored using High-Performance Liquid Chromatography Analysis. Aquatic toxicity samples were assessed by exposing freshwater organisms to the aqueous dispersion of pristine and aged MP, without and with adsorbed pollutants. Acute toxicity bioassays were performed with the microalgae Pseudokirchneriella subcapitata (Selenastrum capricornutum) and the crustacean Daphnia magna according to standard procedures (ISO). Obtained results indicated that UV aging resulted in changes in PET bottle morphology and structure. Carboxyl groups are confirmation of surface degradation. The adsorption capacity of MP increases with a higher aging degree. Adsorption capacity is decreasing with an aging degree. Toxicity is increasing with the complexity of samples but decreases with the aging degree. Mixture (MP and CEC) confirmed higher toxicity in comparison to the individual components. |
