Uptake and translocation of micro/nanoplastics in aquatic plants: Morphological and physiological effects, and potential mechanisms

The abstract should be in keeping with the structure of the dissertation (objective, statement of problem, investigation, conclusion) and should convey the substance of the dissertation.The ubiquitous presence of micro/nanoplastics in aquatic environments has emerged as a significant ecological concern, posing potential risks to a wide range of organisms, including aquatic plants.Despite the growing body of research on the effects of micro/nanoplastics on marine and freshwater fauna, their impact on aquatic flora, particularly submerged freshwater macrophytes such as Egeria densa and Myriophyllum sp.Roraima, remains less understood.This dissertation aims to fill this critical knowledge gap by systematically investigating the uptake, translocation, and subsequent morphological and physiological effects of micro/nanoplastics on these ecologically important macrophytes, while exploring the potential underlying mechanisms that govern these processes.The research employs a multi-faceted approach, combining state-of-the-art microscopic observations, detailed morphological measurements, comprehensive pigment analyses, chlorophyll fluorescence assessments, and sensitive antioxidant defense assays to provide a comprehensive understanding of the harmful effects of micro/nanoplastics on aquatic plants.The studies demonstrate that micro/nanoplastics affect plants at various levels, from root adsorption and photosynthetic efficiency to oxidative stress responses and nanoplastic translocation at the cellular level.The findings highlight the multidimensional nature of micro/nanoplastic pollution, emphasizing the importance of considering factors such as micro/nanoplastic size and concentration, direct and indirect plant exposure, and species-specific characteristics when assessing the ecological impacts of plastic pollution on aquatic plants.This holistic approach provides a more accurate and nuanced understanding of the complex interactions between plastic particles and aquatic flora.Furthermore, this thesis underscores the need to examine the interactions between micro/nanoplastics and other environmental factors, such as the presence of cyanobacteria (Microcystis aeruginosa), to comprehensively understand the ecological consequences of plastic pollution.By investigating the combined effects of micro/nanoplastics and cyanobacteria on aquatic macrophytes, this research provides valuable insights into the complex interplay between multiple stressors in aquatic ecosystems.The findings suggest that the presence of cyanobacteria may exacerbate the adverse effects of micro/nanoplastics on aquatic plants, highlighting the importance of considering these interactions when assessing the overall impact of plastic pollution.This novel aspect of the research contributes to a more realistic and ecologically relevant understanding of the challenges faced by aquatic plants in the face of increasing plastic contamination and harmful algal blooms.The research also reveals distinct uptake, translocation, and physiological impacts of nanoplastics on aquatic plants compared to microplastics.Due to their unique properties at the nanoscale, nanoplastics exhibit different behaviors and interactions with biological systems, potentially leading to more severe consequences for aquatic flora.This dissertation emphasizes the need for further investigation into the mechanisms governing these differences, as well as the development of novel techniques to detect and quantify nanoplastics in aquatic environments.By shedding light on the specific effects of nanoplastics on aquatic plants, this research paves the way for a more comprehensive understanding of the ecological implications of plastic pollution at different size scales.In addition to the direct effects of micro/nanoplastics on aquatic plants, this thesis explores the potential role of plant anatomical features, such as aerenchyma, in facilitating the internal movement of these particles within plant tissues.The findings suggest that the presence of aerenchyma may enhance the translocation of micro/nanoplastics from roots to shoots, potentially increasing the exposure of higher trophic levels to these contaminants.This novel insight highlights the need for further research into the anatomical and physiological factors that influence the uptake and distribution of plastic particles in aquatic plants, as well as the potential ecological consequences of these processes.In conclusion, the findings of this thesis underscore the pressing need for further research and the development of effective mitigation strategies to safeguard aquatic ecosystems from the escalating threat of micro/nanoplastic pollution.By deepening our understanding of how these particles interact with and affect aquatic plants, this study contributes to a more comprehensive approach to addressing the environmental challenges posed by plastic pollution.It highlights the importance of considering interactions between plastic particles and other stressors, as well as the potential role of plant anatomical features, such as aerenchyma, in facilitating micro/nanoplastic movement within plants.The insights gained from this research can inform policy decisions, guide future studies, and contribute to the development of innovative solutions to mitigate the impacts of plastic pollution on aquatic ecosystems.Furthermore, the findings of this thesis emphasize the need for a multi-disciplinary approach, integrating ecological, physiological, and toxicological perspectives, to fully understand and address the complex challenges posed by micro/nanoplastic pollution in freshwater environments.By providing a solid foundation for future research and highlighting the critical importance of protecting aquatic flora from the detrimental effects of plastic contamination, this dissertation contributes to the ongoing efforts to preserve the health and biodiversity of our invaluable freshwater ecosystems.