Gillanders, BronwynReis Santos, PatrickWilliams , Mike (CSIRO)Dolling, Sophie Deborah Louise2025-03-262025-03-262024https://hdl.handle.net/2440/144033Plastic pollution is ubiquitous in marine environments globally. Since the first plastic polymers were synthesised in the early 20th century, plastic has become one of the most used synthetic materials in everyday human life leading to a high prevalence of mismanaged waste. This waste enters marine environments and can break down into many smaller pieces called microplastics (<5mm in diameter). Consequently, microplastic pollution is now considered one of the greatest threats facing the marine environment. Moreover, chemical contaminants such as PFAS, pharmaceuticals and pesticides are becoming increasingly prevalent in our oceans due to anthropogenic activities. Chemical contaminants and microplastic pollution have been shown to interact in the water column, as chemical contaminants can sorb to the surface of plastics. Therefore, plastics can act as vectors for the transportation of chemical contaminants through marine environments and to biota, potentially exacerbating negative impacts. In this thesis, I investigate the interaction between microplastics and chemical contaminants in marine environments and if plastics can be a pathway for chemical impacts on marine biota. I focus specifically on per and polyfluoroalkyl substances (PFAS), pesticides and pharmaceuticals, all pollutant classes currently under regulatory pressure in Australia and globally. Detecting chemical contaminants in the environment and on plastics is costly and most often specified to a particular contaminant class or analytical matrix. This limits broadscale application and comparisons among compounds and environmental matrices. I investigated and developed a methodology for the extraction and analysis of PFAS, pharmaceutical and pesticide contaminants on plastics and fish tissues. This involved trialling five extraction methods and comparing recoveries among trials and selecting the optimum method to be used in subsequent chapters. The optimised method involved ultrasonic extraction with acetonitrile, followed by a microcentrifuge step then Bond Elut Carbon solid phase extraction before analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In the next two chapters, I explore the interactions between chemical contaminants and microplastics in an environmental setting across the coastline of metropolitan Adelaide, South Australia. First, I investigate spatial variation in the chemical contamination of plastics. I found that spatial factors such as contaminant inputs and currents likely influenced the sorption and desorption of compounds from plastics and variation was seen between chemical contaminants. Then, I investigate the contamination of five microplastic types over an eight-month period, finding that sorption and desorption behaviours vary among plastic types, between compounds and through time. Notably, polyvinyl chloride (PVC) was found to sorb less chemical contaminant loads than other plastics, and temporal changes in contaminant load occurred gradually. Across both studies, I found that plastic sorption and desorption did not reflect chemical contaminant load in surrounding waters; both on a spatial and temporal scale. PFAS is currently under increased regulatory concern, both in Australia and around the globe, with several restrictions in place across this group of over 4700 compounds. In my final data chapter, I further employ the method developed in my first data chapter to investigate the presence of novel and legacy PFAS contaminants in an ecologically important estuarine system, across waters, biota and sorbed to plastics placed within the environment. I found that relatively high loads of PFAS occurred within the tissues and livers of 3 fish species, though there were interspecies diberences. Additionally, though PFAS were detected on plastics within the system, there were no clear patterns in sorption during the 70-day experimental period. In this thesis, I confirm the presence of emerging contaminants across South Australian waters, as well as their interactions with microplastics. Global interest in emerging contaminants and their impacts is rising, and this thesis provides novel insights in understanding their complex interactions with plastics in an environmental context, as well as their potential to act as pathways into marine species. Ultimately, this increased understanding provides critical information that can support improved risk assessments as well as regulatory action.enMicroplasticsemerging contaminantsmarinepollutionThesis