Physical, chemical and biological processes and fates ofpetroleum-based plastic and bioplastic pollutants in aquatic environments A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy Taylor D. Gundry BSc (Environmental Science), RMIT University; BSc (Honours) (Applied Science), RMIT University School of Science College of Science, Engineering and Health Royal Melbourne Institute of Technology University October, 2018 Declaration I certify that except where due acknowledgement has been made, the work is that of the author alone; the work has not been submitted previously, in whole or in part, to qualify for any other academic award; the content of the thesis is the result of work which has been carried out since the official commencement date of the approved research program; any editorial work, paid or unpaid, carried out by a third party is acknowledged; and, ethics procedures and guidelines have been followed. I acknowledge the support I have received for my research through the provision of an Australian Government Research Training Program Scholarship. Taylor Gundry 19/10/2018 II Acknowledgements First I would like to express my deep gratitude to my senior supervisor Professor Mark Osborn for his continuous guidance, encouragement and support throughout my PhD journey. Professor Osborn has provided me with the resources to pursue this PhD into plastic pollution and has provided extensive detailed feedback on my writing and for that I am extremely thankful. I also would like to thank my associate supervisor, Dr. Bradley Clarke and Dr. Slobodanka Stojkovic for their guidance in analytical organic chemistry and high-throughput DNA sequencing. The current and past members of my two research groups need to be recognised for their moral and technical support; as well to all the members of the Ball and Bott laboratory groups. A special thank you needs to go to Thomas McGrath and Phoebe Lewis for their help; I would not have been able to complete the analytical chemistry component of my studies without them truly. Thank you to Adam Truskewycz and Adam Kolobaric for being great lab partners and housemates while it lasted. I would also like to thank Joe Stewart for turning me away from pursuing a career in mathematics or history and into science. My parents Adele and Dale and my sister Chelsea need to be thanked for their continued encouragement and support.Finally, my lovely wife Sylwia needs to be acknowledged. This PhD journey has been travelled by two people; thank you for your encouragement when I was low and needed it that most. III Table of Contents Declaration ................................................................................................................................ II Acknowledgements ................................................................................................................. III Table of Contents ..................................................................................................................... IV List of Figures .......................................................................................................................... IX List of Tables ....................................................................................................................... XVII List of Abbreviations ........................................................................................................... XXII Executive Summary ........................................................................................................... XXIV Conference Proceedings ................................................................................................. XXVIII 1 Chapter 1: Introduction ...................................................................................................... 1 1.1 Plastic production and applications .......................................................................... 1 1.2 Production and life-cycle assessments of bioplastics ............................................... 4 1.3 Plastic pollution in aquatic environments ................................................................. 6 1.4 Plastic pollution distribution in the environment ...................................................... 6 1.4.1 Sources and pathways of plastic into aquatic environments ......................... 6 1.4.2 Distribution of plastic in freshwater systems ................................................ 7 1.4.3 Distribution and abundance of plastic in the marine environment ................ 9 1.5 Degradation pathways of plastic debris .................................................................. 14 1.5.1 Abiotic degradation pathways of plastic ..................................................... 14 1.5.2 Biological degradation pathways of plastic ................................................ 16 1.6 Ecological impacts of plastic .................................................................................. 22 IV 1.7 Chemical pollutants associated with plastic debris ................................................. 23 1.7.1 Persistent organic pollutants (POPs) associated with plastic debris ........... 24 1.7.2 Plastic additives of concern ......................................................................... 28 1.8 Microbial biofilms on plastic .................................................................................. 32 1.8.1 The role of microbial biofilms in key environmental functions .................. 32 1.8.2 Microbial biofilms associated with plastic debris ....................................... 32 1.9 Research Aims and Objectives ............................................................................... 34 2 Chapter 2: Experimental Design and sampling scheme .................................................. 35 2.1 Experimental summary ........................................................................................... 35 2.2 Site descriptions ...................................................................................................... 35 2.3 Sample preparation ................................................................................................. 38 2.4 Sample collection and labelling regime .................................................................. 40 3 Chapter 3: Variation in physical and chemical properties of polypropylene and polylactic acid plastics following exposure in natural aquatic conditions ............................................... 42 3.1 Introduction ............................................................................................................. 42 3.2 Methods ................................................................................................................... 52 3.2.1 Plastic surface hydrophobicity analysis via water contact angle (WCA) measurements ............................................................................................................. 52 3.2.2 Plastic Universal Tensile Strength analysis ................................................ 54 3.2.3 Chemical structure and crystallinity analysis of polymer substrates .......... 55 3.2.3.1 Fourier transform infrared (FTIR) spectroscopy .................................... 55 3.2.3.2 Polymer crystallinity analysis ................................................................. 55 3.2.4 Scanning Electron Microscopy (SEM) imaging ......................................... 55 3.2.5 Data analysis ............................................................................................... 56 3.3 Results ..................................................................................................................... 57 V 3.3.1 Variation in water contact angles (WCA) of polymer substrates ................ 57 3.3.2 Variation in tensile strength of polymer substrates ..................................... 59 3.3.3 Chemical structure and crystallinity analysis of polymer substrates .......... 62 3.3.3.1 Crystallinity of polymer substrates ......................................................... 62 3.3.3.2 Fourier transform infrared (FTIR) spectroscopy of polymer substrates . 62 3.3.4 Biofilm formation on polymer substrates after exposure in the Yarra River65 3.4 Discussion ............................................................................................................... 69 4 Chapter 4: Accumulation of polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs) on polypropylene and polylactic acid substrates in aquatic environments ............................................................................................................... 73 4.1 Introduction ............................................................................................................. 73 4.2 Methods ................................................................................................................... 83 4.2.1 Chemical standards and materials ............................................................... 83 4.2.2 Selective Pressurised Liquid Extraction (S-PLE) ....................................... 84 4.2.3 Dual vortex and sonication extraction method of PBDEs and NBFRs from PLA substrates ........................................................................................................... 85 4.2.4 Combined method for transferring polypropylene, polylactic acid and glass extracts into gas chromatrography vials ..................................................................... 86