Standard Presentation (15 mins) Australian Marine Sciences Association 2022

Chemical characterisation of degraded polypropylene, polyethylene, and polystyrene microplastic samples (#308)

Tania Alajo 1 , Elvis Dartey EO Okoffo 1 , Stacey SO O'Brien 1 , Stephen SB Burrows 1 , Francisca FR Ribeiro 1 , Michael MG Gallen 1 , Sarah SE Ede 2 , John JC Colwell 2 , Andrew AW Whittaker 3 , Kevin KT Thomas 1 , Sarit SK Kaserzon 1
  1. Queensland Alliance for Environmental Health Sciences, Dutton Park, QUEENSLAND, Australia
  2. School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane , Queensland, Australia
  3. Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane , Queensland, Australia

Plastics entering the marine environment can degrade into smaller pieces predomintaly through UV-irradiation and mechanical forces, such as wave action and abrasion by particulates. These pieces of weathered microplastics possess characteristic properties different from their virgin counterparts. This study simmulated environmental degradation of selected microplastics under marine conditions using simulated sunlight (0.68 W/m2) and the mechanical abrasion using two types of particulates (sand and pebbles) in seawater. Micro-sized polypropylene, polyethylene and polystyrene of two different forms; beads (size: ~5 mm; shape: oval) and fragments (size: 250-500 µm and 500-1000 µm, shape: irregular) were weathered for up to 84 days.

Surface transformation was characterised by Pyrolysis Gas Chromatography/Mass Spectrometry (Pyr-GC/MS), Fourier-transform Infrared - Attenuated Total Reflection (FTIR-ATR), scanning electron microscopy (SEM), and Gel Permeation Chromatogrpahy (GPC). Simulated marine conditions can potentially influence quantitative measurements using  Pyr-GC/MS, while the technique can also be used to  identify weathering markers (oxidation products) specific for each type of degradation simulated.