Understanding biodegradation of biodegradable plastics in aquatic environments

Tracey Read PhD

School of Chemical Engineering, The University of Queensland

The scourge of plastic on beaches and in the sea is an increasingly common sight and no amount of cleaning up will fix this problem if we don’t tackle plastic waste at the source. One of the big issues of conventional plastic is its longevity in the environment (10s to 100s of years), so part of the solution to combatting this global issue is to switch materials from non-degradable to biodegradable plastics. However, not all ‘biodegradable’ plastics are the same – some are bioderived and do not biodegrade, some do biodegrade but it still takes many years. ‘Biodegradability’ is currently measured under laboratory conditions, often for industrial composting which uses high temperatures. Little is known about what ‘real’, lifetime rates of degradation are for biodegradable plastic litter, particularly in aquatic environments. To address this knowledge gap, we are running an 18-month field trial, testing over 2000 samples of different types of biodegradable plastics, including thick food and beverage packaging and thin biodegradable or compostable plastic bags. Research rigs will be placed at four sites within Moreton Bay, including a sea marina, river marina (estuarine conditions), coastal seabed and open ocean mesocosm tanks. Based on our findings, we hope to understand the true rates of biodegradation of different types of bioplastics, promoting the use of single use bioplastics that are truly ‘biodegradable’ to help tackle the global plastic crisis.