Using infrared lasers to quantity microplastics within the bodies of oysters

Over the last 100 years plastic has become ubiquitous in production and now as waste, contaminating environments globally.

Whilst it has long been accepted that plastic pollution represents a pervasive and increasing threat to marine ecosystems worldwide, the full magnitude of environmental and biological risk posed by plastics remains largely unknown.

In the marine environment, physical and chemical forces as well as ultra-violet radiation, fragment large plastics into increasingly smaller pieces, collectively defined as microplastics (<5mm) and nanoplastics (<0.1µm). The perpetual fragmentation of plastics, as well as the constant addition of fibres and increasing use of microplastics in commercial products, makes it difficult to quantify the true amount of plastic currently in the ocean.

Sampling and extracting microplastics is complex. Fibers, granules, films, and polystyrene spheres ranging in size from 20 μm to 1 m have been collected from shorelines, harbour and estuarine sediments but sampling in this size range is exceptional, and existing studies have largely focus on larger detritus >333μm. Consequently, there is a lack of consistent or quantifiable data for plastic detritus <333μm in diameter, and to date, no way to determine realistic environmental concentrations of these particles and the extent of microplastic contamination. The small size of microplastics makes them available to a range of feeding guilds, and a growing body of research is documenting the various ways that plastics, either through ingestion or ambient exposure. It is also unclear where these smaller sized plastics end up once they have been ingested.

This study at SIMS and the University of Sydney will use novel techniques including Fourier Transformed Infrared lasers to quantify the amount of plastic and to determine the types of plastics found within the bodies of oysters. This work will focus on developing a methodology that can be used to better understand the true risks posed by very small pieces of plastic.

Mitigating washing machine effluent as a source of microplastics is critical to both marine and terrestrial health, but a lack of standardised methods for quantifying and tracking micro and nanoplastics has thus far hindered this effort. There are now developments in filtration systems, that can be fitted to washing machines in order to intercept micro and nonoplastic output. A range of high end technologies will be required to truly test the efficacy of these systems. We also hope that our methodologies can be used in this way.

Research by Katherine Catelotti, from the University of Sydney and Supervisors: Professor Peter Lay, Dr Elizabeth Carter and Professor Maria Byrne all from the University of Sydney and Dr Wayne O’Conner, DPI Fisheries.

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