How we are tracing plastics through the biosphere


If you dispose of a plastic bag after a single use, does it simply breakdown and disappear into the environment without a trace? Do you recycle, use only bio-based plastics, or try to reuse products? The answers to these questions are not as simple as we may think.

 

Plastic Bag credit Ars Electronica
Image: Ars Electronica / Foter


A team of conservationists with the help of Australian scientists using nuclear bioanalytical techniques to study feathers from birds that have ingested degraded plastic pieces- often almost a tenth of their body weight. 

The scientists are trying to find out whether the atomic elements commonly found in plastics are also found in bird feathers, thus giving a record of environmental pollution.
 

Professor Richard Banati is an internationally recognised biomedical scientist who heads the bioanalytics capability at the Australia Nuclear Science and Technology Organisation (ANSTO) and was part of the team of researchers involved in the study. 
 
Professor Banati said the team’s observations were changing perceptions about how the increased degradability of a material, such as plastic, may help to reduce the litter problem but, if not properly managed, might cause a contamination problem in the future. 
 
It has been said that the admixture of more and more degradable plastics to the waste stream of recyclable plastics could become the Achilles heel of recycling, since sorting of the different plastics is becoming increasingly difficult.

 

Plastic Bottles credit Fadzly @ shutterhack
Image: Fadzly @ Shutterhack / Foter


“Plastics have superior material properties in many respects and, therefore, have an important place in our world, but we need to be mindful that trace contaminants contained in a ‘single use’, throw away item, will stay behind without any further decay,” Professor Richard Banati said.  


As part of the degradation of plastics into ever smaller particles, they are not only a source but also a sink for potentially hazardous elements, which they attract and concentrate from the already existing diluted pool of elements, such as mercury, cadmium and arsenic.
 
Plastic have been around for less than a century, but in such a short amount of time has become ubiquitous in our lives. 
 
The work of Professor Banati  is not about demonising plastic, but about opening our eyes to a new view of plastic, at the atomic level, that shows how our environmental, biological and social concerns interconnect – and what opportunities we have using science to find truly sustainable solutions. 
 
Using the mature and well established suite of nuclear analytical techniques allows us to trace at the atomic level products throughout their life cycle with exquisite sensitivity.  
 

The ability to trace is also the ability to more fully account for the fate of a complex synthetic material, such as plastics. 

 

A deeper understanding of the full life cycle particularly of a material used in large quantities is essential to achieving sustainable manufacturing, use and disposal practices.
           

 

Plastic bird gut
This Laysan Albatross chick starved to death because it's parents fed it too much plastic flotsam. Photo Credit: angrysunbird/foter

 

  



The research


Like any other material in the universe, plastic is made up of a certain arrangement of atoms that during the process of degradation are potentially released into the environment. But unlike radioactive waste that scientists can easily trace and show how it decays in a predictable way over time, plastic waste is different as its contaminants such as heavy metals, do not decay and continue to retain their potentially hazardous nature. 
 
The increased presence of certain degradable plastics, including biodegradable plastics, is a challenge for the recycling of plastics more generally since the various plastics can be difficult to sort. Contamination of the waste stream with similar appearing but non-recyclable material by many seen as the Achilles heel of recycling.

A significant portion of plastic waste ends up in our oceans. This problem is well recognised and studied by scientists world wide.

ANSTO contributes to this collaborative research effort by using nuclear technologies to measure minute quantities of material such as the contaminants potentially leaching or being absorbed by degrading plastic material. ANSTO has national and international collaborations current work is being undertaken with Monash University, UTAS and CSIRO.
 
The plastic items studied were collected from the stomachs of Flesh-Footed Shearwater birds over an extended period, as part of a long-term research program lead by conservation scientist Dr Jennifer Lavers. These samples were analysed using two pieces of ANSTO infrastructure. Firstly the Australian Synchrotron in Melbourne was used to measure chemical composition of the plastic samples.
 
Shearwater bird credit ajmatthehiddenhouse
Image: Flesh-Footed Shearwater ajmatthehiddenhouse / Foter

Secondly the OPAL research reactor in Sydney was used to quantify trace elements in the samples. In a method called Neutron Activation Analysis, neutrons from the reactor bombarded the samples, making them slightly radioactive.  Placing the irradiated samples in a spectrometer enabled individual elements to be identified by their characteristic gamma-ray energy spectrum and the intensity of the gamma-ray peaks allowed the concentration of those elements to be quantified. 
 
Scientists demonstrated that common plastics are made up of a complex mixture of elements and chemicals that changes during the degradation process. They also observed that as plastics break down the total surface area of the material increases, thus increasing its absorbency . With this combined knowledge came a new understanding that plastic waste is not only a source but also a sink for contamination in the environment, as it attracts other contaminants that were already present in highly dilute concentrations.
 
The other part of the project was to understand how animals are affected by ingesting plastics. Pelagic birds, like humans, are apex predators and provided a case study for understanding the impact of plastics eaten by animals in the marine environment.
 
xfm feathers
Setting up feathers for the X-ray fluorescence microprobe (x-ray Microspectroscopy) beamline.

Two different groups of birds were studied – some that had eaten plastics and others that had not. Analysing the feathers of these birds, using both the synchrotron light source and neutron activation analysis techniques at the Australian Synchrotron and OPAL, researchers discovered a regular pattern or pulse of growth in the feather as part of normal development.

They also noticed that trace elements usually found in plastic seemed to be transferred from the stomachs of birds that had eaten plastic into their feathers. The research is ongoing, led by Dr Jennifer Lavers, and includes the measurement of other markers of individual bird and population health.
 
  

Further research

 
ANSTO's work forms part of a greater discussion on the issue of marine debris plaguing the world's oceans. Complementary research by a number organisations is also helping to draw a clearer picture on the extent of the problem to help better inform decision makers on finding solutions.
 
Researchers from Australia’s UNSW, using ocean modelling techniques, have been helping redraw ocean boundaries according to science to show the true catchment areas of the garbage patches and which countries have contributed most to the marine plastics problem.
 
Likewise, scientists at the CSIRO, working with citizen scientists and community groups, have visited more than 170 sites around Australia to map out where - and how - marine debris accumulates along Australian coastlines. Their surveys have been helping to identify and understand the threat marine debris poses to our wildlife and ecosystems.