Microplastics, tiny shards of plastic, less than 5mm long, are invading every corner of the planet, from the snows of the arctic to the depths of the oceans. This human-made pollution is having damaging effects on the environment, but research into microplastics and their impact is at an early stage.
For Claire Gwinnett, professor of forensic and environmental science at Staffordshire University, researching the presence of microplastics and microfibres in rivers and seas has been a great chance to apply her experience in forensics to this growing environmental problem.
Gwinnett has undertaken pioneering work to improve the identification of microplastics in water samples. A problem holding back research into microplastics is that samples can easily become contaminated with particles from the environment. Contamination could come from microplastics in the air, on workbenches, from microfibres in researchers’ clothing or any number of sources.
As Gwinnett says: “Every step in the research has the potential to add other contaminants in the environment, so we don’t truly know how much was in the water to start with. Over the past decade, a lot of studies have disregarded microfibres because they are not sure if they have contaminated the samples themselves during the research process.”
This is where her background in forensic science – the analysis of crime scenes for evidence – has come to the fore. “In forensic work, we have created studies and protocols that ensure we are minimising the number of contaminants that we are adding to a sample,” she says. “I’ve been looking at microfibres for 15 years, and now I get the chance to investigate them not only from a crime scene perspective but from an environmental point of view too,” she adds.
This approach to reducing contamination in forensic samples was applied to samples drawn from the depths of the Indian and Atlantic Oceans as part of a study Staffordshire University carried out in collaboration with the University of Oxford and the Natural History Museum. An expedition brought back samples of deep-sea organisms to investigate whether they had ingested microplastics. Forensic fibre protocols used regularly for the criminal justice system to minimise contamination were trialled on board the ship and also in the laboratories where the samples were analysed.
These steps include measuring the presence of microfibres in the atmosphere before the sample is analysed, thoroughly scrubbing and cleaning environments where the samples are exposed to the air and applying filters to water sources to measure the presence of microplastics. This process allows confidence in the reduction of contamination and the ability to be able to monitor and identify potential sources of contaminants by taking comprehensive controls.
The research project proved the presence of microplastics in deep-sea creatures including sea cucumbers, lobsters and crabs taken from depths of 800m to 1,700m. This was the first reliable evidence that microplastics and microfibres had reached even deep-sea creatures, as the methodology Gwinnett used ruled out contamination from other sources.
Gwinnett’s team also are pioneers in applying analytical techniques and observations used in forensic fibre analysis to microplastic samples. Staffordshire University uses protocols that incorporates multiple analytical techniques, starting with a method called polarised light microscopy. This is a common first step in forensic work but uncommon in microplastic research. This technique allows not only the material to be identified, but also extra features such as its cross-sectional shape and whether anything has been added to the fibre such as delustrant. This helps to show the range of different microfibres that might be present in water samples.
Gwinnett’s department has also made use of a patented particle-gathering tape developed for the forensic industry, applying it now to samples filtered from water.
In a recent expedition – funded by the National Geographic and part of the Rozalia Project in the US – to analyse microplastics along the Hudson river, which runs for more than 300 miles, Gwinnett was chief science officer. The expedition aimed to create a “4D heatmap” of microplastics in the air, water and soil along the river. Samples were taken every three miles and analysed for microplastics. The tape allowed better retrieval of the microplastics by ensuring none were missed and also sped up the recovery time, allowing a greater resolution of sampling.
Staffordshire University’s criminal justice and forensic science department is currently creating an automated system that will allow the detection, quantification and characterisation of microfibres from both crime scenes but also from environmental sources. This combines the use of machine learning and computer vision technology, which will allow huge datasets of microplastics to be produced and facilitate researchers to be able to watch out for trends in pollution.
With estimates of up to 51trn pieces of microplastics in the oceans, weighing some 236,000 metric tons, and an average of 8m tonnes of plastic entering our seas every year, urgent action is needed.
Gwinnett argues for a multi-agency approach to reducing microplastics in the oceans: “This is a problem that can only be solved by scientists, governments, the plastic industry and companies such as Coca-Cola working together,” she says.
Public pressure on the plastics industry and governments will be vital to bringing about change, so people must be educated about the science of microplastics. This will build the case for legislation. But Gwinnett warns that there are no easy solutions. “We need to make sure that when we have legislation it is not just a knee-jerk reaction, it has got to be driven by the science and the data,” she says. Staffordshire University’s research will play a key role in influencing and educating the public and politicians about the problems of microplastic pollution.
