A University of New England PhD candidate has developed a method of extracting microplastics from agricultural soils which could be applied around the world
More than 92 per cent of microplastics have been extracted from agricultural soils using a new method, which has prioritised both speed and cost during its development.
Nivetha Sivarajah, a PhD candidate at University of New England (UNE), has led a research team in developing a new multi-criteria framework to identify the most effective method of extracting six common plastic types from different soil textures.
Factors such as extraction time, cost, recovery, environmental impact and spectral integrity were all integrated into the approach, with the end result being described as affordable and accessible.
“We don’t currently have a standard method for this, so once this process has been adopted, it can be used to better understand the true extent of microplastics pollution in agricultural soil,” Sivarajah says.
“It was important to consider cost in our method, as the cheaper it is, the more likely it will be adopted, which is an especially important consideration in low-socioeconomic regions of the world.”
Mulching films, biosolids, sewage sludge, shade nets and waste all degrade over time, forming microplastics that can extensively contaminate agricultural soils.
Negative impacts of this can includes threats to food security, soil health, crop yields and contamination of groundwater.
“This has significant environmental impact and can transfer through the food chain and threaten human health,” Sivarajah says.
The optimised extraction method developed by Sivarajah and the UNE team uses a sequence of organic matter digestion followed by density separation and has achieved a recovery of more than 92 per cent.
It uses reagents with a low environmental impact and costs approximately $5.47 per sample.
Having provided a foundation for scientists to develop global standards, Sivarajah is already looking to the next phase of her research.
Her method is being applied to soil samples collected in Sri Lanka to study the abundance of microplastics in that country’s paddy fields, while she will also study how microplastics migrate through different soil layers, particularly in areas using municipal solid waste compost.
“I am excited to continue working in the UNE Pollution Science Research Group and to put this method to the test in the real world and contribute to groundbreaking research that is protecting human health, food security, and the planet,” she says.
