Farmland across Europe is becoming the world's largest repository of microplastics due to high concentrations of microplastics in fertiliser made from sewage sludge, a new study from Cardiff University in the UK shows.
Microplastics, initially released into the environment from car tires, synthetic textiles, paints and personal care products, are not disappearing in sewage treatment plants but are reappearing in farmlands, the depths of the oceans and on the world’s tallest mountains.
710 trillion microplastic particles are dumped into European soil every year
“Our study sought to determine whether wastewater treatment plants were completely removing microplastics, or whether they were actually still transferring the contamination into the environment,” said lead author James Lofty, a postgraduate student at Cardiff University’s School of Engineering. “Water companies clearly lack strategies for managing microplastics in sewage sludge, meaning these contaminants are being transported back into the soil and ultimately into aquatic environments.”
This practice of returning microplastics to soil and water runs counter to the EU's goal of managing microplastics. On May 12, 2021, the European Commission adopted the "Action Plan for Zero Air, Water and Soil," a key outcome of the European Green Deal. The plan sets a target of reducing microplastics released into the environment by 30% by 2030.
Scientists at Cardiff University, working with researchers at the University of Manchester, estimated that 31,000 to 42,000 tonnes of microplastics - up to 710 trillion particles - are dumped back into European soils every year, mirroring concentrations in surface ocean waters.
UK soil has the highest level of contamination, with 24 microplastic particles per gram of sewage sludge.
The study, published in the journal Environmental Pollution, took samples from the Nash wastewater treatment plant in Newport, South Wales, which treats combined sewage from 300,000 people.
Their analysis showed that the treatment plant could remove 100% of large microplastic particles between 1 and 5 mm in size from the incoming sewage, preventing them from being released into the aquatic environment. However, the research team estimated that the sludge generated by the treatment plant contained up to 24 microplastic particles per gram, equivalent to 1% of the sludge weight.
Sewage sludge is commonly used as fertilizer on farms and spread across Europe, so the researchers combined this information with data from the European Commission and Eurostat to assess the impact of using sewage sludge as fertilizer across the continent.
Because the researchers did not analyze microplastics smaller than 1 mm in size, the actual overall microplastic concentration is likely much higher than their estimate.
The study found that the UK had the highest levels of soil microplastic pollution, with an increase of 500 to 1,000 microplastic particles per square meter of farmland each year, followed by Spain, Portugal and Germany.
Source: Environmental Information Center (https://e-info.org.tw/node/234240)
