Biodegradation of cotton-polyester textiles to understand fate of natural and synthetic microfibres in soil

Microplastics are ubiquitous and have been detected across all environments. While the focus has been on pollution threats posed by plastic particles e.g. derived from fragmented plastic packaging or tyres – the dominant form of microplastic particles identified in environmental samples tends to be microfibres, shed from textiles. Microfibres are believed to enter the environment mainly via laundering of garments, with soil environments forming an important sink for microfibres due to sewage sludge applications from wastewater treatment plants. There is growing awareness that these microfibres are not only synthetic (plastic) but also originate from natural textiles, such as cotton and wool, which have been largely overlooked from an environmental science perspective. With 100 billion new garments made every year, we know little about the environmental impact during ‘wear-and-use’ and at the ‘end-of-life’ of textile microfibres. Therefore, we need to understand the release of microfibres from natural and synthetic fibres from across the garment life-cycle (from manufacture to end-of-life).  We set up an incubation study burying 5 x 5 cm sections of different fabrics in soil, along a gradient of cotton-polyester blends to determine textile biodegradation, microfibre fragmentation and impacts to soil properties. We selected fabrics with contrasting plain dyes (light vs dark colours) to test whether dye quality affected biodegradation rates. Over the course of the short-term incubation, fabric and soil samples were retrieved and analysed for various properties to track changes in fabric samples, microfibres and soils. Here we present some data from the experiment to begin to understand how natural and synthetic fibres biodegrade in soil and their impact on soil properties and soil health.