The amount of microplastic debris in coastal waters may have been significantly underestimated, a new study has found.
Researchers at the Plymouth Marine Laboratory in the UK carried out a study led by scientists, with a focus on coastal waters where microplastics are thought to have the greatest influence on marine life, on both sides of the North Atlantic Ocean. They used a finer-gauge net to gain a more accurate picture of the amount of plastic in the water.
“Our results demonstrate that sampling with a smaller sized mesh yields a significantly higher concentration of microplastics compared to sampling with larger mesh sizes; a consistent result seen across a series of biologically productive coastal stations on both sides of the North Atlantic,” the study notes.
“Both our US and UK datasets reveal that sampling with a 100μm net results in the capture of ten-fold greater microplastic concentrations compared with using a 500μm net. Further, our UK sampling regime revealed a 2.5-fold increase in microplastic concentrations sampled with a 100μm mesh compared to a 333μm mesh. We believe this to be the first study directly comparing microplastics captured with different size mesh using nets towed concurrently.
The research suggests the oceans may be holding as many as 125 trillion microplastic particles, according to the study, which has been published in the journal Environmental Pollution.
Fibres were the predominant type of microplastic identified in all of the researcher’s environmental samples (84% US; 77% UK), being principally black or blue in colour.
Microplastic fibres – defined as 1–5000?μm in diameter – can stem from the breakdown of larger plastic items, such as rope, or the release of microfibres from synthetic garments during washing cycles. Abrasion from clothing is also likely to be a significant source of fibre pollution, demonstrated by high quantities observed in atmospheric fallout and run off from snow melts, the study explains.
Rayon (biopolymer), polypropylene and polyester are widely used in textiles, providing further evidence that wastewater effluent (containing microfibres from clothes washing and degradation of fishing gear) are substantial sources of microplastics in coastal waters.