Warwick team uses fluorescent dye to detect microplastics

Microplastics – classed as plastic debris smaller than 5mm – are a growing threat to the oceans and the marine life that inhabits them. As some eight million tons of plastic enters the oceans each year, it breaks down over time into tiny fragments that can be ingested by fish and other sea creatures. According to Warwick, identifying the levels of plastic pollution can be difficult, with the particles becoming invisible to the human eye as they get smaller.

To help address this issue, the team used a fluorescent dye known as Nile red which attaches itself to plastic particles. It then employed a combination of fluorescence microscopy and image analysis software in a semi-automated process that calculates the concentration of microplastics in a given sample. Examining seawater and beach sand from the English coast around Plymouth, the researchers detected a much larger amount of small microplastics (smaller than 1mm) than was previously estimated, or which could have been found using traditional methods. The work is published in the journal Environmental Science & Technology.