How do scientists analyze microfibers?
Microfibers are tiny synthetic plastic fibers that shed from clothing during laundering. Ever pull out a handful of lint from your dryer? That bundle of lint is actually made up of thousands and thousands of microfibers from your clothes. Microfibers make up over 85% of shoreline debris, according to a 2011 study. But how do scientists study microfibers? Today we’re going to talk about the techniques researchers use to detect and characterize microfibers in the environment!
Where to look for microfibers. That part is easy. Microfibers have been found in nearly every environmental compartment, including soil, air, household dust, water and even snow! Depending on which compartment a researcher decides to sample will determine their sampling technique or how they plan to collect a portion of the compartment to look for fibers.
Separate fibers from natural materials and other plastics. Once a sample is collected, the researcher needs to remove the microfibers from other debris (including other plastics). Often times to remove synthetic (man-made) materials from natural materials, a density separation can be used. For example, the sample is placed in a solution of a particular density and allowed to sit overnight. After time more dense materials, like soils, metals and woody debris, sink, while materials that are less dense, like plastics, float. Manually picking out particles that appear to be plastic may also be an option, though some particles can be too small to pick up or even see with the naked eye. Once the natural material is removed, plastics can be sorted by size (using filters and sieves of different size categories) and by category. Plastics are most often categorized as fragment, fiber, film, foam, and sphere.
Determine type of fiber. What a particle is made of can tell us about it’s source and identifying sources can lead to solutions! Microfibers can be made of natural materials, including cotton and silk, or synthetic materials, including polyester and nylon. Determining chemical composition is not that easy and often requires expensive equipment. Marine debris researchers most often use spectroscopic techniques, including Raman and/or FT-IR spectroscopy, to identify a material’s chemical make-up. These techniques detect how a material interacts with light on a molecular level and generates a chemical fingerprint that can be used to identify the type of material.
Got questions? Ask me about microfiber pollution here!
Image showing microplastic and sand particles collected on a metal sieve collected from wetlands in Scotland as part of a Greenpeace research expedition. Courtesy of Greenpeace.
