Microplastics are all around. Here’s how

    Microplastics are everywhere, but how they move through, and accumulate in, the environment is not completely clear.

    Microplastic particles, seen here in green, travel long distances in soil, but take a few breaks. Credit: Princeton University / Datta Lab

    It’s been assumed that when minute particles travelling through porous materials such as soil and sediment get stuck, they tend to stay there. New research by Princeton University, US, suggests otherwise, however.

    In a paper in the journal Science Advances, Sujit Datta and colleagues report that when the rate of fluid flowing through the media remains high enough, the particles can break free again, often moving substantially further.

    They found that the process of deposition and erosion is cyclical: clogs form then are broken up by fluid pressure over time and distance, moving particles further through the pore space until clogs reform.

    Knowing this will, they hope, help researchers understand how to deploy engineered nanoparticles to remediate contaminated groundwater aquifers.

    In their study they tested two types of particles – accurately named “sticky” and “non-sticky” – and were surprised to find no difference in the clogging and unclogging process itself. What was different was where the clusters formed.

    The non-sticky particles tended to get stuck only at narrow passageways, whereas the sticky ones seemed able to get trapped at any surface of the solid medium they encountered.

    As a result of these dynamics, the researchers say, it is now clear that even “sticky” particles can spread out over large areas and throughout hundreds of pores.

    Porous media are usually opaque, so researchers have only been able to measure what goes in and what comes out, then infer what happened inside. To overcome this, Datta’s team developed a transparent media that closely mimics the structure of soils and sediments, then pumped fluorescent polystyrene microparticles through it.

    And the findings might just be the tip of the iceberg, he says. The goal is to use these observations to improve parameters for larger-scale models to predict the amount and location of contamination.

    Beyond that, the principle could yield insight into how clays, minerals, grains, quartz, viruses, microbes and other particles move in media with complex surface chemistries.

    “Now that we found something so surprising in a system so simple, we’re excited to see what the implications are for more complex systems,” he says.

    Read science facts, not fiction…

    There’s never been a more important time to explain the facts, cherish evidence-based knowledge and to showcase the latest scientific, technological and engineering breakthroughs. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science. Financial contributions, however big or small, help us provide access to trusted science information at a time when the world needs it most. Please support us by making a donation or purchasing a subscription today.

    Latest articles

    Physicists could do the ‘impossible’: Create and destroy magnetic fields from afar

    Home News (Image: © Shutterstock) Scientists have figured out a way to create and cancel magnetic fields from afar. The method involves running electric current through a special...

    Is belief in God a delusion?

    Home News (Image: © Shutterstock) As the pandemic raged in April, churchgoers in Ohio defied warnings not to congregate. Some argued that their religion conferred them...

    Faint ‘super-planet’ discovered by radio telescope for the 1st time

    Home News An artist's impression of the new brown dwarf BDR J1750+3809, or "Elegast." This faint, cold celestial body was detected using radio telescope observations...

    Hubble captures a black hole’s ‘shadow beams,’ yawning across space

    Home News A ring of dusty material surrounding this black hole may be casting its shadow into space, astronomers say. (Image: © NASA, ESA, STScI and...

    Related articles