New study finds underestimation of microplastics in ocean—concentration far greater

A new study estimated the concentration of microplastics in the ocean to be far greater than previously determined.

“Microplastic pollution is a widespread pollutant, found all throughout the oceans, but working out how much is there has been a major challenge for scientists,” Dr. Matthew Cole, co-lead author of this study and Marine Ecologist and Ecotoxicologist at Plymouth Marine Laboratory, said.

Scientists determined that “microplastic concentrations could exceed 3,700 microplastics per cubic meter,” according to the study. And the global plastic budget is around 12.5 to 125 trillion particles as opposed to the previous estimate of 5 to 50 trillion.

“Understanding more about the smaller microplastics present in the ocean is important as it is these smaller particles that are more likely to be ingested by the small marine animals, the zooplankton, that form the basis of marine food webs,” Dr. Ceri Lewis, of the Global Systems Institute at the University of Exeter, said.

In a paper titled “Are we underestimating microplastic abundance in the marine environment? A comparison of microplastic capture with nets of different mesh-size,” published in the journal Environmental Pollution, the study used a finer 100μm (0.1mm) sampling nets as opposed to customary 333μm (0.333mm) or 500μm (0.5mm) coarser sampling nets. The study, which was led by Plymouth Marine Laboratory, including the University of Exeter, “resulted in the collection of 2.5- and 10-fold greater microplastic concentration respectively compared with the 333μm and 500μm meshes,” according to a study statement. The finer mesh collected 2.5 times more microplastics than the 333 micrometer mesh net and 10 times more that a 500 micrometer net, the study determined.

“Microplastics aren’t a uniform type of pollutant, rather they come in all different shapes, sizes and polymer types; determining how many of which types are in the natural environment is rather like looking for needles in a haystack,” Professor Pennie Lindeque, lead author of this study and Head of marine Ecology and Biodiversity at Plymouth Marine Laboratory, said.

The study’s samples came from the Atlantic Ocean—off the coast of Maine and in the English Channel, Newsweek reported. Scientists will use the new estimates of microplastic concentrations to predict the risk to marine life, biodiversity, ecosystem services and productivity. This will in turn “help inform monitoring efforts and provides a clearer benchmark to judge the effectiveness of management scenarios.” the study said.

“Our results, based on sampling in the UK and U.S., suggests we are underestimating the really small pieces of plastic in the marine environment,” Lindeque said. “Using a power law extrapolation we suggest microplastic concentrations could exceed 3700 microplastics m³, that’s far more than the number of say zooplankton you would find in a meter cubed of water.”