New research from the Karlsruhe Institute of Technology (KIT), in conjunction with partners from Austria and the Netherlands, has highlighted an unseen issue with plastic pollution: The researchers have found that the amount of plastic pollution may be under-reported, and we are suffering from multiple blind spots regarding the amount of plastic in our waterways.

The researchers suspect the amount of plastic in the world’s rivers (a key source of getting plastic to the oceans) may be up to 90% higher than we currently think. This is because current methods of calculating plastic pollution rely on surface observation. However, a large amount of plastic may be invisible since it sinks a little and is suspended in the water column.

According to the study lead author Dr. Daniel Valero from the Institute of Water and River Basin Management at KIT:

“As soon as plastic enters a river, it is transported rapidly and can spread throughout the environment…But, depending on its size and material, plastic can behave very differently in the process. It can sink, be suspended in the water, remain afloat or be stopped by obstacles…This is the only way to effectively monitor large rivers from bridges. However, what happens under the water surface has not been sufficiently verified so far.”

Dr. Valero added:

“The bias is significant. If the turbulent character of the transport of plastic particles under the water surface is not considered, then the amount of plastic waste in rivers can be underestimated by up to 90 percent… If you can estimate where the most plastic is, then you also know where a clean-up is most effective.”

For further information see the original study in Water Research here.