Current Techniques for Sampling Microplastics

 A neuston net being dragged through the water for microplastics in the Sargasso Sea. Photo credit  www.sea.edu

A neuston net being dragged through the water for microplastics in the Sargasso Sea. Photo credit www.sea.edu

 Ethan Edson recovering a neuston net after a tow for microplastics in the Sargasso Sea

Ethan Edson recovering a neuston net after a tow for microplastics in the Sargasso Sea

In order to determine the concentration of plastic in the ocean, scientists use a neuston net (pictured above) to sieve through the surface layer and collect particles.  The net is towed behind a boat at a very low speed for a given amount of time, and the resulting catch is analyzed. The net has a cod end which collects any particles that enter the net during the tow.  After the net is brought up on deck, it is washed down and the contents of the cod end are transferred to a sieve, where scientists manually separate out organic debris, plastic particles, and marine organisms.  From there, plastic particles are separated into well plates and sealed up to come back to land for analysis.  

Back on land, scientists measure each individual plastic particle size and use infrared or raman spectroscopy to determine the type of plastic that it is.  This is an incredibly time consuming process that takes careful precision and care for the small and sometimes brittle plastic particles.  Given the amount of time, energy, and money that is required to study the concentration of microplastics worldwide, we have a very poor understanding of the problem.  The MantaRay Microplastic Sampler can help to fill in data gaps that currently exist, and give scientists the data that they need to make informed conclusions about the fate and transport of microplastics all over the world.