It takes a global village to track plastic waste

During a winter storm in January 2014, a container ship spilled thousands of inkjet printer cartridges into the North Atlantic Ocean about 1500 km east of New York. By September of that year, they started washing up on the shores of the Azores archipelago, 1400 km west of Portugal.

The cartridges were linked to the spill because each one is stamped with a product code and use-by date. With that information, a Facebook group that swelled to 55 000 members started collecting data toward the end of 2015 on where and when the cartridges were found.

Using the social-media data and an empirical ocean model, Andrew Turner , Tracey Williams, and Tom Pitchford from the University of Plymouth in the UK have now tracked the spread of the plastic waste across the Atlantic. They found that the cartridges traveled as far as Florida and northern Norway and washed ashore predominantly on south- and west-facing coasts, as shown on the map.

When cartridges are filled with ink or damaged enough to allow seawater to leak inside, their densities are approximately the same as neutrally buoyant particles. So the researchers used Plastic Adrift, an empirically based drift model, to identify the trajectory of the lost cartridges. The locations pinpointed in the simulations agreed, more or less, with the observations, but Turner and his colleagues did identify some outliers. For example, a cartridge found on a Florida beach preceded the simulated arrival time by three years; and another one found at Cape Verde 35 months after the spill never showed up in the model.

The researchers suspect the discrepancies result from the model’s inadequate representation of the effects of wind resistance and nonlinear Stokes drift. Individual fluid parcels slowly drift in the same direction as the larger fluid flow, and the distance that they move is measured as the difference in a parcel’s position after some amount of time.

Inkjet cartridges are obviously not designed to be outside, and it’s uncertain how harmful the spill may be for the health of humans, other animals, and the environment. Exposure to UV light and other weathering embrittled many cartridges, which contributed microplastics to local marine environments. More worrisome is the bromine on the cartridges: It’s used in flame retardants and was identified by x-ray fluorescence analysis. Certain brominated flame retardants contain chemical constituents that have been shown to cause hormone malfunctions and other health concerns in humans. (A. Turner, T. Williams, T. Pitchford, Environ. Pollut. 284, 117131, 2021 .)