Are Plastics in the Oceans Being Hidden by the Winds?

Reporting in Geophysical Research Letters this month, Proskurowski and co-lead author Tobias Kukulka, University of Delaware, said that data col­lected from just the sur­face of the water com­monly under­es­ti­mates the total amount of plas­tic in the water by an aver­age fac­tor of 2.5.

In high winds the vol­ume of plas­tic could be under­es­ti­mated by a fac­tor of 27.

“That really puts a lot of error into the com­pi­la­tion of the data set,” Proskurowski said. The paper also detailed a new model that researchers and envi­ron­men­tal groups can use to col­lect more accu­rate data in the future.

Plastic waste in the oceans is a con­cern because of the impact it might have on the envi­ron­ment. For instance, when fish ingest the plas­tics, it may degrade their liver func­tions. In addi­tion, the par­ti­cles make nice homes for bac­te­ria and algae, which are then trans­ported along with the par­ti­cles into dif­fer­ent regions of the ocean where they may be inva­sive and cause problems.

Proskurowski gath­ered data on a 2010 North Atlantic expe­di­tion where he and his team col­lected sam­ples at the sur­face, plus an addi­tional three or four depths down as far as 100 feet.

“Almost every tow we did con­tained plas­tic regard­less of the depth,” he said.

By com­bin­ing the data with wind mea­sure­ments, Proskurowski and his co-authors devel­oped a sim­pli­fied math­e­mat­i­cal model that could poten­tially be used to match his­tor­i­cal weather data, col­lected by satel­lite, with pre­vi­ous sur­face sam­pling to more accu­rately esti­mate the amount of plas­tic in the oceans.

In addi­tion, armed with the new model, orga­ni­za­tions and researchers in the future might mon­i­tor wind data and com­bine it with sur­face col­lec­tions in order to bet­ter esti­mate how much plas­tic waste is in our oceans.

“By fac­tor­ing in the wind, which is fun­da­men­tally impor­tant to the phys­i­cal behav­ior, you’re increas­ing the rigor of the sci­ence and doing some­thing that has a major impact on the data,” Proskurowski said.

The team plans to pub­lish a “recipe” that sim­pli­fies the model so that a wide range of groups inves­ti­gat­ing ocean plas­tics, includ­ing those that aren’t oceanog­ra­phers, can eas­ily use the model. Following the recipe, which is avail­able now by request, might encour­age some con­sis­tency among the stud­ies, he said.

“On this topic, what sci­ence needs to be geared toward is build­ing con­fi­dence that sci­en­tists have solid num­bers and that pol­icy mak­ers aren’t mak­ing judg­ments based on CNN reports,” he said. Descriptions of the so-called great Pacific garbage patch in wide­spread news reports may have led many peo­ple to imag­ine a giant, dense island of garbage while in fact the patch is made up of widely dis­persed, millimeter-size pieces of debris, he said.

In the future, Proskurowski hopes to exam­ine addi­tional fac­tors, includ­ing the drag of the plas­tics in water, com­plex ocean tur­bu­lence and wave height, that might improve the accu­racy of the model. He also may have the chance to exam­ine the rela­tion­ship between wind speed and depth of plas­tic par­ti­cles. The 2010 expe­di­tion had near-uniform wind con­di­tions so the researchers were unable to test that relationship.

“This is a first pass,” he said.

Other co-authors of the paper are Kara Lavendar Law and Skye Morét-Ferguson, Sea Education Association, and Dylan Meyer, an under­grad­u­ate stu­dent from Eckerd College. Support for the project came from NOAA and the University of Delaware. The researchers relied on data col­lected by stu­dents par­tic­i­pat­ing in the Sea Education Association’s Plastics at SEA program.

Source: University of Washington release