There is a lot of trash in the world's oceans—everything from stray fishing line to abandoned boats, often collected in what scientists and the media refer to as garbage patches, such as the Great Pacific garbage patch. But a new study shows that targeting such patches probably isn't the most efficient way to clean up the high seas. Instead, agencies should focus on removing plastic from China's eastern shores and just a few other select locations around the world.
Plastics in the ocean have substantial environmental and economic impacts, damaging everything from zooplankton to ocean-going ships, so it's kind of a no-brainer that the ocean needs cleaning. Intuitively, the best way to do that is to go to the place where it's most concentrated: the Great Pacific garbage patch, often depicted as a gigantic garbage dump twice the size of Texas floating somewhere between Los Angeles and Honolulu. Indeed, activists and entrepreneurs—notably, The Ocean Cleanup—have already started developing new technologies to clean up the patch and sent flotillas out to map ocean-going trash.
Collecting trash near the coast would also reduce the impact on marine life to one-third what it would be under scenarios that target garbage patches.
The problem is, the Great Pacific garbage patch isn't exactly a patch—it's more like a big vortex with unusually high concentrations of very small bits of plastic, often invisible to anyone trying to catalog it from a ship—and it's hardly the only place where there's trash. In other words, targeting spots like the Pacific patch might not work well, write Imperial College London physics student Peter Sherman and physicist Erik van Sebille. Instead, it might be more effective to stop trash at the source, or rather, at its point of entry into the ocean.
To test that hypothesis, Sherman and van Sebille ran a series of computer simulations, one in which trash collectors, or "sinks," were deployed to the Pacific garbage patch, and others where the sinks were placed closer to land. The simulations took into account ocean currents, the distribution of marine life such as phytoplankton, and the places where the trash originated from (often, East Asia).
The simulations seem to confirm Sherman and van Sebille's hypothesis. In particular, placing the bulk of 29 sinks off the eastern coast of China, along with a few others scattered around the world, would cut the total amount of plastic by 31 percent by 2025. In comparison, deploying the sinks primarily around the Great Pacific garbage patch would cut the amount by only 17 percent. Collecting trash near the coast would also reduce the impact on marine life to one-third what it would be under scenarios that target garbage patches.
While the simulations are not the final word, the authors write their findings "are an indication that oceanic plastic removal might be more effective in removing a greater microplastic mass and in reducing potential harm to marine life when closer to shore than inside the plastic accumulation zones," like the Pacific patch.
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