科学美国人60秒:Sea Garbage Shows Ocean Boundaries

At some point, we all had to memorize the names of Earth’s oceans. But in reality all this water is connected. So how do we know where one body begins and another ends? Just follow the trash—because the location of seafaring garbage can be used to define the oceans’ borders. That’s according to a study in the journal Chaos. [Gary Froyland, Robyn M. Stuart and Erik van Sebille, How well-connected is the surface of the global ocean?]
 
Historically speaking, the planet’s waters have been partitioned into discrete oceans for reasons that are geographical, historical, even cultural. To approach the problem from a more anatomical perspective, researchers came up with a model of how surface waters move. Which is where the rubbish comes in. Flotillas of flotsam are formed by currents that gather the garbage in large floating patches. But the currents also create barriers that minimize mixing between different ocean regions.
 
By modeling these currents, researchers have redefined the borders of the ocean basins based on how readily their waters mix. They find, for example, that a sliver of the Indian Ocean is really part of the south Pacific.
 
The work should help track ocean debris or even the spread of spilled oil. And it could change the way we see our seas.
 
—Karen Hopkin