Plastic proliferates at the bottom of world’s deepest ocean trench

Yet again, plastic is proving to be
everywhere in the sea. During a dive to the bottom of the Mariana
Trench that purportedly reached 35,849 feet, Dallas businessman
Victor Vescovo claims to have found a plastic bag. And it’s not
even the first time: It’s the third time plastic has been
documented in the deepest explored part of the ocean.

Vescovo made his dive in a submersible on
April 28 as part of his “Five Deeps” Expedition, which involve
journeys to the deepest points in each of Earth’s oceans. During
the four hours Vescovo spent at the bottom of the Mariana Trench,
he observed several marine creatures—one of which is a potentially
new species—a plastic bag, and candy wrappers.

Few people have reached such extreme
depths. Swiss engineer Jacques Piccard and U.S. Navy Lieutenant Don
Walsh were the first in 1960. National Geographic explorer and
movie director James Cameron then made a dive to the depths in
2012. Cameron logged 35,787 feet on his dive, just shy of the 62
feet that Vescovo claims to have reached.

A study
released in October 2018^[1]
documented what is still the deepest known piece of plastic—a
flimsy shopping bag—found at a depth of 36,000 feet inside the
Mariana Trench. Scientists found it by looking through the Deep-Sea
Debris Database^[2], a collection of photos
and videos taken from 5,010 dives over the previous 30 years.

Of the classifiable debris logged in the database, plastic was
the most prevalent, and plastic bags in particular made up the
greatest source of plastic trash. Other debris came from material
like rubber, metal, wood, and cloth.

A whopping 89 percent of the plastic in the study was single
use, the type that’s used once and then thrown away, like a plastic
water bottle or disposable utensil.

The Mariana Trench is no dark, lifeless pit; it has plenty of
residents. NOAA’s Okeanos Explorer vessel searched
the region’s depths in 2016^[3]
and found diverse life-forms, including species like coral,
jellyfish, and octopus. The 2018 study also found that 17 percent
of the images of plastic logged in the database showed interactions
of some kind with marine life, like animals becoming entangled in
debris.

Single-use plastics are virtually everywhere, and they may take
hundreds of years or more to break down once in the wild. The
Mariana Trench has higher levels of overall pollution in certain
regions^[4] than some of the most
polluted rivers in China, according to a study in February 2017.
The study’s authors theorized that the chemical pollutants in the
trench may have come in part from the breakdown of plastic in the
water column.

While plastic can enter the ocean directly, such as trash blown
from a beach or discarded from ships, a study^[5]
published in 2017 found that most of it flows into the sea from 10
rivers that run through heavily populated regions.

While the ocean clearly contains much more plastic than a single
plastic bag, the item has now gone from a wind-flung metaphor for
listlessness to an example of how deep an impact humans can have on
the planet.