From: Science and Technology, Tuesday, September 27, 2022
On Thursday, September
22, scientists at the University of California San Diego reported in
the journal Science of the Total Environment that a type of
polyurethane already used in biodegradable land-based products can also break
down when immersed in seawater. This polyurethane is already used as a
substitute for plastic in foams and shoes.
The research team
performed their experiments at the Ellen Browning Scripps Memorial Pier and
Experimental Aquarium. They cut the polyurethane into cubes similar in size and
shape to those naturally formed by EVA plastics. They wrote that several types
of marine bacteria and fungi stick to the polyurethane and break it down to its
component chemicals, which they then consume for food. The polyurethane
microbes had already made detectable progress when the scientists checked the
samples after four weeks in the water.
"Improper disposal
of plastic in the ocean breaks down into microplastics and has become an
enormous environmental problem," said study co-author Stephen Mayfield,
director of the California Center for Algae Biotechnology. "We've shown
that it's absolutely possible to make high performance plastic products that
also can degrade in the ocean."
Humans deposit roughly
8 billion kg of plastic in the ocean each year, where it can be mistaken for
food by marine organisms. Natural forces break the plastic into the small
pieces that we call microplastic, while larger chunks form near-islands, such
as the Great Pacific Garbage Patch [see below]. By mass, about half the patch is commercial
fishing waste, such as discarded nets, but reducing the amount of post-consumer
plastic in the ocean would still make a considerable dent in the planet's
plastic problem.
This type of
polyurethane can be used to make flip-flops and parts of other shoes,
which make up a large portion of the world's plastic waste.
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Great Pacific Garbage Patch
From Wikipedia
The Great
Pacific garbage patch (also Pacific trash vortex and North
Pacific Garbage Patch[1])
is a garbage patch, a gyre of marine debris particles,
in the central North Pacific Ocean. It is located roughly from 135°W to 155°W and 35°N to 42°N.
The collection of plastic and floating
trash originates from the Pacific Rim, including countries in Asia, North
America, and South America. The
gyre is divided into two areas, the "Eastern Garbage Patch"
from California to Hawaii, and the "Western Garbage
Patch" extending from Hawaii to Japan. Despite the common public
perception of the patch existing as giant islands of floating garbage, its low
density (4 particles per cubic metre (3.1/cu yd)) prevents detection
by satellite imagery, or even by casual boaters or divers in the area.
This is because the patch is a widely dispersed area consisting primarily of
suspended "fingernail-sized or smaller"—often microscopic—particles
in the upper water column known as microplastics. Researchers from The Ocean Cleanup project
claimed that the patch covers 1.6 million square kilometres
(620 thousand square miles) consisting of 45–129 thousand metric
tons (50–142 thousand short tons) of plastic as of 2018. Some of the plastic in the patch is over 50
years old, and includes items (and fragments of items) such as "plastic
lighters, toothbrushes, water bottles, pens, baby bottles, cell phones, plastic
bags, and nurdles." The small fibers of wood pulp found throughout
the patch are "believed to originate from the thousands of tons of toilet
paper flushed into the oceans daily."
Research indicates that
the patch is rapidly accumulating. The
patch is believed to have increased "10-fold each decade" since 1945. Estimated to be double the size of Texas,
the area contains more than 3 million short tons (2.7 million metric
tons) of plastic. The gyre contains
approximately six pounds of plastic for every pound of plankton. A similar patch of floating plastic debris is
found in the Atlantic Ocean, called the North Atlantic garbage patch. This growing patch contributes to other
environmental damage to marine ecosystems and species.
The patch was described
in a 1988 paper published by the National Oceanic and Atmospheric
Administration (NOAA). The description was based on research by several Alaska-based
researchers in 1988 who measured neustonic plastic in the North Pacific
Ocean. Researchers found relatively high
concentrations of marine debris accumulating in regions governed by ocean
currents. Extrapolating from findings in the Sea of Japan, the researchers
hypothesized that similar conditions would occur in other parts of the Pacific
where prevailing currents were favorable to the creation of relatively stable
waters. They specifically indicated the North Pacific Gyre.
Charles J. Moore,
returning home through the North Pacific Gyre after competing in the Transpacific
Yacht Race in 1997, claimed to have come upon an enormous stretch of floating
debris. Moore alerted the oceanographer Curtis Ebbesmeyer, who
subsequently dubbed the region the "Eastern Garbage Patch" (EGP). The area is frequently featured in media
reports as an exceptional example of marine pollution.
The JUNK Raft
Project was a 2008 trans-Pacific sailing voyage made to highlight the plastic
in the patch, organized by the Algalita Marine Research Foundation.
In 2009, two project
vessels from Project Kaisei/Ocean Voyages Institute; the New
Horizon and the Kaisei, embarked on a voyage to research the
patch and determine the feasibility of commercial scale collection and
recycling. The Scripps Institute of
Oceanography's 2009 SEAPLEX expedition in part funded by Ocean Voyages
Institute/Project Kaisei also researched the patch. Researchers were also
looking at the impact of plastic on mesopelagic fish, such as lanternfish.
In 2010, Ocean Voyages
Institute conducted a 30-day expedition in the gyre which continued the science
from the 2009 expeditions and tested prototype cleanup devices.
in July/August 2012
Ocean Voyages Institute conducted a voyage from San Francisco to the Eastern
limits of the North Pacific Gyre north, (ultimately ending in Richmond British
Columbia) and then made a return voyage which also visited the Gyre. The focus
on this expedition was surveying the extent of tsunami debris from the Japanese
earthquake-tsunami.
https://en.wikipedia.org/wiki/Great_Pacific_garbage_patch
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