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Plastic Waste
Around 100 million tonnes of plastic are produced each year. 10 percent ends up in the sea.
About 20 % of this is from ships and platforms, 80% from land.
The North Pacific sub-tropical gyre covers a large area of the Pacific, including several island
beaches, in which the water circulates clockwise in a slow spiral.
Winds are light so the currents tend to force any floating material into the low energy
central area of the gyre in astounding quantities, covering an area larger than Texas. This
gyre has also been dubbed the “Asian Trash Trail” the “Trash Vortex” or the “Eastern
Garbage Patch”.
Not all plastic floats, around 70 percent of discarded plastic sinks to the bottom. In the
North Sea, Dutch scientists have counted around 110 pieces of litter for every square
kilometre of the seabed, a staggering 600,000 tonnes in the North Sea alone.
(www.greenpeace.org/international/campaigns/oceans/pollution/trash-vortex)
Top 20 litter Items found during MCS UK Beachwatch 2007 surveys
(Plastic makes up 81% of all litter found on beaches)
Small plastic pieces have been the number one item found in MCS Beachwatch surveys
consecutively since 1998. Plastics consistently account for over 50% of all litter recorded.
Plastics persist in the environment, and never fully disappear. Instead they turn into tiny
pieces as plastic photodegrades rather than biodegrading
www.adoptabeach.org.uk/pages/page.php?cust_id=10
Like other areas of concentrated marine debris in the world's oceans, the Eastern Garbage
Patch has formed gradually over the last decades as a result of higher levels of marine
pollution and the action of prevailing oceanic currents.
The garbage patch occupies a large and relatively stationary region of the North Pacific
Ocean bound by the North Pacific Gyre.
The rotational pattern described by the North Pacific Gyre draws in waste material from the
extremities of the North Pacific Ocean, including the coastal waters off North America and
Japan. As material circulates in the current, wind-driven surface currents gradually move
floating debris toward the centre.
This action has produced unusually high levels of marine debris in the area.
The size of the affected region is unknown, but estimates range from 700,000 km 2 to more
than 15 million km2, (0.41% to 8.1% of the Pacific Ocean).
Sources of pollutants
Charles Moore estimates that 80% of the garbage comes from land-based sources, and
20% from ships at sea. He says that currents carry debris from the east coast of Asia to the
center of the gyre in a year or less, and debris from the west coast of North America in
about five years.
Plastic photodegradation in the ocean
The Eastern Garbage Patch has one of, if not the highest level of plastic particulate
suspended in the upper water column. As a result, it is one of several oceanic regions where
researchers have studied the effects and impact of plastic photodegradation in the neustonic
layer. Unlike debris which biodegrades, the photodegraded plastic disintegrates into ever
smaller pieces while remaining polymers, even down to the molecular level.
As the plastic flotsam photodegrades into smaller and smaller pieces, it concentrates in the
upper water column. As it disintegrates, the plastic ultimately becomes small enough to be
ingested by aquatic organisms which reside near the ocean's surface. Plastic waste thus
enters the food chain through its intense concentration in the neuston.
Photodegradation
Photodegradation is degradation of a photodegradable molecule caused by the absorption
of photons, particularly those wavelengths found in sunlight, such as infrared radiation,
visible light and ultraviolet light. However, other forms of electromagnetic radiation can
cause photodegradation. Photodegradation includes photodissociation, the breakup of
molecules into smaller pieces by photons. It also includes the change of a molecule's shape
to make it irreversibly altered, such as the denaturing of proteins, and the addition of other
atoms or molecules. A common photodegradation reaction is oxidation. This type of
photodegradation is used by some drinking water and wastewater facilities to destroy
pollutants. Photodegradation in the environment is part of the process by which ambergris
evolves from its fatty precursor.
Photo degradation also destoys paintings and other artifacts
Biodegradation is the process by which organic substances are broken down by the
enzymes produced by living organisms. The term is often used in relation to ecology, waste
management and environmental remediation (bioremediation). Organic material can be
degraded aerobically, with oxygen, or anaerobically, without oxygen. A term related to
biodegradation is biomineralisation, in which organic matter is converted into minerals.
Biosurfactant, an extracellular surfactant secreted by microorganism enhances the
biodegradation process.
Biodegradation
Biodegradable matter is generally organic material such as plant and animal matter and
other substances originating from living organisms, or artificial materials that are similar
enough to plant and animal matter to be put to use by microorganisms. Some
microorganisms have the astonishing, naturally occurring, microbial catabolic diversity to
degrade, transform or accumulate a huge range of compounds including hydrocarbons (e.g.
oil), polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), pharmaceutical
substances, radionuclides and metals. Major methodological breakthroughs in microbial
biodegradation have enabled detailed genomic, metagenomic, proteomic, bioinformatic and
other high-throughput analyses of environmentally relevant microorganisms providing
unprecedented insights into key biodegradative pathways and the ability of microorganisms
to adapt to changing environmental conditions
(adapted from Wikipedia)