Marine debris, also known as marine litter, is human-created waste that has
deliberately or accidentally been released in a lake, sea, ocean or
waterway. Floating oceanic debris tends to accumulate at the centre of gyres and
on coastlines, frequently washing aground, when it is known as beach
litter or tidewrack. Deliberate disposal of wastes at sea is called ocean
dumping. Naturally occurring debris, such as driftwood, are also present.
With the increasing use of plastic, human influence has become an issue as
many types of plastics do not biodegrade. Waterborne plastic poses a
serious threat to fish, seabirds, marine reptiles, and marine mammals, as well as
to boats and coasts. Dumping, container spillages, litter washed into storm
drains and waterways and wind-blown landfill waste all contribute to this
problem. Types of debris
Researchers classify debris as either land- or ocean-based; in 1991, the
United Nations Joint Group of Experts on the Scientific Aspects of Marine
Pollution estimated that up to 80% of the pollution was land-based. A wide
variety of anthropogenic artifacts can become marine debris; plastic bags,
balloons, buoys, rope, medical waste, glass bottles and plastic bottles,
cigarette lighters, beverage cans, polystyrene, lost fishing line and nets,
and various wastes from cruise ships and oil rigs are among the items commonly
found to have washed ashore. Six pack rings, in particular, are considered
emblematic of the problem. The US military used ocean dumping for
unused weapons and bombs, including ordinary bombs, UXO, landmines and
chemical weapons from at least 1919 until 1970. Millions of pounds of
ordnance were disposed of in the Gulf of Mexico and off the coasts of at least 16
states, from New Jersey to Hawaii. Eighty percent of marine debris is
plastic. Plastics accumulate because they typically do not biodegrade as many
other substances do. They photodegrade on exposure to sunlight, although they
do so only under dry conditions, as water inhibits photolysis. In a 2014
study using computers models, scientists from the group 5 Gyres, estimate 5.25
trillion pieces of plastic weighing 269,000 tons dispersed in oceans in
similar amount in the Northern and Southern Hemispheres, and one-hundredth
of them in particles in the scale of a sand-size.
= Ghost nets= Fishing nets left or lost in the ocean
by fishermen – ghost nets – can entangle fish, dolphins, sea turtles, sharks,
dugongs, crocodiles, seabirds, crabs and other creatures. These nets restrict
movement, causing starvation, laceration and infection, and, in animals that
breathe air, suffocation. = Nurdles and plastic bags=
Nurdles, also known as "mermaids' tears", are plastic pellets, typically
under five millimetres in diameter, that are a major component of marine debris.
They are a raw material in plastics manufacturing, and enter the natural
environment when spilled. Weathering produces ever smaller pieces. Nurdles
strongly resemble fish eggs. = Plastic=
8.8 million metric tons of plastic waste are dumped in the world's oceans each
year. Asia was the leading source of mismanaged plastic waste, with China
alone accounting for 2.4 million metric tons.
Plastic waste has reached all the world's oceans. This plastic pollution
harms an estimated 100,000 sea turtles and marine mammals and 1,000,000 sea
creatures each year. Pelagic plastic pieces in the center of our ocean’s
gyres outnumber live marine plankton, and are passed up the food chain to
reach all marine life. Plastic shopping bags can clog digestive tracts when
consumed and can cause starvation through restricting the movement of
food, or by filling the stomach and tricking the animal into thinking it is
full. A 1994 study of the seabed using trawl nets in the North-Western
Mediterranean around the coasts of Spain, France and Italy reported mean
concentrations of debris of 1,935 items per square kilometre. Plastic debris
accounted for 77%, of which 93% was plastic bags.
= Deep-sea debris= Litter, made from diverse materials that
are denser than surface water, have been found to spread over the floor of seas
and open oceans, where it can become entangled in corals and interfere with
other sea-floor life, or even become buried under sediment, making clean-up
extremely difficult, especially due to the wide area of its dispersal compared
to shipwrecks. Research performed by MBARI found items including plastic bags
below 2000m depth off the west coast of North America and around Hawaii.
Sources of debris An estimated 10,000 containers at sea
each year are lost by container ships, usually during storms. One famous
spillage occurred in the Pacific Ocean in 1992, when thousands of rubber ducks
and other toys went overboard during a storm. The toys have since been found
all over the world, providing a better understanding of ocean currents. Similar
incidents have happened before, such as when Hansa Carrier dropped 21
containers. In 2007, MSC Napoli beached in the English Channel, dropping
hundreds of containers, most of which washed up on the Jurassic Coast, a World
Heritage Site. In Halifax Harbour, Nova Scotia, 52% of
items were generated by recreational use of an urban park, 14% from sewage
disposal and only 7% from shipping and fishing activities. Around four fifths
of oceanic debris is from rubbish blown onto the water from landfills, and urban
runoff. In the 1987 Syringe Tide, medical waste washed ashore in New
Jersey after having been blown from Fresh Kills Landfill. On the remote
sub-Antarctic island of South Georgia, fishing-related debris, approximately
80% plastics, are responsible for the entanglement of large numbers of
Antarctic fur seals. Marine litter is even found on the floor
of the Arctic ocean. Great Pacific Garbage Patch
Once waterborne, debris becomes mobile. Flotsam can be blown by the wind, or
follow the flow of ocean currents, often ending up in the middle of oceanic gyres
where currents are weakest. The Great Pacific Garbage Patch is one such
example of this, comprising a vast region of the North Pacific Ocean rich
with anthropogenic wastes. Estimated to be double the size of Texas, the area
contains more than 3 million tons of plastic. The gyre contains approximately
six pounds of plastic for every pound of plankton. The oceans may contain as much
as one hundred million tons of plastic. Islands situated within gyres frequently
have coastlines flooded by waste that washes ashore; prime examples are Midway
and Hawaii. Clean-up teams around the world patrol beaches to attack this
environmental threat. Environmental impact
Many animals that live on or in the sea consume flotsam by mistake, as it often
looks similar to their natural prey. Bulky plastic debris may become
permanently lodged in the digestive tracts of these animals, blocking the
passage of food and causing death through starvation or infection. Tiny
floating plastic particles also resemble zooplankton, which can lead filter
feeders to consume them and cause them to enter the ocean food chain. In
samples taken from the North Pacific Gyre in 1999 by the Algalita Marine
Research Foundation, the mass of plastic exceeded that of zooplankton by a factor
of six. Toxic additives used in plastic
manufacturing can leach into their surroundings when exposed to water.
Waterborne hydrophobic pollutants collect and magnify on the surface of
plastic debris, thus making plastic more deadly in the ocean than it would be on
land. Hydrophobic contaminants bioaccumulate in fatty tissues,
biomagnifying up the food chain and pressuring apex predators and humans.
Some plastic additives disrupt the endocrine system when consumed; others
can suppress the immune system or decrease reproductive rates.
The hydrophobic nature of plastic surfaces stimulates rapid formation of
biofilms, which support a wide range of metabolic activities, and drive
succession of other micro- and macro-organisms.
Concern among experts has grown since the 2000s that some organisms have
adapted to live on floating plastic debris, allowing them to disperse with
ocean currents and thus potentially become invasive species in distant
ecosystems. Research in 2014 in the waters around Australia confirmed a
wealth of such colonists, even on tiny flakes, and also found thriving ocean
bacteria eating into the plastic to form pits and grooves. These researchers
showed that "plastic biodegradation is occurring at the sea surface" through
the action of bacteria, and noted that this is congruent with a new body of
research on such bacteria. Their finding is also congruent with the other major
research undertaken in 2014, which sought to answer the riddle of the
overall lack of build up of floating plastic in the oceans, despite ongoing
high levels of dumping. Plastics were found as microfibres in core samples
drilled from sediments at the bottom of the deep ocean. The cause of such
widespread deep sea deposition has yet to be determined.
Not all anthropogenic artifacts placed in the oceans are harmful. Iron and
concrete structures typically do little damage to the environment because they
generally sink to the bottom and become immobile, and at shallow depths they can
even provide scaffolding for artificial reefs. Ships and subway cars have been
deliberately sunk for that purpose. Debris removal
Techniques for collecting and removing marine debris include the use of debris
skimmer boats. Devices such as these can be used where floating debris presents a
danger to navigation. For example, the US Army Corps of Engineers removes 90
tons of "drifting material" from San Francisco Bay every month. The Corps has
been doing this work since 1942, when a seaplane carrying Admiral Chester W.
Nimitz collided with a piece of floating debris and sank, costing the life of its
pilot. Once debris becomes "beach litter", collection by hand and
specialized beach-cleaning machines are used to gather the debris.
Elsewhere, "trash traps" are installed on small rivers to capture waterborne
debris before it reaches the sea. For example, South Australia's Adelaide
operates a number of such traps, known as "trash racks" or "gross pollutant
traps" on the Torrens River, which flows into Gulf St Vincent.
In lakes or near the coast, manual removal can also be used. Project AWARE
for example promotes the idea of letting dive clubs clean up litter, for example
as a diving exercise. On the sea, the removal of artificial
debris is still in its infancy. However some projects have been started which
used ships with nets to catch some plastics, primarily for research
purposes. Another method to gather artificial litter has been proposed by
Boyan Slat. He suggested using platforms with arms to gather the debris, situated
inside the current of gyres. = Plastic-to-fuel conversion strategy=
The Clean Oceans Project promotes conversion of the plastic waste into
valuable liquid fuels, including gasoline, diesel and kerosene, using
plastic-to-fuel conversion technology developed by Blest Co. Ltd., a Japanese
environmental engineering company. TCOP plans to educate local communities and
create a financial incentive for them to recycle plastic, keep their shorelines
clean, and minimize plastic waste. Laws and treaties
Ocean dumping is controlled by international law, including:
The London Convention – a United Nations agreement to control ocean dumping
MARPOL 73/78 – a convention designed to minimize pollution of the seas,
including dumping, oil and exhaust pollution
= European law= In 1972 and 1974, conventions were held
in Oslo and Paris respectively, and resulted in the passing of the OSPAR
Convention, an international treaty controlling marine pollution in the
north-east Atlantic Ocean. The Barcelona Convention protects the Mediterranean
Sea. The Water Framework Directive of 2000 is a European Union directive
committing EU member states to free inland and coastal waters from human
influence. In the United Kingdom, the Marine and Coastal Access Act 2009 is
designed to "ensure clean healthy, safe, productive and biologically diverse
oceans and seas, by putting in place better systems for delivering
sustainable development of marine and coastal environment".
= United States law= In 1972, the United States Congress
passed the Ocean Dumping Act, giving the Environmental Protection Agency power to
monitor and regulate the dumping of sewage sludge, industrial waste,
radioactive waste and biohazardous materials into the nation's territorial
waters. The Act was amended sixteen years later to include medical wastes.
It is illegal to dispose of any plastic in US waters.
= Ownership= Property law, admiralty law and the law
of the sea may be of relevance when lost, mislaid, and abandoned property is
found at sea. Salvage law rewards salvors for risking life and property to
rescue the property of another from peril. On land the distinction between
deliberate and accidental loss led to the concept of a "treasure trove". In
the United Kingdom, shipwrecked goods should be reported to a Receiver of
Wreck, and if identifiable, they should be returned to their rightful owner.
Activism A large number of groups and individuals
are active in preventing or educating about marine debris. For example, 5
Gyres is an organization aimed at reducing plastics pollution in the
oceans, and was one of two organizations that recently researched the Great
Pacific Garbage Patch. Heal the Bay is another organization, focusing on
protecting California's Santa Monica Bay, by sponsoring beach cleanup
programs along with other activities. Marina DeBris is an artist focusing most
of her recent work on educating people about beach trash. Interactive sites
like Adrift demonstrate where marine plastic is carried, over time, on the
worlds ocean currents. On April 11, 2013 in order to create awareness, artist
Maria Cristina Finucci founded The Garbage patch state at UNESCO –Paris in
front of Director General Irina Bokova . First of a series of events under the
patronage of UNESCO and of Italian Ministry of the Environment.
See also Flotsam and jetsam
Kamilo Beach Marine pollution
Project Kaisei Plastic pollution
References External links
Media related to Marine debris at Wikimedia Commons
United Nations Environment Programme Marine Litter Publications
UNEP Year Book 2011: Emerging Issues in Our Global Environment Plastic debris,
pages 21–34. ISBN 978-92-807-3101-9. NOAA Marine Debris Program – US National
Oceanic and Atmospheric Administration Marine Debris Abatement – US
Environmental Protection Agency Marine Research, Education and
Restoration – Algalita Marine Research Foundation
[1] – UK Marine Conservation Society Harmful Marine Debris – Australian
Government The trash vortex – Greenpeace
High Seas GhostNet Survey – US National Oceanic and Atmospheric Administration
Social & Economic Costs of Marine Debris – NOAA Economics
PSA Video: "Plastics Kill" by The Surfrider Foundation's Rise Above
Plastics Program 25 years of debris collected | Visual.ly
How the oceans can clean themselves – TED Talk
Tiny Plastic Bits Too Small To See Are Destroying The Oceans, Business Insider
Ghost net remediation program - NASA, NOAA and ATI collaborating to detect
ghost nets