, Tanzania over one month 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, with the remaining 20% originating from catastrophic events or maritime sources. More recent studies have found that more than half of plastic debris found on Korean shores is ocean-based. A wide variety of man-made objects can become marine debris;
plastic bags,
balloons,
buoys,
rope,
medical waste,
glass and
plastic bottles,
cigarette stubs,
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
U.S. military used ocean dumping for
unused weapons and bombs, including
ordinary bombs,
Unexploded ordnance (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 (although these, of course, do not wash up onshore, and
the U.S. is not the only country who has practiced this). 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 computer models, scientists from the group 5 Gyres, estimated 5.25 trillion pieces of plastic weighing 269,000 tons were dispersed in oceans in similar amount in the Northern and Southern Hemispheres.
Persistent industrial marine debris Some materials and activities used in industrial activities that do not readily degrade, that persist in the environment, and tend to accumulate over time. The activities can include fishing, boating, and aquaculture industries that harvest or use resources in the marine environment and may lose or discard gear, materials, machinery or solid wastes from industrial processes into the water or onto shorelines. This can include anything as large as a fishing boat or as small as particle from a
Styrofoam lobster float. In 2003, a study was conducted to identify types, amounts, sources, and effects of persistent industrial marine debris in the coastal waters and along the shores of
Charlotte County, New Brunswick, and examine any relationship between the amount and types of persistent industrial marine debris, and the types and numbers of industrial operations nearby. Materials like plastic or foam can break down into smaller particles and may look like small sea creatures to wildlife such as birds, cetaceans, and fish, and they may eat these particles. Indigestible material may accumulate in the gut creating blockages or a false sense of
fullness and eventually death from lack of appropriate nutrient intake.
Ghost nets Macroplastic Microplastics Deep-sea debris Marine debris is found on the floor of the Arctic ocean. Although an increasing number of studies have been focused on plastic debris accumulation on the coasts, in off-shore surface waters, and that ingested by marine organisms that live in the upper levels of the water column, there is limited information on debris in the mesopelagic and deeper layers. Studies that have been done have conducted research through bottom sampling, video observation via remotely operated vehicles (ROVs), and submersibles. They are also mostly limited to one-off projects that do not extend long enough to show significant effects of deep-sea debris over time. Research thus far has shown that debris in the deep-ocean is in fact impacted by anthropogenic activities, and plastic has been frequently observed in the deep-sea, especially in areas off-shore of heavily populated regions, such as the Mediterranean. Plastics that are usually negatively buoyant can sink with the adherence of phytoplankton and the aggregation of other organic particles. Other oceanic processes that affect circulation, such as coastal storms and offshore convection, play a part in transferring large volumes of particles and debris. Submarine topographic features can also augment downwelling currents, leading to the retention of
microplastics at certain locations. A Deep-sea Debris database by the Global Oceanographic Data Center of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), showing thirty years of photos and samples of marine debris since 1983, was made public in 2017. From the 5,010 dives in the database, using both ROVs and deep-sea submersibles, 3,425 man-made debris items were counted. The two most significant types of debris were macro-plastic, making up 33% of the debris found – 89% of which was single-use – and metal, making up 26%. Plastic debris was found at the bottom of the Mariana Trench, at a depth of 10,898m, and plastic bags were found entangled in hydrothermal vent and cold seep communities.
Garbage patches (gyres) ==Sources==