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One of the unexpected corollaries of the search for Malaysia Airlines flight 370 has been the increase in public awareness about the tons of garbage that litter our oceans. In the first few weeks after the March 8 disappearance of the passenger jet, searchers scoured huge swaths of the Indian Ocean, and found nothing but garbage. In the process of looking for wreckage from the plane, we received almost daily reports of possible debris from satellite images. These finds turned out to be nothing more than floating piles of trash.
The five ocean gyres
There are five massive garbage gyres, one is located in the Indian Ocean, two in the Pacific Ocean and another two in the Atlantic Ocean. Garbage gyres come together as the trash gets caught in circular ocean currents. This causes stray garbage to move until they collide and merge with one another.
University of New South Whales Researcher Erik Van Sebille has suggested there may be a sixth garbage patch forming in the Arctic Circle in the Barents Sea.
Plastic debris
These garbage gyres are made up of everything from appliances to cargo containers, but they are composed mostly of plastic including around 3.5 million tons of beverage bottles and grocery bags. Plastic constitutes 90 percent of all trash floating in the world’s oceans. The United Nations Environment Program (UNEP) estimated that in 2006, every square mile of ocean hosted 46,000 pieces of floating plastic.
Van Sebille said each of these gyres, “contains so much plastic that if you were to drag a net through these areas you would pull up more plastic than biomass.”
Plastic waste in the oceans poses a serious environmental problem. UV rays from the sun and salt from the sea water cause the plastic to break down, which releases chemicals into the water that then enter the food system according to the Scripps Institute at the University of California San Diego.
Plastic poses some unique problems for ocean ecosystems. Some plastics decompose within a year of entering the water, leaching to potentially toxic chemicals such as bisphenol A, PCBs, and derivatives of polystyrene.
Unlike organic debris, plastic does not biodegrade. The plastic in these debris fields will last for hundreds of years. Over time, plastic in the oceans disintegrates into ever smaller pieces while remaining a polymer. This process continues down to the molecular level and concentrates in the upper water column. Plastic pollution in the form of small particles (diameter less than 5 mm) is called “microplastics.”
Wildlife impacts and the food chain
According to UNEP, at least 267 species worldwide are impacted by plastic debris in the oceans. As the plastic disintegrates, it ultimately becomes small enough to be ingested by a wide range of life forms. Plastics are deadly to a number of species including marine birds and sea turtles. Various investigations including research by Charles Moore found that in some places the overall concentration of plastics was seven times greater than the concentration of zooplankton. Plastics enter the food chain when ingested by aquatic organisms and the impacts go all the way up the chain to humans.
Researchers have discovered that floating debris can also absorb organic pollutants from seawater, including PCBs, DDT, and PAHs. When consumed, plastic has both toxic effects and disruptive impacts on the endocrine system.
Source of debris
It is crudely estimated that 80 percent of the garbage comes from land-based sources and 20 percent is from ships. According to a 2011 EPA report titled, Marine Debris in the North Pacific:
“The primary source of marine debris is the improper waste disposal or management of trash and manufacturing products, including plastics (e.g., littering, illegal dumping) … Debris is generated on land at marinas, ports, rivers, harbors, docks, and storm drains. Debris is generated at sea from fishing vessels, stationary platforms and cargo ships.”Much of the land-based sources of ocean waste originates from the great rivers from around the world
Size of debris fields
According to some media reports, ocean borne garbage is up to “twice the size of the continental United States”. Although these estimates are hardly precise, they range from 700,000 square kilometres (270,000 sq mi) to more than 15,000,000 square kilometres (5,800,000 sq mi).
Investigations, raising awareness and cleanup efforts
There are a wide range of innovative efforts to raise awareness about ocean garbage and cleanup these debris fields. In 2008, a sailing voyage called the “Junk Raft” sought to raise awareness with a three month voyage across the Pacific. Also in 2008, Richard Sundance Owen formed the Environmental Cleanup Coalition (ECC) a collaborative effort to address the issue of North Pacific pollution. They work on developing methods to safely remove plastic and persistent organic pollutants from the oceans.
In 2009, Project Kaisei launched a cleanup study that included two vessels that set out to research and assess the feasibility of commercial scale collection and recycling of ocean borne garbage.
Another 2009 investigation titled the SEAPLEX expedition, involved a 19 day ocean journey by a group of researchers from the Scripps Institution of Oceanography. They spent 19 days studying the distribution of plastic in the gyre which resulted in the most rigorous study to date.
In 2012, Dutch Aerospace Engineering student Boyan Slat unveiled a concept for removing large amounts of marine debris. He subsequently formed an organization called The Ocean Cleanup. This approach is not only cost effective, it is potentially profitable. His idea involves an anchored network of booms that world work like a giant funnel. Propelled by the ocean’s surface currents, debris would drift into specially designed arms and collection platforms where it would be separated from plankton and recycled. Slat’s calculations suggest that using his methods, 7.25 million tons of plastic can be removed from garbage gyres in as little as five years.
South Korean designer Sung Jin Cho has conceived of another innovative approach to removing plastic waste from water. His concept is known as the Seawer Skyscraper. This massive yet portable, self-supported solar-hydro power station, generates electricity using seawater while removing plastic waste. The Seawer filters ocean water and removes plastics and other particles which are recycled in an onboard plant. The purified seawater is stored in a large sedimentation tank at the bottom of the structure before it is released back into the ocean.
Despite these creative approaches to removing debris from the world’s oceans, they will not be able to reach the majority of plastic which have accumulated on the ocean floor.
Of the more than 200 billion pounds of plastic the world produces each year, about 10 percent ends up in the ocean. Much of which (approximately 70 percent) sinks to the bottom and harms life on the ocean floor.
In the North Sea alone, Dutch scientists have counted around 110 pieces of litter for every square kilometre of the seabed. This amounts to a staggering 600,000 tonnes in the North Sea alone. This garbage can smother the sea bottom and kill the marine life.
While efforts to clean up the plastics are laudable, they are not a definitive solution. Plastics break down into smaller polymers and suspend underneath the surface or on the ocean floor making them hard to see and difficult to clean up.
Plastic waste comes from almost every country in the world which makes ocean garbage an international problem requiring international solutions. While we can dispose of our waste more responsibly, the problem extends far beyond waste management. With Around 100 million tonnes of plastic products being produced each year, we need to find solutions at the source.
We need to find alternatives to conventional plastics that are biodegradable and do not contain harmful chemicals.
Source: Global Warming is Real
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