London: The health of our oceans is at grave risk, with a study revealing that more then five trillion pieces of plastic now litter the world's oceans, media reported.
The total weight of all the plastic pieces floating in our oceans is almost 269,000 tonnes, which is as much as two large cruise liners, the Daily Mail reported Wednesday, citing the study.
This was revealed by an international team of scientists who gathered data from 24 expeditions mounted over a period of six years between 2007 and 2013.
Towed nets were used to scoop up plastics from five sub-tropical 'gyres' -- huge areas of circulating ocean currents -- as well as coastal Australia, the Bay of Bengal and the Mediterranean Sea.
Visual surveys provided information about large fragments of plastic material.
This data was combined, and a computer simulation of floating debris dispersal was used to indicate that the oceans have at least 5.25 trillion plastic pieces weighing 268,940 tonnes floating in them.
The plastic material ranged from tiny particles less than a millimetre wide, to 'macro' fragments more than eight inches (20 cm) across.
Sub-tropical gyres are known to gather up plastic materials, but the research revealed that the rubbish was not confined to these ocean “dustbins” alone.
The smallest particles were found to have been distributed to remote parts of the world, including sub-polar regions.
Lead researcher Marcus Eriksen, director of research at the Five Gyres Institute in Los Angeles, said: “Our findings show that the garbage patches in the middle of the five sub-tropical gyres are not the final resting places for the world's floating plastic trash.”
Large plastics appeared to be abundant near coastlines, the scientists found.
However, the amount of “microplastic” particles on the surface of the oceans was much less than expected, suggesting that some of it was being removed.
Removal processes included degradation by sunlight, bio-degradation, loss of buoyancy, entanglement with settling detritus (waste or debris) and ingestion by fish and other organisms.
Writing in the online journal Plos One, the scientists concluded: “This is the first study that compares all sizes of floating plastic in the world's oceans from the largest items to the small microplastics.”
Such a pollution of the world's oceans by plastic debris has been found to be significantly harmful for the marine fauna and big birds like the albatross.
Albatrosses on remote Pacific islands have been ingesting so much of plastic that they are dying. The sharp foreign objects had also lacerated their gut walls.
Moreover, sea turtles are prone to mistaking plastic bags for jellyfish and bodies of sea turtles have been found with their stomachs full of plastic.
It was recently estimated that 90 percent of seabirds found dead on beaches had ingested plastic.