Plastic pollution extends over the entire surface of the world’s oceans but small plastic particles which should be there are missing, according to an international study.
The authors say the findings suggest an unknown sink for small plastic particles and further research is needed to determine which ocean life or systems are responsible and how they may be affected by ingestion of or exposure to plastic waste.
Mass production technologies for plastics emerged in the mid-1900s, followed by plastic waste accumulations in the world’s oceans.
The concentration of plastic debris in ocean samples initially kept pace with increasing plastics production, but levelled off in the 1980s despite continued increases in plastics production and disposal.
Andrés Cózar of the University of Cadiz in Spain and colleagues measured plastic debris contained in ocean surface samples collected during the Spanish Circumnavigation Expedition, a nine-month journey to assess the impact of climate change on the world’s oceans.
The authors analysed data from 3,070 ocean surface samples collected around the world and found that 88% of sample sites contained plastic debris of varying sizes with highest plastics concentrations occurring in the five subtropical ocean areas.
Particle size analysis revealed that plastic fragments between a few microns and a few millimeters in size are under-represented in the ocean surface samples.
The estimated total ocean plastic content, between 10,000 and 40,000 tonnes, was less than previous estimates predicted.
The results suggest that plastic waste in the ocean is widespread but that an unknown mechanism is removing small plastic fragments from the surface waters at a high rate.
According to the authors, further study is needed to find out where the plastic is going and what impact this is having.
The research is published in the journal PNAS.
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