The Atlantic Ocean contains approximately 12–21 million tonnes of microplastic waste in the upper 200 metres, reports a study in Nature Communications. Quantifications of just the three most abundant plastic types in the upper ocean indicate that the amount of plastic in the total Atlantic Ocean is much higher than previously determined.
Assessment of the ecological and environmental damages caused by accumulating microplastics are hampered by the lack of robust quantifications from the systems in which they accumulate, especially in remote locations like the oceans.
Katsiaryna Pabortsava and Richard Lampitt quantified plastic contamination in samples collected at 12 locations along a 10,000 km North-South transect of the Atlantic Ocean. They assessed the abundance of polyethylene, polypropylene and polystyrene litter, the three most common commodity plastics that together make up over half of global plastic waste. At each station, samples were collected from three depths below the ocean surface: 10 metres, 10–30 metres below the mixed layer of the ocean, and 100 metres below the intermediate sample. Plastics were analyzed down to a resolution of around 25 micrometres. In the near surface ocean, they detected up to 7,000 microplastic particles of these three polymer types (32–651 micrometres in size) per cubic metre of seawater.
Based on plastic waste generation trends from 1950–2015 and assuming that the Atlantic Ocean was consistently receiving a fraction of global plastic waste for 65 years, the authors estimated that the input of plastic to the Atlantic waters and sediments was 17–47 million tonnes. When the microplastic mass of the three polymers sampled was combined with previously calculated marine plastic stocks, they found that the total mass of material currently present balances or may even exceed the estimated plastic input into the Atlantic since 1950.
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