Microplastic hotspots forming off UK North Sea coast, researchers say

Microplastic pollution in the world’s oceans is often illustrated with evocative images of wildlife caught in large objects floating on the surface, or of microplastics melting into the sand of otherwise pristine beaches.

The mass of plastics released into the ocean each year is considerable, reaching up to 12.7 million tonnes from river inputs in addition to marine sources from the fishing, aquaculture and shipping industries; however, what is observed on the surface does not correspond accordingly. Therefore, microplastic sinks are lacking in the marine domain.

New research, published in Frontiers of Marine Sciencehas identified the North Sea as home to some of these plastic sinks.

Dr Danja Hoehn and colleagues from the Center for Environment, Fisheries and Aquaculture Science, UK, collected data on microplastics in 2022 using a specialist Neuston microplastic catamaran (a floating catamaran with a flow meter mechanics and a mesh to capture plastics) on the surface of the ocean. This is where microplastics first enter the ocean from land runoff or on-board sources before sinking to the seabed.

Researchers have discovered high concentrations of microplastics in the South Bay of the North Sea, peaking at more than 25,000 items per square kilometer (elements km^-2with an average of ~8,700 items km^-2), compared to neighboring Scottish coasts (average ~4,500 items km^-2) and North-East Atlantic (average ~3,200 elements km^-2) waters.

Compositionally, most microplastics (up to 5 mm) were polyethylene fragments (67%; used in everyday items such as shopping bags, water bottles, and children’s toys ), polypropylene (16%; plastic packaging, automotive parts and textiles). , such as sportswear) and polystyrene (8%; packaging, housings of electrical appliances, including microwaves and refrigerators, as well as disposable medical equipment).

Mesoplastics (5–25 mm) and macroplastics (greater than 25 mm) were present at lower concentrations of around 2,000 elements km^-2 and ~1,000 items km^-2 respectively, mainly consisting of fragments and filaments from the decomposition of larger plastics, but also including microbeads and films.

Although the use of microbeads in cosmetic and personal care products has been banned in the UK since 2018, their persistence suggests transport from other countries to the region by ocean currents. Among all marine litter, 11 colors have been identified in plastics, most of which are white and attributable to plastic bags.

Microplastic and mesoplastic pollution hotspots have been identified just off the coast of East Anglia, where the aforementioned maximum concentrations were identified at two nearby sites.

Despite the spatial differences in the concentration of microplastics, their presence throughout the study area highlights the scale of the problem, as well as the influence of currents bringing plastic waste from other countries into these accumulation areas.

That said, average concentrations in the UK hotspot are still much lower than previously observed elsewhere, including ~254,000 element km.^-2 off the coast of northwest Spain in 2017, ~40,000 items km^-2 off the west coast of Portugal in 2019 and ~1 million articles km^-2 to the Canary Islands in 2024.

Tackling plastic pollution in these regions is an ongoing mission, with a number of national and international initiatives underway. These include the UK’s Marine Strategy, which aims to develop an indicator of microplastics in marine sediments; the North-East Atlantic Environmental Strategy, focused on the reduction and prevention of marine litter inputs; and the United Nations Environment Agency, which hopes a legally binding move will end plastic pollution by 2040.

With ever-increasing demand for plastics currently exceeding 400 million tonnes per year, it is essential to understand plastic contamination in Earth’s oceans in order to implement strategies to protect it for generations to come .

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