The amount of microplastics on the seabed has tripled in 20 years
(sustainabilityenvironment.com) – Microplastics contaminates every terrestrial ecosystem. The fragments of microscopic dimensions are driven by the wind on top of the mountains and dragged by the currents on the bottom of the sea depths. It is right here, hundreds or thousands of meters below the water level, that the greatest accumulations are found. In 2020, a study published by Science revealed that the highest levels of microplastics on the seabed are those of the Tyrrhenian: up to 1.9 million fragments on an area of 1 m2 only. Now a new research, conducted by the Universitat Autonoma de Barcelona, has calculated that the amount of microplastics has increased by 3 times over the last 2 decades.
Intact since the 1960s: the fate of microplastics on the seabed
Two main results of the study published in Environmental Science & Technology, the first to give an estimate of the tendency of accumulation of microplastics on the seabed. First, the analysis of the samples -collected in the north-western Mediterranean- reveals that the fragments are preserved, without alterations, mixed with marine sediments. Lack of erosion, oxygen and light prevents material degradation.
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And then a characteristic of the growth curve of microplastics: it closely follows the trend of global plastic production between 1965 and 2016. “Specifically, the results show that, since 2000, the amount of plastic particles deposited on the seabed has tripled and that, far from decreasing, the accumulation has not stopped growing to imitate the production and global use of these materials” explains researcher Laura Simon-Sánchez.
Three common polymers: polyethylene (PE) and polypropylene (PP) flakes from food packaging, bottles and films, and synthetic polyester fibres from clothing. These three types are present in average concentrations of 1.5 mg per kilogram of sediment taken from the seabed. The researchers sampled the Mediterranean seabed between Barcelona and the Ebro River delta, near Tarragona, aboard the oceanographic vessel Sarmiento de Gamboa.