JAN 31, 2023 4:10 PM PST

Plastic Debris on the Ocean Floor Has Tripled in 20 Years

A new study shows that the total amount of microplastic deposited on the bottom of oceans has tripled in the past two decades! This increase coincides with the type and volume of consumption of plastic products by human society. Despite many awareness campaigns that have encouraged society to reduce the use of single-use plastic, the data from this study show that our society is far from achieving this goal.

This study was developed by the Institute of Environmental Science and Technology of the Universitat Autonoma de Barcelona (ICTA-UAB) and the Department of the Built Environment of Aalborg University (AAU-BUILD) and recently published in the journal Environmental Science and Technology.

The study provides the first high-resolution analysis of microplastic pollution in sediments obtained from the ocean floor in the northwestern Mediterranean Sea. The team collected five sediment cores from the sea floor in November 2019. Each core sample is 37 centimeters (about 14.5 inches) long, and represents the sea floor from 1965 to 2019. Over time, sediment builds up on the sea floor. Thus, the top of the sample would represent the year 2019 and the bottom of the sample would represent the year 1965, and hence, the microplastic mass sequestered in the sea floor models the global plastic production over this time period.

The team found that the amount of microplastic particles on the sea floor has tripled since 2000. In addition, they found that these microplastics remain unaltered, unchanging since they were deposited on the sea floor, even those that were deposited decades ago. Degradation would then only occur in beach sediments, on the surface of the sea, and in the sea itself. Once the particles are trapped at the bottom of the sea, they no longer degrade. The team believes that this is either due to a lack or erosion, oxygen, or light.

There are three types of microplastics that were analyzed: polyethylene, polypropylene, and polyester. Polyethylene and polypropylene particles originate from packaging, bottles, and food films, for example, while polyester originates from synthetic fibers in clothing fabrics. The abundance of these types of particles reached a value of 1.5 mg per kg of sediment, where polypropylene was the most abundant, followed by polyethylene and polyester, respectively. This large abundance was found in the upper regions of the sediment cores, which represent the most recent years in the samples.

Thus, it is evident that single-use plastic products leave a mark on our environment. Once these microplastics reach the sea floor, they no longer degrade, and leave a permanent signature of human pollution. The world is far from reducing single-use plastics, but policies on a global level may help reverse this serious problem.

Sources: Daily Mail, Science Daily

About the Author
Doctorate (PhD)
I'm a stellar astrophysicist by training with a passion for formal and informal education and diversity and inclusion in STEM. I love to take a humanistic approach to my work and firmly believe that all of humanity is united under one sky.
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