A new study compared synthetic ropes used in the maritime industry. Credit: University of Plymouth
According to new research, the hauling of rope aboard maritime vessels could lead to billions of microplastic fragments entering oceans every year.
The University of Plymouth's International Marine Litter Research Unit conducted the study. It is the first to examine the possibility that rope could be a source of marine plastic pollution.
This study compared several synthetic ropes used in the maritime sector, but with different ages, wear surfaces and materials to assess the amount and characteristics of microplastics that were produced during their use.
This was done by simulating the rope hauling activity on both field and laboratory experiments. It is usually performed aboard maritime vessels like fishing boats.
These results showed that for every meter of rope, both new and old ropes could release approximately 20 microplastic fragments to the ocean.
However, as the rope gets older it can release significantly more fragmentstwo-year-old ropes shed on average around 720 fragments per meter, while 10-year-old rope releases more than 760 fragments per meter.
According to Science of the Total Environment researchers, the length of the fishing rope used in each haul can reach up to 220m depending upon the vessel type and the depth of the ocean.
This research simulates rope hauling, which is a common activity onboard maritime vessels. Credit: University of Plymouth
Based on 50m of rope being pulled from a boat, the researchers estimate that every time new rope is brought to shore, it could release 700 to 2000 microplastic pieces. The release of used rope could be as high as 40,000 pieces.
There are more than 4500 fishing vessels currently in use in the UK. Their estimates indicate that this could lead to anywhere from 326 million to 17 miliarde microplastics entering the ocean each year, just from the UK fleet.
Dr. Imogen Napper (Research Fellow) led the study. She stated that these estimates were made after carrying a weight of 2.5 kg. However, the majority of maritime activities involve heavier loads which can cause friction and possibly more fragments. This highlights the need for standards in rope replacement, maintenance and recycling in the maritime sector. It also highlights the need for continued innovation in synthetic rope design, with the goal to reduce microplastic emissions.
Plymouth University was the first institution to raise awareness about the problem of marine microplastics. In 2019, the Queen's Anniversary Prize was awarded to the University of Plymouth for Higher and Further Education.
Research done in conjunction with the Fishing for Litter initiative has shown that commercial fishermen are acutely aware that marine litter could cause long-lasting damage to their catch and to the entire industry.
The University is also involved in a project to develop biodegradable fish gear that can be used on small and large boats.
Professor Richard Thompson OBE, FRS, Head, International Marine Litter Research Unit said that "for centuries, most everyday items such as rope and netting used for the maritime industry were produced using natural resources. Plastics have been replacing natural resources in a steady increase in production since the 1950s. However, plastic's durability has created a significant environmental problem once products reach the end or, as was shown in this study in this case, when they begin to shed microplastics. A greater awareness of these issues is starting to be reflected in society. This study highlights a previously unknown, but significant source of microplastics. It also reinforces the need for collaboration to bring about lasting and positive changes.
Continue reading Microplastics can be hidden in sediments by ocean fishermen
More information: Science of the Total Environment, Imogen Ellen Napper and colleagues, Potential microplastic releases from the maritime sector: Abrasion of Rope, (2021). Information from Science of the Total Environment: Imogen Ellen Napper and colleagues, Potential microplastic releases from the maritime sector: Abrasion of Rope, (2021). DOI: 10.1016/j.scitotenv.2021.150155
