Potential microplastic release from the maritime industry: Abrasion of rope

While land-based sources of plastic pollution have gained increasing attention in recent years, ocean-based sources have been less well studied. The aim of this study was to compare a variety of ropes (differing in age, wear surface and material) to quantify and characterise the production of microplastic during use. This was achieved by simulating, in laboratory and field experiments, rope hauling activity which is typically performed on board maritime vessels, such as fishing boats. Microplastic generation was quantified by collecting fragments that were released as a consequence of abrasion. Notably, we show that microplastic fragments generated from rope wear during use were characteristically irregular in shape, rather than fibrous such as those assigned to syn-thetic rope by previous studies. Therefore, we suggest that some of the plastic fragments found in the marine en-vironment may have been falsely attributed to land-based sources but have in fact arisen form the abrasion of rope. Our research found that new and one-year old polypropylene rope released significantly fewer microplastic fragments (14 +/- 3 and 22 +/- 5) and less microplastic mass (11 +/- 2 and 12 +/- 3 mu g) per metre hauled compared to ropes of two (720 +/- 51, 247 +/- 18 mu g) or ten (767 +/- 55,1052 +/- 75 mu g) years of age. We show that a substantial amount of microplastic contamination is likely to directly enter the marine environment due to in situ rope abra-sion and that rope age is an important factor influencing microplastic release. Our research suggests the need for standards on rope maintenance, replacement, and recycling along with innovation in synthetic rope design with the aim to reduce microplastic emission. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

This study compared ropes of different ages and materials to quantify microplastic production during use. It found that irregularly shaped microplastic fragments released from rope wear may have been falsely attributed to land-based sources. New and one-year-old polypropylene ropes released significantly fewer microplastic fragments compared to older ropes, indicating that rope age is a key factor influencing microplastic release.