Concern is growing about pollution from floating plastic debris, which can be become entangled with or ingested by wildlife. In contrast, pollution by microplastics has received little scientific or regulatory attention, say the researchers.
Microplastics enter the oceans via wastewater and through the breakdown of plastic debris and have been shown to be persistent in surface and deep ocean waters and in deep sea sediments.
Tests have shown that a single polyester fleece jacket can release more than 1,900 fibres per wash, while around half of discarded plastics are buoyant in seawater and maybe subject to degradation by ultraviolet radiation and decomposition. More than half of the research stations in the Antarctic have no wastewater treatment systems, the research reports.
To estimate the level of microplastics currently in the Southern Ocean, the research team analysed existing data and samples taken from around the Peruvian base on King George Island.
It’s estimated that up to 500kg of microplastic particles from personal care products and up to 25.5 billion clothing fibres enter the Southern Ocean per decade as a result of tourism, fishing and scientific research activities. While this is negligible at the scale of the Southern Ocean, the researchers say it may be significant at a local scale.
The research was carried out in association with the Cientifica del Sur University in Peru.
Dr Huw Griffiths, a marine biogeographer with the British Antarctic Survey and co-author of the research, said: “The threats to marine ecosystems presented by microplastics have been identified as a major global conservation issue but major questions concerning plastic in the Southern Ocean remain unanswered.
“Our understanding of the sources and fate of plastics in these waters is limited at best. Given the low numbers of people present in the Antarctic, direct input of microplastic from wastewater is likely to be below detectable limits at a Southern Ocean scale.
“However, microplastics generated from macroplastic degradation or transferred into the Southern Ocean across the polar front may be a major contributor to the high levels of microplastics recorded at some open ocean sites.
“In addition to tighter regional regulation on the use and release of plastics in the Southern Ocean, we believe that a greater understanding of their distribution and impact is required. To understand fully the sources and scale of this pollution would require an internationally co-ordinated effort.”
'Microplastics in the Antarctic marine system: An emerging area of research’ –was published in the Science of the Total Environment and is available at ScienceDirect.