Plastic Particles

According to the United Nations Environment Programme marine debris is any persistent, manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal environment. Of the 120 marine mammal species listed on the IUCN Red List 54% are known to have been entangled in or have ingested plastic debris, according to the Global Environment Facility's report, Marine Debris: Defining a Global Environmental Challenge. Evidence of harmful effects of plastic on wildlife is mostly restricted to observations on individual specimens that have become entangled in or have ingested plastic debris. Plastic debris has also been implicated in the transport of non-native invasive species which can raft considerable distances on floating debris. Physical effects, such as entanglement of seals and other animals in drift plastic, increases with the size and complexity of the debris and potential chemical effects are likely to increase with a reduction in the size of plastic particles.

A good part of the marine debris from land-based sources results from unsustainable production, consumption, and poor waste management. Increased development, urbanization, and consumerism lead to increases in the use of disposable and non-degradable products and packaging, which results in increased generation of solid waste. Poor management or mishandling of waste materials creates the foundation for land-based sources of marine debris. The sources and movement pathways for plastic in the marine environment are in the publication Plastic Debris in the OceanUNEP Yearbook 2011

Large quantities of debris can now be found in the most remote places of the ocean, and persist almost indefinitely in the environment. Dr. Melanie Bergmann from the Alfred Wegener Institute for Polar and Marine Research reports that biologists have recorded increasing amounts of plastic litter in the Arctic deep sea.Their studies confirm that the amount of marine debris lying on the seabed, mostly plastic, has doubled today compared to ten years ago.

This represents a significant cause for concern, although much of this growing threat to biodiversity and human health is easily preventable with solutions that are readily available. The Convention on Biological Diversity’s report on Impact of Marine Debris on Biodiversity: Current Status and Potential Solutions highlights plastic items as “the most abundant type of marine debris on a global scale” and states that plastic is also the most frequently reported debris material encounted by marine organisms. The impacts of plastic pollution in the oceans are identified as a priority issue in the UNEP Year Book 2011: Emerging Issues in Our Global Environment.

The degradation time for plastic in the marine environment is, for the most part, unknown. Estimates are in the region of hundreds of years. Plastic in the ocean tends to fragment into smaller particles of similar composition, a process aided by the action of the waves and wind. Microplastics are mostly fibrous but can be granular, approximately 20 micrometres in diameter, and brightly colored according to a study in the Northeast Atlantic. It was also noted that it was only possible to quantify fragments that differed in appearance from sediment grains or plankton.

There are two sources of microplastics, each subject to further degradation. The first is plastics manufactured to be of a microscopic size, primary microplastics. These plastics are typically used in facial-cleansers and cosmetics, as air-blasting media, and vectors for drugs. Secondary microplastics are tiny plastic fragments derived from the breakdown of larger plastic debris, both at sea and on land. The structural integrity of plastic debris is reduced by fragmentation and photo-degradation, which increases the susceptibility to fragmentation resulting from abrasion, wave-action, and turbulence in marine or coastal environments. A diameter of 1.6 nanometers, a nanoplastic, is the smallest detected in the oceans and in years to come this diameter will have an increased presence. Common sources of primary and secondary microplastics include fishing gear, household items and plastic packaging. Clothing, a polyester shirt for example, releases thousands of microplastic fibres in every wash.

Microplastics in sediments from the rivers Elbe (A), Mosel (B), Neckar (C), and Rhine (D). Note the diverse shapes (filaments, fragments, and spheres) and that not all items are microplastics (e.g., aluminum foil (C) and glass spheres and sand (D), white arrowheads). The white bars represent 1 mm. Source: Wagner et al. 2014. 

Impacts and Contaminants

The transportation of invasive species and alterations in the structure of the microbial communities in the seabed are additional impacts of microplastics in marine or coastal environments. Bryozoans, barnacles, polychaete worms, hydroids, and mulloscs are the most numerous species to be transported on plastic particles. Microplastics function as sites for the colonization of microorganisms, forming plastic-associated biofilms and having the capacity to influence the ecology.

 

Marine microplastics contain a wide-range of organic contaminants, such as polychlorinated biphenyls (PCB’s) and bisphenol A (BPA). Samples from beaches along the North Atlantic Ocean contain microplastics of consistent densities of common consumer plastics, whereas in the open ocean samples 99% of the microplastics had densities less than the density of surface seawater, a result of further degradation. Microplastics, with a large surface area to volume ratio, are susceptible to contamination, by a number of waterborne pollutants, including aqueous metals, endocrine disrupting chemicals, and persistent organic pollutants. These coated microplastics may be transported across oceans polluting otherwise pristine ecosystems.

What’s the Big Deal with Microplastics? is an article which explores issues surrounding microplastics in the marine environment. The article is part of a new Atlantic Canadian Fisheries Blog called Small Scales produced by the Ecology Action Centre.

Go to top