Plastics help keep our food and drink fresh, lightweight vehicles to save fuel, maintain sterile environments, and insulate buildings. So society uses an increasing amount of plastic materials each year and many of these are single-use or only used for a short lifetime. As a result this leads to a growing waste management challenge for society due to their low value. The careless or poor disposal of plastic items means that many such items find their way into the natural environment and may then become widely dispersed. In particular plastics are frequently deposited in our rivers, oceans and coastal regions, as shown in the image to the right.
A key property that makes plastics suitable for many applications, in particular in packaging, is their ability to prevent the ingress of water and to be resistant to the attack of bacteria. Unfortunately these properties also lead to plastics being difficult to be broken down or degraded under many natural environmental conditions. Consequently if carelessly discarded in the environment plastics will last for a long time, (as shown below) and begin to accumulate.
As an introduction to plastic pollution and how it is monitored watch the video below. In particular note the discussion on plastics at the end of their life, their appearance and the sizes of those that are collected.
Plastic pollution in the rivers and oceans
- In the video above, why are there growing concerns about the smaller plastic particles?
- These can become trapped and retained. They may also act as a vector to transport chemicals to the creatures that ingest them. This affects both creatures in the seas, beaches and consequently may influence our food chain.
The term microplastics has been coined for plastic fragments that have dimensions smaller than 5mm and many of these were seen in the previous video. Due to their small size many marine species can ingest microplastics, even such small creatures as zooplankton (Botterell et al., 2019) upon which other sea creatures feed. This provides a pathway into our food chain, for instance plastic debris has been found in fish and shellfish (Rochman et al, 2015). It is noteworthy that this same study also found fibres from synthetic (i.e. plastic) textiles in some fish samples from the USA. Such fibres may well have originated from laundry and passed through wastewater treatment plants, which members of the public may not have considered as a source of plastic pollution. Furthermore researchers have demonstrated that performing laundry can produce a large number of microfibers in the wastewater (Hartline et al., 2016).
It should be remembered that as members of society we can all have an influence on plastic pollution in the products we buy, how we use them and how we dispose of them.
It is clear from our discussion so far that plastic pollution is a significant challenge and one that scientists are continuing to research. However scientists, engineers and technologists are also researching ways to tackle plastic pollution by developing more environmentally friendly plastics. For instance a recent study compared the degradation of several biodegradable polyesters in both freshwater and seawater finding that only one example showed 100% degradation under the test conditions after 1 year (Bagheri et al., 2017). This highlights that it is a complicated issue for society though, as some of the biodegradable polyesters tested would degrade if composted under appropriate industrial composting conditions due to the elevated temperatures and the presence of a greater number of bacteria.
Starch film derives from a natural polymer and is increasingly being modified for use in plastic packaging applications. However again it should be disposed of in an appropriate manner, particularly as starch based bioplastic carrier bags were shown to degrade in soil or compost but were very slow to degrade in seawater (Accinelli et al., 2012).
It should be remembered that as members of society we can all have an influence on plastic pollution in the products we buy, how we use them and how we dispose of them. Notably we are all able to adopt a responsible approach and so try to better satisfy the 3Rs of reduce, reuse and recycle where plastics are concerned especially around the issues of littering and pollution in our rivers and oceans.
Further reading and references
This article was adapted in part from the Open University course S350 Evaluating Contemporary Science.
Accinelli, C., Saccà, M. L., Mencarelli, M., Vicari, A., Deterioration of bioplastic carrier bags in the environment and assessment of a new recycling alternative, Chemosphere, (2012) 89, 136–143.
Bagheri, A. R., Laforsch, C., Greiner, A., Agarwal, S., Fate of So-Called Biodegradable Polymers in Seawater and Freshwater, Global Challenges, (2017) 1, 1700048.
Botterell, Z. L. R., Beaumont, N., Dorrington, T., Steinke, M., Thompson, R. C., Lindeque, P. K., Bioavailability and effects of microplastics on marine zooplankton: A review, Environmental Pollution, (2019) 245, 98e110.
Hartline, N. L., Bruce, N. J., Karba, S. N., Ruff, E. O., Sonar, S. U., Holden, P. A., Microfiber Masses Recovered from Conventional Machine Washing of New or Aged Garments, Environ. Sci. Technol, (2016) 50, 11532−11538 DOI: 10.1021/acs.est.6b03045.
Rochman, C. M., Tahir, A., Williams, S. L., Baxa, D. V., Lam, R., Miller, J. T., Teh, F.-C., Werorilangi, S., Teh. S. J., Anthropogenic debris in seafood: Plastic debris and fibers from textiles in fish and bivalves sold for human consumption. Sci. Rep. (2015) 5, 14340, doi: 10.1038/srep14340.
Main image of plastics on the beach - copyright of the BBC.
Video of plastics in the ocean from Bang Goes the Theory - copyright of the BBC. Series 7, episode 1, 4 March 2013.
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