The Life Cycleof Plastic
Modern-day society relies on different types of plastics to function in their day-to-day lives, but once that item has fulfilled its desired function it is thrown away. Once an item made of plastic is discarded it has approached the final leg of its lifecycle. Currently, the life cycle of plastic has three different fates. Those three fates have been described as, “recycled or reprocessed into secondary material…plastics can be destroyed thermally…plastics can be discarded and either contained in a managed system, such as sanitary landfills, or left uncontained in open dumps or in the natural environment” (Geyer et. at, 2017). In the mentioned situations there are still large amounts of waste being produced from removing plastic from the environment. Meaning that the plastic that has been created will leave a lasting impact on the environment. Figure 1 depicts the life cycle of plastic and how the end of the plastic life cycle has more phases than the production and use. Although a large percentage of this plastic waste ends up in the three stages mentioned by Geyer, “an estimated 12 to 18% of plastic waste ends up in the environment through inadequate management and littering” (Brahney et. al, 2021).
Figure 1: The life cycle of plastic products (excluding energy input and emissions) created in STAN Software (Hahladakis et. al, 2018).
As plastic moves throughout the environment, once discarded it can be transported by “ocean circulation patterns, marine currents, and microplastic drift have been shown to be important drivers in the distribution of plastic…migratory wildlife, rivers, wind, and surface waters, in general, are also considered important vectors and strongly influence the flux mechanisms and source-sink dynamics of plastic pollution in different ecosystems including transfer from terrestrial to marine environments” (Bank et. al, 2019). When pieces of plastic debris move through these currents they continuously break down into smaller and smaller fragments. These small fragments are then able to disperse throughout the environment more freely. “Micro and nano plastics can be fragmented from macroplastics through mechanical degradation, a process that can be accelerated by chemical and biological weathering” (Sipe et. al, 2022). Once these plastics break down they become more immersed into the environment, which will then make removal difficult.
Figure 2: A conceptual model for plastics and microplastics transportation. The possible pathways are labeled with numbers. (Su, L. et. al, 2021)
The majority of the research on how plastic, especially microplastics, travels through the environment is focused on the marine environment. However, it can be seen in both figures that plastic fragments will also have negative long-term impacts on terrestrial ecosystems. Microplastics and nano plastics will settle into the soil which will negatively impact agricultural practices and how fertile the soil is. Chemicals will slowly release out of the plastic particles into the land and soil. This chemical pollution can affect the terrestrial and aquatic environments just as much as the physical particles of plastic.
Bank MS, Hansson SV. 2019. The Plastic Cycle: A Novel and Holistic Paradigm for the Anthropocene. Environmental Science & Technology. 53(13):7177–7179. doi:https://doi.org/10.1021/acs.est.9b02942.
Brahney J, Mahowald N, Prank M, Cornwell G, Klimont Z, Matsui H, Prather KA. 2021. Constraining the atmospheric limb of the plastic cycle. Proceedings of the National Academy of Sciences. 118(16).
doi:https://doi.org/10.1073/pnas.2020719118. https://www.pnas.org/content/118/16/e2020719118.
​
Geyer R, Jambeck JR, Law KL. 2017. Production, use, and fate of all plastics ever made. Science Advances. 3(7). doi:https://doi.org/10.1126/sciadv.1700782.
Hahladakis JN, Velis CA, Weber R, Iacovidou E, Purnell P. 2018. An overview of chemical additives present in plastics: Migration, release, fate and environmental impact during their use, disposal and recycling. Journal of Hazardous Materials. 344:179–199. doi:https://doi.org/10.1016/j.jhazmat.2017.10.014. https://www.sciencedirect.com/science/article/pii/S030438941730763X.
Sipe JM, Bossa N, Berger W, von Windheim N, Gall K, Wiesner MR. 2022. From bottle to microplastics: Can we estimate how our plastic products are breaking down? Science of The Total Environment. 814:152460. doi:https://doi.org/10.1016/j.scitotenv.2021.152460.
Su L, Xiong X, Zhang Y, Wu C, Xu X, Sun C, Shi H. 2022. Global transportation of plastics and microplastics: A critical review of pathways and influences. Science of The Total Environment. 831:154884. doi:https://doi.org/10.1016/j.scitotenv.2022.154884.