Dr. Philipp Lengsfeld
Primary source paper: A comprehensive review of microplastics: Sources, pathways, and implications – 2020
This outline provides an introductory review on the topic of microplastics. The term microplastics (MPs) was first coined in the scientific literature by Thompson et al. (2004). They described microplastics as very small plastic particulates and fibres, usually smaller than 5 mm. Research on microplastics has steadily grown in recent times in comparison to other conventional water quality pollutants (e.g. heavy metals, nutrients, etc.). Due to its durability, persistence, and potential harmful effects on the environment, it is no surprise that microplastics has drawn attention as an emerging pollutant (Yano et al., 2020).
We present key excerpts from a review paper to highlight the sources, pathway, and impacts of microplastics for general introductory understanding of this interesting environmental topic.
MPs are characterized by their physical and chemical aspects. Physical characteristics of MP mostly a concern in sizes, shapes, and colors since they are mistakenly ingested as food by animals and marine organisms (Hidalgo- Ruz et al., 2012). MP particles are made up of polymers with different chemical compounds. These polymers are all thermoplastics, which means that plastic materials were melted and heated to produce useful products.
Aside from atmospheric deposition, stormwater runoff and wastewater are the primary pathways for land-based MP (Magnusson et al., 2016). Although wastewaters may contain the largest amount of pollutants, the amount of MP can be significantly reduced by the wastewater treatment process.
Sources and Impact
Urban areas are the major contributors to MP in the environment. Since urban areas are characterized by high population densities, sites that are adjacent to urban areas were found to have higher amounts of MP particles (Horton et al., 2017). The abundance of land-based MP sources is a significant factor affecting the detection or concentrations of MP in surface waters and large water bodies. On the other hand, sea- based MP mainly originate from marine coatings of cargo ships (Boucher & Friot, 2017). Overall, the combined effects of atmospheric deposition, land-based sources, and sea-based sources can collectively increase the number of MP on natural water bodies.
Exposure to MP can be categorized into physical, chemical, and biological effects. Ingestion and entanglement are the most common cases in which MP can be accumulated in animal tissues. In the case of small microorganisms, the presence of MP may result in death by drowning, starving, and suffocation (Allsopp et al., 2006). MP are made up of polymeric compounds that can have negative health effects. Some polymers and additives in plastics are resistant to biodegradation and cause disruption in endocrine functions through bioaccumulation processes (Li et al., 2018). MP also served as a carrier of pollutants on its way to water bodies. MP can sorb lubrication oils, heavy metals, persistent organic pollutants, and other toxic chemicals that can be released when ingested and transported into waters (Wang et al., 2018). Microorganisms that can also easily attach to MP surfaces and be transported together in various environmental media. This means that bacteria and other pathogenic organisms can be released to water bodies through MP (McCormick et al., 2014). The ingestion of MP on humans can cause infertility, cancer, and obesity (Sharma and Chatterjee, 2017). Based on a conducted research, there will be more MP in the oceans than fishes by the year 2050 (Auta et al., 2017).
A range of factors can influence the distribution of MP across the ecosystem including human activities, population, and land use. Continuous study and research about MP are important to evaluate and prevent the implications brought about by the presence of MP in the environment. Low impact development (LID) facilities or pollutant management facilities can be used as possible treatment mechanisms for reducing the amount of MP in stormwater and wastewater. The complex pathways and transport mechanisms of MP are considered as the major challenges in quantifying the actual amount of MP in the environment. Further studies concerning the development of predictive models and control strategies are also necessary to limit the adverse effects of MP in the environment and human health.
Primary source paper – Yano, V., Reyes, N., Geronimo, F., Jeon, M., Kim, Y., Kim, L. (2020). A comprehensive review of microplastics: Sources, pathways, and implications. Journal of Wetlands Research Vol. 22, No. 2, May 2020, pp. 153-160.
Allsopp, M., Walters, A., Santillo, D., & Johnston, P. (2006). Plastic Debris in the World’s Oceans. World.
Auta, H. S., Emenike, C. U., & Fauziah, S. H. (2017). Distribution and importance of microplastics in the marine environment. A review of the sources, fate, effects, and potential solutions. Environment International.
Boucher, J., & Friot, D. (2017). Primary microplastics in the oceans: A global evaluation of sources. Primary microplastics in the oceans: A global evaluation of sources.
Hidalgo-Ruz, V., Gutow, L., Thompson, R. C., & Thiel, M. (2012). Microplastics in the marine environment: A review of the methods used for identification and quantification. Environmental Science and Technology.
Horton, A. A., Walton, A., Spurgeon, D. J., Lahive, E., & Svendsen, C. (2017). Microplastics in freshwater and terrestrial environments: Evaluating the current understanding to identify the knowledge gaps and future research priorities. Science of the Total Environment.
Li, J., Liu, H., & Paul Chen, J. (2018). Microplastics in freshwater systems: A review on occurrence, environmental effects, and methods for microplastics detection. Water Research.
Magnusson, K., Eliasson, K., Fråne, A., Haikonen, K., Hultén, J., Olshammar, M., … Voisin, A. (2016). Swedish sources and pathways for microplastics to the marine environment. A review of existing data. IVL Svenska Miljöinstitutet.
McCormick, A., Hoellein, T. J., Mason, S. A., Schluep, J., & Kelly, J. J. (2014). Microplastic is an abundant and distinct microbial habitat in an urban river. Environmental Science and Technology.
Sharma, S., & Chatterjee, S. (2017). Microplastic pollution, a threat to marine ecosystem and human health: a short review. Environmental Science and Pollution Research.
Thompson RC, Olsen Y, Mitchell RP et al (2004). Lost at sea: where is all the plastic? Science 304:838–838.
Wang, F., Wong, C. S., Chen, D., Lu, X., Wang, F., & Zeng, E. Y. (2018). Interaction of toxic chemicals with microplastics: A critical review. Water Research.