A sunny day, clear skies, and warm sands. Relaxing at the beach can put one at ease and take all the troubles away. This picture asks a darker question: How much plastic can you find? During a beach cleanup, one group of volunteers collected two, one-gallon buckets weighing in at 20 pounds total. The majority of the culprits consisted of small plastic pieces (94 pieces smaller than an inch) and plastic bottle caps (42 pieces). Plastic entangled in seaweed and a nearby road means increased pollution heading out to sea. Those were just the plastics seen with the naked eye. What you think is sand could actually be bits of broken down plastic.
Most plastics have a significantly short time being used compared to how long they take to break down. A takeaway cup from our favorite coffee shops can take 30 years to break down, but that does not mean it goes away completely. They break down into smaller fragments and leach into our waterways. Microbeads were a hit with hygiene products, especially exfoliating face cleansers. Every day, people wash with face wash or exfoliating hand soap. The small plastic beads have a use for a minute or two before being washed down the drain. Water treatment plants only catch so much, with as much as 170,900 particles per kilogram reported in sewer sludge. Sewer sludge is a byproduct of waste treatment, consisting of semi-solid organic matter such as food waste, human waste, and contaminants. Sludge can be used in agriculture, meaning microplastics in sludge enter the environment. What does not end up in sludge goes into the water. Microbeads from cosmetics and skin care products slip through the treatment plants’ filters and make their way to the nearest outsource: ponds, lakes, and streams. Commercial and recreational fishing are also large contributors to plastic pollution in the ocean. Nylon nets and fishing line break or are improperly disposed of, increasing the chances of them being washed out to sea with the incoming tide.
The macro- and micro-plastics that do not end up back on land are swept away by the ocean currents. The plastic gets caught in the middle of oceanic gyres, or large rotating currents, and floats together to create patches of plastic ‘land’. There are five major gyres: northern and southern Pacific Ocean, northern and southern Atlantic Ocean, and Indian Ocean. They are located at the furthest points between land masses and are responsible for churning the ocean, making sure water flows across the globe. The Great Pacific Garbage Patch, located between the Americas and Asia, has the highest concentration of plastic on Earth, measuring 1.6 million square kilometers as of 2021. Ocean currents meet and create a self-rotating system where warm water meets cold water. These currents carry buoyant materials with them, which get trapped in the gyre. Once there, both macro- and micro-plastics sit static, degrading over time from the sun’s heat which introduces chemicals to the water and increases chances of ingestion. Marine animals not only eat plastic, but get trapped in nets, bags, and other plastic pieces floating loosely on these masses. Entanglement of marine mammals can alter behavioral characteristics, like decreased success with foraging and limiting mobility, or cause physical stress, causing abrasions and asphyxiation. If the animal is unable to untangle itself, it will grow with the plastic around them which leads to increased stress and mortality.
Macro- and micro-plastics in water systems are mistaken for food throughout the trophic levels. Located at the bottom of the food web are zooplankton. They mistake microplastic as food items and consume them, which then are eaten by fish and crustaceans. Larger predators consume their prey items until there is nowhere left to go. This causes harm to multiple species since plastic uptake accumulates through the trophic levels, or where an organism is in the food chain like in Figure 3. Research observed an equal amount of microplastic intake compared to food items in cod located in northern Alaska. The cod are not getting the nutrients they need to survive, leading to decreased health, blocked intestinal systems, and ultimately increased mortalities. For animals who rely on cod to meet their dietary and nutritional needs, there is a lack of nourishment if the cod only eats plastic. This is such a common phenomenon that researchers now take plastic into consideration when building food webs, introducing new systems solely based on plastic movement through the ecosystem. Moving up the food web, marine birds are affected by microplastics as they eat fish and use them to feed their young. Like fish, birds can also mistake plastic pieces on the beach as prey. Marine birds take in food near the ocean’s surface, and studies dating back as far as the 1960s have shown plastic in their intestinal tracts. A study in 1969 documented stomach contents of 100 Laysan albatross (Diomedia immutabilis) carcasses. Approximately 94% of the objects were buoyant, with 30% being documented as plastic. In the span of 50 years, however, increased plastic means increased consumption and more species affected.
While humans do not consider themselves animals, they are part of the same food web all wildlife partakes in. Humans are high in the food chain, farming fish in artificial ponds similar to how cows are farmed for beef; this action is referred to as aquaculture. Aquatic food items are diet staples for some cultures, and tracing plastic through the food chain can help us find which, if any, specific marine species are microplastic sources. On small islands, humans use the soil itself as food, including it in spices, marinades, and bread. A study conducted in 2022 observed plastic in all soil samples on the island of Hormoz, located close to Iran. A significant amount of these plastics were fibrous materials that came from local or tourist clothing.
Single-use plastics break down over time, allowing microplastics to seep into our bodies and our ecosystems. Reusing plastic containers and bottles is harmful to a person’s health. The amount of microplastics in our waterways makes the simple act of consuming salt or drinking water from the tap hazardous, increasing one’s plastic intake. Research shows a single person ingests as much as millions of microplastics in a year, and a study conducted in 2021 found microplastics, a completely man-made material, inside women’s placentas. The plastics were linked to dyes, colorants, and stains that are found in finger paints, clothing, and air fresheners. We are contaminated before we are even born. Once inside the body, plastics break down and become part of the system, inhibiting metabolism and increasing obesity risk.
Demand for plastic has been steadily rising across the globe since its creation in 1907. From the smallest creeks to the largest oceans, plastic is found in all water bodies. However, we see little improvement in recycling methods. Each type of plastic may require a different way to recycle it due to its chemical makeup. It is important we work more efficiently and effectively to control our plastic pollution. Increasing recycling centers as well as the efficiency of existing centers can decrease microplastic pollution. Organizations like Alliance for the Great Lakes can help clean up plastics already on coastlines and beaches. Ocean Cleanup, a nonprofit organization, uses metal grates to catch debris in rivers, as well as patrol with nets in the ocean to catch stray rubbish. However, it is up to the individual to take the initiative as well. Whether it is a park, beach, or shopping mall, it is important to dispose of rubbish appropriately. Even if it is not yours, it would help the environment if you took it with you to throw it away in the proper receptacles. We must all do our part to keep the Earth plastic-free.
About the Author
Sara Dzialowy is an Aquarist Intern at OdySea Aquarium and a Master’s student in the Art of Biology through Project Dragonfly at Miami University-Ohio and Brookfield Zoo. With a focus on aquatic conservation and public education, she is passionate about inspiring others to protect marine life.
References
- Alliance for the Great Lakes (n.d.) About Alliance for the Great Lakes. https://greatlakes.org/about/
- Amiri, H., Hoseini, M., Abbasi, S., Malakootian, M., Hashemi, M., Jaafarzadeh, N., Turner, A. (2022). Geophagy and microplastic ingestion. Journal of Food Composition and Analysis. 106, 104290. https://doi.org/10.1016/j.jfca.2021.104290
- Azzarello, M. Y., van Vleet, E. S. (1987). Marine birds and plastic pollution. Marine Ecology – Progress Series. 37. 295-303. https://www.int-res.com/articles/meps/37/m037p295.pdf
- Baekeland, L. H. (1910). Bakelite, a condensation product of phenols and formaldehyde, and its uses. Journal of the Franklin Institute. 55-60. https://doi.org/10.1016/s0016-0032(10)90300-1
- Baheti, P. (n.d.). How is plastic made? A simple step-by-step explanation. British Plastics Federation. https://www.bpf.co.uk/plastipedia/how-is-plastic-made.aspx
- Bayo, J., Martinez, A., Guillen, M., Olmos, S., Roca, M. J., Alcolea, A. (2017). Microbeads in commercial facial cleansers: Threatening the environment. CLEAN – Soil, Air, Water. 45(7). https://doi.org/10.1002/clen.201600683
- Butterworth, A. (2016). A review of the welfare impact on pinnipeds of plastic marine debris. Frontiers in Marine Science. 3. 149. https://doi.org/10.3389/fmars.2016.00149
- Diepens, N. J., Koelmans, A. A. (2018). Accumulation of plastic debris and associated contaminants in aquatic food webs. Environmental Science & Technology. 52. 8510-8520. https://doi.org/10.1021/acs.edt.8b02515
- Greenly, C., Gray, H., Wong, H., Chinn, S., Passmore, J., Johnson, P., Zaidi, Y. (2021). Observing and tracking the great Pacific garbage patch. Small Satellite Conference. https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=5096&context=smallsat
- Iyare, P. U., Ouiki, S. K., Bond, T. (2020). Microplastics removal in wastewater treatment plants: a critical review. Environmental Science: Water Research & Technology. 6. 2664-2675. 10.1039/D0EW00397B
- Kannan, K., Vimalkumar, K. (2021). A review of human exposure to microplastics and insights into microplastics as obesogens. Frontiers in Endocrinology. 12. https://doi.org/10.3389/fendo.2021.724989
- Kirstein, I., Gomiero, A., Vollertsen, J. (2021). Microplastic pollution in drinking water. Current Opinion in Toxicology. 28, 70-75. https://doi.org/10.1016/j.cotox.2021.09.003
- Nelms, S. E., Duncan, E. M., Patel, S., Badola, R., Bhola, S., Chakma, S., Chowdury, G. W., Godley, B. J., Haque, A. B., Johnson, J. A., Khatoon, H., Kumar, S., Napper, I. E., Niloy, M. N. H., Akter, T., Badola, S., Dev, A., Rawat, S., Santillo, D., Sarker, S., Sharma, E., Koldewey, H. (2021). Riverine plastic pollution from fisheries: Insights from the Ganges River System. Science of the Total Environment. 756. https://doi.org/10.1016/j.scitotenv.2020.143305
- Olmo-Gilabert, R., Fagiano, V., Alomar, C., Rios-Fuster, B., Compa, M., Deudero, S. (2024). Plastic webs, the new food: Dynamics of microplastics in a Mediterranean food web, key species as pollution sources and receptors. Science of the Total Environment. 918. https://doi.org/10.1016/j.scitotenv.2024.170719
- Provencher, J. F., Borrelle, S. B., Bond, A. L., Lavers, J. L., van Franeker, J. A., Kuhn, S., Hammer, S., Avery-Gomm, S., Mallory, M. L. (2019). Recommended best practices for plastic and litter ingestion studies in marine birds: Collection, processing, and reporting. Facets. 4(1). 111-130. https://doi.org/10.1139/facets-2018-0043
- Ruiz, S. (2024). Giant nets to clean garbage from the ocean. The New Atlantis. 78. 86-88. https://www.jstor.org/stable/27332601
- World Wildlife Fund Australia (2021) The lifecycle of plastics. https://wwf.org.au/blogs/the-lifecycle-of-plastics/
- Yang, W. (2015). Through the gyre: A review on ocean plastic pollution in the great Pacific garbage patch. Monthly Notices of the Royal Astronomical Society. 1-4.