September 13, 2019
Posted by: Emily Engle
A three-part exploration into one of the world’s smallest oceanic pollutants with some of the largest adverse global consequences. This series seeks to dive beneath the surface to uncover how these particulates came to exist in our water ways, their associated biological and ecological impacts, and the costs of their proliferation here on the Georgia coasts. To finish, this series will provide a list of better buying options to ensure you as the consumer are empowered to make educated purchasing decisions, and to help limit microplastics from continuing to deteriorate our oceanic systems.
Part 1: Plastic Proliferation
Society has a predisposed image of the plastic pollution plaguing our planet: marine animals with fishing line tangling their extremities and six-pack rings wrapped around helpless creatures. Over the past decade it has become increasingly evident that plastic pollution permeates far beyond what the eye can see: It is the contamination concealed beneath the ocean’s surface that haunts biota. Seafarers have long feared the unknown threats lurking in the depths, but now it is no longer “Jaws” or the “Kraken”, but minute anthropogenic debris haunting humanity. Marine microplastic pollution, of small plastic particulates, microbeads, and microfibers, is an ever-evolving issue directly affecting the health and diversity of ocean ecosystems; it subsequently affects human health, fisheries, and local economies. Microplastic pollution in our oceans is projected to increase, fostering harmful toxicological and physical effects on ocean biota, with studies indicating possible human health impacts due to accumulation of hazardous chemicals like persistent organic pollutants (POPs) in living tissues (Thomson, 2015). In response to the potential unprecedented harm of marine microplastics, it is imperative that science gains a better understanding of their effects, and the globe mobilize in the form of a reduction in their oceanic input through limiting microfiber and microbead production and decreasing plastic litter. The following paragraphs will discuss how microplastics enter our oceans, and their associated effects.
What exactly are these so-called microplastics? Will I see them littering the high tide line along with abandoned bottles, milk jugs, and 6 pack rings? In short: no. A majority of the tiny pollutants are invisible to the naked eye, which may explain why their proliferation has gone largely unnoticed until recently. Microplastics are a subcategory of plastic pollution and are categorized as any synthetic organic polymer pollutant less than 5 millimeters in length. Their small size and large abundance make them particularly susceptible to introduction to biotic ecosystems. These contaminants are often in the form of direct pollutants as microbeads or secondary pollutants as fragmented plastic partials or synthetic fibers. Microfibers are produced through synthetic fabric manufacturing and washing, while microbeads originate from personal care products, like soaps and toothpaste. These contaminants enter oceans through drains due to inadequate filtration of wastewater (used water from sinks, washing machines, showers, etc.) and the minute particles’ ability to pass through wastewater treatment facilities. Fragmented pieces of plastic enter watersheds through improper plastic trash disposal like littering and illegal dumping. These larger (macro- and mezzo-) sized plastic pollutants flow through watersheds eventually entering the oceans. There they begin to break down and fragment into microplastic particulates.
There are an estimated 5 trillion plastic pieces weighing over 250,000 tons adrift in world oceans today (Eriksen et al., 2014). Due to the large-spread nature of plastic pollution and difficulties in isolating and accurately quantifying microplastics, limited information is known on the magnitude of their impacts, illuminating the need for a greater research effort. There is, however, a consensus amongst the scientific community on their presence in aquatic environments and the threat they pose to biota (da Costa et al., 2016). Microplastics pose threats to ecosystems through three primary avenues: 1) Bioaccumulation, 2) their tendency to attract and retain other harmful synthetic pollutants, and 3) physical blockages.
Research has sought to understand how these particulates biomagnify through food webs (accumulate in organisms throughout different trophic levels, compounding with higher concentrations at higher trophic levels). Microplastics possess the ability to permeate biological membranes, presenting a means for biological accumulation of contaminants in organic tissues (da Costa et al., 2016). Particulates become bio-accessible when chemical changes fostered by biotic (living) or abiotic (physical) factors reduce the molecular weight of the polymers, making them brittle. This can result in powdery fragments that either float or sink and are susceptible to ingestion and incorporation into marine biomass at low trophic levels (Andrady, 2011). These low-tier organisms, like zooplankton are then consumed by higher trophic levels enabling the biomagnification of microplastics and related toxins. This results in higher contamination levels in top predators like tuna, mahi-mahi, sharks, and swordfish that are harvested for human consumption.
This illustration summarizes microplastic degradation and subsequent biomagnification through marine food webs.
(Wright et. al, 2013)
Microplastics act as vessels for other floating synthetic contaminants. Researchers have discovered their relation to the bioaccumulation of persistent organic pollutants (POPs) in biotic systems. POPs are chemical compounds which were widely produced during industrial booms in the wake of World War II, like Polychlorinated biphenyls (PCBs), Dichlorodiphenyltrichloroethane (DDT), and dioxins. These contaminants are often toxic or carcinogenic, resistant to degradation via biological, chemical, and photolytic processes, and known to bioaccumulate. In the context of marine environments, POPs are hydrophobic (repel water) allowing for their accumulation on solid plastic particulates. They concentrate in organic fatty tissues and pose threats to human health when consumed; however, quantifying the scope of the pollution has been difficult. The hazards associated with these carcinogenic contaminants have resulted in many regulatory agencies around the world banning the production of POP creating items; regardless, their residual nature results in their continued prominence in both terrestrial and aquatic environments. The breakdown of plastics determines their bioavailability and surface area, which subsequently dictates their susceptibility to attachment by POPs in ocean water. Studies mutually suggest that microplastics and POPs foster negative impacts on biota, though there are some discrepancies over the degree of retention of microplastics and related toxins in biotic tissues and organisms.
Upon ingestion particles can also create physical blockages in organisms’ digestive and circulatory systems which may result in mortality. With increasing quantities of plastics entering marine environments, we will see growing amounts of particulates taken-in by organisms and associated consequences of consumption.
The world undeniably has a huge plastic problem. However, this problem percolates beyond the great garbage patch circling in the North Pacific Gyre. It’s the microfibers circling our laundry drains, and the plastic litter circling our storm drains which have also plagued our oceans; and, its these pollutants which will inevitably end up back on our plates. We are now experiencing the consequences of unlimited plastic production and consumption. We must ask ourselves, is every face wash, toothpaste, fleece jacket, or red solo cup really worth the health of our oceans? Are we truly willing to compromise the wellbeing of marine resources, like fishing and sea food, on which people across the world so depend for the sake of convenience? Our place on the Atlantic seaboard gives us a unique relationship to the ocean: as kids, many were raised boating in the waters, grew up eating fish they caught, and spent long summer days being baked by the southern sun and subsequently cured by the salty air. Children today do not have the luxury of care-free ocean experiences. They have to be more mindful of the fish they catch, and the plastic particulates plaguing aquatic species systems. In part two we will take an in-depth look at the current effects and future impacts of microplastic pollution on Georgia’s coast. Although these minute anthropogenic particulates are some of the smallest plastic contaminants in our ocean, they pose some of the greatest threats. Going forward, it is important we stay informed and mobilize to limit our plastic production to protect our oceans and inevitably, ourselves.
To learn more about Persistent Organic Pollutants, visit the EPA’s website: https://www.epa.gov/international-cooperation/persistent-organic-pollutants-global-issue-global-response
To learn more about Microplastic Pollution, visit NOAA’s website, https://oceanservice.noaa.gov/facts/microplastics.html, or check out some of the papers cited below:
Andrady, A. L. (2011). Microplastics in the marine environment. Marine Pollution Bulletin. Retrieved from: https://doi.org/10.1016/j.marpolbul.2011.05.030
Brown-Williams, H., Lichterman, J., Norris, S. & VanDerslice, J. (2008). Fish Contamination: Environmental and Health at Risk. Perspectives: 3(1), 1-8. http://www.healthresearchforaction.org
da Costa, J. P., Santos, P. S. M., Duarte, A. C., & Rocha-Santos, T. (2016). (Nano)plastics in the environment - Sources, fates and effects. Science of the Total Environment. Elsevier. Retrieved from: https://doi.org/10.1016/j.scitotenv.2016.05.041
Eriksen, M., Lebreton, L. C. M., Carson, H. S., Thiel, M., Moore, C. J., Borerro, J. C., & Reisser, J. (2014). Plastic Pollution in the World’s Oceans: More than 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea. PLoS ONE: 9(12). Retrieved from: https://doi.org/10.1371/journal.pone.0111913
Holden, P., Bruce, N., Hartline, N., Karba, S., Ruff, B. & Sonar, S. (2016). Microfiber Pollution and the Apparel Industry. Unpublished: Bren School of Environmental Science and Management. http://www.esm.ucsb.edu/research/2016Group_Projects/documents/PataPlastFinalRep ort.pdf
Hoellein, T. J., Kelly, J. J., McCormick, & A., London, M. (2016). Microplastic in rivers is abundant, mobile, and selects for unique bacterial assemblages. American Geophysical Union. Retrieved from: https://agu.confex.com/agu/os16/meetingapp.cgi/Paper/92690
Leonard, A. (2011). The Story of Stuff. Retrieved From: http://storyofstuff.org/wp- content/uploads/2017/02/TheStoryOfMicrofibers_AnnotatedScript-1.pdf
Thompson, R. C. (2015). Microplastics in the marine environment: Sources, consequences and solutions. Marine Anthropogenic Litter (pp. 185–200). Springer International Publishing. Retrieved From: https://doi.org/10.1007/978-3-319-16510-3_7
Thompson, R.C., Olsen, Y., Mitchell, R.P., Davis, A., Rowland, S.J., John, A.W.G., McGonigle, D., Russell, A.E. (2004). Lost at sea: where is all the plastic? Science: 304 (5672), 838. Retrieved from: http://science.sciencemag.org/content/304/5672/838
Rochman, C. M., Tahir, A., Williams, S. L., Baxa, D. V., Lam, R., Miller, J. T., ... Teh, S. J. (2015). Anthropogenic debris in seafood: Plastic debris and fibers from textiles in fish and bivalves sold for human consumption. Scientific Reports: 5(1), 14340. https://doi.org/10.1038/srep14340
Sutton, R. (2015). Microplastic Contamination In San Francisco Bay – Fact Sheet. Retrieved From: https://www.sfei.org/microplasticfacts
**Header photo: Small plastic particulates representing a form of microplastic pollution. Image Retrieved from: https://www.chatelaine.com/wp-content/uploads/2019/07/everything-you-should-know-about-microplastics-810x608-1562867872.jpg