Plastic Pollution in the Ocean: the World’s Dirty Secret

Versatile, durable, and ubiquitous, plastic provides tremendous benefits to our society as consumer goods or industrial inputs—if in the right place, of course.

The resulting convenience notwithstanding, plastic only makes brief appearances in our daily lives—not entirely by design but by human choices. Having fulfilled our needs, we discard the synthetic material, without any regard for its destiny and impact. Unsurprisingly, plastic items end up crowding the environment, depleting natural resources, and jeopardizing human welfare.

Marine Plastic Overview

Besides landfills and incinerators, plastic products may find their way into our waterways and the Ocean. Needless to say, such movement is by no means natural. Equally perplexing or concerning is the sheer volume of plastic entering the marine environment. Indeed, a 2015 study estimated that, as of 2010, about 8 million metric tons of plastic debris enter the ocean annually (1).

Marine Debris ( Paulo Oliveira & Alamy / The New York Times)

Discounting unlawful marine discharge of plastic, inadequate waste management appears to be the culprit. Indeed, plastic leakage amounted to 28.9 million tons in 2010. First released into rivers or other fresh waterways, discarded plastic items travel from inland areas to open seas—under the influence of water currents. For example, China’s Yangtze, one of the world’s longest rivers, harbors 1,496,481 tons of such plastic annually (2).

Upon reaching the ocean, plastic debris spread across open waters in accordance with current and wind patterns. Five gyres, or rotating ocean currents, exist in the Pacific, Atlantic, and Indian Oceans. Under the influence of these whirlpool-like systems, plastic mass and particles mingle with other marine garbage (3). They tend to concentrate in regions known as garbage patches.

Notably, the “Great Pacific Garbage Patch (GPGP)” remains the most famous example. Covering 0.6 million square miles, its size is comparable to that of Texas, California, Montana, and New Mexico combined (4). GPGP also far exceeds its counterparts elsewhere in terms of plastic accumulation: 1.8 trillion pieces of plastic that weigh approximately 72,000 metric tons float near the surface (5). Parts of plastic fishing tools, such as nets and ropes, constitute around half of the gyre’s mass, while hard plastics, like sheets and films, roughly account for the remainder. Altogether, global oceans carry at least 250 metric tons of plastic (6). Though far from negligible, this figure appears insignificant before the aforementioned 8 million tons of marine plastic. 

The Great Pacific Garbage Patch (Techsmart)

Where did the remaining 99 percent go? While no universally accepted theories exist, scientists have proposed several plausible explanations. Increasingly more plastic products resurfaced along the coast, suggesting a possible pathway. 

In hope of validating this assumption, the Ocean Cleanup developed a model that took oceanic current dynamics into account. The Netherlands-based nonprofit pointed to global shorelines as the most likely location of the vast majority of marine plastic, totaling about 110 million metric tons (7). Its founder, Boyan Slat argued in his co-authored paper that landmass captures a portion of plastic debris, while the remainder settle near the seabed; a small portion likely escapes to shallow coastal waters; whether trapped in sediments or floating in water, however, the synthetic polymer will face its inevitable degradation into microplastic (8). 

Marine Plastic Distribution (Our World in Data)

Furthering said investigation, Alethea Mountford developed a computer model that considered plastics of three different densities. The Newcastle University researcher found strong support for significant microplastic buildup at much greater and varied depths of the Ocean than previously believed (9). 

Despite growing interest in relevant research, the existing body of literature on microplastic remains small and limited. Though suffering from inadequate information, the scientific community has attributed impacts on ecological welfare, economic activities, and human health to marine plastic and its degradation.

At the macroscopic level, plastic debris presents a direct threat to marine organisms (10). For example, a sea turtle may interact with fishing nets, only to find itself trapped or entangled. This compromise of movement limits feeding activities. On the other hand, plastic bags could interfere with sea species’ navigation and cause injuries, most severe of which is suffocation. 

A Sea Turtle Entangled in a Plastic Mesh (ScieNews)

Moreover, animals often inadvertently consume plastic objects, which appears to them indistinguishable from food. Unable to remove the chemical substance from their digestive tracts, they risk malnourishment and other health issues. In rare cases, plastic debris introduces non-native creatures, such as algae or barnacles, that attach to its surface to new marine ecosystems. With greater competitive advantages, these invasive species will crowd out their indigenous counterparts. 

Another reason why local biodiversity is at risk from plastic pollution rests upon the polymer’s interaction with environmental conditions. Plastic can interact with other environmental stressors to alter pollution concentration, temperatures, and acidity in the area (11). Large masses of floating debris also block sunlight from parts of the ocean, thus inhibiting the growth of photosynthetic creatures like algae and planktons (12). 

In simpler words, larger marine plastic generally jeopardizes animals’ chance of survival. 

In comparison, the detection of smaller microplastic proves a much more difficult undertaking. Akin to a sesame seed in size, these subparts measure less than 5 millimeters in length (13). Current scientific studies hold that plastic, instead of decomposing, break down into pieces of smaller sizes (14). The discussion below will address various degradation pathways for marine plastic. 

Small Plastic Pellets on the Finger (pcess609 / iStock / The Source Magazine)

Abiotic and biotic processes, usually in this order, aid in the production of microplastic (15). From interaction with seawater, heat, and ultraviolet radiation, plastic polymers degrade hydrolytically, thermally, and photolytically. The breakage of intermolecular bonds produces smaller plastic fragments. This condition proves ideal for colonization of marine microbes, whose extracellular enzymes further aid in the degradation process (16). 

Recent studies have found these particles far from prevalent, abundant, and concentrated in the Ocean than previously believed. Jamie-son et al. sampled the species of Lysiannassoidea amphipod, which typically reside at depths ranging from 7,000 to 10,890 meters, and detected ingested microplastics in the creature’s hindguts (17). Scientific expeditions in the much distant Arctic likewise returned ice samples containing 154,000 plastic particles per liter (18). These findings suggest that microplastic has spread to virtually all corners of the world’s oceans. 

Plastic products’ unique compositions, namely the presence of various additives, further complicate their degradation. Common varieties include plasticizer, antioxidants, and stabilizers (19). In particular, the latter two render plastic more degradation-resistant. Given enough time under sufficient conditions, however, additives, too, can degrade and leach from plastic polymers into the Ocean.

Leaching of Plastic Additives and Sorption of Contaminants in the Ocean (NOAA)

Once in the environment, these mostly toxic chemicals ultimately pose health threats to humans. Indeed, scientists considered them carcinogenic and disruptive to the endocrine system (20). By ingesting these substances, often by accident, small sea creatures pass them up the food chain. Via this pathway, Persistent Organic Pollutants (POP), widely used as pesticides and insecticides, could attach to plastic and endanger food safety (21). 

Another example is the well-documented chemical bisphenol A (BPA). This toxic substance is capable of disrupting reproductive functions and inducing cardiovascular disease (22). Following legislation in 11 states, FDA banned BPA in 2012 (23). These regulatory actions notwithstanding, BPA was present in canned foods, sports water bottles, and baby products manufactured prior (24). Under certain conditions, BPA in marine plastic will also find its way into our body. 

Nanoplastic (Green) in a Zebra Fish Cell (UAB / CREAF / Healthcare in Europe)

As concerning as microplastic may appear, its derivatives—nanoplastics—can even induce illness and disrupt human functions (25). Measuring as small as 1 nanometer, these particles can travel easily through gut, lungs, and skin epithelia. Once internalized, they absorb a collection of proteins to form a “corona” that alters their features with increased toxicity. Such interaction ultimately produces agglomeration and deposition within human organs. Their toxic effects include inflammation, oxidative stress and apoptosis, and metabolic homeostasis. For example, studies on mice linked inflammation in lung and liver cells, adverse neurological effects, irregular cell death, and gut microbiota imbalance to polystyrene particles. These substances also hamper other metabolic processes necessary for healthy cells. 

Human health aside, marine plastic buildup undermines economic activities across the globe. The fishing industry could suffer reduced production as plastic debris crowds the habitats of certain seafood. A socio-economic impact simulation in the English Channel and France Manche region, identified beach cleanups and tourism loss as two major areas of economic burdens (26). In particular, measures taken to reduce marine plastic in the two seas could produce environmental benefits of about $680 million annually. 

A Plastic-filled Beach (Johannes P. Christo / Reuters / World Economic Forum)

Financial analyses provided further insights in support for the arguments above. Judith Schali, World Trade Institute researcher, estimated that cleanup operations could cost $13 billion annually (27). Furthermore, the fishing industry in the Asia-Pacific region may suffer a loss of $1.17 billion each year. Expenses stem from the need to repair damaged fishing gears, and additional revenue loss may incur from poor overall quality of fish. 

The international community must assume drastic measures to clean up the ocean. Given current industry trends, global cumulative production of plastic will reach 34 billion metric tons by 2050 (28). Approximately 10 percent of said figure, marine plastic discharged to the ocean that year could total 3 billion metric tons. Without adequate human interference, this estimate will likely prove accurate and alarming: a 300-fold increase from today’s numbers. 

In other words, uncontrolled marine plastic could produce irreversible, astronomical damage to ecosystems, economies, and human health—if previous projections and cost-benefit analyses hold. 

Growing body of research has helped raise salience on the issue of marine litter. However, the alarming accumulation of plastic in the ocean warrants immediate response from the global community. Existing alternatives that address the problem may take a technological, policy, or community-based approach.  

California’s Ban on Single-Use Plastic Bags (YNC)

Policy instruments at local, national, and international levels will complement each other for best results. In California, for example, bans on single-use plastic items have curbed plastic waste production from the source (29). The rationale behind this law echoes within Frank G. Wells Environmental Law Clinic at UCLA and Surfrider Foundation; members of these two expert groups favored legislation targeting bags, straws, and expanded polystyrene foam food containers, citing the great volume of waste produced from thence (30). 

Congress also took measures as early as 2006 through the signing of the Marine Debris Act (31). Amended several times since, this piece of legislation requires The National Oceanic and Atmospheric Administration (NOAA) to “identify, determine sources of, assess, prevent, reduce, and remove” marine litter that may jeopardize domestic economy, “marine environment, and navigation safety”. 

Rep. Alan Lowenthal’s News Conference Address on Domestic Plastic Pollution (Sarah Silbiger / Getty)

Plastic pollution in the ocean has garnered much attention beyond the United States as well, particularly in international conventions. 186 sovereign parties, including all top plastic waste producers, signed the binding agreement at Basel to “protect human health and the environment from hazardous waste” (32). While it failed to target all plastic waste, the document “restricts the transboundary movement of waste”, a step in the right direction. In a positive light, the Center for International Environmental Law (CIEL) sought to amend the Basel Convention to implement more stringent, well-defined policies amid increased global plastic production. 

Popular, or social, pressure can be the key to legislative change. When exercising your voting power, it is important to evaluate candidates for their campaign’s environmental component. Consider those who share the vision of a sustainable future and have realistic plans to execute it. Similarly, consumers can demand corporate change or promise to reduce impact from operations. Nestlé, Volvo, and Coca-Cola are a few examples in the food, automobile, and beverage industries where corporate interest conforms to legitimate social demand (33). 

A number of exciting technologies, if adequately developed, have great potential for marine applications (34). At the manufacturing stage, implicated industries need to increase the share of biodegradable plastics in their product portfolios; funding research and development of alternative materials to plastic is another important, necessary approach to adopt. Moreover, the introduction of wetlands along coastlines may serve as a buffer zone to intercept a large number of riverine garbage. Debris-cleaning vessels could target floating plastic already present in the ocean. To this end, an unified database plotting marine plastic distribution will improve the efficiency of such expeditions through route optimization (35). Lastly, coagulation technology presents an opportunity to remove microplastic from seawater and render it drinkable. 

Activists at Nestlé’s Malaysian Headquarter (Greenpeace International)

Community endeavors likewise warrant our attention (36). Anyone could organize or partake in a cleanup project targeted at local streets, rivers, and beaches. Reducing plastic consumption, especially in food packaging, also helps. Consider reusable utensils as opposed to single-use items offered at most retail locations. For unwanted items, such as undersized clothing, donation to those in need often proves a good idea. Practice the three R’s: reduce, reuse, and recycle. 

The 21st Century saw the rise of many serious global environmental challenges. Our generation has the responsibility of protecting existing resources for our offsprings. Take actions today to preserve our ocean—a life-teeming place that invokes wonder and awe, for ages to come.






































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