10.5 The Problem with Plastic

Assess the environmental impact of and remedies for plastic pollution in the oceans.

Plastic is cheaper than most natural materials, and it often performs better. Nearly everything we use is composed at least partly of plastic: electronics (cell phones and computers), packaging, facial scrubs, toothbrushes, credit cards, bags, bottles, car parts, combs and hairbrushes, clothing—modern society depends on plastic. So how is plastic relevant to physical geography or the oceans? The answer has to do with these statistics:

  1. Each year, about 300 million metric tons of plastic are made. That is about 42 kg (92 lb) per year for each person on Earth.

  2. More plastic has been made in the last 10 years than in all of the previous 100 years.

  3. Only about 5%–10% of all plastic made is recycled.

  4. Most plastic is not biodegradable (it cannot be broken down by decomposers). About 40% of plastic is disposed of in landfills, and the rest is either still in use or litters the continents and oceans.

What Happens to Plastic in the Oceans?

How does plastic get into the oceans? Most of the plastic entering the oceans comes from streams flowing into the sea and from beaches. Plastic trash in the streets of towns and cities is washed into storm drains, then into rivers, then into the oceans.

About 70% of all plastic that enters the oceans eventually sinks to the seafloor. There it is swept away by deep-ocean currents to accumulate in ocean basins. That plastic will persist for thousands to tens of thousands years or longer. Large accumulations of plastic presumably lie somewhere on the seafloor, but they have not yet been found.

Question 10.10

What is the Great Pacific Garbage Patch?

The Great Pacific Garbage Patch is a concentration of plastic that has entered the ocean through storm drains and rivers in urban areas and collected in the North Pacific Gyre.

The 30% of plastic that remains suspended in the sunlit epipelagic zone is carried on the ocean gyres. Eventually, that plastic collects in the center of the gyre in what is often referred to as a garbage patch or plastic vortex. The Great Pacific Garbage Patch, a region of concentrated plastic litter formed by the North Pacific Gyre, is the largest and best known of these collections. It is made up of an estimated 100 million metric tons of plastic trash. This suspended plastic ranges in size from massive clumps of fishing nets to minuscule bits of plastic invisible to the human eye. Most of the pieces are less than 1 cm (0.4 in) in length and cannot be seen from a boat. Towing a fine sieve (net) through the water catches them (Figure 10.34).

Figure 10.34

Suspended plastic. Charles Moore, one of the first discoverers of the plastic in the oceans, holds a jar containing small bits of plastic captured by a towed sieve. Note that the plastic is suspended in the water, not floating.
(Courtesy of Algalita Marine Research Institute)

Great Pacific Garbage Patch

A region of concentrated plastic litter formed by the North Pacific Gyre.

The plastic in garbage patches is undetectable to satellites because most of it is suspended just beneath the water surface. Yet ocean current patterns are well known, and computer simulations reveal where the plastic collects, as shown in Figure 10.35.

Figure 10.35

Locations of plastic in the ocean gyres. This map shows the probable locations of concentrated plastic debris in the oceans predicted by computer simulations of ocean current patterns. Each of the regions of plastic concentrated in the gyres covers an area roughly equivalent to the continental United States. Red areas show the greatest concentration of plastic particles. Light blue and white areas have the lowest plastic concentrations.
(Nikolai Maximenko, International Pacific Research Center, SOEST, University of Hawaii)

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Transported by ocean currents, suspended plastic finds its way to the most remote areas. There, waves wash it onto beaches, where it collects and breaks down further (Figure 10.36).

Figure 10.36

Plastic trash on a remote beach. This beach is on tiny uninhabited Henderson Island that is 37.3 km2 (14.4 mi2) in extent. Henderson Island is part of the remote Pitcairn Islands in the South Pacific. Most of this plastic originated from fishing boats and from Asia, some 11,000 km (7,000 mi) distant.
(© John Salmon)

How Does Plastic in the Oceans Pose a Problem?

Suspended plastic provides a surface onto which many forms of life cling, creating what's called the plastisphere. Some of this life can be harmful. For example, bacteria in the genus Vibrio, which cause cholera and other human health ailments, have been found on ocean plastic. Researchers suspect that such pathogens are able to persist longer and travel farther as they cling to plastic particles adrift in the ocean.

Suspended plastic particles in the oceans also attract and adsorb (bind to their surface) toxic chemicals that have entered ocean waters (such as PCBs and DDEs from industrial activity and pesticides from agricultural spraying). Plastics have been found to carry concentrations of PCBs and DDEs 1 million times those of seawater. The toxins may then enter organisms that eat the plastic. Scientists have documented ingestion of microscopic bits of plastic by organisms such as barnacles, krill (small shrimplike organisms), and fish that filter-feed on plankton. Toxins from the plastic particles could then work their way through almost all marine trophic levels and even into terrestrial trophic systems, eventually finding their way to our dinner plates. It is not yet known, however, whether these toxic chemicals are making their way through marine food webs.

Plastic does more obvious harm to marine life when animals eat it or become entangled in it (Figure 10.37). Scientists estimate that 100,000 marine mammals and sea turtles are killed by plastic each year, mostly through entanglement.

Figure 10.37

Plastic threatens marine animals. (A) This green sea turtle is dining on a jellyfish, a main food for sea turtles. To sea turtles, translucent plastic bags suspended in the water look like jellyfish. Ingested plastic can kill a sea turtle by blocking its digestive tract. (B) This adolescent Laysan albatross (Phoebastria immutabilis) from Kure Atoll probably died of starvation as its parents fed it a diet of plastic. Its stomach was filled with 340 g (12 oz) of trash. Plastic ingestion is a common cause of mortality for albatross nestlings on Hawai‘i. Worldwide, seabird mortality from eating plastic is estimated to be about 1 million birds per year. Fish mortality related to plastic is unknown.
(A. © Ai Angel Gentel/Flickr/Getty Images; B. © David Liittschwager/National Geographic/Getty Images)

Plastic debris is not limited to the oceans. In 2012, scientists found that the Great Lakes contain high concentrations of microscopic plastic particles. Most of them come from facial cleansers that contain tiny plastic beads.

Fixing the Problem

The problem with plastic in the oceans resembles other situations in which a pollutant released into the environment by people has led to problems in Earth’s physical and biological systems later on. Toxic air pollutants (Section 1.4), CFCs in the ozonosphere (Section 1.5), and carbon in the atmosphere (Section 6.3) are three examples we have examined in this book.

As of 2014, a cumulative total of 29 billion metric tons of plastic had been made. At this rate, by the middle of this century, a total of roughly 40 billion metric tons of plastic will have been made, mostly in the United States, Europe, and China. There is too much plastic being made to clean it up after it has entered the environment, and doing away with plastic altogether is not practical.

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What can society do? There is no single solution. An important step toward addressing this problem is making the problem widely known. As Figure 10.38 demonstrates, a social media campaign to inform the public is under way.

Figure 10.38

Plastic pollution awareness. This message about plastic pollution in the oceans captures the viewer’s attention and conveys the information at a glance. Many major cities, such as Los Angeles, and even states, such as Hawai‘i, have already implemented, or are considering, a ban on plastic bags in grocery stores. Such measures have passed because the public supports them.
(© 2011 Ferdi Rizkiyanto)

What can an individual do? Reduce, reuse, and recycle. Many of the plastic items that enter the oceans are designed to be one-use items, such as water bottles, grocery bags, and utensils. These items are used for only a few days, hours, or even minutes. They then spend millennia in landfills or in the environment. About half of all plastic made is made to be disposed of immediately.

To address this issue, closed-loop systems need to be developed. In a closed-loop system, plastics would be designed to be reused and recycled indefinitely. Many plastics made now (such as PVC, polyurethane, and polystyrene foam) have properties that make them difficult or impossible to recycle.

Another important step is to create plastics that biodegrade in the environment. Biodegradable vegetable-based plastics, made from plants such as corn, are becoming increasingly available. The more consumers demand them, the more they will be made available. Biologically based and reusable plastics are two important solutions to this problem.

Modern society needs plastic, and it needs healthy ecosystems. The two need not be mutually incompatible. The way plastic is perceived and manufactured will certainly change as more people become aware of this growing ecological problem.

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