Ocean plastic pollution explained

Plastic leaks into the ocean from thousands of sources all over the world every day. Increasing consumption combined with improper waste management in many countries has made plastic pollution a worldwide problem, causing damage not only to the environment but also to human health and economies.

Humans produce over 400 million metric tons of plastic annually. That’s roughly the weight of all humans on the planet — and plastic production is projected to keep going up.

So of this 400 million tons that gets produced each year – how much actually ends up in the ocean? Less than 0.5 percent .

This is because only a small proportion of plastic is disposed of incorrectly, and an even smaller part of that enters waterways. This does not mean the ocean plastic pollution problem is “small” – over 1 million metric tons is still a massive amount of pollution.

So how does plastic become ocean plastic, and what factors can influence it? Let’s dig deeper.

MOST PLASTIC EITHER SINKS OR BEACHES WITHIN A MONTH

Nearly half of the plastic sinks directly because of its low buoyancy. Of the other half which floats, our research shows most of it doesn’t go far out in the ocean — about 80% of floating plastic will beach on a coastline within a month of leaking into the ocean. Some objects may be washed out to sea again, but coastlines are the final resting place for most floating ocean plastic. This can have serious consequences for the coastal environment and the fishing and tourism industries, as well as high cleanup costs for coastal communities.

If we take a PET bottle as an example; it is likely to sink as it fills up with water, but the cap, which is made of different type of plastic (HDPE), will stay afloat for much longer. High-density polyethylene (HDPE) products are most likely to travel long distances.

TRAPPED IN THE GYRES

It can take years for a plastic piece to break free from these coastal waters and be carried out to the open ocean – but once it’s out there, it can stay there for a long time.

Plastic accumulates in huge subtropical oceanic areas called gyres – massive circular currents that trap the floating plastic for decades, if not centuries.

There are five gyres in our oceans. The most polluted – and best-studied – is the infamous Great Pacific Garbage Patch, located in the North Pacific Ocean, between Hawaii and California.

The Great Pacific Garbage Patch is estimated to be twice the size of Texas – that’s triple the size of France or Thailand. However, the garbage patch is not a solid island of trash, a common misconception — it’s more often compared to a plastic soup.

Around 100 million kilograms of plastic float in the Great Pacific Garbage Patch, which contains 1.8 trillion pieces larger than 0.5 mm. That is about 160 pieces per person living on the planet. About 92% of the floating plastic mass in the Great Pacific Garbage Patch consists of larger objects. Only about 8% of the mass is microplastics. However, these larger objects are continually fragmenting into smaller pieces, which are much harder to clean up; the longer the problem exists, the worse it gets.

WILDLIFE

Marine wildlife suffers the most direct and damaging effects of ocean plastic pollution. From all kinds of fish to turtles, seals, crustaceans, micro-organisms and many other forms of life, the damage caused by plastic pollution to marine animals is increasingly visible as we learn more about this problem.

One of plastic’s biggest assets as a material is its durability. However, this means that once plastic enters the ocean, it will persist there for long periods; it won’t go away by itself. The oldest pieces we have found in our cleanup catches date back to the 1960s — and during this whole period, marine life is bearing the consequences.

Entanglement and ingestion have been found to impact 914 megafaunal species, of which more than 100 are endangered. As an example, the Mediterranean monk seal’s (Monachus monachus) second leading cause of death (after deliberate killing) is fishing gear entanglement. Our researchers have spotted whales in the Great Pacific Garbage Patch, indicating they are exposed to and affected by high quantities of plastic pollution. The Great Pacific Garbage Patch has 180 times more plastic than biomass, indicating that plastic could be a primary food source for organisms in this region.

A DELICATE ECOSYSTEM

Any marine ecosystem is finely balanced, and any change to that balance can seriously impact the inhabitants. Floating plastic debris can allow species such as coastal organisms to spread far from their usual environments and thrive in the open ocean – upsetting the balance in the GPGP. This can be damaging to marine life naturally occurring in ocean garbage patches, such as neuston .

Some plastic not only contains harmful additives and chemicals but also acts as magnets for toxins from the surrounding air or water, so the longer a piece of plastic is out there, the more harmful it can become to any animal that ingests it.

Degradation is slow but constant, so the larger objects are a ticking time bomb, breaking down over time and raising levels of microplastics exponentially. Smaller objects impact and travel up the food chain — a food chain that ends with us humans.

OXYGEN AND CARBON

Research on Prochlorococcus, an abundant bacteria/phytoplankton in the ocean that produces oxygen, has shown that leaking toxins from plastic negatively affects their oxygen production and their reproduction.

Oceans not only produce oxygen , but also pump carbon down to the seabed. Zooplankton found ingesting microplastic consumed 40% less carbon biomass. The fecal pellets of zooplankton also sink at a lower rate when consuming significant doses of microplastic, which also may have an impact on the carbon pump.

HUMAN HEALTH

Microplastic is all around us — in our seafood, tap water, and salt, to name a few sources. Studies indicate that plastic can pass through the blood-brain barrier in mice as quickly as 2 hours after consumption. Research has found that it potentially poses acute and (sub) chronic toxicity, carcinogenicity, and developmental toxicity.

However, the long-term effects on our health are not yet fully understood, and given how omnipresent it is, it is hard to isolate its full effects.

ECONOMIES

According to a Deloitte study, plastic pollution has been estimated to cost up to 19$ billion USD per year to the global economy. The costs considered stem from the impact on fisheries, aquaculture, tourism, and governmental cleanup. Derelict fishing gear also poses a safety risk to vessels at sea if they get stuck in propellers, which we also experienced firsthand.