Microplastics, Breaking It Down
If you’ve ever gone for a walk on the beach, it’s likely that you’ve probably come across a piece of plastic litter. Unfortunately this is an experience that is all too common. If not collected, this debris will eventually find its way into our oceans. Once there, ultraviolet radiation in sunlight makes the plastic brittle, and heat and wave action break it down into flakes. These flakes are further shredded by the elements, until they become small enough where they drift like snow through the water column.
These plastic particles become so small that they are considered food for many marine organisms. Some fish consume the particles out of the water column directly, and some organisms like the grass shrimp gobble them up once they’ve fallen farther to the muddy ocean floor. Some other plastic pieces may wash back up onto beaches and salt marshes where they become food for burrowing worms and filter-feeding oysters.
The same weathering processes that act on the plastic debris in the water, are exacerbated even further on land. Plastic will break up far faster on a hot, bright, abrasive place like a beach than it will in deeper, colder water. So consider the plastic bottle I’m sure you’ve come across in a salt marsh. Eventually that bottle will disappear from view. The plastic will still remain in the environment, it just won’t be of a size that we can see.
Before these plastics become “micro” plastics, they can have detrimental impacts on many animals. Sea turtles mistake plastic bags for jellyfish, and albatrosses often mistake red plastic debris for squid. These plastics can block or abrade the animal’s guts. They can’t get adequate nutrition and will likely starve or lose the energy to search for food, fend off predators, or reproduce. But scientists now have compelling evidence that tiny bits of plastics can be just as detrimental for small marine life.
The National Oceanic and Atmospheric Administration defines microplastics as pieces smaller than 5 millimeters (about the width of a pencil eraser). Many plastic particles in the ocean are probably from ordinary household items that were used once, discarded, and degraded over time into tiny bits. Half of the plastic manufactured today is intended for one-time use. Other sources of microplastics can come from clothing, microbeads, resin pellets, and even the shedding of tires on our cars.
Plastic is so ubiquitous it is even in our clothing (nylon and polyester). Synthetic microfibers break off from clothes during the washing process (1,900 microfibers in a single washing), and slip past wastewater treatment plants into our waterways. These synthetic microfibers have even been found in our lowcountry oysters (research from 2013 undergraduate students under the supervision of Phil Dustan, biologist at the College of Charleston).
Microbeads are another fascinating source of microplastic in our waterways. These are used in toothpaste, exfoliating scrubs, facial cleanser, etc.. A single bottle of facial cleanser can have 350,000 microbeads that wash down the drain and slip through wastewater treatment plants.
Resin pellets are a form or microplastic showing up on our shorelines with more and more frequency. These pellets, which are about the size of a grain of rice, are used by various manufacturers, melted into molds and shaped into products ranging from plastic toys to automobile components. Resin pellets often spill from the manufacturing sites or from shipping containers, finding their way into nearby creeks and rivers, or into the ocean directly.
Let’s not forget that a large majority of the microplastic found in the ocean is actually from the wearing of our tires as we drive on roadways. In 2014 biologist John Weinstein and his graduate students at The Citadel Military College studied microplastics in Charleston waterways, finding that over 50% of the particles were actually microscopic, black, elongated tubes - later determining these were pieces of car tire. A 2014 study by Pieter Jan Kole at The Open University of The Netherlands, estimated that tires account for as much as 10 percent of overall microplastic waste in the world’s oceans. A 2017 report by the International Union for Conservation of Nature put that number at 28 percent. Tire wear and tear is a stealthy source of microplastics in the environment.
So besides the basic physical impacts of ingestion, what other issues do microplastics bring to the table? Well, plastic bits in aquatic environments can act as magnets for many pollutants (like PCBs and DDT). The smaller the particle, the more likely its surface is to capture and bind more pollutants. A geochemist at Tokyo University found that resin pellet surfaces contained concentrations of PCBs 100,000 times to 1 million times higher than the surrounding water or sediment.
Once bound to the plastic particles, the pollutants can be more easily taken up by fish and organisms that people eat. Both PCBs and DDT were banned in the US in the 1970s, but they are still widely found in marine environments around the world today. Both of these contaminants bioaccumulate up the food chain, and will eventually move into tissues where they act as endocrine disruptors, confusing the hormones of the animal.
In addition to attracting organic pollutants, plastic particles are at the same time fracturing and shredding into smaller pieces, which releases a cocktail of chemical additives. Virtually all plastic consumer products have various additives (flame retardants, antimicrobials, dyes, fillers). Examples of additives are Bisphenol A (BPA) and phthalates, which have been shown to leach out of plastics into water and also confuse the hormone levels in aquatic animals. So as those plastics break into smaller and smaller bits, they release their additives, while at the same time they are attracting other harmful contaminants to their surfaces.
Plastics in the ocean have become globally ubiquitous. Hundreds of aquatic organisms - from invertebrates to fish and whales - consume plastics. Today, marine bacteria and algae are even making new habitats on raft-like surfaces of tiny, buoyant plastic flakes. Any effort to strip the sea of tiny plastic pieces and particles - even if this were possible - would also rob the ocean of the bacteria and phytoplankton that form the base of the food web. Charles Moore, a sailor and oceanographer has been credited with discovering and bringing public attention to a massive stretch of floating plastic debris in the midst of the North Pacific Gyre in 2003, since named the Great Pacific Garbage Patch. Charles also founded the Algalita Marine Research Institute which supports expeditions to study plastics in the ocean.
Marine organisms are being exposed to a one-two punch that’s new to evolution. Plastics are introducing cocktails of additives and ingredients into the ocean. At the same time, plastics are attracting great concentrations of chemicals already present in the environment. The fact that plastics can do both - disperse some contaminants and attract other contaminants - is pretty novel. A plastic item can be a sink for contaminants but also a source of them. There is really nothing else in the ocean that does both.
Let’s consider 10 things you can do for trash-free seas:
CAN IT. Use a trash can with a lid.
TAP IT. Drink tap water in a reusable bottle.
STOW IT. Be a green boater.
BUTT IN. Write your legislator asking for policies that address ocean trash.
REMOVE IT. Join volunteer cleanups.
BUTT OUT. Use an ashtray so cigarette butts don’t reach water.
RECYCLE IT. Most plastic materials can be recycled.
REUSE IT. Use reusable shopping bags, coffee mugs, and picnic supplies.
BUY LESS. Buy less to reduce the amount of plastic reaching the ocean.
REINVENT IT. Send emails to companies asking them to reduce packaging and create new ocean-friendly materials for their products.
Other efforts to reduce microplastic pollution require real system change —that is, a new approach to how we produce, use, and dispose of plastic. For resin pellet pollution, ensuring robust implementation of pellet management plans and procedures will help reduce pellet pollution by 80% by 2040. As for textiles, redesigning fabrics to minimize microfiber shedding and installing in-line filters in washing machines can contribute to a 77% decrease in this type of pollution in the same period. In regards to microplastics from tire wear, improving the design and reducing the number of miles driven by commuters (increasing use of public transport) can nearly halve pollution by 2040.
Source of this article:
Hibbetts, J. (2014). The Global Plastic Breakdown, How Microplastics Are Shredding Ocean Health. Coastal Heritage Magazine, 28(3).