PFQAC Learning Center
In December, researchers from the Autonomous University of Barcelona in Spain published a new study in the journal Chemosphere showing that individual tea bags steeped in boiling water can release micro- and nanoplastic particles, which are then ingested by the drinker. And it's not just a few particles here or there. The researchers found that the bags can release particles in the billions, adding to the body of work already out there presenting the dangers of microplastics from tea bags.
Why is plastic a problem? Fundamentally, plastic is waste.
What is waste? It is hard to define because the degradation of plastic yields such an immense array of products with varying size, morphology, and chemical composition, not to mention the associated matter and organisms that accumulate and colonize the surface.
How it impacts the environment. The main problem with plastic is that it combines components in a way that is novel to the environment of Earth, so that the microorganisms that would otherwise process and transform any waste products through biogeochemical cycles are not able to do so. This leads to the question of whether plastic pollution represents a sufficient force to be an agent of evolution.
The habits and life styles of microorganisms are varied in their consumption and production of energy and matter, and their interaction with particles as well as their position in the food web. Therefore, the presence of plastic and its associated spectrum of waste products offers the opportunity to enact change at various points in an ecological network.
Please let us know a few of your favorite interests. This series will explore these ideas in weekly articles focused on topics chosen by the surveys.
What happens when plastic is discarded?
A significant fraction of plastic escapes the waste management pipeline and enters the environment through both intentional and unintentional human actions. Once plastic is exposed to the non-sterile environment, it begins accumulating a biofilm, and the properties that characterized the plastic during its life cycle begin to change. Thus begins the degradation process, the characteristics and timeline of which depends on the type of plastic, its intended use, its chemical and physical structure including additives, and the environment to which it is leached. Once exposed, a biofilm begins to form almost immediately.
What is a biofilm?
A biofilm is an ecosystem on a microscopic scale which is attached to a particle which could be natural or synthetic. It can consist of photosynthetic and heterotrophic organisms, including bacteria (some, but not all (or even most), of which can be harmful to human health), algae, and viruses (the majority of which target bacteria as their hosts). In addition to these living components, cellular byproducts or substances in the environment can become sorbed to the plastic surface and potentially transported long distances, including pollutants of concern such as heavy metals. This yields a complex interaction between discarded plastics and the environment which is still poorly understood, but which is vital to understand given the present and increasing loads of plastic that escapes the waste management system. It has been proposed that the biofilm community inhabiting plastics represents a unique ecosystem with as yet unknown effects on a global scale.
My story… as a plastic yogurt container
To start my yogurt containing career, I was forged from polypropylene, a type of plastic suitable for food storage. This is important to know because my degradation journey is based on my chemical structure and physical characteristics. In particular, polypropylene is a rigid and very crystalline structure, which makes it difficult for microorganisms to degrade (Maddah 2016). Also, I am a relatively low density plastic so when the tide comes in and takes me into the water I tend to float, because I am less dense than the brackish water in the Chesapeake Bay.My future
I thought I was going home to be with the other trash…there I was enjoying my trip on the dumpster truck back home to my landfill, having fulfilled my destiny as a conduit for yogurt…anyway, the next thing I knew, we all were jostled when we went over a big bump and out I flew into the great wide world. I thought maybe I would get picked up on the side of the road and back comfortably in a trash bag, but this was not so…the next few weeks were a blur.
Welcome to the beach
When I came to, I was all alone on a beach in what I presumed to be the Chesapeake Bay, based on my knowledge of geography that all young yogurt containers learned in primary school. I seemed to be in an intertidal location because for a portion of the day the sun would beat down on me and disrupt the chemical bonds that made me a suitable and durable container for yogurt (Gewert et al. 2018; Sorasan et al. 2021). Then, the tide would come in and temporarily submerge me. The ebb and flow of the water proved damaging as well by way of mechanical abrasion and this was the start of my fragmentation.
A social magnet
I seem to be a popular meeting area for all variety of organisms including bacteria, some archaea, fungi, microscopic plants, and even some animals. And it all happened so fast! Almost instantly (Rummel et al. 2017). They all gathered on my fragments because it afforded shelter from the dangers of the open water like sunshine, predators, nutrient limitation, and even some protection from some things like antibiotics (Flemming et al. 2016). Not only did this create a whole ecosystem but it also changed the buoyancy of my fragments and led to some of them sinking, sometimes all the way to the sediment, being consumed by animals higher in the trophic chain, or simply accumulating material until the surface was altered enough to fragment and serve as a source of allochthonous carbon for heterotrophic plankton.
All this could then lead to what was once a yogurt container becoming a part of the microbial or biological carbon pump, where the carbon I once contained could be incorporated into biomass, enter into the cycle of labile carbon, or be sequestered as refractory carbon in the water column or stored at the bottom of the ocean or in the sediment (Galgani et al. 2022). Conversely, the biofilm consisting of microorganisms, extracellular polymeric substances, and (in)organic matter shielded my fragment from the sun and prevented further degradation from UV light (Rummel et al. 2017).
A world traveler & meeting strangers
There were also some opportunistic animal pathogens such as Vibrio that just used my fragments to travel to places they otherwise couldn’t get to, they weren’t interested in the community generated by my fragments (Kesy et al. 2020). It is my recalcitrance that makes me a suitable vessel for transporting such organisms long distances–it takes much longer for my particles to break down than other detritus such as leaves or fecal snow.
A fragmented lifestle
Some of my fragments got so small that they can even cross cell membranes and wreak havoc on tissues of higher animals, possibly causing damage to the digestive or respiratory system. Although, an amphipod consumed some of my fragments and its digestive system created even smaller nano-fragments (Mateos‑Cárdenas et al. 2020), so my interaction with animals’ digestive systems can itself lead to further fragmentation, which can be redistributed into the environment once they are egested. It is these smallest of fragments too that can directly impact biogeochemical cycles in addition to indirectly via interaction with the microorganisms responsible for elemental cycling.
My future
In total, I will likely persist as fragments at varying stages of decomposition for a very long time, possibly centuries, and may be transported via currents and turbulence to oceanic gyres where plastic debris tends to accumulate, the deep ocean, various biota, or enter into the carbon cycle. When all is said and done, the final result will be the production of carbon dioxide from my hydrocarbon backbone, as well as transformation in a yet-to-be-discovered form of the additives I contain that once made me an excellent container for yogurt. I will contribute to the geologic record of the Anthropocene by making my home in a strata that in the years to come will define the time period where humans roamed the Earth, eating yogurt.
Introduction
Though there is general agreement that plastic takes a very long time to degrade, it might be worth thinking about what the degradation process is and the products generated by it. Plastic is a catch-all term for a diverse suite of materials, so understanding the degradation of plastic is extremely complicated and difficult to observe.
What is degradation?
It could be classified as mechanical or chemical. These do not occur in isolation and likely interact to generate a spectrum of differently sized and shaped fragments, and with different chemical properties. It is rare, more likely nonexistent, to understand the complete timeline of degradation starting with a “pristine” plastic.
Consider an empty water bottle. Has there ever been a water bottle exposed to the forces of nature, monitored until it was “completely” degraded? What does that mean? What does it look like? It remains a mystery. However, it is known that plastic that gets into the environment, and then into human bodies, can wreak biological havoc.
Amount of Degredation
Large plastics, still in the form that they were manufactured, can interact with large animals when mistaken for a food source, for example.
At the smaller end of the size range (which is much harder to detect), plastic can cross biological membranes and, for example, affect the endocrine system in humans by interacting with and disrupting our natural hormones. This is especially concerning considering that microplastics have been found in human blood and even fetuses.
Understanding the Degredation Process & Spectrum
To better understand how plastic harms wildlife and humans, we must understand how plastic degrades and how the spectrum of materials generated from this degradation process can affect organisms at every step, from a single cell to a whale whose digestive system is stuffed full of plastic. Plastics break down through a number of processes, including:
- Photodegradation: UV light can interact with oxygen to create free radicals which affect the plastic surface and cause structural chemical changes leading to disintegration.
- Thermooxidative degradation: High temperatures can cause similar changes as photodegradation but these effects penetrate beneath the surface layers.
- Hydrolytic degradation: Incorporation of a water molecule can break apart molecules of the polymer into its simpler constituent compounds.
- Biodegradation: Though generally resistant, microorganisms may, at some stages, be capable of metabolizing the carbon or additives in plastic.
Overview
The scientific study of plastic pollution is still relatively novel. It encompasses multiple disciplines depending on the type of information sought and there is disagreement among researchers about, for example, methods for quantifying plastic in the environment. There are questions about movement through the environment, toxicology (to humans and organisms throughout the food chain), facilitation of pathogen spread, degradation mechanisms, outcomes and timelines of breakdown, or affects on nutrient cycling, to name a few.
Goals
The baseline goal of monitoring and quantifying plastic pollution is still far from consensus, though there is fairly strong agreement on the type of steps performed. For example, samples can be collected from the water column, sediment, or different types of organisms (such as deep sea limpets). There are different types of instruments that can be used to this end, from a simple bucket scoop to a plankton net. Once the sample is collected, it undergoes processing in the lab.
Laboratory
The steps generally include a density separation, organic material digestion, staining with a fluorescent dye, and finally quantification of (micro)plastic. The purpose of the density separation is to divide the plastic from the rest of the sample—usually, a dense solution (for example, highly concentrated salt) is mixed with the sample so that the less dense plastic floats to the top layer, which is subsequently removed. Another step is the organic matter digestion, which removes material that could be potentially mistaken for plastic in the quantification step after the sample has been dyed. The final step is to mix the sample with a dye that fluoresces under blue light, which enables quantification of microplastic particles.
Future
This is one example of a workflow from sample collection to microplastic quantification. It is one of many possible solutions that have been proposed, and each step is performed slightly differently depending on the type of researcher, materials used, and the goal of the research.
The PFQAC Plastics Science series will explore the different plastic types and their characteristics. Below is a high-level summary of the individual articles to follow.
Polyethylene Terephthalate (PET or PETE) - #1
- Characteristics: Clear, strong, lightweight, gas/moisture barrier
- Common uses: Beverage bottles, food containers, synthetic fibers
- Recyclability: Highly recyclable, commonly accepted
- Recycled into: Fleece, fiber, new containers
High-Density Polyethylene (HDPE) - #2
- Characteristics: Stiff, strong, resistant to chemicals/moisture
- Common uses: Milk jugs, shampoo bottles, detergent containers
- Recyclability: Easily recycled, widely accepted
- Recycled into: Plastic lumber, recycling bins, pipes
Polyvinyl Chloride (PVC) - #3
- Characteristics: Strong, durable, good chemical resistance
- Common uses: Pipes, siding, flooring, medical devices
- Recyclability: Rarely recycled, difficult to process
- Environmental concerns: Can release toxic chemicals
Low-Density Polyethylene (LDPE) - #4
- Characteristics: Flexible, tough, good moisture barrier
- Common uses: Plastic bags, squeeze bottles, flexible lids
- Recyclability: Limited recycling acceptance
- Recycled into: Garbage can liners, floor tiles
Polypropylene (PP) - #5
- Characteristics: Heat resistant, strong, good chemical resistance
- Common uses: Food containers, auto parts, bottle caps
- Recyclability: Moderately recyclable, acceptance growing
- Recycled into: Ice scrapers, rakes, battery cases
Polystyrene (PS) - #6
- Characteristics: Lightweight, insulating, rigid or foamed
- Common uses: Foam cups, takeout containers, packaging
- Recyclability: Rarely recycled, difficult to process
- Environmental concerns: Breaks into small pieces, persists in environment
Various Other Plastics - #7
- Includes: Polycarbonate, acrylic, nylon, bioplastics
- Characteristics: Vary by specific type
- Common uses: Water bottles, sunglasses, electronics
- Recyclability: Generally not recyclable through standard programs
Polyethylene Terephthalate (PET)
Polyethylene Terephthalate (PETThere are two major categories of plastic, thermoset and thermoplastic:
- Thermosets are produced by hardening a malleable substance (non-recyclable).
- Thermoplastics are produced by heating and shaping to form products (recyclable).
Polyethylene Terephthalate (PETPolyethylene terephthalate (PET or PETE) is a thermoplastic often used to produce beverage or food containers, clothing fibers, and other common products (see below). This type of plastic comprises about 9% of the total plastic industry mainly in the form of packaging. Its increasing pattern of demand follows that of total plastic production.
Common Uses & Applications
PET's versatility makes it ideal for various applications:
Food and Beverage Packaging
- Carbonated drink bottles
- Water bottles
- Food containers
- Condiment bottles
- Ready-meal trays
Textile Industry
- Polyester fibers
- Clothing
- Industrial fabrics
- Upholstery materials
Other Uses
- Medical packaging
- Film and sheet materials
- Strapping materials
- Electronic components
Chemical Structure & Properties
Polyethylene terephthalate (PET) is a thermoplastic polymer formed through a polycondensation reaction between terephthalic acid and ethylene glycol. Its molecular structure consists of repeating C10H8O4 units, creating long polymer chains that give PET its characteristic properties:
- High tensile strength
- Chemical resistance
- Clarity and transparency
- Excellent moisture barrier
- Good gas barrier properties
- Temperature resistance up to 70°C (158°F)
- Density of 1.38 g/cm³
Environmental Impact
Due to its lightweight and low density, PET tends to float which characterizes its environmental effect and the type of wildlife it encounters. In addition, the additives added during the manufacturing process may leach into the contents of the container and be consumed by humans.
Advantages
- Highly recyclable.
- Lower energy production footprint compared to glass.
- Lightweight reduces transportation emissions.
- Can be recycled multiple times.
Challenges
- A significant contribution to plastic waste.
- Microplastic generation through degradation.
- Marine ecosystem impacts.
- Long decomposition time (450+ years).
- The production relies on fossil fuel resources.
Recycling Process & Opportunities
PET can be indefinitely recycled to yield products like food containers, carpet fibers, or non-food containers. beverage containers (bottle-to-bottle), polyester fiber for clothing, carpeting materials, industrial strapping, food packaging materials, and construction materials.
The recycling process is summarized in the following steps:
- Consumer collection through recycling programs
- Automated sorting using infrared technology
- Manual quality control
- Separation by color and quality
- Crushing and grinding into flakes
- Washing to remove contaminants
- Separation from other plastics
- Drying and decontamination
- Melting and reforming
Overview
The two types of polyethylene (low and high) are the most commonly used types of plastic and are found in many everyday items such as containers and also construction materials. We are likely to encounter this type of plastic very frequently.
Common Uses & Applications
One interesting application of HDPE is as a liner in landfills to prevent pollutants from leaching into groundwater or soil. While products made of HDPE pile up in the landfill, HDPE in another form provides protection from the detriments of plastic pollution. Such an application highlights the benefits of plastic that have led to their proliferation and infiltration of every corner of society and the complexity when it comes to risk assessment. It also demonstrates the variability of products that can be produced from even a single type of plastic. It is also used in other construction settings or automobiles.
Chemical Structure & Properties
The production and resultant chemical structure of HDPE depends on its desired function. The monomer constituent of HDPE is ethylene which is a colorless, flammable gas and a hydrocarbon. Ethylene subunits are linked together, the process of which determines the plastic’s characteristics. Key steps in the process include temperature, pressure, and cooling time. These will affect the extent of crystallinity (this could be thought of as regularity or structure) of the plastic, which will determine the properties of the plastic such as flexibility or rigidity, strength, and chemical stability.
Environmental Impact
Like other types of plastic, the degradation timeline is long and mechanical or chemical fragmentation, when it does occur, results in production of smaller pieces of plastic known as microplastic. However, the shape generated in the fragmentation of HDPE may be less harmful to organisms than other types of plastic. There is risk of accumulation in soils, groundwater, surface water, or tissues of organisms. Another major environmental impact is the production of toxic or greenhouse gases during plastic production including methane, carbon monoxide, or nitrous oxide. Petrochemical plants where plastics are manufactured leach toxic substances in the air and water of surrounding communities, often leading to heightened incidence of cancer and other serious illness.
Recycling Process & Opportunities
Since HDPE is a thermoplastic, it is recyclable. The process generally includes collection, sorting, cleaning, shredding, heating/melting, and molding into new products. This type of plastic can be “upcycled” into plastic “lumber” that can be used to create structures and this process can be a good source of employment opportunities.
A single-use plastic bag pollutes the environment throughout its entire lifecycle - from manufacturing to disposal - while serving its purpose for a very short time. This stark imbalance between momentary convenience and lasting environmental damage exemplifies the unsustainable nature of single-use plastics. This type of plastic pollution has a relatively simple, straightforward solution: reusable bags.
Plastic bags are made from oil and natural gas - finite resources with well-documented environmental impacts. While our dependence on fossil fuels for transportation and energy remains unavoidable due to limited alternatives, single-use plastic bags represent an unnecessary drain on these resources, especially given the readily available alternatives.
Banning single-use plastic bags in favor of reusable alternatives would conserve significant non-renewable resources. While paper bags might seem like a viable alternative, they too present environmental challenges, requiring the harvest of trees - another finite resource. There's no justification for depleting our forests when durable, reusable bags offer a superior solution.
Despite having a clear alternative, we continue to default to the convenience of single-use plastic bags. The shift to reusable bags represents a simple yet significant step toward sustainability - one that requires minimal sacrifice while yielding substantial environmental benefits.
Let the Commissioners know that you want the Centreville Ordinance on Single-use Plastic Carry-out Bags expanded to the rest of Queen Anne’s County.
Just leave a message by call or email.
410-758-4098
The Chesapeake Bay is home to a diverse array of fish species, including both saltwater and freshwater varieties.
Saltwater Fish
Striped Bass (Rockfish): The most iconic fish of the Bay, prized for its fighting ability and delicious taste.
Bluefish: Aggressive predators with sharp teeth, known for their fast-paced fishing action.
Speckled Trout: A popular game fish that thrives in the Bay's brackish waters.
Red Drum: A powerful fish that puts up a strong fight when hooked.
Croaker: A small, bottom-dwelling fish that is a popular target for recreational anglers.
Spot: Another small, bottom-dwelling fish that is commonly used as bait for larger fish.
Flounder: Flatfish that camouflage themselves on the bottom of the Bay.
Cobia: Large, migratory fish that are often found near structures like wrecks and piers.
Spanish Mackerel: Fast-swimming predators that are a popular target for anglers.
Black Drum: Large, bottom-dwelling fish that can grow to impressive sizes.
Black Sea Bass: A popular game fish that is often found around structures.
Tautog: A bottom-dwelling fish that is known for its tough fight and delicious taste.
Freshwater Fish
Largemouth Bass: A popular game fish that is found in many of the Bay's tributaries.
Smallmouth Bass: Another popular game fish that is found in clearer, cooler waters.
Catfish: A variety of catfish species, including channel catfish and blue catfish, are found in the Bay's freshwater rivers and streams.
Sunfish: A variety of sunfish species, including bluegill and redear sunfish, are popular panfish.
Crappie: A popular panfish that is often found in the Bay's tidal rivers and creeks.
Perch: A variety of perch species, including white perch and yellow perch, are common in the Bay's freshwater tributaries.
This is just a small sample of the many fish species that can be found in the Chesapeake Bay. The Bay's diverse ecosystem provides habitat for a wide variety of fish, making it a popular destination for anglers of all skill levels.
