Plastics Flashcards
(36 cards)
What has caused the dramatic increase in marine debris since the mid-20th century?
The surge in the use of synthetic plastic materials—valued for their durability, low cost, and versatility—has led to widespread plastic waste. Since plastics do not biodegrade, they accumulate in natural environments, particularly in oceans and coastal zones.
How much plastic waste was estimated to have entered the ocean from land in 2010?
Between 4.8 and 12.7 million metric tons of plastic entered marine systems from land-based sources, primarily through rivers, stormwater runoff, and mismanaged waste disposal.
What role does international trade play in plastic pollution?
Countries like the USA and UK export large quantities of plastic waste for recycling. However, inadequate handling in receiving countries often leads to improper disposal and leakage of plastic into rivers and oceans.
What proportion of marine litter is made up of plastic items?
Up to 80% of marine litter consists of plastic, reflecting its dominance among marine debris and highlighting the persistent nature of plastic pollution in the ocean.
Why do plastics remain in the marine environment for so long?
Plastics are non-biodegradable and resistant to environmental degradation. Their chemical stability means they persist for decades or even centuries, causing long-term environmental damage.
How many plastic pieces are estimated to be floating in global oceans?
Estimates range from 15 to 51 trillion plastic particles, showing the vast and difficult-to-measure scale of plastic pollution on the ocean’s surface and in deeper layers.
What percentage of plastic has been recycled, discarded, or produced recently?
Less than 10% of plastic has been recycled, more than 50% has been discarded (often to landfills or the environment), and over half of all plastic ever produced was made after 2000, reflecting a rapid production increase.
Where does a large portion of plastic waste end up?
Much of it remains near shorelines, in estuaries, or on beaches, contrary to the belief that most plastic floats into the open ocean.
What defines microplastics, and how prevalent are they?
Microplastics are plastic particles smaller than 5 millimetres. They are extremely widespread, with approximately 4.85 trillion microplastic particles estimated to be present in the oceans globally.
What are primary microplastics?
These are intentionally produced small plastic particles, such as microbeads (used in cosmetics), nurdles (raw plastic pellets), and microfibres (shed from synthetic fabrics during washing).
What are secondary microplastics?
These form from the breakdown of larger plastic debris through environmental forces like sunlight (UV exposure), wave action, and abrasion, leading to fragmentation into smaller pieces over time.
How does degradation contribute to microplastic generation?
UV radiation and physical stress weaken the polymer bonds in plastics, causing them to fragment into smaller pieces, which increases their surface area and environmental exposure.
What factors influence the movement of microplastics from freshwater to coastal waters?
The polymer type, size, and density of plastic particles determine whether they float or sink, and how far they are transported by currents from rivers into estuaries and coastal marine environments.
How does plastic density affect its buoyancy in different water bodies?
Plastics with density < 1.0 g/mL (like polypropylene) float in freshwater and seawater. Plastics with density > 1.0 g/mL may sink in freshwater but could float in denser seawater (typically ~1.02–1.03 g/mL).
Give examples of low- and high-density plastics.
Low-density: Polypropylene (PP) ~0.9 g/mL
High-density: Polytetrafluoroethylene (PTFE/Teflon) ~2.2 g/mL, PVC >1.3 g/mL
What happens to negatively buoyant plastics in oceanic waters?
They sink and accumulate in benthic (bottom) habitats, which may have long-term ecological effects on organisms that dwell on or near the seafloor.
What impacts do large plastic items have on marine life?
Larger items can entangle marine animals, block digestive tracts, and lead to injuries, suffocation, or death, especially among turtles, seabirds, and marine mammals.
How do microplastics affect marine ecosystems?
Microplastics are ingested by a wide range of organisms, from zooplankton to large fish, disrupting feeding behavior, digestion, reproduction, and entering the food chain.
What are nurdles, and why are they harmful?
Nurdles are small plastic pellets used in plastic production. Marine animals mistake them for food, which can cause malnutrition, internal injury, and contribute to toxic chemical exposure.
What toxic substances do microplastics adsorb in the ocean?
Microplastics attract and bind toxins like DDT, PCBs, and heavy metals, making them even more dangerous when ingested by marine organisms.
How does size affect microplastic bioavailability?
Smaller particles are more likely to be mistaken for food or passively ingested by filter feeders like zooplankton and bivalves. Particles from 0.5 to 816 µm have been observed in marine organisms.
Why does plastic density influence bioavailability?
Denser plastics can develop biofilms quickly, altering their appearance and increasing the likelihood of ingestion by species that feed on organic matter or detritus.
How does abundance influence bioavailability?
The greater the abundance of microplastics in a given environment, the higher the probability that organisms will ingest them either intentionally or accidentally.
How does colour affect plastic consumption?
Marine organisms are attracted to certain colours. For instance, copepods and euphausiids prefer red, blue, or black particles, making plastics in those colours more likely to be consumed.
