Presentación que se desarrollo para la población estudiantil y publico en general en la ciudad de Huarmey y por invitación de la SubGerencia de Gestión Ambiental del Municipio Provincial de Huarmey, en favor de concientizar y brindar educación ambiental a la población, gracias por esta oportunidad.
4. Plásticos en Nuestro Planeta Tierra
A medida que la demanda mundial de materiales plásticos sigue creciendo, La gestión de los residuos
plásticos seguirá siendo un desafío mundial. En 2014, la producción mundial de plástico superó los 311
millones de unidades métricas de toneladas, un aumento del 4,0% con respecto a 2013.1 En 2010, de 2,5mil
millones de toneladas métricas de residuos sólidos generados por 192 países, alrededor de 275 millones de
toneladas consistieron en plástico. Se estimó que entre 4,8 y 12,7 millones de toneladas terminaron en el
océano como resultado de una gestión inadecuada de residuos sólidos.
La preocupación por los desechos plásticos visibles está aumentando, mientras que La investigación informa
sobre la creciente presencia y abundancia de microplásticos en ambientes marinos. Estas pequeñas piezas de
plásticos, entre el tamaño de un virus y una hormiga, ahora se pueden encontrar en todo el mundo: en el
agua de los lagos y mares, en el sedimento de ríos, mares y deltas, y en los estómagos de varios organismos
que van desde el zooplancton hasta las ballenas. Microplásticos han sido detectados en entornos tan
remotos como un Lago de montaña de Mongolia y sedimentos de aguas profundas depositados cinco
kilómetros por debajo del nivel del mar. Un estudio estimó que, en promedio, cada kilómetro cuadrado de
los océanos del mundo tiene 63,320 partículas de microplástico flotando en la superficie, con variaciones
regionales significativas, por ejemplo, concentraciones en los mares de Asia oriental son 27 veces mayores.
Organismos marinos–incluyendo zooplancton, invertebrados, peces, aves marinas y ballenas: pueden estar
expuestas a microplásticos a través de ingestión de agua e indirectamente como depredadores en las redes
tróficas.
5. Existen 7 océanos principales en el mundo.
¡El 71% de la superficie de la Tierra está cubierta por océanos!
6. Zona neustónica: En la superficie
– Aquí es donde se encuentra la
mayor parte de la contaminación
plástica. Muchos tipos de plásticos
que utilizamos a diario (polietileno,
poliestireno, polipropileno) flotan
porque su densidad es menor que
la del agua de mar.
Zona pelágica: Debajo de la superficie
– A veces, el viento empuja el
plástico debajo de la superficie.
Zona bentónica: En el fondo marino
– os tipos de plástico que son más
densos que el agua de mar
terminan en el fondo del mar.
Zona Neustónica
Zona Pelágica
Zona Bentónica
7. Viento
La fricción del viento en el agua superficial
hace que comience a moverse en la misma
dirección.
+ Rotación de la Tierra
El agua empujada por el viento se desvía a la
derecha de su trayectoria en el Hemisferio
norte y a la izquierda de su trayectoria en el
Hemisferio sur.
Esto se llama efecto Coriolis.
= Corrientes oceánicas
8. El origen del plástico
• Sintetizado en 1907
• Barato
• Energía mínima
• 20 principales tipos (North y Halden, 2013)
Retrieved from http://exclusive.multibriefs.com/content/walmart-
joins-worldwide-effort-to-reduce-its-plastic-consumption/waste-
management-environmental
Retrieved from https://www.recycleandrecoverplastics.org/plastic-
materials/plastic-bottles/plastic-bottles-istock-926200658-medium-2/
Retrieved from https://www.dailydot.com/irl/straw-ban-ableism-
restaurant-thread/
9. Producción de plástico
• 1950 1.5 millones tons
• 2014 299 millones tons
• 2019 1.3 billones tons
• 8 millones tons enter the oceans (Nelms et al., 2015)
Retrieved from https://www.sundried.com/blogs/news/how-bad-is-the-global-plastic-pollution-problem-and-what-can-we-do-
about-it
11. Categorías de contaminación por
plásticos
• Plásticos grandes
o Entrelazamiento
o Ingestión con efectos visibles
• Plásticos pequeños
o Ingestión
o Obstrucción gástrica
o Efectos fisiológicos
o Transferencia trófica
Retrieved from https://inhabitat.com/peanut-the-story-
behind-the-poor-sea-turtle-deformed-by-a-six-pack-ring/
Retrieved from https://ocean.si.edu/ocean-
life/seabirds/laysan-albatrosses-plastic-problem
12. ¿Qué es el plástico?
¿Cuáles son sus propiedades
químicas?
¿ Cuáles son sus propiedades físicas?
¿Cuáles son los pros y los contras de
usar plástico?
14. El petróleo es el hidrocarburo que
se encuentra debajo de la
superficie de la Tierra, enterrado
en las rocas.
Es un combustible fósil; se formó
durante millones de años a partir
de plantas / animales muertos que
fueron enterrados bajo muchas
capas de sedimento.
Los seres humanos extraen el
petróleo de la Tierra y lo refinan
para fabricar gasolina, plásticos y
otros productos.
¡El petróleo es un recurso
limitado!
15. el término científico para el plástico es:
sin tetico poli mero
juntos
para establecer
muchas
partes
juntar muchas partes; también conocido como material hecho por el hombre
16. polimerización
De esto están hechas las
bolsas de plástico.
monomero = una parte
polimero = muchas partes
Ejemplo: Etileno
Polietileno
17. Todos los plásticos son orgánicos:
contienen átomos de carbono.
Otros materiales orgánicos son:
- Madera (celulosa)
- Cabello (queratina)
- ADN
19. Tipos de termoplásticos
Se puede reformar cuando se
calienta(como un cubo de hielo)
PE = Polietileno (bolsas)
PP = Polipropileno (material de
laboratorio científico)
PA = Poliamida (nailon)
PVC = Policloruro de vinilo
(tuberías)
PS = Poliestireno (espuma de
poliestireno)
Tipos termoendurecibles
No se puede reformar cuando se
calienta(como un huevo)
• Poliéster (suéteres)
• Silicona
¡El plástico no se puede reciclar indefinidamente como el
vidrio o el metal!
20. Los tipos de termoplásticos se pueden
Por ejemplo, el plástico de una botella de
agua podría usarse para hacer un banco de
parque.
El reciclaje se produce cuando más de un tipo
de plástico se recicla a la vez.
Con cada ciclo, el valor del producto
disminuye. Por lo tanto, hay un número
limitado de veces que se puede reciclar el
21. los compuestos se
descomponen en compuestos
naturales más simples
mediante agentes biológicos;
p.ej. bacterias.
La mayoría de los plásticos no
son biodegradables.
Algunos plásticos biodegradables
se han fabricado a partir de
almidones vegetales, pero aún
necesitan condiciones específicas
para degradarse.
los compuestos se
descomponen en partes más
pequeñas del mismo
polímero por radiación UV; es
decir, la luz del sol.
La mayoría de los plásticos se
fotodegradan con el tiempo.
El polímero plástico sigue siendo
el mismo, pero se vuelve
quebradizo y se rompe en
pedazos diminutos que se liberan
fácilmente al medio ambiente.
22. No sabemos con certeza cuánto tiempo tarda
el plástico en descomponerse de un objeto en
pequeños fragmentos llamados
microplásticos.
Pero, lo que realmente importa es que al
final, el plástico se quedará en el océano,
como piezas microscópicas que ni siquiera
podemos recoger en una red.
¡Con un tamaño tan pequeño, el plástico aún
puede ser dañino para los animales marinos!
24. METALES VIDRIOS PLÁSTICOS RESIDUOS
ORGÁNICOS
PELIGROSOS GENERALES PAPEL Y
CARTÓN
TIPOS DE RESIDUOS
DE ACUERDO A LA LEY N° 27314
“LEY GENERAL DE RESIDUOS SOLIDOS”
NTP 900.058.2005
NTP 900.058.2005 “ Código de Colores
para los Dispositivos de Almacenamiento de los Residuos”
25. TIEMPO DE DEGRADACIÓN
1-5 MESES 1-2 AÑOS 3-5 AÑOS 30 AÑOS 40 AÑOS
100-AÑOS 200 AÑOS 1000 AÑOS 1000 AÑOS NO SE DEGRADA
1-2 MESES
600 AÑOS
26.
27. Pros
1. Sirve para muchos propósitos
diferentes para hacer nuestras
vidas más eficientes
2. Ligero y duradero
3. Sirve para muchos propósitos
médicos
4. _______________
5. _______________
Contras
1. Está hecho de un recurso no
renovable: los combustibles fósiles.
2. No se biodegrada y degrada nuestro
medio ambiente en cambio
3. No se puede reciclar indefinidamente
4. ________________
5. ________________
28. ¿Qué son los microplásticos?
• Piezas más grandes cuantificadas en piezas
más pequeñas
– Movimientos de olas
– Luz ultravioleta
– Abrasión física
Retrieved from https://www.brushmable.com/blogs/mable-lifestyle/microplastics-the-smallest-big-problem
29. ¿Qué se clasifica como microplástico?
• Clasificados según longitude
• <5 mm considerados microplásticos
(Oberbeckmann et al., 2015, p. 554)
31. ¿Cómo afectan los microplásticos a los organismos
acuáticos?
• Respiración
• Ingestión directa o indirecta
• Obstrucción gástrica
• Efectos fisiológicos
– Toxicidad hepatica
– Alteración endocrina
– Plaguicidas
– Microorganismos
Retrieved from https://www.odt.co.nz/news/national/still-waiting-—-long-road-marine-protection-
area
Retrieved from https://www.worldwildlife.org/stories/what-do-sea-turtles-eat-
unfortunately-plastic-bags
32. ¿CUÁLES SON LOS EFECTOS DE LOS RESIDUOS
SOLIDOS EN LAS ESPECIES ACUÁTICAS?
33. Incluyendo:
Asfixia
Enredo
Hambruna
[Jeanne Gallagher] photographer, Cynthia Vanderlip
[Jeanne Gallagher] unknown--Courtesy of Algalita Marine Research Foundation
Los efectos perjudiciales de los macroplásticos
en la vida silvestre están bien documentados,
particularmente en ambientes acuáticos.
Seal entangled in plastic Photographer unknown
Snapping turtle deformed by plastic
Albatross chick ingesting plastic
34. “Los desechos plásticos se están acumulando en hábitats terrestres y acuáticos en todo el mundo.
Estos escombros se están fragmentando progresivamente en pedazos más pequeños ... La abundancia
en la columna de agua ha aumentado considerablemente en los últimos 40 años, y esta tendencia
refleja el aumento global de la producción de plástico ”. (Browne, Galloway y Thompson, 2009)
[Jeanne Gallagher] Courtesy of Algalita Marine
Research Foundation
Microscopic plastic particles
35. Fragmentos de plástico ingeridos
por organismos marinos
"... los estudios han demostrado que los microplásticos son ingeridos
por una gran variedad de taxones marinos ... incluyendo aves,
mamíferos, peces e invertebrados ... los microplásticos pueden pasar a
través de la red trófica a medida que los depredadores consumen
presas". (GESAMP 2015)... los animales que se alimentan por
filtración, como las jaleas y las salpas que se alimentan de redes
mucosas, fueron ... fuertemente impactados por los fragmentos de
plástico ... Los alimentadores por filtración están en el extremo inferior
de la cadena alimentaria, ... se sabe que cincuenta especies de peces y
muchas tortugas se los comen ... acumulando plástico en sus
estómagos ". (Tamanaha y Moore, 2007)
[Jeanne Gallagher] Courtesy of Algalita Marine Research Foundation
Microplástico en el tracto
digestivo de un anfípodo
Ingestión de plástico con sal
36. Los microplásticos trasladados del intestino a la hemolinfa de una especie
de mejillón (Mytilus edulis) persistieron durante más de 48 días.
Study by Browne, Dissanayake, Galloway, Lowe & Thompson (2008):
Depredadores de
mejillones:
• aves
•cangrejos
•estrella de mar
•buccinos depredadores
•humanos
37. "Se detectaron concentraciones relativamente altas de microplásticos
en mejillones y ostras belgas cultivados comercialmente ... Como
resultado, la exposición alimentaria anual para los consumidores
europeos de mariscos puede ascender a 11.000 microplásticos por
año". (GESAMP, 2015).
“En 2015, los investigadores tomaron
muestras de pescados y mariscos que
se vendían para consumo humano en
los mercados de Indonesia y
California. Encontraron fibras
plásticas y textiles en una cuarta parte
de los animales ”. (Krieger, 2016)
38. “Cuando los humanos o los roedores ingieren microplásticos, se ha
demostrado que se trasladan del intestino al sistema linfático y circulatorio ...
pueden comenzar a surgir efectos adversos debido a las interacciones de las
partículas con las células y los tejidos ... estos incluyen efectos nocivos a nivel
celular ... La exposición humana es también motivo de preocupación si se
consumen mariscos que contienen microplásticos ”(GESAMP, 2015)
Micro-partículas de plástico
39. Los fragmentos de plástico concentran contaminantes
orgánicos persistentes (COP) y los transfieren a todo
el mundo y a los organismos vivos.
"... se ha demostrado que el plástico adsorbe y concentra
contaminantes hidrófobos, incluidos bifenilos policlorados, diclorodifenil
tricloroetano y nonilfenol, del medio marino en concentraciones varios
órdenes de magnitud superiores a las del agua de mar circundante".
(Mato et al., 2001)
“Si se ingieren plásticos, podrían actuar como un mecanismo que facilite
el transporte de productos químicos a la vida silvestre. Esto puede ser
particularmente relevante para los microplásticos, ya que tendrán una
proporción mucho mayor de área de superficie a volumen que los
artículos más grandes ... ”(Browne et. Al., 2009)
40. "... los cálculos y las
observaciones
experimentales
muestran
consistentemente que el
polietileno (PE) acumula
más contaminantes
orgánicos que otros
plásticos como el
polipropileno (PP) y el
cloruro de polivinilo
(PVC)". (Teuten et. Al.,
2009)
41. Microplásticos primarios vs secundarios
• Primarios
– Tamaño de micras
– Producción
industrial: textil,
farmacéutica,
cosmética
• Secundarios
– Fragmentación y
degradación
– Agricultura, ropa,
pesca, automóvil,
hogar Retrieved from https://encounteredu.com/multimedia/images/sources-of-microplastics
42. ¿Cómo se transportan los microplásticos a lo
largo de la cadena alimentaria?
(Medrano et al., 2015, p. 76)
43. ETAPA DE LOS MICROPLÁSTICOS EN LA RED TRÓFICA
6) CONSUMO POR
HUMANOS
1) FOTODEGRADACION
2) ABSORCION
DE TOXICOS
3) ALIMETACION
DE PLACTON
4) ALIMETACION DE
ESPECIES MARINAS
5) CONSUMO POR
MAMIFEROS
63. “UNAM cuna de los grandes hombres y mujeres del presente y
futuro”
“Cuidado y sostenibilidad de los ecosistemas
acuáticos marinos”
“UNIVERSIDAD NACIONAL
DE MOQUEGUA”
64. “DETERMINACIÓN DE
MICROPLÁSTICOS EN ESPECIES
ÍCTICAS E INVERTEBRADOS DEL
LITORAL,
PUERTO DE ILO-PERÚ”
TESISTAS:
Romy Lizett Montalván
Vásquez
Yordy Armando Dávila Lima
65.
66. MEDIO AMBIENTE Y
RECURSOS NATURALES
MARINOS
GRUPO DE
INVESTIGACION Y
TECNOLOGIA DEL
AGUA (CONTINENTALES
Y MARINO COSTEROS)
67.
68.
69.
70.
71.
72. UBICACIÓN
Punta Coles se ubica al sur del Perú (17°42'04.63” S – 71°22'21.41” O) en la provincia de Ilo, región Moquegua.
Se encuentra a 7 km al suroeste de la provincia de Ilo.
73. Potoyunco El piquero peruano El pelícano peruano El cormorán guanay
El pingüino de Humboldt El albatros viajero Gaviota peruana Gaviota Dominicana
71 % of the Earth surface is covered by ocean!! The vastness of the ocean makes it seem infinite, but even so, human activities have affected the most remote areas. Plastic has been found to accumulate in very high concentrations in at least 5 (NP, NA, SP, SA, Indian) of the 7 oceans (circled in red).
Not only is the ocean wide, but it is deep! The average ocean depth is between 4 and 6 kilometers. The deepest part of the ocean is the Mariana Trench which is 11 km.
However, most plastics are slightly less dense than seawater (which is about 1000 kilogram per cubic meter or 1 g/cm^3)
This means that they float at the surface of the ocean. The very top layer of the ocean is called the neustonic (pronounced “Newstonic”) zone.
The microplastic doesn’t float on top of the surface, like you’ll find many larger objects. Rather, they are found stuck to the bottom of the surface layer through surface tension. Due to their small size and the reflective properties of the surface layer, these pieces are hard to see from above the surface, standing at the rail of a ship for example.
Below the neustonic zone, you’ll find the pelagic zone. Some plastics can be found in this layer when they are mixed below the surface by wind and waves. Some plastics will sink when their density increases due to bacteria, algae or other animals that grow/live on them. Another process which may cause plastics to move down through the water column is photodegradation. Polystyrene plastic is actually more dense than water, but in its Styrofoam form it floats because of trapped air. When polystyrene polymers break off, they can sink.
The lowest layer of the ocean is called the benthic zone. This is the part of the ocean just above the seafloor. Plastics which have a density higher than seawater are found here. Due to the difficulty of sampling plastic from the seafloor, there is not very much data about how much plastic is actually there. It is safe the say though, that the most benthic plastics will be found near the coast, the source of most plastic marine debris.
There are two main forces which cause the ocean surface currents.
The first is the wind.
Wind blowing over the surface of the ocean pulls the water at the surface of the ocean by friction.
Think of the beach on a windy day… the sand blows with the wind and the surface of the ocean looks rough and choppy.
There are different wind systems which dominate various latitudes zones of the globe. In the region between the Equator and about 30 degrees North and South, the winds move from East to West. These are called the Trade Winds.
Further north to that, between 30 degrees and 60 degrees in both the Northern and Southern Hemisphere, the wind blows mainly from the West to the East. These winds are called the Westerlies. In the region between 60 degrees and the North and south Pole, the winds blow from East to West just like the Trade winds. These winds are called the Polar Easterlies.
If wind was the only force moving the surface water, we would expect the surface water to move in the same way as the wind.
But as we saw in the video, that’s not what we observe.
The second force which determines the surface currents is the rotation of the Earth. Earth rotates from West to East on a titled axis around the sun.
This causes water to be deflected (or pushed) off its path. One way to describe this effect is to tell the students to imagine being on a merry go round at the fair. If you walk in a straight line from one side of the merry go round to the other while it is spinning, you will end up further to the left than you expected (if it is spinning clockwise), and to the right if it is spinning counterclockwise.
This effect is called the Coriolis Effect.
The wind and Earth rotation together are the main forces which cause the large scale surface currents (gyres pronounced “jire”). On a smaller scale, there are many other factors which cause the complex patterns that you saw in the video.
Durable, made to last – hence the persistence in our oceans
Despite the deleterious implications of trophic transfer of pollutants and the consequent increased awareness about plastics in the environment, the demand for plastics has continued to rise over the past sixty years due to their durability and low cost (Kitamoto et al., 2011).
Evidence has demonstrated that all continents are affected by plastic pollution, and consequently the gravity pollution of water sources has dramatically intensified (Gregory, 2009).
As plastics are persistent contaminants, it is inevitable that marine species will encounter plastic items and be impacted through ingestion and entanglement.
Although these effects can be easily observed when organisms become entangled in larger plastic items, there are less obvious repercussions from minuscule pieces of plastics known as microplastics.
Ingestion with visible effects example: sea turtle with straw lodged in its nasal and throat passages
Lets get started!!
In this first part of the presentation, we will discuss 4 main questions. Answering them will help us understand what exactly plastic is. It is such a fundamental aspect of our lives that everyone should know what it actually is.
Here are some images of different items that we use everyday. They are all made out of plastic. Toys, containers, water bottles, utensils, synthetic clothing… the list goes on.
Plastic has so many different appearances. How can so many different things with so many different functions be made out of the same thing?!
Plastic is not found in nature. We can’t grow it, or get it from a tree. It is human made. So what is it made out of?? And how does it become plastic?
Plastic is made out of the same thing which we use to drive our cars. It is a limited resource!!! This means that there is a finite amount of it on earth, and it does not regenerate as quickly are we are using it. Fossil fuels were formed over millions of years, but we are pumping it out of the ground at a rate of about 88 million barrels/ day or 3.5 billion gallons each day!! This could not go on indefinitely even if the entire globe was filled with petroleum (which it isn’t).
So now that we know what it is made of, we want to know HOW it is made..
Let’s first take a look at the origins of the word “plastic”
Plasticos is Greek for “to be molded or shaped”
The scientific term for plastic is “synthetic polymer”
If we break down this term into smaller parts we can better understand what it means.
Syn means together
Thetic refers to “to set down”
Poly means many
Mer means part
When we put these all together we get “to set together many parts”
This gives us a clue as to how plastic is made, and makes us wonder, “What are these parts?”
Plastic is formed from the chemical bonding of many small molecules: kind of like a long daisy chain, or paperclip chain.
Each small part is called a monomer (which means “one part”). Through the chemical process of polymerization, long chains called polymers are formed.
One example is Ethylene which is polymerized to form polyethylene; an enzyme catalyzed reaction.
An ethylene molecule is 2 carbon atoms connected by a double bond where each carbon is also bonded to two hydrogen atoms.
This is one of the most simple plastic monomers, and also most commonly used. About 80 million tons of polyethylene are produced each year. Many single use plastic items are made from polyethylene, including the infamous shopping bag, lunch baggies, water bottles.
Ethylene is only one monomer. There are different monomers and many types of plastic.
All plastics are organic. This means that they contain carbon.
You can think of carbon as the backbone for the polymer chain.
Carbon is the 6th element in the Periodic Table.
It contains 6 neutrons and 6 protons in its nucleus, and has 6 electrons.
The four electrons in the outer shell/ring, allow for carbon to make 4 bonds. This arrangement allows many different combinations or ways for carbon to bond. Many chained molecules found in nature contain carbon as the “backbone.”
For example, wood (cellulose), hair (keratin) and DNA are all organic chained molecules which use carbon as the connecting piece.
Now that we understand the chemical structure of plastic, we can look at the industrial process through which plastic is made.
Step 1. Crude oil is drilled and pumped out of the ground and is transported to an oil refinery.
This is where the oil is heated over many steps to very high temperatures. At each temperature stage a different product is formed. Refined oil containing the plastic monomers are produced at the highest temperatures.
Step 2. The oil is transported to a petrochemical plant where the polymers are formed through chemical reactions using catalysts. The polymerization process results in masses of plastic resin (often in the form of “nurdles” or pellets).
Step 3. At a production factory, the plastic resin is reheated and combined with additives and other chemicals depending on the end-product and is molded/shaped into the end product.
There are 2 main categories of plastic: Thermoplastic types and thermoset types.
The two types are distinguished by their properties after production. Thermoplastic types are more versatile because they can be melted and reshaped multiple times. A good analogy is an ice cube: water can be frozen in a certain shape, then melted and frozen again in a different shape.
Thermoset plastics are shaped, then after which polymers are permanently cross-linked. These types of plastics can’t be reshaped or recycled in any way.
Frying an egg is a good analogy for producing thermoset plastics. After they are cooked, the egg cannot be reshaped.
The most common types of plastics we use in our daily lives are thermoplastics. However, thermoplastic does not mean that plastics can be recycled indefinitely in the way that glass and metal can.
Ask your students if they recognize the names for any of these plastics types listed on the slide.
Plastics are very difficult to recycle because the plastic must be sorted carefully and may not contain any other plastic types or materials.
It must be cleaned first and cut into small pieces.
Sorting plastics is difficult because it is hard to determine what kind of plastic an item is made of if it is not labeled.
Plastics are usually contaminated in someway. Either several plastic types are used in the same product, or the plastic was made with many additives and other chemicals which change its properties.
All of these things make recycling plastic a very inefficient and costly process. As a result, most plastics are not recycled; even the ones you put in your recycling bin!!!
So what happens to all the plastics which don’t become recycled or down-cycled???
Plastics are not biodegradable, like most natural waste (food scraps, paper, gardening waste, etc..)
This is because polymers are too large for bacteria to digest and break down.
Instead, plastics degrade over time when they are exposed to the Ultra violet radiation from the sun. These high-energy rays slowly break the bonds in the polymers, causing the plastic to become brittle. You can ask your students if they have ever sat in a plastic patio chair which has been outside for several summers. Perhaps they have notices the small cracks, powdery feeling and stiffness of the chair as compared to a new one.
In contrast to biodegradation where the molecules are broken down into the fundamental elements and most basic molecules, in photo-degradation, polymers are simply shortened, until there is only one monomer. However, all of the monomers and shorter polymers still exist in the environment. These are still harmful to organisms in the marine environment.
One question you may have is how fast plastic degrades in the ocean.
Unfortunately, the answer to this question is still not known by scientists who study plastic pollution.
One belief is that plastic remains in the ocean for hundreds to thousands of years.
On the other hand, a recent study suggested that plastic items break down within 1 year!
However, there is consensus that even the smallest of plastic pieces are still harmful for marine animals.
Plastics can break down to sizes smaller than a millimeter until they are no longer visible to the human eye. Such small pieces of plastic have the potential to be filtered out of the water by organisms such as fish, filter feeders like mussels, worms, etc.
The images show microplastics of varying size.. Top (largest), bottom (smallest- a small plankton (looks like a fish), a diatom (the transparent box-like thing is also a plankton) and the red plastic filament pointed out by the arrow)
Rochman, 2018.
Here is a short list of the pros and cons of plastic.
After going through the list ask your students if they can come up with more points for each column. Write them on the board so the students can keep them in mind!
Although larger plastics have negative implications for aquatic organisms through ingestion and entanglement, it is the degradation of larger plastics into smaller pieces known as microplastics that poses the greatest threat to aquatic life.
(Oberbeckmann et al., 2015, p. 554).
These small particulates become readily bioavailable and directly impact aquatic life through respiration, ingestion, gastric obstruction, physiological effects, chemical transfer, or trophic transfer, potentially causing liver toxicity, endocrine disruption, decreased fecundity, and lower survival rates (Lusher et al, 2016).
https://www.tandfonline.com/doi/full/10.1080/26395940.2019.1580151
The fibers of synthetic clothing are mainly released by washing into sewage treatment plants and eventually into aquatic ecosystems. The heavy use of agricultural plastics allows plastics to enter the soil, degrade into microplastics, and reach the ground or surface water through the action of wind and runoff.
(Medrano et al., 2015, p. 76).
Organisms directly target the microplastics as prey, or inadvertently ingest them through filter feeding processes. These microplastics are then transported through the food chain and the interacting food webs, causing these contaminants to biomagnify through higher trophic levels.