Saturday, July 22, 2017

Ocean Polluted with Plastic


By 2050 – more plastic than fish in the seas

According to a joint study conducted by Ellen MacArthur Foundation and World Economic Forum, by 2050, plastic in the oceans will outweigh fish! It predicts, at the going rate, by 2050 there will be 895 million tons of fish and 937 million tons of plastic waste in the oceans around the world.

Now that the country has brought in more stringent legislations against the use of plastic it is high time to contemplate totally moving away from synthetic plastic and looking for alternatives. Also serious is the issue of plastic disposal as humankind has dumped enough and more plastic on the earth surface and the sea.

Ocean pollution by plastic waste is becoming a grave threat to the health of the oceans and the creatures living in it. The quantity of plastic entering the ocean from waste generated on land was hitherto unknown. A team of American and Australian researchers led by Dr. Jenna R. Jambeck, Associate Professor in the College of Engineering at the University of Georgia, USA, by linking worldwide data on solid waste, population density, and economic status, estimated the mass of land-based plastic waste entering the ocean. According to the study 275 million metric tonnes (MT) of plastic waste was generated in 192 coastal countries in 2010, with 4.8 to 12.7 (on average 8) million MT entering the ocean. An abridged version of the study is published in the International Solid Waste Association (ISWA) website, under the title "Plastic waste inputs from land into the ocean".

Plastics – Here, There and Everywhere

Plastics are "Here, There and Everywhere". As polymer chemist Prof. Andrew Holmes at the University of Melbourne famously said to ABC Science, "No one in their daily life within a period of 10 minutes isn't touching something that is made of plastic". But for all the benefits plastic has given us, disposing it — particularly those designed to be used only once, such as packaging, disposable cups, syringes etc. — has become a major environmental issue. That’s the volume of the problem on the land. But the irony is that good part of this plastic ultimately end up in the sea.

Plastic generally gets into the ocean from the coasts, where people live. Every minute, it is estimated that one ton of plastic makes its way into the ocean. About 80% of the plastics in the ocean come from land-based activities (as opposed to marine activities).

It is difficult to pinpoint where all that refuse originates, and researchers think that much or most of it probably comes from the nation's densely-populated coastlines. This takes into account the concept of coastal population, i.e. the population that lives within 100 km from the shore. (In Sri Lanka the coastal population stands at 14.6 million). Even from far inland, plastic trash can end up in sea by travelling thousands of kilometers into the oceans, believe researchers. But once in the ocean, currents move the plastic around. Plastic in the ocean impacts fish and other marine life. 

Dr. Chris Wilcox, marine and atmospheric scientist at Commonwealth Scientific and Industrial Research Organization (CSIRO) Hobart, Tasmania told the ABC Science "About every 10 years the amount of plastic produced doubles around the world". The plastic production has increased 20-fold in the last 50 years, and it is continuing to rise further. With global production of plastic increasing exponentially, the amount of plastic finding its way into the ocean too will get much bigger, year on year.

To make matters worse, plastic is made to be strong and durable, so it can take a long time to break down. In the natural environment, the main things that break down plastics are the sunlight, oxygen and water. The rate at which plastic breaks down depends on the conditions and the type of plastic. It breaks down faster if exposed to physical abrasion and sunlight. In the marine environments, it breaks down faster in surf zones than if it is buried under sediment in an estuary. At the same time, there's a lot to do with the thickness and density of the plastic, and the presence of UV stabilizers in it. However, in general, synthetic plastic takes around 450 years to decay. On the contrary, the bio degradable plastic takes only six months to decay.

However, the degradation process of plastic poses numerous problems to the animal health and environment. According to Prof. Holmes, "The problem is that normal degradation leaves particles that can still be harmful to living beings — particularly the nanoparticles and the microparticles. That includes so-called degradable polymers used in some plastic bags, which have starch added to help them fall apart".

Plastics in the ocean

It is estimated that there are up to 51 trillion particles or 236,000 tonnes of plastics in the sea. Although that is a lot, it is nowhere near the estimated 8 billion tonnes that went into the oceans in 2010 alone. Then what intrigues the scientists is that "where has the "missing" plastic gone?".

Although plastic is widespread in the open ocean, it is particularly concentrated in the five major ocean gyres — rotating currents of water — in the Pacific, Atlantic and Indian Oceans. The largest and best known of these is the Great Garbage Patch in the north Pacific — a concentrated soup of microplastics, or tiny fragments less than 5 millimeters across, which is almost the size of Europe.

There are two types of plastics that float: polyethelene, which is used to make milk jugs and plastic bags, and polypropolene, which is used for things like bottle caps, straws and dairy containers. As they travel out to sea plastics get ground down into small, hard cubes, which can be eaten by marine animals.


Plastics are also home to microbes in a phenomenon dubbed the "plastisphere". These microbes may be simply using the plastic to float around the ocean, but there is some evidence they may play a role breaking down the plastic.

Plastics should become more abundant as they break down in size, but recent research found the concentration of the smallest particles, between a few microns and a few millimetres, was much lower than expected. These particles settling in the bottom of the ocean is one possibility. Scientists have found evidence of microplastics in deep-sea sediments from the Atlantic Ocean, Mediterranean Sea and Indian Ocean.

Impact on marine animals

Animals get wrapped up in monofilament fishing line nets, plastic bags, balloons, and straps.

According to Dr Wilcox, "Getting entangled in plastic is the biggest issue faced by the marine animals". His research has estimated that between 5,000 and 15,000 sea turtles are entangled each year by derelict fishing gear washing ashore in northern Australia alone.

"Anything that is long or flexible or sheet-like is the worst."

The second biggest issue is the impact of eating plastic — it is estimated around 90 per cent of seabirds are doing so. These plastics can cause blockages of the gut or perforation of the intestines.

Ingestion of plastic can also cause toxic chemicals such as phthalates — a plasticiser that effects the hormone system — to leach into the animal. Dr Wilcox has demonstrated "These are later deposited in the animals’ fat tissues".

Immediate solution

Dr Wilcox strongly believes that "The solution to all this stuff is on land and it has to do with changing our supply chains around packaging, how we use packaging, and how we take care of packaging".

The main problem he thinks was how cheap plastic was. "If plastic had a fee or deposit associated with it we would produce and consume less."

He said one way of doing this was to introduce container deposit schemes, which had been shown to reduce the amount of drink containers in the environment by 60 per cent.

"That is a big deal, as beverage containers make up 40 per cent of the waste in the environment."

Consumers could also press retailers to use less plastic packaging, Dr Wilcox said.

"In many cases individuals have been able to drive significant local change by governments and businesses."

The way forward

According to Prof. Holmes, the world may have to move to fully biodegradable plastics, made out of plants.

But these too have drawbacks, especially related to land use. "The challenge is, is there enough arable land to produce the building blocks of plastic when we also need to produce food?"

In the meantime, he said, we must recycle anything we can.

"Ideally all plastics should be recyclable, but at present that is not the case."

Prof. Holmes said plastics that cannot be recycled — such as those used in plastic bags or expanded polystyrene foam used in coffee cups and packaging around electronic goods — must be responsibly disposed into landfill or by burning.

"The plastic waste in the oceans is disastrous for marine and bird life, and the human race has to avoid disposal of this waste in a way that enables it to enter drains, rivers, and eventually the ocean," he said.