Microplastics

What exactly are microplastics and how have they become such a critical aspect of marine pollution? Since its introduction into academic literature in a 2004 paper, the term microplastic has generally been used to describe pieces of plastic that are smaller than 5mm in diameter, as per the NOAA definition. Though this is not considered a definitive description, as certain studies have pointed out the differences in size that exist across papers due to varying methods of capture. Calls have been made from people within the scientific community for a more rigid definition of the term microplastic to allow for more reliable comparison of differently sourced data. Nonetheless, one thing that we are certain of is that they are incredibly small, and with 5mm being the most widely used boundary, their size, or lack of, is what makes them so hard to quantify in the environment.

Spectroscopic analysis has discovered pieces as small as 20 nanometers in diameter (0.00002mm) - how do we keep track of these in the vast expanse that is the ocean? Quite simply we can't really, or at least we struggle to do so. As a review of all things microplastic points out, there are various ways by which we can attempt to quantify microplastics in the environment, but as of yet there is no robust solution, and ultimately, the fate of microplastics in the ocean remains an elusive phenomenon. This is not to say that there is no hope, as they were once an extremely understudied aspect of marine pollution, and it wasn't even until the turn of the century that they were considered a pollutant within their own right. Whereas they are now receiving a rapidly growing amount of attention, which is certainly an encouraging sign of progress. Another sign of such progress? Look no further than the White House.

Ban microplastics? Obama thinks so

Yes - Barack Obama does think that a ban of microplastics would be a good idea and has in fact signed a bill to pass such a ban. The ban specifically refers to the manufacture and introduction of microbead plastics used in cosmetics, which are one of the primary sources of microplastics in our oceans. These microbeads exist in common facial scrubs that you are more than likely to have come across in your local supermarket or may have even used. Studies have shown that the number of microbeads to be washed down the drain, with one just one use of a facial scrub, ranges from 4,500 to as many as 94,000 individual beads! These may not carry the issues associated with entanglement and choking that come with larger pieces of plastic and debris, but they come with their own different type of problem.

The sorptive properties of microplastics are what cause a threat to marine life, as they can carry harmful chemicals such as PCBs and DDTs (there will be a more in-depth look at this in my next post). Facial scrubs do not provide the only primary source of microplastic in the oceans, as they also exist in certain toothpastes and come from clothes too. Studies estimated that an average 6kg clothes wash of acrylic fabric can release in excess of 700,000 fibres into the environment. The primary release of microplastics into the ocean should therefore warrant significant concern, and the video below shows the attempts being made to raise such concerns.

Whilst the primary release of microplastics into marine environments certainly seems to contribute a large volume of plastic debris, it is the secondary release that perhaps poses a more daunting reality. This secondary production involves the gradual breaking down of larger pieces of plastic, eventually into small microplastics. This fragmentation and degradation of plastics occurs over varying periods of time at sea, depending on the properties of the item, but exact processes by which this degradation occurs are speculative and limited to controlled laboratory work. Though an example of a known process by which this fragmentation occurs is photodegradation - where plastics at the sea surface are broken down into smaller pieces by sunlight.

Why are these secondary microplastics more daunting? Well, the primary source of microplastics is something we have a greater control on right now - petitions and bills are in the pipeline to ban them from production. However, as was mentioned in my first post, there is already a colossal volume of plastic in our oceans, the entire amount of which is vulnerable to degradation into microplastics. Whilst we can improve our management and disposal of plastic waste in the future, to stop it getting into the ocean, the plastics that are already in there are largely out of our control and thus represent a huge potential source of microplastics yet to be added to the great big blue. 

As has been discussed, the abundance of microplastics in the ocean is something that is of great difficulty to measure, but it is likely large number with a fair few zeros on the end of it, hence their growing significance. It was briefly touched upon that the sorptive properties of plastics facilitates the transportation of harmful chemicals, which is essentially what makes these plastics the threat that they are, and this is something that we will look at in my next post.

Waste by the Ocean

Previously, I have spoken about just how much plastic is going into our oceans and where it is coming from. Now, we can have a look at what effects it is having, as not only is this waste creating an eye-sore when washed up on beaches around the world, it can also get into the food chain, our food chain. The recent popular hit 'Cake by the Ocean' features the band DNCE on a sunny beach in paradise throwing cake at each other and eating it. Here, we take a more cynical look at what it really is that we might be ingesting at our favourite seaside eateries, when we're not filming extravagant, cake-themed music videos. In fact, whether you're by the beach or not, it is important to consider the state of the seafood which you are eating. 

In the EU, any genetically modified product is required to advertise itself as such on the packaging. Also, across Europe in recent years, countless pesticides have been banned on farms due to health implications, amongst other reasons. There is a clear concern over the condition of the food we are putting into our bodies, and rightly so, and as far as plastic is concerned, we are certainly moving in the right direction with regard to abolishing it from our oceans. For example, the use of plastic bags in the UK has drastically decreased since the 5p charge was added. 

However, there is still work to be done; we want to be seeing headlines such as 'Use of microplastics banned in cosmetics', not 'Microplastics should be banned in cosmetics' (microplastics are a significant aspect of marine waste that will be discussed in detail in my next blog post). Whilst steps are being made, worries over the contents of the seafood we are consuming do not seem to receive the same concern that other food sources perhaps do. There appears to be a slight disconnect between the waste we are pumping into our oceans and the food we are taking out of it. Like pesticides might affect our corn on the cob, plastic bottle caps might affect our fish and chips.  

In 2013, fish accounted for around 17% of the global population's intake of animal protein - in some countries this figure was over 25%. This is particularly the case for countries such as Iceland and Greenland, who live in an environment not best-suited to growing crops, and so are extremely reliant on fish. With seafood therefore being responsible for a significant proportion of the globe's diet, we must deeply consider what the contents of this food supply might be. 

In addition to the 44% of seabird species that ingest plastic, there are over 250 marine organisms worldwide, and counting, that are known to have been affected by marine debris. This is due to the fact that when plastics in the ocean are broken down into small pieces, marine organisms can mistake them for food. There have been studies on how these plastics can be of detriment to human health once they have found their way into the environment. The plastics contain various harmful chemicals that are produced during part of the manufacturing process, and these can be absorbed into the guts of the organisms which ingest them. Then it's a simple case of dot-to-dot; fish absorb chemicals, humans eat fish. The precise effects on human health that this process has are so far unknown due to this being a relatively understudied phenomenon, hence further research has been advocated. 

Unfortunately, real fish do not use plastic bags to escape captivity (Source)

In a developing world of rising population and growing consumerism, it is important to consider the effects that our actions are having on the environment and how they may come back around to harm us. As previously mentioned, the next post will be about microplastics. These are the 'small pieces' of plastic that marine organisms can mistake for food. I will be discussing exactly what they are and how they have become such a prominent aspect of marine waste. Finally, just a parting thought for any readers at the end of today's topic - think about the food your food is eating!

How does it get there?

In the previous post I touched upon just how much waste is in our oceans, to try and illustrate the sheer size of the issue we have on our hands - an issue made up of over 5 trillion pieces, to be a bit more precise. To give some context to the matter it might be useful to explore exactly where it is that all this waste is coming from, as finding the root of the problem is one way of helping kick start the solution to it. The short video below provides a basic conceptualisation of the various journeys that marine debris can take in order to get to the ocean.

Essentially, marine debris comes from us, humans. Some of us leave it lying around on the beach, some of us dump it in an over flowing bin. We may even drop it on the street, miles away from any beach or coastal resort, but if it makes its way into a drainage system it'll almost certainly end up in the sea. This video demonstrates the importance for each and every one of us to act consciously when thinking about how we dispose of everyday waste such as plastic bags and food wrappers. However, one aspect that this video does fail to touch upon is the impact that large companies and organisations have on waste inputs into the sea. 

Some of the prime culprits of marine dumping are fisheries. Studies in the UK have shown that fisheries remain responsible for a large amount of marine waste that is being washed up on our shores - despite international conventions that have been set up to stop exactly that. The International Convention for the Prevention of Pollution from Ships, also known as MARPOL, was adopted in 1973 with the sole purpose of preventing and minimising pollution from ships. However, these studies have shown that in many cases the rules and regulations are simply being ignored. 

Developing countries are also coming under increasing scrutiny with regard to their management, or mismanagement, of plastic waste. Economic growth is strongly associated with an increased per capita consumption of goods, and studies have shown that this is creating a volume of waste that many developing countries do not have the infrastructure to deal with. This is ultimately leading to uncontrolled or open landfill sites where waste materials are vulnerable to being blown away into the ocean. A map of the top contributing countries according to this trend is shown in Figure 1 below.

Figure 1: Top 10 countries for mismanaged waste (CNN, adapted from Science 2010)

Figure 2 below nicely sums up the relative contributions to ocean waste from some of the various sources discussed. It may be evident that fisheries pose a problem regarding the dumping of waste in our oceans, and developing countries absolutely need to find a way to better manage their storage of waste. However, the pie chart proves there is no doubt that we the people need to act more responsibly when throwing away our waste.

Figure 2: Sources of marine waste in 2009 (Ocean Conservancy 2012)

As was alluded to in my opening post, plastic marine waste is not the only pollutant of our oceans. Chemical waste also poses a huge threat to the condition of our seas. Sewage systems are one of the methods of transportation whereby chemicals that are a threat to the ocean's ecosystems can make their way into the sea. Once there, these substances can lead to the reduction of oxygen levels and cause decay of submarine plant life. Industries are also often responsible for dumping toxic chemicals directly into rivers which eventually lead to the ocean. As well as being deadly to marine life due to the toxins contained in these chemicals, the temperature of them when dumped can also cause what is known as thermal pollution, whereby organisms die as a result of the heat. 

Then there is also the problem of pesticides. Designed to be lethal to particular organisms, farmers can use them to significant effect in trying to achieve larger crop yields. However, they can also be lethal to other organisms when they eventually make their way into the sea. Predominantly, this occurs as surface water runoff. When rain water runs off the ground surface it takes the pesticides with it when it enters streams and rivers, and you guessed it, these eventually wind their way into the ocean. A small amount can also enter rivers and streams as a result of 'spray drift'. This is when the pesticide being sprayed is carried to the water bodies directly by the wind, though this process is not thought to make as significant a contribution as the runoff component does.

So there we have it - that is how marine waste, both physical and chemical, manages to find its way into the ocean. In the upcoming posts we'll be having more of a look at some of the many possible impacts that this waste can have once it is in the sea. 

The Ocean: Earth's Biggest Trash Can

As Earth's population continues to grow, the production and subsequent disposal of waste is becoming an increasingly pressing issue. Think plastic cups; they're fairly small and insubstantial objects that you probably don't spend too much time worrying about. However, just one of these can take over 50 years to decompose, so with an estimated 8 million tonnes of plastic being dumped in the ocean each year, an almost incomprehensible amount has built up since disposal in the sea first began. The biggest collection of ocean waste stretches from Japan to America and is known as the Great Pacific Garbage Patch, a diagram of which is shown in Figure 1. The extent of this patch is so large that scientists estimate it could even be bigger than the USA. 

Some of you may perhaps be wondering why there is so much waste in our oceans - don't we just put rubbish in the bin? There is in fact a host of ways by which waste can make its way into the ocean, including the mismanagement of landfill sites, shipping casualties, and quite simply littering at the coast. Whether by accident or on purpose, it is something we must try and regulate in order to reduce the damaging effects it can have on ocean life.

Figure 1: the Great Pacific Garbage Patch (National Geographic 2016)

However, dumping of plastics in the ocean is not the only component of marine pollution. Chemical waste from industry and agriculture often gets into streams and rivers which eventually wind their way to the sea, polluting it further. Once in the ocean, these chemicals can become part of the food chain and have a damaging effect on migrating bird populations. Not only does this chemical waste effect wildlife, but it can also influence climate and in fact contribute to global warming. The release of nitrates from fertilisers into the ocean can increase the production of nitrogen, a greenhouse gas, by enhancing microbial growth at the sea surface.

The impact of these chemicals will be explored in greater detail throughout this blog, as well as exactly what happens to those plastics once they have entered the ocean, besides floating from the east coast of Japan to the sunny sands of California. We'll also be looking at what plans are being made, from surfing entrepreneurs to government officials - who will find the most effective solution to help tackle the growing problem of rubbish in our seas?

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