We all buy products which we never really thought had plastic in them (toothpaste?!), and up until recently, I'm sure we all used copious amounts of plastic bags before the 5p charge starting hitting our student pockets hard. The more prudent among us will re-use our water bottles, and try to use the correct bins at University (although I recently had a look and a lot of the different bin holes all lead to the same bag...). And whether we do this out of genuine concern for the environment, or just to save money, it never really crosses our mind how these products are made, or what the next step is in their journey once we consume them.
So how does all of this plastic end up in the ocean?
Plastic pollution in our oceans has been widely researched, and many campaigns exist to advocate a change. However, riverine pathways to the oceans have not received due attention, despite their being one of the main systems that transport anthropogenic plastic litter into oceans (Rech et al, 2014). A 2013 study into the Laurentian Great Lakes found higher concentrations of microplastics than any other water body on Earth, with up to 466,000 microplastic particles/km2 downstream of two major cities. This proximity to both urban centres and industrial plants greatly increased pollution levels within the lakes. Many of these particles entered the lakes through drainage systems and sewage treatment overflow - especially during periods of heavy rain. With such massive pollution levels, these lakes 'represent an important, potential upstream source of plastic pollution into the North Atlantic Gyre'.
This failing of designated water-treating infrastructures is not isolated to the Great Lakes. Morritt et al, (2014) conducted a study looking at sub-surface items in the upper Thames Estuary. In a short period of time, 8490 plastic items were captured in fyke nets. 20% of these were sanitary products, and sites of higher contamination were in the vicinity of sewage treatment plants. Again, it can be assumed that these plants are not effectively treating or managing waste, and letting it filter out into rivers means it will eventually reach the sea. Below is an overview of the findings from the Thames:
While this litter can be the result of direct disposal, and illegal dumping into waterways, it can also more be the result of heavy rainfall washing the streets clean and transferring the pollutants into sewers and then rivers. While the Port of London Authority operates the 'driftwood service', using Passive Driftwood Collectors (PDCs) to scoop up larger floating debris, this ignores the unseen debris polluting the benthic zone which are gradually fragmenting into smaller particles as they abrade on each ebb and flood tide. Litter is too easily circumventing the barriers meant to stop it.
The main concern highlighted by both of these studies is the lack of attention being focused on our freshwater bodies. Not only are they polluted on the surface, but also within the water column. This inattention is allowing continued pollution by the very infrastructures designed to filter out rubbish and maintain clean rivers. If sewage plants can not handle the amount of rubbish, there needs to be an re-evaluation in their design. If London, a financial hub city, cannot maintain the health of the Thames, then how can other cities and countries which lack the technology, resources, and money be expected to create their own waste management industries and maintain them to a efficient standard? If nations can not address the problem of plastic pollution in water ways to which they have riparian rights, then how could we ever organise a global, international system to clean our oceans and prevent their continued pollution?
Waste management is one of the fundamental focal points to find a solution to the problem of Plastic Soup, and there needs to be greater transparency in the successes and failings of this industry. My next posts will be evaluating current trends and paradigms in waste management, in both global and local contexts, as well as the detrimental effect of inadequate management.
Some excellent points made - the freshwater aspect sparks my interest. A huge amount of attention is given to other forms of freshwater pollution (acidification, eutrophication and the like) but as you say, there is very little thought given to the potential for plastic pollution. It would be really interesting to see how extensive the plastic soup contamination of more isolated freshwater bodies such as ponds is - lack of connectivity might be a good thing for once!
ReplyDeleteThat's true, it's notoriously difficult to clean up marine plastic because of ocean currents - hopefully isolated water bodies stand a better chance!
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