Sources of Microplastics
Updated: Aug 20, 2021
During Project IMPACT we previously discussed that Microplastics can be separated into Primary and Secondary Microplastics. Building on this, we can further delve into the various sources of each type since each enters the environment in its own way.
These Microplastics are produced in a form which is already in a Microplastics format, meaning they are already less than 5mm in size. Plastic production pellets for example regularly fall off ships in their billions when shipping containers fall overboard during storms. These individual pellets then circulate with the tides and become a pesky issue for marine wildlife that mistaken these pellets for food, leading to the animal ingesting the plastics and feeling full. Of course, this ‘full’ feeling is the plastic building up inside the gut which then blocks and real nutrients from being ingested.
The use of tiny plastic pellets as skin exfoliators is common within cosmetic products, along with the breaking down of synthetic fibers used in clothing within washing machines. Both these sources of microplastics are likely to end up in the sea from domestic waste water drains since they are small enough to pass through filtration systems, entering the marine environment and joining the other plastics being circulated by currents. Given their tiny size, these are ingested by marine animals at all levels of the food chain. The smallest organisms again mistake these for nutrients and follow the same path as larger animals, however since they are lower down in the food chain, the accumulation in predators higher up in the food chain means that microplastic loads could be larger than expected.
Other such sources are also from fishing and boating activities. As ropes fray over time, their individual strands are released in much the same way as clothing fibres but usually stronger and more durable given the more hardy nature of the plastics used in ropes. Styrofoam is also a large source of microplastics locally, used by fishermen for multiple applications such as transportation, floatation devices or markers. Given its fragile nature, the styrofoam is easily broken and fragments into its singular pieces which average at around 2mm each.
The stark contrast with Secondary Microplastics is that these form from the degradation of larger pieces of plastics debris that find their way in the marine environment. Plastic bottles, jerrycans and alike become weathered by UV rays and wave action. As these large pieces become more and more brittle, the pieces break apart creating a cascading effect where-by each fragment will continue to break down to the nano level. Every single type of plastic has its own timeframe for this degradation, with tyres for example taking a much longer time to breakdown than a plastic bottle, but nonetheless the result is the same.
Can we collect these plastics?
The reality is that once plastics reach the sub 5mm level, it is somewhat impossible to collect them from the environment without also possibly removing organisms. Their entry into all different levels of the food chain and habitats causes all sorts of complexities when considering removal. Activities such as clean-ups can play a helpful part in this process since they collect larger pieces which can become Secondary Microplastics if left in the marine environment.