The Life Cycle Of Plastic
In today’s world, plastics are everywhere. These petroleum-based materials are used everywhere from our kitchens to the most advanced machines. However, they have a short history compared to other man-made materials. Commercial production of plastic began in the 1950s, after which the total amount of global primary plastic ever produced rose from 380Mt to 7,800Mt, with an 8.4% compounded annual growth rate. Production has soared in recent decades; half of the world’s plastics were produced within the past 15 years. In 2015 alone, 407 Mt of primary plastics were produced. As the global economy develops, the world plastic production will continue to increase.
Waste Generation, Recycling and Disposal
Most of the plastics produced go through a short service life. 40% of the world’s plastics are produced for the packaging sector, where they have an average service life of less than one year. We use plastic packaging for a few minutes, and dispose of it after a single use. With the increase in production, annual global plastic waste rapidly grew from 275 Mt to 302 Mt from 2010 to 2015. The situation in Hong Kong is similar. Locally, 2,132 tonnes of plastic waste is generated every day, with an average 4% annual growth rate.
Most of the plastic we discard is also poorly managed. By 2015, the global recycling rate of nonfibre plastic waste was 9% and the incineration rate was 12%, which means an astonishing 79% of plastic ever produced has ended up in landfills or the natural environment.
Plastic recycling rates vary among different places. In Hong Kong, 14% of the plastic waste is recovered, of which only 5.7% is treated locally. Until recently, the rest was exported to the mainland. Yet, with China now restricting its plastic waste imports, Hong Kong is facing more challenges in waste management.
Plastics that are not recycled or incinerated get disposed in landfills, open dumps or the natural environment. None of the commonly used plastics are considered easily degradable. There are various types of plastic degradation that are classified by causing agents. It is likely that plastics will not naturally degrade into petrochemicals (the material they are made from) in any degradation process. Instead, they break into smaller pieces. We actually don’t know for sure if all this debris will completely disappear. The history of plastics is too short to give us a good answer. Sometimes plastics will hardly break down given improper oxygen level, bacterial activity, UV radiation and other environmental conditions. According to HKEDP, plastic made up 21% of landfill waste in Hong Kong. It not only occupies precious space in our quickly filling landfills, but also releases contaminants to the surrounding habitats and pollutes the groundwater.
If our uncontrolled plastic addiction and poor waste management continue, there could be an estimated 12,000 Mt of plastics globally in landfills and the natural environment by 2050. This will pose a great threat to our living environment, especially the marine environment.
Plastic Are Ubiquitous In The Ocean
Many of the world’s plastics remain mismanaged and enter the ocean. Plastics on the land can be washed into the rivers by rainwater and float all the way to the sea, which is the main source of ocean plastics. How much plastic waste has ended up in the ocean via the land? Yearly, between 4.8 and 12.7 million tonnes enters the oceans from coastal countries. The exact amount of plastic in the ocean is unknown. However, 4977 Mt of plastic has been dumped in landfills or the environment throughout human history, and all of it has the possibility of entering the world’s largest plastic sink, the ocean.
The result is harmful and observable. In the notorious Great Pacific Garbage Patch (GPGP), thousands of tonnes of plastic is trapped by the ocean gyre and form plastics archipelagos that are larger than France. The GPGP also grows exponentially. According to recent research, now there are at least 79 thousand tonnes of plastic in the GPGP, forming a plastic sea of 1.6 million km2. It may sound overwhelming, but this is not the full picture. Most of the ocean plastic pieces are actually “invisible”. Only 1% of plastics that are supposed to be floating in the ocean according to estimates can be observed. Yet, this is not even the full picture. Scientists mainly attribute it to shore deposition, predation (ingestion by marine animals), sinking and fragmentation.
Accumulating evidence is pointing to the abundance and broad spatial extent of microplastics, which are defined as particles < 5mm. Microplastics are directly produced for synthetic fibres and personal care products and larger plastics will naturally break into microplastics over time. Microplastics are invisible and ubiquitous. Scientists have found a considerable amount of microplastics in Arctic sea ice and the most remote Pacific islands, away from human population centres and major shipping activities.
Research by Sustainability Office Intern Bingo Xu 2018