From heavy metals to hydrocarbons and oil to plastic debris, marine pollution is a world-wide problem. According to a review by H.S. Auta et al. published in 2017 by Environment International, plastic composes 80-85% of marine litter, and on our current trajectory, the amount of plastic litter in water bodies will only increase. Microplastics don’t decompose easily, and with increasing production and few effective clean-up methods currently implemented on a broad scale, we’re likely to see more and more microplastics in our environment.
Microplastics are generally classified as either primary or secondary. Primary microplastics are those intentionally manufactured and are often found in face cleaners, toothpastes, and other cosmetics. The use of primary microplastics is becoming increasingly popular in the cosmetics industry, often replacing natural ingredients. Secondary microplastics are those created when larger plastics break down due to environmental factors, such as exposure to sunlight or ocean waves.
Microplastics have a wide variety of detrimental impacts on our environment, as well as directly on ourselves. Not only do microplastics collect in sediment along ocean floors, but they also end up in our food and other biomass. Chemicals leached from these microplastics over time are toxic pollutants that can create imbalances in ecosystems and food webs, destroy habitats, facilitate the spread of invasive species, and harm flora and fauna when absorbed or consumed.
As described in this 2020 review article by E. Schmaltz et al., current solutions to reduce marine microplastics entail both prevention and removal techniques. Leading prevention techniques involve installing filters in storm and wastewater drains, some of which are fine enough to catch microplastics as well as macroplastics. Mechanical technologies that skim plastics off of water bodies are being developed as some of the newest removal techniques. Technologies for use in domestic settings are also being developed, such as laundry balls that trap synthetic microfibers, so that microplastics don’t reach waterways.
A unique solution to the growing plastic problem is the development of bioplastics, which are defined as either bio-based or biodegradable plastics. Plastics that are engineered to be biodegradable—able to be broken down with the help of microorganisms—are considered a short-term solution to the plastic problem, as there are many problems with biodegradable plastics: they commonly contain harmful additives, are expensive to produce, and require specific collection and composting technologies. The more sustainable bio-based plastics are created out of renewable feedstocks—natural resources that can replenish themselves quickly. These bio-based plastics are a more viable solution to plastic pollution, as they are sustainable and decompose naturally.
Due to the size of microplastics, there are significant limitations on current manual removal techniques. Another proposed solution is biodegradation, which is the use of microorganisms to decompose microplastics. Some microorganisms have been found to use the carbon in plastic as an energy source, and biofilms, which are communities of microorganisms, can already be found naturally occurring on plastic litter. Many microorganisms can adapt quickly to new environments, meaning that biodegradation could be used in a variety of situations to both prevent the introduction of microplastics into marine environments by treating wastewater before it reaches water bodies, and by treating already contaminated environments.
This article was edited by Lydia Guertin and Anagha Aneesh.