Microplastics in aquatic environments: a review of recent advances

Global production and usage of plastics have skyrocketed to 368 Mt in 2019, resulting in increasing amounts of plastic waste concentrating in natural and urban ecosystems (particularly rivers and oceans), through landfills, incineration or illegal disposal. As highlighted herein, due to the production and degradation of larger plastics, micro- and nanoplastics are introduced to these ecosystems, causing detrimental impact on plants and animals, including humans, through accumulation in living systems. Although toxicity impacts are not clearly established, long-term accumulation of microplastics in living systems can have an adverse impact on health and function. Critically, this review explores state-of-the-art physical, chemical and biological methods for removing and destroying new and legacy microplastics in aquatic ecosystems (natural and urban). Currently, there are no standardised, accepted and cost-effective methods for complete removal of microplastics from these aquatic ecosystems. Gaps in knowledge and recommendations for future research to help inform practice and legislation are highlighted. A key consideration highlighted in the review is that microplastics cycle through ecosystems – natural and engineered. These do not operate in silos, and waste from treatment processes could be a conduit for (unintended) recontamination of microplastics. Hence, there is a need to take a whole-system approach when developing innovative removal or destructive solutions, and ultimately, reducing plastic use remains the best option to safeguard future environmental and public health.