Microplastics in aquatic environments - a review of recent advances

Global production and usage of plastics have skyrocket to 368 million tons in 2019, resulting in increasing amounts of plastic waste concentrating in our natural and urban ecosystems (especially rivers and oceans), via landfill, incineration, or illegal disposal. As highlighted herein, due to the production and degradation of larger plastics, micro and nano plastics are introduced to these ecosystems, causing detrimental impact to plants and animals, including humans, through accumulation in living systems. Though toxicity or health impact are not clearly established, long term accumulation of microplastics in living systems can lead to impact on health of such systems. Critically, this review explores state-of-the art physical, chemical, and biological methods to remove and destroy 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 through the review is that microplastics cycle through ecosystems - natural and engineered, these do not operate in siloes and waste from treatment processes could be a conduit for (unintended) recontamination of microplastics. Hence there is a need to take a whole systems approach when developing innovative removal or destructive solutions and, ultimately, reducing plastic use remains the best option to best safeguard future environmental and public health.