An innovative eight-phase methodology for analyzing microplastics in soil ecosystem

In today’s world, plastics find extensive usage, owing to their favorable properties and affordable costs. The widespread use of these non-biodegradable materials, however, makes them a waste management nuisance and global environmental concern. It is estimated that by 2050, approximately 12 billion metric tons of plastic waste will be dumped onto landfills. Plastics entering soils undergo intense weathering and breakdown, resulting in the formation of microplastics (MPs), or plastic fragments less than 5mm in size. These MPs accumulate in soils, alter their chemical and biological characteristics, and exacerbate the menace of plastic pollution. Not only do these MPs pose risks to soil health, but they also affect soil organisms and contaminate plants, endangering the integrity of the entire food chain.

Given the recent attention to microplastic pollution in soils, there is still a lack of a systematic, comprehensive, and standardized procedure for sampling, separating, and analyzing soil MPs. Current analytical methods for soil MPs are usually modified versions of existing marine research, which seldom acknowledge the inherent complexities of soil ecosystems. To address this research gap, a team led by Prof. Yong Sik Ok from Korea University have now critically evaluated the current analytical approaches for soil MPs and proposed a novel, comprehensive, eight-phase methodology for examining MPs in soils. Prof. Ok is the Chair and Program Director of the Sustainable Waste Management (APRU SWM) Program for the Association of Pacific Rim Universities (APRU), and President of the International ESG (Environmental, Social and Governance) Association (IESGA), and President of the International Society of Trace Element Biogeochemistry (ISTEB), besides being a highly cited researcher since 2018. Elaborating further on their study, Prof. Ok says, “In a world grappling with the escalating challenges of plastic pollution, our critical evaluation provides crucial insights that can offer significant support for global industries, in line with the United Nations Sustainable Development Goals (SDGs) and ESG principles.” The article was published in Critical Reviews in Environmental Science and Technology on 16 January 2024.

In this work, Prof. Ok and his team emphasize the importance of soil sampling, homogenization, aggregate dispersion, and examine the physicochemical and biological properties of soils before analyzing the MPs in soils. Based on their analysis, the team suggested a comprehensive methodology, with eight phases, for analyzing soil MPs.

These phases include 1) careful planning for soil sampling; 2) collecting representative samples; 3) processing the samples, including drying and sieving; 4) characterizing the soil to determine its physicochemical and biological properties; 5) pretreating the soils before separating MPs from it; 6) separating the MPs from the clay and organic components of the soil; 7) identifying the MPs visually or chemically; and finally 8) quantifying the MPs per kilogram of dry soil. In this methodology, each phase recognizes the significance of considering soil-specific properties, understanding how these can interfere with MP analysis, and overcoming these interferences and other methodological challenges.

This new methodology thus provides a streamlined approach for the analysis of soil MPs, ensuring accuracy, precision, reliability, and quality assurance, while reducing potential sources of error or contamination. Moreover, this methodology is easy to reproduce under different settings. Interestingly, the implications of this methodology extend beyond the scientific community. While this systematic approach facilitates data and research comparability and advances scientific understanding, it also promotes international collaboration and knowledge sharing and supports policy development for managing MP pollution.

“Our proposed eight-phase methodology serves as a basis for developing standardized methods for analyzing soil MPs. Such globally accepted standards can be aligned with regulations under the United Nations Environment Programme and can be used for developing international agreements for managing plastic waste. Furthermore, our methodology can prove to be a valuable tool and reference for industries, policymakers, and researchers worldwide, who are committed to combating plastic pollution and safeguarding the environment,” concludes Prof. Ok.

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Reference
DOI: https://doi.org/10.1080/10643389.2023.2301052

Authors: Piumi Amasha Withana^1,2, Sachini Supunsala Senadheera^1,2, Defu He³, Michael S. Bank^4,5, Cheng Gu⁶, Sung Yeon Hwang⁷, and Yong Sik Ok^1,2

Affiliations:
¹Korea Biochar Research Center, Association of Pacific Rim Universities (APRU) Sustainable Waste Management & Division of Environmental Science and Ecological Engineering, Korea University, Republic of Korea

²International ESG Association (IESGA), Republic of Korea

³School of Ecological and Environmental Sciences, Shanghai Engineering Research Center of Biotransformation of Organic Solid Waste, East China Normal University, China

⁴Institute of Marine Research, Norway

⁵University of Massachusetts Amherst, USA

⁶State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, China

⁷Department of Plant & Environmental New Resources, Kyung Hee University, Republic of Korea

About APRU Sustainable Waste Management Program
As a network of leading universities linking the Americas, Asia, and Australasia, APRU (the Association of Pacific Rim Universities) brings together leaders, researchers, and policymakers to exchange ideas and collaborate toward practical solutions to combat the challenges of the 21st century. The APRU Sustainable Waste Management Program focuses on adopting environmentally friendly practices to manage waste effectively, while minimizing its negative impacts on the environment and human health. It involves various strategies and approaches to reduce, reuse, recycle, and properly dispose of waste materials together with ESG and sustainability concepts. Prof. Yong Sik Ok at Korea University serves as the Chair and the Program Director of the program which is co-directed by Prof. William Mitch at Stanford University.

About Professor Yong Sik Ok
Professor Yong Sik Ok is a KU HCR Professor. He is the Chair and Program Director of the Sustainable Waste Management Program for the Association of Pacific Rim Universities (APRU) and the President of the International ESG Association and the International Society of Trace Element Biogeochemistry. He maintains a worldwide professional network by serving as the Editor-in-Chief of CleanMat (Wiley Open Access) and the Co-Editor-in-Chief of Critical Reviews in Environmental Science and Technology (CREST, five-year IF:13.6) at Taylor and Francis. Moreover, Prof. Ok has hosted many conferences and forums focusing on Sustainability, UN SDGs, and ESG. The recently concluded 6th Global Conference on ESG Management & Sustainability marked another milestone in Prof. Ok’s ongoing journey toward achieving sustainability and ESG goals together with Prof. Jay Hyuk Rhee (President, KU ESG Research Institute & President, International ESG Association) at Korea University Business School. Importantly, Prof. Ok will chair the 4th Australian Circular Economy Conference, scheduled to take place in Sydney, Australia, in October 2024, together with Prof. Ali Abbas, Director, Waste Transformation Research Hub and the Associate Dean Research, Faculty of Engineering, The University of Sydney.