{"id":83952,"date":"2025-04-09T12:00:10","date_gmt":"2025-04-09T03:00:10","guid":{"rendered":"https:\/\/www.waseda.jp\/top\/en\/?p=83952"},"modified":"2025-04-07T10:19:09","modified_gmt":"2025-04-07T01:19:09","slug":"life-in-a-nutshell-new-species-found-in-the-carapace-of-late-cretaceous-marine-turtle-2-2-2-2-2-2-2-2-2-2-2-3-3-2-2-3-2-3-2-2-2-3-2-2-2-3-3-2-2-3-2-2-3","status":"publish","type":"post","link":"https:\/\/www.waseda.jp\/top\/en\/news\/83952","title":{"rendered":"Nanoplastics in Soil: How Soil Type and pH Influence Mobility"},"content":{"rendered":"

Nanoplastics in Soil: How Soil Type and pH Influence Mobility<\/strong><\/h1>\n

Researchers conduct batch<\/em> adsorption testing in different soil types to understand the adsorption and aggregation behavior of nanoplastics in soil<\/em><\/p>\n

Nanop<\/strong>lastic<\/strong>s<\/strong> are an increasing threat to the ecosystem; however, their mobility in the soil is still underexplored. Against this backdrop, researchers from Waseda University<\/strong> and the<\/strong> National Institute of Advanced Industrial Science and Technology investigated the adsorption and aggregation behavior of <\/strong>nano<\/strong>plastic<\/strong>s<\/strong> in different types of soil under different pH conditions. The study offers new perspectives on the migration and environmental interactions of nanoplastics, while broadening our knowledge of pollution dynamics and soil contamination processes.<\/strong><\/p>\n

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Image title: How pH and soil composition influence nanoplastic adsorption
\nImage caption: Researchers investigate the effect of soil pH and surface properties on the adsorption and aggregation behavior of plastic nanoparticles.
\nImage credit: Kyouhei Tsuchida from Waseda University, Japan
\nLicense type: Original content
\nUsage restrictions: Cannot be reused without permission.<\/p><\/div>\n

Plastics are everywhere\u2014from packaging and textiles to electronics and medical devices. As plastic waste breaks down, it releases microscopic particles that can penetrate our ecosystems, hinder plant growth, and potentially transfer harmful pollutants to organisms, including humans. Therefore, these plastic particles are a potential threat to the ecosystem, especially in their nanoparticulate form (1\u2013100 nm diameter) which can penetrate the environment through different routes, including the soil beneath our feet.<\/p>\n

With this in mind, a team of researchers from Japan set out to study the migration behavior of nanoplastics in different soil types. The study was led by Kyouhei Tsuchida, a PhD student from the National Institute of Advanced Industrial Science and Technology (AIST) and Waseda University, Japan, with fellow students Yukari Imoto, Takeshi Saito and Junko Hara also from AIST, and Professor Yoshishige Kawabe from the Department of Resources and Environmental Engineering, Waseda University. This study was published online in the journal Science of The Total Environment<\/em> on April 4, 2025.<\/p>\n

The researchers focused on the adsorption of the nanoplastics on soil and the aggregation characteristics of both the nanoplastics and soil particles under varying pH conditions. \u201cThe aggregation properties of nanoplastics and their adsorption onto soil particle surfaces are known to affect their migration in soil,<\/em>\u201d notes Tsuchida, \u201cWe conducted experiments to analyze these traits to get a better understanding of the migration of nanoplastics<\/em>.\u201d The research team focused on three major aspects. First, the homo or self-aggregation of the nanoplastics. Second, the adsorption properties of the nanoplastics onto soil, and third, how the adsorption of nanoplastics affects the aggregation of soil particles.<\/p>\n

To understand the behavior of the nanoplastics under different soil conditions, the researchers used two different types of soil: andosol (volcanic soil) and fine sand. \u201cBoth andosol and fine sand have extremely different properties, and we utilized these two to get a broader idea of how the behavior of nanoplastics changes with respect to soil composition and surface characteristics<\/em>,\u201d explains co-author Hara.<\/p>\n

For the self-aggregation studies of the nanoplastics, the team first prepared a suspension of polystyrene nanoparticles under three different pH conditions. Further, they determined its particle size, aggregate particle size, and zeta potential\u2014a measure of the electrical charge on particle surfaces, which helps determine the stability of nanoparticles.<\/p>\n

Additionally, the researchers tested the adsorption properties of the polystyrene nanoparticles onto the two soil types under varying pH conditions. To analyze the adsorption behavior, the researchers used batch adsorption testing. \u201cWe used batch adsorption testing to gain a deeper insight into how plastic particles accumulate in soil pores. This property hasn\u2019t been well explained in column studies<\/em>,\u201d explains co-author Kawabe.<\/p>\n

The analysis of aggregation and adsorption involved advanced instrumental techniques, including laser diffraction, UV spectroscopy, and zeta potential analysis. According to the results, no aggregation was observed in the polystyrene nanoparticles owing to the high negative charge on the polystyrene nanoparticles. \u201cThe highly negative zeta potential of the <\/em>polystyrene nanoparticles causes repulsion between the particles and remains unaffected by pH changes,<\/em>\u201d reports Tsuchida. \u201cThis was in contrast to that observed for <\/em>the adsorption properties of the nanoplastics onto soil. <\/em>P<\/em>olystyrene<\/em> nanoparticles adsorbed<\/em> onto soil which was influenced by pH,<\/em> and further, aggregation of the soil particles.\u201d<\/em><\/p>\n

The results, therefore, suggest that the soil type and pH of the solution can critically alter the movement of nanoplastics in the soil. Understanding these crucial aspects could help to reform policies and strategies for mitigating plastic pollution.<\/p>\n

Reference<\/strong><\/p>\n

Authors<\/strong>: Kyouhei Tsuchida1,2<\/sup>, Yukari Imoto1<\/sup>, Takeshi Saito1<\/sup>, Junko Hara1<\/sup>, Yoshishige Kawabe<\/a>2<\/sup>
\nTitle of original paper<\/strong>: Effect of solution pH on nanoplastic adsorption onto soil particle surface and the aggregation of soil particles
\nJournal<\/strong>: Science of the Total Environment
\n<\/em>DOI<\/strong>:10.1016\/j.scitotenv.2025.178712
\nArticle Publication Date:<\/strong>04 April 2025
\nAffiliations:
\n<\/strong>1<\/sup>National Institute of Advanced Industrial Science and Technology (AIST), Japan.
\n2<\/sup>Department of Resources and Environmental Engineering, Waseda University, Japan<\/p>\n

About Kyouhei Tsuchida from Waseda University<\/strong> and AIST<\/strong><\/p>\n

Mr. Kyouhei Tsuchida is a doctoral student at Waseda University and a researcher at the National Institute of Advanced Industrial Science and Technology (AIST). At AIST, he is a part of the Integrated Research Center for Nature Positive Technology, where his specialization is studying environmental risk and transport phenomena of pollutants.\u00a0He has co-authored several publications and has presented his work at different international conferences, including the American Geophysical Union’s annual meeting in 2023. His key research focuses on environmental risk and transport phenomena of pollutants, including the development of novel methods to measure nano\/microplastic concentrations in soil.<\/p>\n","protected":false},"excerpt":{"rendered":"

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