Tracking Microplastics Across Air, Water, and Soil: What Spectroscopy Reveals About Global Pollution

Tracking microplastics across air, water, and soil: what spectroscopy reveals about global pollution © Somi Danita -chronicles-stock.adobe.com

Microplastics Under the Microscope

Microplastics are no longer confined to oceans or water bodies. A recent study published in the Journal of Contaminant Hydrology presents a comprehensive view of microplastic (MP) contamination across aquatic, terrestrial, and atmospheric environments. Authored by T.R. Choudhury, S. Riad, F.J. Uddin, M.A. Maksud, M.A. Alam, A.S. Chowdhury, A.N. Mubin, A.R.M.T. Islam, and G. Malafaia, the research draws on extensive spectroscopic analysis to characterize microplastic types, shapes, sizes, and chemical compositions in various ecosystems (1).

The work spans institutions including Shahjalal University of Science and Technology (Bangladesh), the University of Dhaka, Sylhet Agricultural University, the University of Coimbra (Portugal), and the Federal University of Mato Grosso do Sul (Brazil), highlighting a globally collaborative approach (1).

Spectroscopy at the Core of Identification

Central to the research is the application of Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy to classify polymer types and degradation states of microplastics. These tools provide non-destructive, high-resolution chemical fingerprinting critical to distinguishing among polymers such as polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC), even after significant environmental weathering (1).

Spectroscopic results confirmed that environmental samples contain both primary and secondary microplastics, often originating from industrial activity, consumer goods, tire wear, and synthetic textiles. The study emphasized that airborne microplastics can be even more challenging to analyze due to minute size and mixture with organic matter—conditions where Raman spectroscopy proved especially valuable (1).

Microplastics in Multiple Ecosystems

The study classified microplastic contamination into three major environmental compartments (1):

1. Aquatic systems: Rivers, lakes, and oceans where microplastics are transported long distances and ingested by aquatic organisms.
2. Terrestrial soils: Agricultural and urban soils increasingly contaminated through biosolid application, irrigation with plastic-laden water, and atmospheric deposition.
3. Atmospheric media: Airborne microplastics suspended in wind and dust, which can deposit in remote regions through atmospheric transport.

Researchers observed significant differences in microplastic morphology and polymer type between compartments, with fibrous particles dominating the atmospheric and soil environments, and fragments more common in aquatic systems.

Microplastics as Pollutant Carriers

An important aspect discussed in the paper is the role of microplastics as carriers or "vectors" for toxic substances such as heavy metals, persistent organic pollutants (POPs), and pathogenic microbes. Spectroscopic evidence of surface adsorption and changes in polymer oxidation states suggest a dynamic interaction between microplastics and environmental contaminants (1).

These interactions increase the ecological risk posed by microplastics, making them not just physical pollutants but also chemical mediators that alter biogeochemical cycles and trophic interactions.

Global Disparities in Management Approaches

Beyond characterization, the researchers conducted a policy review, revealing that global management of microplastics remains fragmented. Low-income and developing regions lack robust monitoring, legislative action, and waste management infrastructure, despite being disproportionately affected (1).

The study calls for standardized analytical techniques (especially spectroscopic protocols), improved public awareness, and international cooperation to reduce production, improve recycling, and enhance detection capabilities (1).

Looking Ahead

While spectroscopic methods have enhanced microplastic detection and understanding, the authors argue that further development of portable, field-ready instruments could improve real-time monitoring across remote or resource-limited regions (1,2).

The paper concludes by recommending that policymakers integrate multispectral detection data into comprehensive environmental models to better predict the transport and transformation of microplastics.

References
(1) Choudhury, T. R.; Riad, S.; Uddin, F. J.; Maksud, M. A.; Alam, M. A.; Chowdhury, A. S.; Mubin, A. N.; Islam, A. R. M. T.; Malafaia, G. Microplastics in Multi-Environmental Compartments: Research Advances, Media, and Global Management Scenarios. J. Contam. Hydrol. 2024, 265, 104379. DOI: 10.1016/j.jconhyd.2024.104379

(2) Kan, J.; Deng, J.; Ding, Z.; Jiang, H.; Chen, Q. Feasibility Study on Non-Destructive Detection of Microplastic Content in Flour Based on Portable Raman Spectroscopy System Combined with Mixed Variable Selection Method. Spectrochim. Acta, Part A 2025, 326, 125195. DOI: 10.1016/j.saa.2024.125195