Author: Dr Ramamoorthy Ayyamperumal
Journal: Journal of Physics and Chemistry of the Earth (A/B/C)– Elsevier(Impact Factor-4.1)
Urban soils across rapidly developing cities like Chennai are becoming hotspots for a lesser-known but dangerous pollutant—microplastics (MPs). These tiny plastic fragments, once part of everyday products, are now altering soil health, affecting ecosystems, and posing long-term risks to human and environmental well-being.
Our recent study sheds light on this growing concern by analyzing 25 soil samples collected from diverse urban locations in Chennai. These samples underwent rigorous testing to determine key physicochemical properties such as pH (ranging from 7.0 to 9.8) and organic matter content (0.19% to 23.6%).
Key Findings:
- Extraction and Analysis: MPs were isolated using a zinc chloride-based density separation and categorized by shape and color. The most common forms were fragments and fibers, with white/transparent and blue/purple being dominant.
- Polymer Composition: FTIR spectroscopy revealed that polypropylene, polystyrene, and nylon were the most frequently detected polymers.
- Concentration Levels: MP particles ranged from 6 to 31 per 100 g of soil, with Sample 18 showing the highest load.
- Contamination Assessment: Based on the Pollution Load Index (PLI), all sites were classified under Hazard Category I, indicating low to moderate contamination.
Statistical Insights:
- A strong negative correlation was found between MP abundance and organic matter content (Pearson’s r = –0.512, p = 0.013).
- Principal Component Analysis (PCA) further supported this inverse relationship, while showing a positive association with soil pH.
Spatial mapping revealed pollution hotspots, likely due to land use and waste disposal practices, pointing toward urban planning and waste management gaps. This research emphasizes the increasing presence of MPs in urban environments and supports the need for ongoing monitoring and mitigation through bioremediation, adoption of biodegradable alternatives, enhanced waste infrastructure, and public engagement.
Future investigations must prioritize long-term field experiments to better understand how different plastic polymers behave over time in soil systems. These studies should examine how microplastics interact with:
- Soil microbiota, potentially disrupting microbial diversity and function
- Nutrient cycling, affecting soil fertility and productivity
- Contaminant mobility, where plastics may act as carriers for heavy metals and toxic compounds
By integrating these approaches and deepening scientific understanding of microplastic-soil interactions, sustainable urban soil management can be achieved, safeguarding soil health and supporting resilient agricultural productivity in rapidly urbanizing regions.
-Microplastics in Urban Soils: A Silent Threat Beneath Our Feet-