FTIR based assessment of microplastic contamination in soil water and insect ecosystems reveals environmental and ecological risks

Microplastic (MP) pollution has emerged as a critical global environmental concern, impacting soil, water, and insect ecosystems. This study quantified MP prevalence in soil, water, and insect samples collected from specified rural and semi-urban study areas in the southern India, using Fourier-transform infrared (FTIR) spectroscopy for contamination assessment. The results revealed a predominance of polypropylene/polystyrene (PP/PS; 91.3%), followed by polyethylene (PE; 15.1%), polyethylene terephthalate (PET; 9.2%), and polyamide (PA; 6.2%). Insect samples showed high MP adherence, particularly in blister beetles, click beetles, and carpenter bees, suggesting their role as vectors for MP dissemination, mainly through adherence pathways. FTIR analysis confirmed characteristic MP absorption peaks at 1637.6 cm⁻¹ (PP/PS), 1031.9 cm⁻¹ (PE), 582.5 cm⁻¹ (PET), and 3448.7 cm⁻¹ (-OH groups), indicating interactions between MP and organic matter. FTIR analysis of soil samples showed PE as the dominant MP, with higher quantities in garbage sites (36.0%) and residential areas (34.9%) compared to agricultural farms (18.9%). Soil samples varied significantly, with bulk density (1.1–1.4 g cc⁻¹), porosity (36.1–58.0%), and organic carbon content (0.7–1.9%), indicating potential impacts on fertility and microbial activity. Water samples from irrigation sources showed detectable PET (1.2%) and PA (0.7%) concentrations, with a distinct peak at 2316.5 cm⁻¹, raising concerns about agricultural sustainability and food safety. These findings highlight the urgent need for stricter waste management regulations and further studies into the long-term environmental and human health risks of MP pollution.