The first report on emerged microplastics in deep-sea sediment: Insights from the Central Indian Ocean Basin.

Microplastics (MPs, <5 mm) are widespread in coastal ecosystems and pose a growing global concern; however, their presence in deep-sea environments remains underexplored, especially in the Indian region. This study addresses this gap by providing the first comprehensive documentation of MPs in the Central Indian Ocean Basin (CIOB) at a depth of 5000 m, marking the initial effort to assess their presence and abundance in deep-sea core samples. The study investigated the MP concentration, composition and potential sources, revealing a size range between 10 μm and 4900 μm, with average abundances recorded at BC20 (10.2 ± 6.2 MPs/g), the PRZ (6.4 ± 5.0 MPs/g), and the IRZ (4.5 ± 0.8 MPs/g). Fibres constituted 54.9 % of the MPs, primarily blue, black, and red, and the predominant polymer was polyacetylene (50 %), followed by polyvinyl alcohol and polyvinyl chloride. These findings highlight the significant presence of MPs in the deep sea, underscoring the need for a better understanding of their transport and deposition mechanisms. This research is vital for shaping conservation strategies and policies aimed at mitigating MP pollution in marine ecosystems, emphasizing the urgency for further investigations in this region.