Unveiling the deep-sea microplastic Odyssey: Characteristics, distribution, and ecological implications in Pacific Ocean sediments

Microplastics (MPs) in deep-sea environments are a growing concern due to their potential ecological risks and the deep sea's role in global biogeochemical cycles. This study investigated the characteristics and distribution of MPs in sediments from the Pacific Ocean at depths of 4900–7016 meters across three regions: Western Pacific (WP), Central Pacific (CP), and Eastern Pacific (EP). MPs were detected at all sampling sites, with the highest abundance in WP (111.3 ± 75.1 items/kg dw ) and the lowest in CP (49.4 ± 18.7 items/kg dw ). Site S 9 was recorded as the peak abundance (270.1 ± 107.4 items/kg dw ) in WP. MPs were predominantly fibers (94.8%) in black, gray, and blue hues, mainly composed of polyester and rayon. Statistical analysis showed significant regional variations, reflecting anthropogenic impacts and complex deposition mechanisms. Risk assessments indicated low to medium hazard levels (PLI <10, PRI ≤ III), but the potential ecological impacts remain concerning. This study highlights the significant variability in MP distribution across regions, emphasizing the importance of region-specific mitigation strategies. It calls for comprehensive, long-term research to better understand MP sources, deposition processes, and ecological impacts in deep-sea ecosystems. • Microplastics were found in Pacific deep-sea sediments at depths of 4900–7016 meters. • Western Pacific sediments have the highest microplastic abundance and fiber dominance. • Polyester and rayon dominated microplastic composition, reflecting human activity. • Risk assessments indicated low to medium hazard levels in deep-sea ecosystems. • Results stress the need for region-specific and long-term pollution management.