The deep sea is increasingly recognized as the ultimate global sink for marine microplastics, yet its true storage capacity and primary pollution sources remain largely constrained by shallow sampling and a historic focus on land-based inputs. Here, we conducted a high-resolution investigation of microplastic pollution in deep-sea sediments (4,500~6,000 m) across 18 stations in the Western Pacific Ocean. By expanding the vertical sampling depth to 20 cm, we reveal that microplastics penetrate significantly deeper than the commonly assessed surface layer (0~10 cm), with subsurface (10~20 cm) abundances (3.88 ± 0.58 items/g) comparable to those at the surface (4.38 ± 0.61 items/g). LDIR identified acrylates (15.8%) and fluororubber (15.3%) as the dominant polymers, providing compelling empirical evidence that direct maritime emissions—specifically ship antifouling coatings—constitute a massive, previously underestimated point source in the open ocean. Furthermore, we observed polymer-specific, redox-driven aging dynamics: PE and PET exhibited higher weathering in nearly oxic surface layers, whereas PU showed elevated degradation in anoxic subsurface zones. These findings indicate that the deep sea is a dynamic, highly selective weathering environment rather than an inert sink. Ultimately, this study highlights the urgent need to integrate maritime paint emissions and deeper benthic storage into global marine microplastic mass balance models.

Tire additives are released during tire wear and can enter roadside air with fresh or resuspended particles and, for some compounds, through volatilization. Once airborne, they may partition between gas and particle phases, undergo atmospheric transformation, and reach terrestrial surfaces through dry and wet deposition. However, how much atmospheric deposition contributes to the transfer of tire additives from roadside air to soils and plants remains unclear. This review traces major tire additives and their transformation products from their occurrence, phase partitioning, and transformation in the atmosphere, through deposition, to their subsequent fate at the soil–plant interface. Available evidence shows that these processes are strongly compound-specific. Some additives remain mainly particle-associated, whereas others have substantial gas-phase fractions, and environmental aging can further change both parent compounds and transformation products before deposition. Field studies confirm the deposition of tire and road wear particles and selected tire additives, while controlled soil and plant experiments show retention, transformation, release, and plant uptake after environmental entry. However, the contribution of atmospheric deposition to additive burdens in field soils and crops is still difficult to separate from runoff, irrigation, road splash, and other rubber-related sources. Acute toxicity of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone (6PPD-Q) is well established in highly sensitive aquatic species, whereas risks associated with atmospheric deposition in terrestrial systems and humans remain poorly characterized. Overall, atmospheric deposition represents a possible pathway by which tire additives are transferred from roadside air to terrestrial environments. Quantifying its contribution will require phase-resolved measurements, robust source attribution, and coordinated monitoring across air, deposition, soil, and plants.