Global mapping for the occurrence of all-sized microplastics in seafloor sediments

These files contain critical data obtained through experiments or analyses, which serve as the foundational data for this study. Supplementary Data Table 1 provides detailed sampling information for 155 marine sediment samples globally, including coordinates, sampling depth, sampling date, sampling area, depth partition, cruise information, research vessel, and sampling instrument type and models. Supplementary Data Table 2 presents the abundance of microplastics in marine sediments, both in terms of number and mass, including the abundance of 20 microplastic categorys. Uncertainty in microplastic abundance was quantified separately for 12 oceanic regions and six depth zones using a Wilcoxon signed-rank test and Monte Carlo simulations. Supplementary Data Table 3 presents the basic morphological characteristics of the monitored microplastics, including abundance data for 19 color types, 7 shape categories, 87 detailed polymer types, and 6 size ranges. Supplementary Data Table 4 provides the average carbon concentration and carbon ratio in microplastics from each sediment sample. Supplementary Data Table 5 provides environmental parameters for each sediment sampling site, including the flow characteristics of ocean surface currents (Eastward sea water velocity, Northward sea water velocity, Sea surface wave from direction, Sea surface wave significant height and Stokes drift velocity of particles), TOM and TOC content in sediments, and the corresponding particle size of microplastics. Supplementary Data Table 6 provides global ocean 2D latitude-longitude grid data at a resolution of 0.5° and the corresponding SRTM15+V2.7 @ 1.9 km seabed depth data at a resolution of 1 arc minute. Supplementary Data Table 7 (Table MP Extraction Process workflow) presents key information extracted from 150 peer‑reviewed studies retained after screening. It includes core sediment‑sampling metadata (latitude–longitude and water depth), a fully transparent description of the MP extraction workflow (density separation/floatation and chemical digestion), the make and model of identification instruments, microplastic abundance with associated standard deviations, and the corresponding DOIs; Table MP Correction Process presents abundance values recalibrated to the full‑size microplastic estimates, harmonized across studies by accounting for the extraction medium, digestion reagent, and identification technology reported in each publication. Supplementary Data Table 8 reports the physical parameters of surface waves and seafloor currents, together with depth partition, for 155 sampling stations from this study across the five oceans, 2,024 screened literature-derived stations, and 168,492 two-dimensional global ocean latitude–longitude grid points. Supplementary Data Table 9 reports global gridded estimates of seafloor microplastic abundance generated using an XGBoost model trained under an integrated bootstrapping and leave‑one‑cluster‑out data‑splitting scheme. For each grid cell, we provide the ensemble mean, standard deviation, and coefficient of variation across resamples.