Patterns and trends in marine microplastics density distributions using a long-term, global, field database

We evaluate global microplastics particle density distribution using field data from 1972 to 2022, made available by the NOAA (National Oceanic and Atmospheric Administration) NCEI (National Centers for Environmental Information) global marine microplastics database. We resampled the measured microplastics density data from NOAA NCEI into a regularly spaced 1° × 1° grid and applied ordinary block kriging on a 1° × 1° mask map of the global oceans to spatially interpolate the gridded data. Climate data were retrieved from the Climate Data Store of the Copernicus Climate Change Service. Our evaluation suggests that global microplastics particle density roughly doubled every decade but that there are regional variations. Global average microplastics density correlates strongly with total global precipitation and seasonal changes appear strong in the North Pacific but not in the North Atlantic. We find that microplastics density in the North Pacific increases with El Niño Southern Oscillation and Pacific Decadal Oscillation respective indices ONI (Oceanic Niño Index) and PDO, and decreases with North Atlantic Oscillation index, NAO. In the western North Atlantic, there is no demonstrable relationship with any of these low-frequency oscillations. Our microplastics density distribution maps are expected be useful for verifying satellite remote sensing algorithms, assessing overlaps with sensitive and vulnerable populations, species, and ecosystems, and assessing climate change impacts.