Atmospheric microplastic emissions from land and ocean.

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Pollution Studies

Background:

• Microplastics (MPs) are recognized as pervasive global pollutants.
• The atmospheric distribution and emission rates of MPs remain poorly quantified.
• Existing estimates of atmospheric MP emissions vary significantly.

Purpose of the Study:

• To compile a global dataset of atmospheric MPs.
• To compare measured atmospheric MP concentrations with model simulations.
• To refine estimates of global atmospheric MP emissions from land and ocean sources.

Main Methods:

• Compilation of a global atmospheric microplastic dataset.
• Development and application of size-aligned microplastic model simulations.
• Comparison of model outputs with measured atmospheric MP concentrations.
• Estimation of land-based and oceanic MP emissions using a scaling method.

Main Results:

• Model simulations indicated a two to four orders of magnitude overestimation of measured atmospheric MP concentrations.
• Median atmospheric MP concentrations over the ocean were 27 times lower than over land.
• Estimated global land-based emissions (6.1 × 10^17 particles/year) significantly exceed oceanic emissions (2.6 × 10^16 particles/year).
• Land sources dominate the number of emitted MP particles but not necessarily the mass.

Conclusions:

• Atmospheric microplastic emissions are likely lower than previously estimated.
• Land-based sources are the primary contributors to the number of atmospheric microplastic particles.
• Further research into the size distribution of microplastic emissions is warranted to understand mass contributions.