Constraining the atmospheric limb of the plastic cycle

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Pollution Studies

Background:

• Plastic pollution is a major global environmental and social challenge.
• The atmosphere plays a significant role in transporting microplastics to remote regions.
• Understanding microplastic sources and transport is crucial for mitigating pollution.

Purpose of the Study:

• To identify the primary sources of atmospheric microplastics in the western United States.
• To quantify the contribution of different sources to atmospheric microplastic deposition.
• To assess the global transport and deposition patterns of microplastics.

Main Methods:

• Utilized in situ observations of microplastic deposition.
• Employed an atmospheric transport model.
• Applied optimal estimation techniques to constrain emission sources.

Main Results:

• Roads were identified as the dominant source (84%) of atmospheric microplastics in the western US, followed by the ocean (11%) and agricultural soil dust (5%).
• Most continents were found to be net importers of microplastics from the marine environment.
• Results indicate that non-biodegradable polymers will continue to cycle through Earth's systems.

Conclusions:

• Secondary re-emission sources, particularly roads, are critical contributors to atmospheric microplastic pollution.
• Legacy plastic pollution significantly contributes to the global atmospheric burden of microplastics.
• Further research is needed to reduce uncertainties in microplastic transport, deposition, and source attribution.