The Role of the Atmosphere in Distributing Microplastics Globally
Microplastics have become a global concern as they are carried by the atmosphere to even the most remote locations on Earth. These tiny particles can be inhaled by humans and animals, raising health concerns. Once in the air, microplastics eventually settle, contributing to environmental pollution in oceans and soils worldwide.
Insights from a New Study on Airborne Microplastics
Research conducted by the University of Vienna’s Department of Meteorology and Geophysics sheds light on the origins of airborne microplastics. Using a combination of global measurements and computer modeling, the study estimates that land-based sources emit over 20 times more microplastic particles into the atmosphere than oceanic sources. This significant finding, published in Nature, challenges previous assumptions about the primary sources of these pollutants.
Understanding the Sources
Microplastics have been detected in the atmosphere worldwide, eventually settling in isolated regions. They originate from direct sources like tyre abrasion and textile fibers, as well as from polluted land and ocean surfaces that release particles into the air. The new study provides a clearer understanding of the scale of these emissions and the contributions from each source, shifting the focus from oceans to land as the main emitter.
Modeling and Measurements
Researchers Ioanna Evangelou, Silvia Bucci, and Andreas Stohl analyzed 2,782 atmospheric microplastic measurements from global studies. By comparing these observations with a transport model that used three published emission estimates, they identified a significant discrepancy. The model predicted far more microplastic particles than were observed, sometimes by several orders of magnitude. This led to adjustments in the model, improving the accuracy of emission estimates for land and ocean sources.
Land vs. Ocean Emissions
After recalibration, the study revealed that while earlier models overestimated land emissions, land remains the predominant source of airborne microplastics. Ocean emissions were also revised downward. According to lead author Andreas Stohl, “The now scaled emission estimates show that over 20 times more microplastic particles are emitted on land than from the ocean.” However, Ioanna Evangelou highlighted that the emitted mass is greater over the ocean due to the larger average size of oceanic particles.
Addressing Data Uncertainties
This research advances our understanding of microplastic distribution via the atmosphere, but uncertainties persist. As Andreas Stohl notes, “The data situation is still not satisfactory, and there are still major uncertainties. More measurements are needed so that we know how much microplastic comes from traffic and how much from other sources. The size distribution of the particles is also highly uncertain, and thus the total amount of plastic transported in the atmosphere.”
Key Takeaways
- Global measurements of atmospheric microplastics were compared with model simulations.
- The model’s overestimation of microplastic particles suggests that previous emission estimates were too high, especially for land sources.
- Land emissions of microplastic particles are over 20 times higher than ocean emissions.
- More precise measurements are needed to refine emission estimates, particularly regarding the size distribution of plastic particles.
Original Story at www.sciencedaily.com