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| Image Credit: Scientific Frontline / AI generated |
Scientific Frontline: "At a Glance" Summary
- Main Discovery: Terrestrial sources emit over 20 times more microplastic particles into the atmosphere than oceanic sources, challenging previous assumptions that the ocean was the primary emitter.
- Methodology: Researchers collected 2,782 globally distributed atmospheric microplastic measurements and compared them against a transport model using three different emission estimates, subsequently rescaling the emission data to reconcile significant discrepancies between the model and observations.
- Key Data: While land areas emit >20 times more individual particles, the total emitted mass is actually higher over the ocean due to the significantly larger average size of oceanic particles.
- Significance: This study provides the first rescaled, observation-based estimate of global microplastic emissions, revealing that current models had overestimated atmospheric microplastic concentrations and deposition rates by several orders of magnitude.
- Future Application: These improved emission estimates will refine global pollution transport models and help isolate specific contributions from sources like road traffic (tyre abrasion) versus other land-based activities.
- Branch of Science: Meteorology and Geophysics.
- Additional Detail: Primary terrestrial sources were identified as tyre abrasion, textile fibers, and the resuspension of already contaminated dust and soil.
The atmosphere is an important transport medium that carries microplastics to even the most remote parts of the world. These microplastics can be inhaled and pose a health risk to humans and animals. They can also settle out of the atmosphere and contaminate oceans and soils worldwide. A new study by the Department of Meteorology and Geophysics at the University of Vienna estimates microplastic emissions from land-based and oceanic sources into the atmosphere based on global measurement data and model simulations. The results: over 20 times more microplastic particles are emitted on land than from the ocean. The study was recently published in Nature.
It is now well documented that the atmosphere worldwide is contaminated with microplastic particles, which then settle even in the most remote parts of the world. The microplastics originate from primary sources such as tire abrasion or textile fibers, as well as from the resuspension of already contaminated land or the ocean. However, the magnitude of these emissions and their distribution among emission sources was previously unknown. In previous studies, the ocean was often cited as the main source.
Systematic comparison of model calculations and measurements
In the current study, Ioanna Evangelou, Silvia Bucci and Andreas Stohl from the University of Vienna collected 2,782 globally distributed individual measurements of microplastics in the atmosphere from the literature. The meteorologists then compared these measurements with simulations with a transport model that used three different published emission estimates. The scientists found that the model overestimates the number of microplastic particles in the atmosphere and their deposition on the Earth's surface by several orders of magnitude, both over land and over the ocean. Using this systematic discrepancy between model results and observations, the Vienna-based researchers were able to rescale the emissions separately for land and ocean emissions. This resulted in improved emission estimates.
Specifically, it turned out that the number of particles emitted on land had to be revised significantly downwards to reconcile the model results with the measurements. Ocean emissions were also largely overestimated. When asked where more microplastics enter the atmosphere, the study's lead author, Andreas Stohl, says: "The now scaled emission estimates show that over 20 times more microplastic particles are emitted on land than from the ocean." "However, the emitted mass is actually higher over the ocean than over land, which is due to the larger average size of oceanic particles," adds first author Ioanna Evangelou.
More measurements needed to clearly classify microplastic pollution
With this study, the scientists are taking an important step towards better estimating the pollution of the atmosphere with microplastics and their global transport. "However, 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.” summarizes Andreas Stohl, lead author of the study.
Research material: What Is: Microplastics
Published in journal: Nature
Title: Atmospheric microplastic emissions from land and ocean
Authors: Ioanna Evangelou, Silvia Bucci, and Andreas Stohl
Source/Credit: Universität Wien
Reference Number: es012126_01
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