Organic particles modulate soot mixing in the atmosphere

February 13, 2019, Environmental Molecular Sciences Laboratory
Credit: CC0 Public Domain

In the atmosphere, individual soot particles emitted from human activities often encounter and combine with organic material, forming soot-containing particles. A research team led by scientists from the U.S. Department of Energy's (DOE) Pacific Northwest National Laboratory/EMSL and Michigan Technological University established a link between the viscosity of the organic material and its distribution within the soot-containing particle. This mixing configuration is important because it alters the particles' ability to absorb and scatter solar radiation.

The scientists discovered that organic material of low viscosity partially or completely encapsulated soot particles, while highly viscous organic material often attaches to the surface of co-existing soot particles or do not even stick together, remaining separate.

Soot particles strongly absorb solar radiation, and therefore, affect Earth's energy balance. However, their strongly depend on how the individual soot particles mix with other particles in the atmosphere (internal mixing).

This study identified the viscosity of organic matter in the atmosphere as a key factor that influences the distribution of organic matter within soot-containing particles. These findings will improve aerosol models that predict the mixing state of soot via condensation and coagulation processes, thereby improving radiative forcing calculations and climate predictions.

Organic particles in the atmosphere exhibit a wide range of viscosity, depending upon their and the surrounding environmental conditions, such as temperature and relative humidity. As soot particles combine with organic particles in the atmosphere, the distribution of soot and organic material in the combined particle determines its overall optical properties and radiative forcing-warming or cooling effects.

Taking scanning electron microscopy images at different view angles, researchers investigated soot-containing particles collected during DOE's Carbonaceous Aerosol and Radiative Effects Study (CARES) in Sacramento, California, in June 2010. Their results indicate that organic material of low to intermediate viscosity often engulfed soot, while highly viscous organic material attaches to the soot surface or remains separated from it. Soot particles engulfed by low viscosity organics become coated and can be approximately represented by a "core-shell" model, where the soot particles are at the center of an idealized spherical shell made of the organic material. In contrast, increasing viscosity results in limited (partial) engulfing, and hence the formation of non-core-shell configurations.

These findings establish a link between the viscosity of and its distribution when mixed internally with . Accounting for the effects of viscosity of organic matter on the mixing state of soot-containing in numerical models will improve estimates of radiative forcing from .

Explore further: Researchers used diesel pollution to understand how soot forms ice in cirrus clouds

More information: Noopur Sharma et al. Physical Properties of Aerosol Internally Mixed With Soot Particles in a Biogenically Dominated Environment in California, Geophysical Research Letters (2018). DOI: 10.1029/2018GL079404

Related Stories

Putting the squeeze on soot

November 14, 2018

Running diesel engines and gas turbines at high pressure to boost power output and efficiency is harmful for the environment. Burning fuel at high pressure can significantly change the soot particles that are produced, William ...

Less is more when it comes to soot

April 5, 2016

Small particles emitted into air during the burning of hydrocarbon fuels damage the human respiratory system and enhance the greenhouse effect. In their agglomerated form, these particles form soot that consists predominantly ...

Recommended for you

Archaeologists discover Incan tomb in Peru

February 16, 2019

Peruvian archaeologists discovered an Incan tomb in the north of the country where an elite member of the pre-Columbian empire was buried, one of the investigators announced Friday.

Where is the universe hiding its missing mass?

February 15, 2019

Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the "normal" matter in the Universe. New results from NASA's Chandra X-ray Observatory may have helped them ...

What rising seas mean for local economies

February 15, 2019

Impacts from climate change are not always easy to see. But for many local businesses in coastal communities across the United States, the evidence is right outside their doors—or in their parking lots.

The friendly extortioner takes it all

February 15, 2019

Cooperating with other people makes many things easier. However, competition is also a characteristic aspect of our society. In their struggle for contracts and positions, people have to be more successful than their competitors ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.