New class of airborne particles unaccounted for in climate models

Dec 14, 2004
Secondary electron (SE) images of CaCO3 and China loess particles before and after reaction with gaseous HNO3 in the presence of

Dry dust reacts with air pollutants to form dewy particles whose sunlight-reflecting and cloud-altering properties are unaccounted for in atmospheric models. "Calcite-containing dust particles blow into the air and encounter gaseous nitric acid in polluted air from factories to form an entirely new particle of calcium nitrate," said Alexander Laskin, a senior research scientist at the Department of Energy's Pacific Northwest National Laboratory in Richland, Washington.

"These nitrates have optical and chemical properties that are absolutely different from those of originally dry dust particles, and climate models need to be updated to reflect this chemistry." Calcite dust is ubiquitous in arid areas such as Israel, where this past winter Laskin and colleagues Vicki Grassian, chemistry professor at the University of Iowa, and Yinon Rudich, professor of environmental sciences and energy research at the Weizmann Institute of Science, collected particles for analysis. Laskin presented their findings Tuesday at the American Geophysical Union fall meeting.

Working from a mountaintop, the team collected dust that had blown in from the northern shores of Egypt, Sinai and southern Israel. The particles had mingled with air containing pollutants that originated from Cairo. They analyzed nearly 2,000 individual micron-sized particles and observed the physical and chemical changes with an array of techniques at the W.R. Wiley Environmental Molecular Sciences Laboratory at PNNL.

A key change in the properties of the newly formed nitrate particles is that they begin to absorb water and retain the moisture. These wet particles can scatter and absorb sunlight -- presenting climate modelers, who need to know where the energy is going, a new wild card to deal with. Companion studies of dust samples from the Sahara and the Saudi coast and loess from China show that the higher the calcium in the mineral, the more reactive they are in with nitric acid. And once the particle is changed, it stays that way.

"When dust storms kick up these particles and they enter polluted areas, the particles change," Laskin said. "To what extent this is happening globally, as more of the world becomes industrialized, we don't know. But now we have the laboratory and field evidence that shows it is definitely happening. The story is much more complicated than anybody thought."

Explore further: Suddenly, the sun is eerily quiet: Where did the sunspots go?

add to favorites email to friend print save as pdf

Related Stories

Fox bid for Time Warner sparks content merger race

1 hour ago

Even though Rupert Murdoch's $76 billion bid for rival media giant Time Warner Inc. has been rejected, that doesn't mean how you watch TV shows and movies will stop changing any time soon.

BlackBerry stock falls after Apple-IBM deal

1 hour ago

Blackberry stock fell sharply Wednesday, one day after the announcement of a landmark deal between rivals Apple and IBM to offer custom-tailored apps for businesses.

Comet ISON's dramatic final hours

2 hours ago

(Phys.org) —A new analysis of data from the ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft has revealed that comet 2012/S1 (ISON) stopped producing dust and gas shortly before it raced past ...

Recommended for you

Fermi finds a 'transformer' pulsar

3 hours ago

(Phys.org) —In late June 2013, an exceptional binary containing a rapidly spinning neutron star underwent a dramatic change in behavior never before observed. The pulsar's radio beacon vanished, while at ...

New launch date set for ISS delivery vessel

4 hours ago

A robot ship will be launched from Kourou, French Guiana, after a five-day delay on July 29 to deliver provisions to the International Space Station, space transport firm Arianespace said Tuesday.

The heart of an astronaut, five years on

5 hours ago

The heart of an astronaut is a much-studied thing. Scientists have analyzed its blood flow, rhythms, atrophy and, through journal studies, even matters of the heart. But for the first time, researchers are ...

User comments : 0