January 19, 2012

Scientists open Dust Library


Aggregate interplanetary dust particle

We may think of libraries as places that gather dust, but a library of dust itself? In this article from the New Scientist, we learn about some researchers who have started just that:

Welcome to the dust library. With 63 individual particles cataloged, the collection is hardly dust’s answer to the great library of Alexandria, but there are plans to expand. Besides, far from being dry, this is a genre of unexpected delights…

Our knowledge of dust is diverse, if a little haphazard. Among other things, we know that British stately homes are covered in a fine layer consisting mostly of skin, hair and fabric fibres; that indoor dust can pose more of a threat to health than the outdoor variety; and that city air is teeming with bacteria from dog faeces. But there is one glaring gap in our dusty repertoire, which stems from the fact that the stuff is generally studied in bulk: no one had ever looked at what an individual dust particle is actually made of. Until now.

Researchers James Coe at Ohio State University in Columbus and Katherine Cilwa at the University of Michigan began collecting dust quite by accident. While experimenting with the use of infrared light to determine the chemical composition of various substances, sloppy sampling one day revealed an unexpected spectrum: dust. They were hooked. Hoovering up samples from all around them, they had captured 63 solitary dust particles, submitted them to infrared spectroscopy. And the Dust Library was born.

According to the New Scientist, the beginnings of this unusual library tells us:

The most common component was organic material, present in 40 of the 63 particles – exactly what is unclear, but it could be anything from pollen to sloughed-off bits of researcher. Quartz, found in 34 particles, came next, followed by carbonates (17 particles) and gypsum (14). “The minerals blow in,” says Coe. “They come from all over the world.” Other ingredients included air pollutants and fertiliser chemicals.

Anyone counting will also have noticed that there are already more components than particles. That is because most specks of dust are conglomerates, which means they may take an infinite variety of forms, much like snowflakes. The next obvious step was to find out what individual conglomerates looked like, but pinpointing exactly which speck corresponded to which spectrum wasn’t going to be easy.

A quick-witted undergraduate, Matthew McCormack, who was working on the project with them, figured out how to take a dust particle’s image with an electron microscope, so the conglomerate particles could be identified, cross-referenced with the infrared spectroscopy, as it where.

The researchers say their work has particular potential for public health, given that dust-related deaths – mainly from respiratory disease and stroke – are thought to number around 10,000 each year in the UK alone….Recent research suggests that organic material causes some of the worst health problems, says Coe. He is currently calibrating the sensor with known chemicals so that his team can tell the exact nature of any organic components they come across.

Coe’s students are also collecting samples from smoking lounges and parking lots with the aim of creating reference libraries with particles from different environments.

Next: Stay tuned for the Library of Water!

Valerie Merians is the co-founder and co-publisher of Melville House.