What Causes The Smell Of Spring?

There’s an unmistakable scent people associate with springtime. The description for the scent varies, but most would agree that the smell is a mix of dirt and something else. The ‘something else’ is the part that varies. Scientists at the Swedish University of Agricultural Sciences, the John Innes Centre, and Lund University have determined the compound responsible for the indescribable scent of spring. Popular Mechanics has the details:

The secret? Geosmin, the soil-based compound responsible for those hard-to-describe olfactory sensations. Our noses are so finely attuned to the organic compound, in fact, that we can detect it better than sharks can recognize blood.

For the first time, scientists at the Swedish University of Agricultural Sciences, the John Innes Centre, and Lund University have identified why this distinct scent has persisted: a symbiotic relationship between a six-legged worm, known as the springtail, and Streptomyces, a type of bacteria commonly found in soil.

"In field experiments, springtails were attracted to odours emitted by Streptomyces colonies," the authors say in their paper, which appeared earlier this month in the journal Nature Microbiology.

Streptomyces, for its part, produces organic compounds used in everything from chemical weapons to antibiotics. It also produces geosmin and other volatile organic compounds (VOCs) that easily become gases or vapors.