• picture
  • picture
  • picture
  • picture
Public Radio's Environmental News Magazine (follow us on Google News)

Note on Emerging Science

Air Date: Week of

“Excuse me!”

Researchers find naturally occurring laughing gas in clam bellies. But as Liz Gross reports the impact on the climate is not so funny.


YOUNG: It’s Living on Earth. I’m Jeff Young

CURWOOD: And I’m Steve Curwood.
Just ahead – the strange things that ride the tide – but first, we head under the surf for this note on emerging science from Liz Gross.


GROSS: Laughing gas can make a dental patient happy as a clam. But scientists were not so happy to find clams belching out this powerful greenhouse gas.


GROSS: A recent study by Danish and German biologists analyzed digestion in a number of aquatic bottom feeders, including mollusks and insect larvae. The belly gas of these invertebrates contained levels of laughing gas – or nitrous oxide – that surprised the scientists.

Nitrous oxide is the fourth largest contributor to global warming. Pound for pound, this gas traps 310 times as much heat as carbon dioxide. While burning fossil fuels is the most common source of nitrous oxide emissions, worms living in nitrogen-rich soil also release the gas. The recent study though was the first to measure the emissions from animals living in rivers, streams and oceans.

But the researchers found it’s not the clams themselves that release the gas - it’s their lunch. These animals feed on sediment full of nitrogen-hungry bacteria.

“Excuse me!”

And thanks to runoff from fields treated with chemical fertilizer, there are plenty of nitrates out there. Usually, the bacteria don’t break down these nitrates. But in environments with no oxygen, like the belly of a clam or a snail, they do – releasing laughing gas in the process.

With demand for nitrogen fertilizer increasing, and global greenhouse gas emissions going up, nitrous oxide in mollusk burps is no laughing matter.

That’s this week’s note on emerging science. I’m Liz Gross.



For the scientific paper Nitrous oxide emission by aquatic macrofauna published by Stief, Poulsden, Nielson, Brix, and Schramm in the March 17, 2009 Proceedings of the National Academy of Sciences of the US, click here.


Living on Earth wants to hear from you!

Living on Earth
62 Calef Highway, Suite 212
Lee, NH 03861
Telephone: 617-287-4121
E-mail: comments@loe.org

Newsletter [Click here]

Donate to Living on Earth!
Living on Earth is an independent media program and relies entirely on contributions from listeners and institutions supporting public service. Please donate now to preserve an independent environmental voice.

Living on Earth offers a weekly delivery of the show's rundown to your mailbox. Sign up for our newsletter today!

Sailors For The Sea: Be the change you want to sea.

Creating positive outcomes for future generations.

Innovating to make the world a better, more sustainable place to live. Listen to the race to 9 billion

The Grantham Foundation for the Protection of the Environment: Committed to protecting and improving the health of the global environment.

Contribute to Living on Earth and receive, as our gift to you, an archival print of one of Mark Seth Lender's extraordinary wildlife photographs. Follow the link to see Mark's current collection of photographs.

Buy a signed copy of Mark Seth Lender's book Smeagull the Seagull & support Living on Earth