Mudslides following Chinese quake may cause CO2 release in upcoming decades

Washington, March 3 (ANI): A new study has shown that mudslides that followed the earthquake that struck China on May 12 last year, may cause a carbon-dioxide (CO2) release in upcoming decades equivalent to two percent of current annual global carbon emissions from fossil fuel combustion.

The magnitude-7.9 Wenchuan quake was followed by many aftershocks in the Sichuan Basin, an area that, because of its geological features - deep valleys enclosed by high mountains with steep slopes - is already prone to landslides.

May is also the rainy season in Sichuan, and the combination of aftershocks and major precipitation events in the days following the earthquake caused severe mudslides.

Mudslides wipe away plants and topsoil, depleting terrain of nutrients for plant regrowth and burying swaths of vegetation.

Buried vegetable matter decomposes and releases carbon dioxide and other gases to the atmosphere.

The expected carbon dioxide release from the mudslides following the Wenchuan earthquake is similar to that caused by Hurricane Katrina's plant damage, reported Diandong Ren, of the University of Texas at Austin, and his colleagues, who used a computer model to predict the ecosystem impacts of the mudslides.

According to Ren, the vegetation destruction will lead to a loss of nitrogen from the quake-devastated region's ecosystem twice as large as the loss of that nutrient from California ecosystems because of the October 2007 wildfires there.

As the biomass buried by the China quake rots, 14 percent of the nitrogen will be spewed into the atmosphere as nitrous oxide, a pollutant typically released from agricultural operations, automobiles, and other sources.

Although landscapes devastated by the Chinese earthquake may re-green soon, the recovery will be cosmetic.

"From above, the area will look green in a few years, because grass grows back quickly, but the soil nutrients recover very slowly, and other kinds of plants won't grow," said Ren.

To predict ecosystem impacts of the mudslides, Ren and his collaborators applied a comprehensive computer model of landslides that incorporates several physical parameters, such as soil mechanics, root mechanical reinforcement (the root's grip of the dirt, which mitigates erosion), and precipitation.

Ren's model also shows that the primary mudslides following the earthquake removed large areas of nutrient-rich topsoil, leaving behind deep scars in the land that will take decades to recover, preventing the re-growth of vegetation. (ANI)