At first, Li was flummoxed. Then, he says, he realized that deserts are "like a dry ocean."
The pH of oceans is falling gradually as they absorb CO2, forming carbonic acid. "I thought, 'Why wouldn't this also happen in the soil?' " Whereas the ocean has a single surface for gas exchange, Li says, soil is a porous medium with a huge reactive surface area. One question, Tans notes, is why the desert soils would remain alkaline as they absorb CO2. Li suggests that ongoing salinization drives pH in the opposite direction, allowing for continual CO2 absorption. But where the carbon goes--whether it is stowed largely as calcium carbonate or other salts--is unknown, Li says.
Join us on our
Share this page with your friends
on your favorite social network: