快猫短视频

SPEEDING up part of the ocean鈥檚 natural carbon cycle might help slow global
warming. That鈥檚 the thinking behind a plan to lock up carbon dioxide from power
plant emissions by mixing the gas with limestone and seawater, and then dumping
it in the ocean.

Carbon dioxide in the atmosphere normally mixes with seawater at the ocean鈥檚
surface to form carbonic acid. From there it is slowly circulated to the sea
floor, where it reacts with sediments to form relatively inert calcium
bicarbonate.

鈥淣aturally, this reaction takes 5000 or 10,000 years,鈥� says biogeochemist Ken
Caldeira of Lawrence Livermore National Laboratory in California. 鈥淲e鈥檇 like to
have it occur over seconds or minutes in a reactor vessel at a power plant.鈥�

Other schemes for locking up carbon in the ocean, for example injecting
CO₂ directly into the deep sea, or fertilising the ocean with iron to
increase organisms鈥� CO₂ consumption have led to fears that they would
take a heavy toll on the local marine environment
(快猫短视频, 20 October, p 7).

Increasing the level of CO₂ in the atmosphere boosts the
concentration of carbonic acid, which erodes coral reefs. Dissolving CO
₂ directly in seawater wouldn鈥檛 solve that problem. But locking the carbon
up in calcium bicarbonate first would help lower the acidity.

There is an environmental downside to the Livermore group鈥檚 technique though,
as the large quantities of limestone needed would probably have to come from
strip mining.

The researchers have begun laboratory trials of their method, and hope to
test it in a power plant by 2003.