引自:ScienceDaily (Jan. 29, 2009) —

Making bales with 30 percent of global crop residues – the stalks and such left after harvesting – and then sinking the bales into the deep ocean could reduce the build up of global carbon dioxide in the atmosphere by up to 15 percent a year, according to just published calculations.

将农作物桔杆成捆固定到海洋深处,可能是另外一种有效的海洋固定碳的方法; 可能占了地球上每年固定总碳的15%..

Just past the continental shelf in the Gulf of Mexico -- the shelf is marked with the blue line -- a fan of sediment has formed on the seafloor made up of silt and debris that settles out of Mississippi River waters flowing into the gulf. These alluvial, or submarine, fans are found wherever rivers run into the ocean. Crop residues sunk in such fans would become covered with silt, further ensuring that carbon would be locked away for long periods. (Credit: S. Strand/UW/U.S. Geological Survey)

Worldwide, farming is mankind's largest-scale activity. Thirty percent of the world's crop residue represents 600 megatons of carbon that, if sequestered in the deep ocean with 92 percent efficiency, would mean the amount of carbon dioxide in the atmosphere would be reduced from 4,000 megatons of carbon to 3,400 megatons annually, Strand says. That's about a 15 percent decrease.

The proposed process would remove only above-ground residue. Strand bases his calculations on using 30 percent of crop residue because that's what agricultural scientists say could sustainably be removed, the rest being needed to maintain carbon in the soil. Crop residue would be baled with existing equipment and transported by trucks, barges or trains to ports, just as crops are. The bales would be barged to where the ocean is 1,500 meters, or nearly a mile, deep and then the bales would be weighted with rock and sunk.

"The ocean waters below 1,500 meters do not mix significantly with the upper waters," Strand says. "In the deep ocean it is cold, oxygen is limited and there are few marine organisms that can break down crop residue. That means what is put there will stay there for thousands of years."

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