Natural iron fertilization can lock atmospheric CO2 in the ocean

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Washington, Jan 31 (ANI): In a new research, scientists have found that natural iron fertilization can lock atmospheric carbon dioxide (CO2) in the ocean.

The research, conducted by an international team led by Raymond Pollard of the National Oceanography Centre, Southampton, in the Southern Ocean, found that natural iron fertilization enhanced the export of carbon to the deep ocean. cientists have generally accepted the fact that biological productivity in large areas of the Southern Ocean is limited by the supply of iron, an important micronutrient for phytoplankton.

However, downstream of ocean islands in this study area, massive phytoplankton blooms have been observed, leading to the idea that the islands themselves are somehow fertilizing the ocean with iron.

The team showed that this natural iron fertilization enhanced phytoplankton growth and productivity and the amount of carbon exported from the surface layer (100 meters) by two to three times.

Moreover, they found that the amount of carbon stored at 3,000 meters and in the sediment was similarly two to three times higher beneath the natural fertilized region than for the nearby iron-poor region.

"This work demonstrated for the first time that Southern Ocean phytoplankton blooms fueled by natural sources of iron have the potential to sequester carbon in the deep ocean," said Matthew Charette, a marine chemist at the Woods Hole Oceanographic Institution (WHOI).

The team conducted their experiment in 2004-2005 on the seas around the Crozet Islands and Plateau at the northern boundary of the Southern Ocean, about 1,400 miles (2,200 kilometers) southeast of South Africa.

These seas provided a natural laboratory, because each spring, the waters north of Crozet experience an enormous bloom containing billions of individual phytoplankton and covering 120,000 square kilometers (the size of Ireland).

In contrast, the area south of Crozet experiences only a small, short bloom later in the season.

"Our first question was, where does the iron come from?" said Charette.

Since the currents move from south to north over Crozet, the researchers reasoned that iron could be entrained in the water column as it flows over the plateau.

Using sediment traps and sediment cores, the researchers uncovered the first evidence that carbon deposited at 3,000 meters and in the sediment was two to three times higher beneath the natural fertilized region than for the nearby iron-poor region.

According to Pollard, the finding has significant implications for proposals to mitigate the effects of climate change through purposeful addition of iron to the ocean. (ANI)

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