The finding does not change estimates of the oceans' total carbon uptake, but it reveals the surprisingly large role of tropical oceans and major rivers.
The tropical North Atlantic had been considered a net emitter of carbon from the respiration of ocean life. A 2007 study estimated that ocean's contribution to the atmosphere at 30 million tons of carbon annually.
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Amazon River. |
The new study, appearing in PNAS Early Edition the week of July 21, finds that almost all the respiration is offset by organisms called diazotrophs, which pull nitrogen and carbon from the air and use them to make organic solids that sink to the ocean floor.