By John Toon Researchers have identified a simple feedback effect that may help control oxygen levels in the earth's atmosphere by altering the productivity of marine organisms. By adjusting the internal oceanic recycling of a key nutrient in response to changing levels of oxygen, the feedback effect would regulate the growth of ocean plants that produce oxygen as a by-product of photosynthesis. Described in a paper published January 26 in the journal Science , the work provides new information on how complex geological and biological systems work together to maintain the planet's environment within the narrow bounds necessary to support life. It may also provide additional clues to other complex aspects of atmospheric chemistry.
Researchers prepare a box core sediment sampling device to make measurements off the coast of Peru.
We now have a direct link between inorganic and biological processes that at first seemed to be very disconnected. Van Cappellen and coauthor Ellery D. Ingall of the University of Texas at Austin's Marine Science Institute base their conclusions on levels of the nutrient phosphorus measured in both modern and ancient sediments taken from the ocean floor. With changes in water oxygenation, major changes were always observed in the distribution of phosphorus in the sediments. In both ancient and modern sediments, the researchers measured larger amounts of phosphorus in sediments produced during conditions in which oxygen levels in the surrounding ocean water were high. Conversely, low levels of water oxygenation corresponded to reduced amounts of phosphorus stored in the sediments.