The Journal of Young Investigators: An Undergraduate, Peer-Reviewed Science Journal

10 February 2005 - Land air pollution may increase the productivity of the oceans, according to a study published in the February issue of the Journal of Geophysical Research — Atmospheres. Funded by the National Science Foundation, the research could help scientists understand the connections between land and ocean.

Author Nicholas Meskhidze and co-author William Chameides, both from the Georgia Institute of Technology, found evidence that sulfur dioxide in air pollution interacts with iron found naturally in dust storms. The sulfur dioxide, produced from power plants and factories, converts the iron into a highly acidic form, which can be dissolved in water. When this converted form of iron reaches the ocean, it becomes available to phytoplankton, tiny marine organisms responsible for almost half of Earth’s photosynthesis. Iron is necessary for phytoplankton growth, especially in nutrient-poor areas.

"I knew that large storms from the Gobi deserts in northern China and Mongolia could carry iron from the soil to remote regions of the northern Pacific Ocean," Meskhidze said. "But I was puzzled because the iron in desert dust is . . . not readily available to the plankton."

Using satellite and in-flight data of two Gobi dust storms in 2001, Meskhidze found that the smaller storm had a higher concentration of sulfur dioxide. When this storm passed over the northern Pacific, there was a boost in phytoplankton production. In contrast, there was no increase in phytoplankton production when the larger storm passed, because the concentration of sulfur dioxide was too low to convert the iron into a usable form.

According to Meskhidze and Chameides, phytoplankton may also play a role in the cycling of greenhouse gases, particularly carbon dioxide. An increase in phytoplankton photosynthesis could help to reduce the amount of carbon dioxide in the atmosphere.

“It appears that the recipe of adding pollution to mineral dust from East Asia may actually enhance ocean productivity and, in so doing, draw down atmospheric carbon dioxide and reduce global warming," said Chameides.

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