沙漠风暴的强度可能影响海洋浮游植物

Each spring, powerful dust storms in the deserts of Mongolia and northern China send thick clouds of particles into the atmosphere. Eastward ¹ winds sweep these particles as far as the Pacific, where dust ultimately settles in the open ocean. This desert dust contains, among other minerals, iron -- an essential nutrient ² for hundreds of species of phytoplankton that make up the ocean's food base. Now scientists at MIT, Columbia University, and Florida State University have determined ³ that once iron is deposited in the ocean, it has a very short residence time, spending only six months in surface waters before sinking into the deep ocean. This high turnover ⁴ of iron signals that large seasonal ⁵ changes in desert dust may have dramatic effects on surface phytoplankton that depend on iron. , ,"If there are changes to the sizes of deserts in Asia, or changes in the way people are using land, there could be a larger source of dust to the ocean," says Chris Hayes, a postdoc in MIT's Department of Earth, Atmospheric ⁶, and Planetary Sciences (EAPS). "It's difficult to predict how the whole ecosystem ⁷ will change, but because the residence time [of iron] is very short, year-to-year changes in dust will definitely have an impact on phytoplankton." , ,The team's results are published in the journal Geochemica et Cosmochimica Acta. Co-authors include Ed Boyle, a professor of ocean geochemistry at MIT; David McGee, the Kerr-McGee Career Development Assistant Professor in EAPS; and former postdoc Jessica Fitzsimmons.