Scientists Find New Way to Estimate Global Rainfall and Track Ocean Pollution

MIAMI — Feb 15, 2011 — A study by scientists at the University of Miami (UM) Rosenstiel School of Marine & Atmospheric Science suggests a new way to estimate how much of the ocean’s pollution is falling from the sky. The new findings can help improve scientific understanding of how toxic airborne chemicals, from the burning of fossil fuels and industrial power plants emissions, are impacting the oceans globally.

By measuring Beryllium-7 (⁷Be) isotope concentrations in the ocean, which isfound naturally throughout Earth’s atmosphere, Rosenstiel School scientists David Kadko and Joseph Prospero were able to provide a method to accurately estimate rainfall in remote regions of the ocean. The two-year study measured ⁷Be deposited in rain collectors at two sites in Bermuda and compared these estimates to those observed in the nearby Sargasso Sea.

“Over vast areas of the oceans the only rainfall data available are those made by using conventional rain collectors placed on islands,” said Prospero, professor of marine and atmospheric chemistry at the UM Rosenstiel School. “However, rainfall on the island is not necessarily representative of that which falls in the surrounding ocean. Our paper shows that properly placed rain collectors on Bermuda do yield rainfall rates that agree with those determined through the ⁷Be measurements.”

Rainfall is a major pathway by which man-made airborne pollutants and other naturally occurring chemicals enter the oceans.

Berrylium-7, like man-made pollutants and other naturally occurring chemicals, attaches itself to atmospheric dust particles and enters the ocean during rain events. By understanding this process, scientists can establish new ways to quantify airborne pollutants deposited to the ocean.

“The accumulation of ⁷Be in the upper ocean provides a means of assessing ⁷Be deposition to the ocean on regional and global scales,” said Kadko, professor of marine and atmospheric chemistry at the Rosenstiel and lead author of the study. “This then can be used to assess the deposition of other chemical species.”

The paper, titled “Deposition of ⁷Be to Bermuda and the regional ocean: Environmental factors affecting estimates of atmospheric flux to the ocean” was published in the Feb. 9 issue of the American Geophysical Union Journal of Geophysical Research.

About the University of Miami’s Rosenstiel School
The University of Miami’s mission is to educate and nurture students, to create knowledge, and to provide service to our community and beyond. Committed to excellence and proud of the diversity of our University family, we strive to develop future leaders of our nation and the world. Founded in the 1940’s, the Rosenstiel School of Marine & Atmospheric Science has grown into one of the world’s premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life. For more information, please visit www.rsmas.miami.edu.