Air Study Sheds Light on Ecosystem

By isolating aerosol particles from an area in the Amazon basin nearly untouched by humans, a team of researchers led by Harvard Professor of Environmental Chemistry Scot T. Martin was able to examine how plant emissions,  cloud formation, and precipitation affect each other in an unadulturated ecosystem.

About 500 years ago, the clouds over the continents and the clouds over the ocean were similar to each other, Martin said. This is no longer true in most areas due to pollution. Martin added that the results of this recent study showed that this resemblance can still be seen in the Amazon, the “Green Ocean.”

Martin left Harvard  for the 2007-08 academic year to study first at the Max Planck Institute in Germany and then at the University of São Paulo in Brazil, where he began to work on the project, the findings of which were reported in a recent issue of Science.

Martin and the team collected data about environmental particles in a 40-meter tower, sucking the air down in tubes with a vacuum pump on the ground. The particles were then measured and analyzed by online mass spectrometers.

The study, because it was conducted in an area devoid of most human activity, could provide a starting point to investigate how humans affect the climate, said University of Colorado Postdoctoral Fellow and contributor to the study Delphine K. Farmer.

“In pre-industrial times, this cycle was really important,” said Farmer, referring to how plants and rainfall affect each other. “But by human activity, we are changing the importance of cycle.”

Martin pointed to the potential implications of this study. “We are understanding how the science system of the earth operated before human influence,” said Martin. “That’s important for two reasons: we can understand how we have changed the earth system, and, as we think about global climate change and technological solutions, we want to be sure that we don’t have unintended negative consequences.”

Martin hopes to continue the study next year.

“We don’t know how the pollution changes this dynamic cycle and what that means for climate change,” said Farmer. “But we got a starting place to think about it so that’s really the key.”


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