AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Anthropogenic Influence on Particle Rebound and Phase State in Amazonia
Adam Bateman, Zhaoheng Gong, Antonio O. Manzi, Paulo Artaxo, Rodrigo A. F. Souza, SCOT MARTIN, Harvard University
Abstract Number: 424 Working Group: Aerosol Chemistry
Abstract Particulate matter (PM) in the Earth’s atmosphere occurs as liquids, semisolids, and solids. The physical state of organic PM can constrain the available mechanisms of growth and reactivity, ultimately affecting the number, size, and composition of the particle population, especially over Earth’s forested regions. Non-liquid PM was recently reported over a boreal forest of Northern Europe. Herein, the physical state, including the response to relative humidity (RH), was investigated for PM (< 1 µm) over the tropical rain forest of central Amazonia during the GoAmazon 2014/5 campaign.
Under background conditions in the absence of urban pollution, liquid particles dominated for the range of ambient RH. Under polluted conditions, the rebound response curves shifted toward those of non-liquid particles. The shift was significant enough to indicate the occurrence at ambient RH of at least some non-liquid particles in the atmospheric particle population. The concentrations of biomass burning compounds, aromatic species, and less-oxidized organic species correlated positively with the shifts in the response curves to higher RH, suggesting a causative relation between shifts in particle composition and shifts in non-liquid and liquid states. In turn, the mentioned species have sources related to human activities, including biomass burning, regional industrial activities, and urban pollution.