A31A-0009
Anthropogenic Effects on the Mixing State of Aerosols over Manaus during the Green Ocean Amazon (GoAmazon) Campaign
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Matthew W Fraund1, Don Pham1, Tristan Harder2, Rachel O'Brien3, Bingbing Wang4, Alexander Laskin5, Mary Kathleen Gilles2 and Ryan Moffet1, (1)University of the Pacific, Stockton, CA, United States, (2)Lawrence Berkeley National Lab, Berkeley, CA, United States, (3)Massachusetts Institute of Technology, Cambridge, MA, United States, (4)Pacific Northwest National Laboratory, Richland, WA, United States, (5)Pacific North West National Laboratory, EMSL, Richland, WA, United States
Abstract:
The role that anthropogenic aerosols play in cloud formation is uncertain and contributes largely to the uncertainty in predicting future climate. One region of particular importance is the Amazon rainforest, which accounts for over half of the world’s rainforest. During GoAmazon2014/15 IOP2, aerosol samples were collected at multiple sites in and around the rapidly growing industrial city of Manaus in the Amazon basin. Manaus is of scientific interest due to the pristine nature of the surrounding rainforest and the high levels of pollution coming from the city in the form of SO2, NOx, and soot. Some sites, such as the Terrestrial Ecosystem Science center (TES, also designated ZF2) located to the north of Manaus, represent air masses which have not interacted with emissions from the city. The comparison of pristine atmosphere with heavy pollution allows both for the determination of a natural baseline level of pollutants, as well as the study of pollutant’s impact on the conversion of biogenic volatile organic compounds to secondary organic aerosols. Towards this goal, samples from ZF2 and other unpolluted sites will be compared to samples from the Atmospheric Radiation Measurement (ARM) climate research facility in Manacapuru (T3), which is southwest (downwind) of Manaus. Spatially resolved spectra were recorded at the sub-particle level using scanning transmission X-ray microscopy (STXM) at the carbon, nitrogen, and oxygen K-absorption edges. Scanning electron microscopy coupled with energy dispersive x-ray spectroscopy (SEM/EDX) was also performed on to characterize higher Z elements. These two techniques together will allow for the mass fraction of atmospherically relevant elements to be determined on a per-particle basis. We will apply established procedures to determine the mixing state index for samples collected at ZF2 and T3 using elemental mass fractions. Preliminary results will be presented which focus on investigating the difference between mixing state indices of aerosol samples collected at these two sites, due to anthropogenic emissions. The ultimate goal is to use the mixing state index as a parameter which enables changes in the composition of aerosols to be modeled with more certainty as well enabling a quantification of the anthropogenic effects on natural rainforest atmosphere.
