Work Package 2 - AeroAGE
In WP2 (AeroAGE), headed by FZJ, the consortium’s expertise and resources for simulating and understanding the aging and atmospheric processing of anthropogenic and biogenic emissions will be exploited to simulate current and future aerosol composition. The formation and chemical aging of different types of ambient aerosols (e.g. SOA, mineral dust, and biomass burning aerosols) will be studied. Realistic conditions of the oxidation of gaseous precursors and subsequent SOA formation, biomass burning emissions and coated mineral dust particles in the atmosphere are crucial to understand the underlying processes and their chemical evolution and impact. Therefore, a comprehensive set of simulation experiments will be conducted representing typical atmospheric oxidation processes using oxidation flow tubes that allow simulation of long exposures, a continuous stirred tank reactor and an outdoor atmosphere simulation chamber studying the aging processes for a wide range of atmospheric relevant parameters and conditions (including daytime and nighttime).
RESEARCH METHODOLOGY AND APPROACH OF AeroAGE
The chemical transformation of ambient aerosols, containing an enormous number of organic compounds, will be comprehensively investigated and characterized. Additional to the direct biogenic (vegetation) and anthropogenic emissions (e.g. combustion), oxidation (aging) of volatile organic compounds (VOC) vastly increase its chemical complexity . Herein, formation of oxidation products, organic coatings on dust particles, transformation of biomass burning emissions and secondary organic aerosols (SOA) are heavily dependent on parameters such as oxidant, NOx concentrations, and their precursors . Therefore, we will study representing systems of ambient aerosols – according to the (RCPs) - under controlled conditions. This comprises comprehensive physical and chemical analyses (in conjunction with WP3) and estimated future atmospheric compositions. Available simulation environments (see below) enable us to examine a large parameter range from hours to days. For these tasks specially designed flow tubes and simulation chambers will be used:
i) SAPHIR++, a continuous stirred tank reactor (CSTR), designed to steady state conditions, allows for controlled variations of multiple atmospheric parameters, e.g. radical concentration and therefore the degree of aging. Relevant pollutants (e.g. like NOx, NH4, SO2) can be added while keeping all other parameters constant. SAPHIR++ is also suitable to introduce primary aerosol particles like mineral dust to determine the effect of aging on the organic coatings of primary aerosol.
ii) SAPHIR , an atmosphere simulation chamber will be used to study chemical aging close to real atmospheric conditions concerning precursor concentration and SOA yields and by using natural sunlight. SAPHIR will be utilized to investigate simple systems using single biogenic or anthropogenic precursors up to highly complex real plant emissions using the plant chamber SAPHIR-PLUS . SAPHIR-PLUS also allows simulating different conditions to realize stress induced plant emissions that are expected to become a significant contribution of emitted biological VOC .
iii) The oxidation flow reactor (OFR/PAM) at WIS will allow extending the aging time to about 1 week, thus extending the capabilities of the SAPHIR and SAPHIR++ chambers. Various organic and inorganic precursors will be used in these experiments for complementing the SAPHIR++ experiments.
These setups allow to bridge the results from high concentration flow tube experiments to the atmosphere simulation at realistic conditions. Chemical and physical characterization of the aged oxidation products, both in the gas and aerosol phase, will be determined using a comprehensive set of instrumentation deployed at the simulation chambers. E.g. quantitative size and chemical aerosol mass loading information, chemical bulk parameters like oxygen-to-carbon-ratio (O:C) will be measured using high-resolution time-of-flight aerosol mass spectrometry (HR-TOF-AMS)  coupled to thermal desorption aerosol gas chromatography (TAG)  providing additional molecular marker identification. These facilities and measurement capabilities provide the basis to conduct targeted studies. The mobile exposure lab (see WP3) will be deployed to the SAPHIR++ facility for conducting the exposure experiments on site. This approach has never been tried before and opens up a unique new level of exposure experiments.
 Goldstein, A. H. et al., Environ. Sci. Techn. 41(5): 1514-1521, 2007
 Shrivastava, M. et al., Rev. Geophys. 55(2): 509-559, 2017
 Rohrer, F. B. et al., Atm. Chem. Phys. 5: 2189-2201, 2005
 Hohaus, T. et al, Atm. Meas. Techn. 9(3): 1247-1259, 2016
 Bergstrom, R. M., Atm. Chem. Phys., 14(24): 13643-13660, 2014
 Canagaratna, M. R et al., Mass Spectrom. Rev. 26(2): 185-222, 2007
 Williams, B. J. et al., Aerosol Sci. Technol. 48(4): 358-370, 2014