|Berlanga, Jesus - Western Kentucky University|
|Van Rooy, Paul - University Of California|
|Purvis-roberts, Kathleen - Claremont Colleges|
|Cocker, David - University Of California|
|Silva, Philip - Phil|
|Nee, Matthew - Western Kentucky University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2016
Publication Date: 8/20/2016
Citation: Berlanga, J., Van Rooy, P., Purvis-Roberts, K., Cocker, D.R., Silva, P.J., Nee, M. 2016. Uptake of organic sulfur and nitrogen compounds by aerosols. Meeting Abstract. 2.
Technical Abstract: Efforts have been undertaken to monitor and model the uptake of medium-sized organic compounds found above agricultural waste. Field effects performed by our collaborators monitor both the gas phase compounds present in a chicken house in Kentucky; using PILS-IC sampling, the contents of PM2.5 particles are analyzed simultaneously. These data are compared to benchmark studies in aerosol chamber experiments also performed by our collaborators. To evaluate the uptake of compounds such as dimethyl sulfide, dimethyl disulfide, and trimethylamine, and their subsequent oxidation and conversion to ionic species, both the gas-phase and PILS-IC data are required. Established kinetic models are parametrized (including levels of oxidizers such as O3 and OH) from gas-phase measurements in dry chamber experiments. Then, the changes to the observed kinetics as a result of controlled relative humidity experiments indicate rates of uptake by aerosols with increasing water content. Once the uptake rates, and therefore the concentrations in the aqueous phase as a function of time, are established, they are used as the inputs into established aqueous-phase oxidations (e.g., conversion of SO2 to SO42-) to model the extent to which compounds within particulate matter contribute to the development of key aqueous inorganic ions. Analysis of the chamber experiments show that sulfur and nitrogen are both readily incorporated into particulate matter, with some dependence observed of the uptake based on relative humidity. Molecular modeling experiments have also recently begun in our group to identify trends in the uptake of the key gas-phase components of our system. Starting with SO2 and NH3, we initialize classical molecular dynamics systems of our analyte impinging on a two-dimensional slab of POL-3 water. The trends in the surface interaction (likelihood of attachment, residence time, depth relative to interface) are evaluated. Ultimately, the assembly of a large database of these properties will help establish the relative importance of aerosol particles in the uptake, transport, and reactivities of the heteroatom organic compounds which are central to modeling atmospheric conditions in and around agrarian land-use regions. Accurate treatment of the physical (and potentially photophysical) properties will feed back into atmospheric models such as WRF-Chem and other predictive tools to help model long-range effects. These preliminary classical studies also provide a fertile test bed for generating multi-body potentials for more accurate modeling of the types of surface interactions which can dominate aerosol behavior.