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This dataset and the methods used to obtain it were described in "Molecular insights on aging and aqueous phase processing from ambient biomass burning emissions-influenced Po Valley fog and aerosol” submitted to Atmospheric Chemistry and Physics in March of 2018. Briefly, two samples of ambient fog water and two samples of ambient aerosol collected in the Po Valley (Italy) during the 2013 Supersito field campaign were analyzed using negative mode electrospray ionization Fourier transform ion cyclotron mass spectrometry (FT-ICR MS). The extent of “fresh” vs. “aged” biomass burning influence was estimated prior to FT-ICR MS analysis using proton nuclear magnetic resonance and Aerodyne high resolution time of flight aerosol mass spectrometry analysis. The fog samples SPC0106F and SPC0201F had "fresh" and "aged" influence respectively. The aerosol samples BO0204N and BO0213D had "fresh" and "aged" influence respectively. The water-soluble extracts were analyzed by recording 200 transient scans each with a mass resolving power of 400,000 (defined at m/z 400). The transients were co-added using the Midas Co-Add tool and molecular formula assignments were made using Sierra Analytics Composer software, as described in previous studies (e.g., Zhao et al., 2013; Dzepina et al., 2015). The resulting molecular formula assignments were reviewed manually for their credibility with respect to: oxygen to carbon ratio (O/C), hydrogen to carbon ratio (H/C), double bond equivalents (DBE), and absolute PPM mass error. The assigned molecular formulas were also analyzed using DBE and oxygen number trends as described by Herzsprung et al. (2014) and the unreliable formula assignments were removed.


Zhao, Y., Hallar, A. G., and Mazzoleni, L. R.: Atmospheric organic matter in clouds: exact masses and molecular formula identification using ultrahigh-resolution FT-ICR mass spectrometry, Atmos Chem Phys, 13, 12343-12362, 2013.

Dzepina, K., Mazzoleni, C., Fialho, P., China, S., Zhang, B., Owen, R. C., Helmig, D., Hueber, J., Kumar, S., Perlinger, J. A., Kramer, L. J., Dziobak, M. P., Ampadu, M. T., Olsen, S., Wuebbles, D. J., and Mazzoleni, L. R.: Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory: a case study with a long-range transported biomass burning plume, Atmos Chem Phys, 15, 5047-5068, 2015.

Herzsprung, P., Hertkorn, N., von Tumpling, W., Harir, M., Friese, K., and Schmitt-Kopplin, P.: Understanding molecular formula assignment of Fourier transform ion cyclotron resonance mass spectrometry data of natural organic matter from a chemical point of view, Anal Bioanal Chem, 406, 7977-7987, 2014.