Source apportionment of particulate matter and trace gases near a major refinery near the Houston Ship Channel

Supplementary material to "Seasonal differences in formation processes of oxidized organic aerosol near Houston, TX"

“…BBOA corresponds to local emissions under relatively low wind speed or regional transport under relatively high wind speed. This finding is consistent with a previous study conducted in another site in Houston (Wallace et al, 2018). BBOA can gradually age during transport, leading to a broad range of O/C.…”

“…The commonly used tracer of biomass burning is levoglucosan (C6H10O5), which has significant signal of fragment ions at C2H4O2 + (m/z 60) and C3H5O2 + (m/z 73) (Cubison et al, 2011). These m/z ions have been widely used as tracers for BBOA in AMS datasets (Cubison et al, 2011;Zhang et al, 2011;Kim et al, 2017;Wallace et al, 2018). The ion signal of C2H4O2 + in mass spectra of BBOA is higher than that in HOA and COA for our dataset (main text, Fig.…”

“…As observed in Table S2, F4 in the six-factor solution is an unrealistic factor with both high H:C and O:C ratios, which is not physically meaningful. As defined in Equation S1, the spectral overlapping fraction (SOF) derived from the spectral contrast angle between factors can be used to access the degree of similarity between the mass spectra of PMF factors (Wan et al, 2002;Wallace et al, 2018). SOF varies between 0 and 1 for factors with null and complete mass spectrum overlap, respectively.…”

“…The mass spectra of HOA is characterized by the presence of alkyl fragments, with strong signal of non-oxygenated species at m/z 43 (C3H7 + ), m/z 55 (C4H7 + ), m/z 56 (C4H8 + ) and m/z 57 (C4H9 + ) (main text, Fig. 7), which is generated during fossil fuel combustion (Lanz et al, 2008;Morgan et al, 2010;Ng et al, 2010;Wallace et al, 2018). Strong correlations were found between the time series of HOA and the CnH2n+1 + and CnH2n-1 + ions, e.g., C3H7 + (r = 0.93 and 0.97 for the winter and summer dataset, respectively), C4H7 + (r = 0.93 and 0.96), C4H8 + (r = 0.94 and 0.92) and C4H9 + (r = 0.90 and 0.99).…”

Emission factor, relative ozone formation potential and relative carcinogenic risk assessment of VOCs emitted from manufacturing industries

“…Industrial manufacturing sectors are reported as the major VOC emission sources[28,36]. Several previous studies have assessed cancer risks for inhalation exposure to VOCs in industrial areas, but most of them focus on the ambient VOCs[60][61][62].…”