Organic aerosol formation in urban and industrial plumes near Houston and Dallas, Texas

Abstract

[1] We present measurements of organic aerosol (OA) in urban plumes from Houston and Dallas/Fort Worth as well as in industrial plumes in the Houston area during TexAQS-2006. Consistent with the TexAQS-2000 study, measurements show greater amount of aerosol mass downwind of the industrial centers compared to urban areas. This is likely due to higher emission and processing of volatile organic compounds (VOCs) from the industrial sources along the Houston ship channel. Comparisons of the current measurements with observations from the northeastern (NE) United States indicate that the observed ratios of the enhancement above background in OA, DOA, to the enhancement above background in CO, DCO, downwind of urban centers of Houston and Dallas/Fort Worth are within a factor of 2 of the same values in plumes from urban areas in the NE United States. In the ship channel plumes, DOA/DCO exceeds that in the urban areas by factors ranging from 1.5 to 7. We use a chemical box model to simulate secondary organic aerosol (SOA) formation from anthropogenic and biogenic VOCs in different plumes using recently reported dependencies of SOA yields on VOC/NO x ratios. Modeled SOA to CO enhancement ratios are within a factor of 2 of measurements. The increase in SOA from biogenic VOCs (BVOCs) predicted by the chemical box model as well as by a separate analysis using a Lagrangian particle dispersion model (FLEXPART) is <0.7 mg per standard m 3 (sm À3 ). We find no evidence for a substantial influence of BVOCs on OA formation in our measurements in Houston area.

Surface tension prevails over solute effect in organic-influenced cloud droplet activation

“…the Jimenez et al 37 study applies here and 20% uncertainty of RIE 36 is applicable to the data presented in this manuscript. Moreover, this uncertainty limit or even a smaller one is confirmed by the data presented in the Figure S2.1.1.…”

Urban impacts on regional carbonaceous aerosols: Case study in central Texas

“…Two major air quality studies have been conducted in the gulf coast region of Texas: the Texas Air Quality Study 2000 (TexAQS 2000) and the Texas Air Quality Study 2006 (TexAQS 2006). These studies indicate high potential for urban outflow of organic matter and secondary aerosol from Texas metropolitan areas (Fan et al, 2005;Bates et al, 2008;Bahreini et al, 2009;Massoli et al, 2009;Russell et al, 2009;Zhang and Ying, 2010). A more recent study characterizing PM 2.5 in Houston, TX, identifies industrial activities and traffic in and around the Houston Ship Channel as major sources of PM 2.5 (Sullivan et al, 2013).…”

Sources and characteristics of summertime organic aerosol in the Colorado Front Range: perspective from measurements and WRF-Chem modeling

“…Composition-dependent collection efficiency was applied to all the data (Middlebrook et al, 2012a). The estimated uncertainty in the mass concentration of OA was ∼ 30 % (Bahreini et al, 2009) and the detection limit was ∼ 0.4 µg m −3 (15 s interval measurements).…”