Source apportionment of formaldehyde during TexAQS 2006 using a source‐oriented chemical transport model

Abstract

[1] In this study, a source-oriented version of the Community Multiscale Air Quality (CMAQ) model was developed and used to quantify the contributions of five major local emission source types in Southeast Texas (vehicles, industry, natural gas combustion, wildfires, biogenic sources), as well as upwind sources, to regional primary and secondary formaldehyde (HCHO) concentrations. Predicted HCHO concentrations agree well with observations at two urban sites (the Moody Tower [MT] site at the University of Houston and the Haden Road #3 site operated by Texas Commission on Environmental Quality). However, the model underestimates concentrations at an industrial site (Lynchburg Ferry). Throughout most of Southeast Texas, primary HCHO accounts for approximately 20-30% of total HCHO, while the remaining portion is due to secondary HCHO (30-50%) and upwind sources (20-50%). Biogenic sources, natural gas combustion, and vehicles are important sources of primary HCHO in the urban Houston area, respectively, accounting for 10-20%, 10-30%, and 20-60% of total primary HCHO. Biogenic sources, industry, and vehicles are the top three sources of secondary HCHO, respectively, accounting for 30-50%, 10-30%, and 5-15% of overall secondary HCHO. It was also found that over 70% of PAN in the Houston area is due to upwind sources, and only 30% is formed locally. The model-predicted source contributions to HCHO at the MT generally agree with source apportionment results obtained from the Positive Matrix Factorization (PMF) technique.

Developmental and reproductive effects of chemicals associated with unconventional oil and natural gas operations

“…A cluster of wells located in a small area can lead to the significant accumulation of VOCs in the surrounding air (76). Formaldehyde was found in air samples in a drilling dense area in Garfield County in rural western Colorado and near residential sites (78); it can also be produced during the combustion of natural gas (79). Formaldehyde and acetaldehyde can also form from the chemical reaction caused by sunlight interacting with NO x and VOCs (78).…”

NO<sub>2</sub> and HCHO measurements in Korea from 2012 to 2016 from Pandora spectrometer instruments compared with OMI retrievals and with aircraft measurements during the KORUS-AQ campaign

“…This is important because of HCHO's potential impact on health (Zhang et al, 2013;Zhu et al, 2017) and because it plays a strong role in tropospheric reactions leading to the formation of boundary layer ozone. Sources of HCHO are from atmospheric reactions with volatile organic compounds (VOC) emitted from ground sources and industrial activities (Lei at al., 2009).…”

Houston’s rapid ozone increases: preconditions and geographic origins

“…This suggests that the increases in O 3 levels on some NTOC days are due at least in part to heightened chemical production above usual levels. Although there is some debate about the exact ratio of primary to secondary HCHO production in Houston, [24–28] the nature of the HCHO has little bearing on the conclusion that the NTOCs are the result of chemical production. If the HCHO is primary, this is direct evidence for an emission event as HCHO could be emitted, for example, from an overactive and inefficient industrial process flare.…”