Primary and secondary sources of formaldehyde in urban atmospheres: Houston Texas region
We evaluate the rates of secondary production and primary emission of formaldehyde (CHâO) from petrochemical industrial facilities and on-road vehicles in the Houston Texas region. This evaluation is based upon ambient measurements collected during field studies in 2000, 2006 and 2009. The predominant CHâO source (92 ± 4% of total) is secondary production formed during the atmospheric oxidation of highly reactive volatile organic compounds (HRVOCs) emitted from the petrochemical facilities. Smaller contributions are primary emissions from these facilities (4 ± 2%), and secondary production (~3%) and primary emissions (~1%) from vehicles. The primary emissions from both sectors are well quantified by current emission inventories. Since secondary production dominates, control efforts directed at primary CHâO emissions cannot address the large majority of CHâO sources in the Houston area, although there may still be a role for such efforts. Ongoing efforts to control alkene emissions from the petrochemical facilities, as well as volatile organic compound emissions from the motor vehicle fleet, will effectively reduce the CHâO concentrations in the Houston region. We do not address other emission sectors, such as off-road mobile sources or secondary formation from biogenic hydrocarbons. Previous analyses based on correlations between ambient concentrations of CHâO and various marker species have suggested much larger primary emissions of CHâO, but those results neglect confounding effects of dilution and loss processes, and do not demonstrate the causes of the observed correlations. Similar problems must be suspected in any source apportionment analysis of secondary species based upon correlations of ambient concentrations of pollutants.
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https://n2t.org/ark:/85065/d7pk0gtr
eng
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2016-01-01T00:00:00Z
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2012-04-05T00:00:00Z
Copyright Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License.
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