Title: | Isotopic composition of formaldehyde in urban air |
Address: | "Department of Physics, Portland State University, Portland, Oregon 97207, USA. arice@pdx.edu" |
ISSN/ISBN: | 0013-936X (Print) 0013-936X (Linking) |
Abstract: | "The isotopic composition of atmospheric formaldehyde was measured in air samples collected in urban Seattle, Washington. A recently developed gas chromatography-isotope ratio mass spectrometry analytical technique was used to extract formaldehyde directly from whole air, separate it from other volatile organic compounds, and measure its (13)C/(12)C and D/H ratio. Measurements of formaldehyde concentration were also made concomitant with isotope ratio. Results of the analysis of nine discrete air samples for delta(13)C-HCHO have a relatively small range in isotopic composition (-31 to -25 per thousand versus VPDB [+/-1.3 per thousand]) over a considerable concentration range (0.8-4.4 ppb [+/-15%]). In contrast, analyses of 17 air samples for deltaD-HCHO show a large range (-296 to +210 per thousand versus VSMOW [+/-50 per thousand]) over the concentrations measured (0.5-2.9 ppb). Observations of deltaD are weakly anticorrelated with concentration. Isotopic data are interpreted using both source- and sink-based approaches. Results of delta(13)C-HCHO are similar to those observed previously for a number of nonmethane hydrocarbons in urban environments and variability can be reconciled with a simple sink-based model. The large variability observed in deltaD-HCHO favors a source-based interpretation with HCHO depleted in deuterium from primary sources of HCHO (i.e., combustion) and HCHO enriched in deuterium from secondary photochemical sources (i.e., hydrocarbon oxidation)" |
Keywords: | Air/*analysis Carbon Isotopes Chemical Fractionation *Cities Formaldehyde/*analysis Hydrogen/analysis Photochemistry; |
Notes: | "MedlineRice, Andrew L Quay, Paul eng Research Support, U.S. Gov't, Non-P.H.S. 2009/12/01 Environ Sci Technol. 2009 Dec 1; 43(23):8752-8. doi: 10.1021/es9010916" |