TAILIEUCHUNG - Volatile organic compound measurements at Trinidad Head, California, during ITCT 2K2: Analysis of sources, atmospheric composition, and aerosol residence times

A sample of 200 consumers was drawn randomly from rural and urban locations in the two main regions of the Eastern Cape, namely the former Transkei homeland area and the former Ciskei homeland area. By means of structured questionnaires, the respondents were interviewed in relation to where they buy their groceries from, the types of foods they bought, their present and future buying patterns, preferred food products, and their reasons for choice of particular food products. In addition, information was obtained on a number of personal characteristics and circumstances of the respondents, including their health status, income, and family. | JOURNAL OF GEOPHYSICAL RESEARCH VOL. 109 D23S16 doi 2003JD004026 2004 Volatile organic compound measurements at Trinidad Head California during ITCT 2K2 Analysis of sources atmospheric composition and aerosol residence times Dylan B. Millet 1 Allen H. Goldstein 1 James D. Allan 2 Timothy S. Bates 3 Hacene Boudries 4 Keith N. Bower 2 Hugh Coe 2 Yilin Ma 5 Megan McKay 1 Patricia K. Quinn 3 Amy Sullivan 5 Rodney J. Weber 5 and Douglas R. Worsnop4 Received 30 July 2003 revised 23 October 2003 accepted 29 October 2003 published 7 July 2004. 1 We report hourly in-situ observations of C1-C8 speciated volatile organic compounds VOCs obtained at Trinidad Head CA in April and May 2002 as part of the NOAA Intercontinental Transport and Chemical Transformation study. Factor analysis of the VOC data set was used to define the dominant processes driving atmospheric chemical composition at the site and to characterize the sources for measured species. Strong decreases in background concentration were observed for several of the VOCs during the experiment due to seasonal changes in OH concentration. CO was the most important contributor to the total measured OH reactivity at the site at all times. Oxygenated VOCs were the primary component of both the total VOC burden and of the VOC OH reactivity and their relative importance was enhanced under conditions when local source contributions were minimal. VOC variability exhibited a strong dependence on residence time slnX 44 r2 where slnX is the standard deviation of the natural logarithm of the mixing ratio and this relationship was used in conjunction with measurements of 222Rn to estimate the average OH concentration during the study period X 105 molec cm3 . We also employed the variability-lifetime relationship defined by the VOC data set to estimate submicron aerosol residence times as a function of chemical composition. Two independent measures of aerosol chemical composition yielded consistent residence .

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