tailieunhanh - Atmospheric volatile organic compound measurements during the Pittsburgh Air Quality Study: Results, interpretation, and quantification of primary and secondary contributions

Further, solid matrices that are not amenable to the use of a coring technique should be collected in such a way as to preserve their integrity. Transferring of these solids with spatulas or similar devices into sampling containers is discouraged as this disrupts the sample pore spaces and greatly increases the sample surface area available for volatilization. For soil piles, fresh (unexposed), soil at an adequate depth (representative of concentrations from the interior of the pile) should be sampled. Gravel or concrete samples may need to be manually transferred into VOC sampling containers quickly and in a condition and. | JOURNAL OF GEOPHYSICAL RESEARCH VOL. 110 D07S07 doi 2004JD004601 2005 Atmospheric volatile organic compound measurements during the Pittsburgh Air Quality Study Results interpretation and quantification of primary and secondary contributions Dylan B. Millet 1 2 Neil M. Donahue 3 Spyros N. Pandis 3 Andrea Polidori 4 5 Charles O. Stanier 2 5 Barbara J. Turpin 4 and Allen H. Goldstei 2n1 Received 3 February 2004 revised 7 April 2004 accepted 22 April 2004 published 25 January 2005. 1 Primary and secondary contributions to ambient levels of volatile organic compounds VOCs and aerosol organic carbon OC are determined using measurements at the Pittsburgh Air Quality Study PAQS during January-February and July-August 2002. Primary emission ratios for gas and aerosol species are defined by correlation with species of known origin and contributions from primary and secondary biogenic sources and from the regional background are then determined. Primary anthropogenic contributions to ambient levels of acetone methylethylketone and acetaldehyde were found to be 12-23 in winter and 2-10 in summer. Secondary production plus biogenic emissions accounted for 12-27 of the total mixing ratios for these compounds in winter and 26-34 in summer with background concentrations accounting for the remainder. Using the same method we determined that on average 16 of aerosol OC was secondary in origin during winter versus 37 during summer. Factor analysis of the VOC and aerosol data is used to define the dominant source types in the region for both seasons. Local automotive emissions were the strongest contributor to changes in atmospheric VOC concentrations however they did not significantly impact the aerosol species included in the factor analysis. We conclude that longer-range transport and industrial emissions were more important sources of aerosol during the study period. The VOC data are also used to characterize the photochemical state of the atmosphere in the region. The .

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