Validation of Speciated Nonmethane Hydrocarbon Compound Data Collected During the 1992 Atlanta Intensive as Part of the Southern Oxidants Study (SOS)

Abstract

Volatile hydrocarbons play an important role in the photochemical formation of tropospheric ozone, especially in urban atmospheres. In order to assess the significance and relative impact of biogenic and anthropogenic hydrocarbon emissions as precursors of ozone formation, a program to monitor a suite of 56 common nonmethane hydrocarbons (NMHCs), the 1992 Atlanta Intensive, was implemented as part of the Southern Oxidants Study (SOS). During the last decade, Atlanta has averaged approximately 12 days of ozone nonattainment per year, typically occurring in summer during periods of air stagnation. Under current EPA guidelines, this classifies the Atlanta metropolitan area as having a serious ozone nonattainment problem.

This study constituted a significant example of an intensive data collection effort for NMHCs. Three independent laboratory groups using a common standard operating procedure were involved in the analysis of both time integrated (hourly) and discrete canister samples collected over a wide perimeter in the Atlanta area during August-September, 1992. A total of 3,185 chromatograms were generated during the course of the intensive. The total NMHC data set was validated after the multiple factors affecting its reliability were comprehensively examined.

This paper presents the systematic procedure used to validate the 1992 Atlanta Intensive NMHC data; that procedure is currently being used to validate other large sets of data, and is expected to be incorporated in upcoming SOS air quality measurement studies.