ATMOSPHERIC AEROSOL SOURCE-RECEPTOR RELATIONSHIPS: THE ROLE OF COAL-FIRED POWER PLANTS

Abstract

This report describes the technical progress made on the Pittsburgh Air Quality Study during the period of February through July of 2001. The major effort during this period involved the set-up and initiation of the ambient monitoring campaign. The central sampling station next to the Carnegie Mellon University in Scheleny Park was completed. Baseline measurements began on June 1, 2001, and the first intensive sampling period occurred between June 30, 2001 and August 3, 2001. Data were collected at both the central site and a set of satellite sites surrounding Pittsburgh. Preliminary examination of the data has been initiated. This report presents results of PM-2.5 mass and chemical composition measured on a 24-hr basis for the July intensive period. The average PM-2.5 concentration at the central monitoring site for the July intensive was 23 {micro}g/m{sup 3}. The variation in PM-2.5 levels indicates that a wide range of atmospheric conditions occurred during the month of July, and, therefore, the data will be useful for evaluating the performance of air quality models over a range of conditions. During July, the major chemical components of the PM-2.5 mass are sulfate and organic material. Elemental carbon and nitrate only contribute a small part of the PM-2.5 mass on a 24-hr average basis. Comparing the measured PM-2.5 mass and the sum of the chemical components indicates problems with the mass balance. The total measured mass tends to be larger than the sum of the major chemical components at high PM levels, and smaller than the sum of the components at low PM levels. There are many potential explanations for the observed discrepancies; however, preliminary data suggests that water may be the source of the mass balance discrepancy at high PM levels.