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INTERCOMPARISION OF SEMI-CONTINUOUS MEASUREMENTS OF NITRATE AND SULFATE AT THE EPA ATLANTA SUPERSITE, AUGUST 1999
Citation:
Weber, R., D. Orsini, Y. Duan, Y. N. Lee, F. Brechtel, P. Klotz, H. ten Brink, P. K. Dasgupta, S. Hering, E. Edgerton, P A. Solomon, AND K. Baumann. INTERCOMPARISION OF SEMI-CONTINUOUS MEASUREMENTS OF NITRATE AND SULFATE AT THE EPA ATLANTA SUPERSITE, AUGUST 1999. Presented at AGU Fall Meeting, San Francisco, CA, December 15-19, 2000.
Impact/Purpose:
The PM Supersites Program is an ambient monitoring program intended to address the scientific uncertainties associated with fine particulate matter. The main objectives of the Supersites Program are as follows: 1) characterize particulate matter in a way that contributes to the understanding of source-receptor relationships and supports development of State Implementation Plans (SIPs), 2) develop and test advanced measurement methods for potential use in national monitoring networks, and 3) support health and exposure studies by providing detailed chemical and physical data at one or more central monitoring sites.
The specific objectives of this task are to provide scientific review and coordination of the technical aspects of the Supersites Program. This includes coordination among all Supersites projects and other projects which support Supersites objectives, overseeing of the data management, and coordinating the communication of data analysis and modeling results to the scientific community and other stakeholders. Products include a number of peer-reviewed journal articles (approaching 200 or more), final reports from each project, a relational database than includes not only Supersites data, but most aerometric data collected in the continental US and SE Canada during the period July 2001 to August 2002, and a policy relevant findings synthesis entitled Key and Policy Relevant Findings from the Supersites Program and Related Studies. Also supporting the synthesis is a major international conference where results will be presented from air quality methods, measurements, modeling, and data analysis studies with similar objectives to the Supersites program and during the time period of the Supersites Program, i.e., the last 5-7 years.
Description:
The Atlanta Supersite was one of the first Environmental Protection Agency (EPA) Supersites dedicated to the study of fine particles (PM2.5). The study involved intensive measurements during the month of August 1999, at a site situated near the center of Atlanta. One of the studies major objectives was to provide a platform for testing and intercomparing newly developed techniques for the measurement of fine particle chemical composition. As part of this study, five state-of-the art instruments were deployed for rapid on-line measurements of PM2.5 nitrate and sulfate concentration. Sampling rates for these instruments ranged from 7 minutes to 1 hour. The various instruments deployed were: a denuder difference approach (Edgerton), two systems based on condensation of water vapor onto particles followed by ion-chromatography (IC) analysis of the collected droplets (Slanina and Weber/Lee), an automated filter collector with online extraction via water flushing and IC analysis (Dasgupta), and measurement of evolved gases from flash vaporization of particles collected by impaction (Hering).
During the one-month intensive, ambient concentrations of nitrate and sulfate varied significantly. Sulfate concentrations ranged from 0.1 to 70 micrograms per meter cubed. Nitrate concentrations were generally much lower, ranging from 0.1 to 5 micrograms per meter cubed. All the rapid measurements revealed a fine structure in the temporal variation of nitrate and sulfate that was not observed by the 12 and 24 hour integrated samplers.
These rapid measurements of nitrate and sulfate will be intercompared and also cross-compared with 12 and 24 hour integrated filter measurements of nitrate and sulfate (Solomon and Baumann).
This work has been funded wholly or in part by the United States Environmental Protection Agency. Portions of the work were performed under Contract Nos. 68-D5-0040 and 68-D-00-206 by Research Triangle Institute and Cooperative Agreement CR 824843. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.