Stack Dust Sampling: in-Stack Filter or E.P.A. Train

The Environmental Protection Agency has recommended or specified methods for the measurement of participate concentrations in flue gases. The EPA Train for this measurement originally comprised two segments: the front half and the impinger train downstream from the filter proper. This review examines the controversial areas implicit in the use of this EPA Train or the revised EPA train which eliminates the impinger train.     

Source Apportionment: Findings from the U.S. Supersites Program

Abstract

Receptor models are used to identify and quantify source contributions to particulate matter and volatile organic compounds based on measurements of many chemical components at receptor sites. These components are selected based on their consistent appearance in some source types and their absence in others. UNMIX, positive matrix factorization (PMF), and effective variance are different solutions to the chemical mass balance (CMB) receptor model equations and are implemented on available software. In their more general form, the CMB equations allow spatial, temporal, transport, and particle size profiles to be combined with chemical source profiles for improved source resolution. Although UNMIX and PMF do not use source profiles explicitly as input data, they still require measured profiles to justify their derived source factors. The U.S. Supersites Program provided advanced datasets to apply these CMB solutions in different urban areas. Still lacking are better characterization of source emissions, new methods to estimate profile changes between source and receptor, and systematic sensitivity tests of deviations from receptor model assumptions.     

Source apportionment: findings from the U.S. Supersites Program

Receptor models are used to identify and quantify source contributions to particulate matter and volatile organic compounds based on measurements of many chemical components at receptor sites. These components are selected based on their consistent appearance in some source types and their absence in others. UNMIX, positive matrix factorization (PMF), and effective variance are different solutions to the chemical mass balance (CMB) receptor model equations and are implemented on available software. In their more general form, the CMB equations allow spatial, temporal, transport, and particle size profiles to be combined with chemical source profiles for improved source resolution. Although UNMIX and PMF do not use source profiles explicitly as input data, they still require measured profiles to justify their derived source factors. The U.S. Supersites Program provided advanced datasets to apply these CMB solutions in different urban areas. Still lacking are better characterization of source emissions, new methods to estimate profile changes between source and receptor, and systematic sensitivity tests of deviations from receptor model assumptions.     

An examination of the 6:00 a.m.-9:00 a.m. measurements of ozone precursors in the New York City metropolitan area

In recent years, ambient measurements of hourly ozone precursor concentrations, namely speciated and total nonmethane organic compounds (NMOCs), have become available through the Photochemical Assessment Monitoring Stations (PAMS) program. Prior to this, NMOCs were measured in the central business district using a canister to obtain the 3-hr integrated sample for the 6:00 a.m.-9:00 a.m. period. Such sampling had been carried out annually for nearly a decade at three locations in the New York City metropolitan area. The intent of these measurements, along with measurements of the other ozone precursor, NO(x), was to provide an understanding of ozone formation and the emissions loading and mix in the urban area. The analysis of NMOC and NO(x) measurements shows a downward trend in the case of NMOC. In addition, we compared the canister-based NMOC concentrations with data obtained from the PAMS program for the 6:00 a.m.-9:00 a.m. period. Analysis of the NMOC concentrations reveals poor spatial correlation between the various monitors, reflecting the effect of localized emissions. This suggests that NMOC measurements made at a single location cannot be viewed as representative of the entire region. On the other hand, correlations were found to be higher among the NO(x) monitors, indicating the commonality of emission     

Das Interview: 10 Jahre UWSF — Z. Umweltchem. ?kotox

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