Urban Emissions of Nitrogen Oxides, Carbon Monoxide, and Methane Determined from Ground-Based Measurements in Philadelphia.

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  • Additional Information
    • Source:
      Publisher: American Chemical Society Country of Publication: United States NLM ID: 0213155 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1520-5851 (Electronic) Linking ISSN: 0013936X NLM ISO Abbreviation: Environ Sci Technol Subsets: MEDLINE
    • Publication Information:
      Publication: Washington DC : American Chemical Society
      Original Publication: Easton, Pa. : American Chemical Society, c1967-
    • Subject Terms:
      Air Pollutants*/analysis ; Carbon Monoxide*/analysis; Carbon Dioxide/analysis ; Environmental Monitoring ; Humans ; Methane/analysis ; Nitrogen Oxides/analysis ; Philadelphia
    • Abstract:
      Nitrogen oxides (NO X ) and methane impact air quality through the promotion of ozone formation, and methane is also a strong greenhouse gas. Despite the importance of these pollutants, emissions in urban areas are poorly quantified. We present measurements of NO X , CH 4 , CO, and CO 2 made at Drexel University in Philadelphia along with NO X and CO observations at two roadside monitors. Because CO 2 concentrations in the winter result almost entirely from combustion with negligible influence from photosynthesis and respiration, we are able to infer fleet-averaged fuel-based emission factors (EFs) for NO X and CO, similar in some ways to how EFs are determined from tunnel studies. Comparison of the inferred NO X and CO fuel-based EF to the National Emissions Inventory (NEI) suggests errors in NEI emissions of either NO X , CO, or both. From the measurements of CH 4 and CO 2 , which are not emitted by the same sources, we infer the ratio of CH 4 emissions (from leaks in the natural gas infrastructure) to CO 2 emissions (from fossil fuel combustion) in Philadelphia. Comparison of the CH 4 /CO 2 emission ratios to emission inventories from the Environmental Protection Agency suggests underestimates in CH 4 emissions by almost a factor of 4. These results demonstrate the need for the addition of long-term observations of CH 4 and CO 2 to existing monitoring networks in urban areas to better constrain emissions and complement existing measurements of NO X and CO.
    • Accession Number:
      0 (Air Pollutants)
      0 (Nitrogen Oxides)
      142M471B3J (Carbon Dioxide)
      7U1EE4V452 (Carbon Monoxide)
      OP0UW79H66 (Methane)
    • Publication Date:
      Date Created: 20210331 Date Completed: 20210426 Latest Revision: 20210426
    • Publication Date:
      20221213
    • Accession Number:
      10.1021/acs.est.1c00294
    • Accession Number:
      33788543