title: Sourcing methane and carbon dioxide emissions from a small city: Influence of natural gas leakage and combustion.
abstract: Natural gas leakage and combustion are major sources of methane (CH4) and carbon dioxide (CO2), respectively; however, our understanding of emissions from cities is limited. We mapped distribution pipeline leakage using a mobile CH4detection system, and continuously monitored atmospheric CO2and CH4concentrations and carbon isotopes (δ13C-CO2and δ13C-CH4) for one-year above Ithaca, New York. Pipeline leakage rates were low (<0.39 leaks mile-1), likely due to the small extent of cast iron and bare steel within the distribution pipeline system (2.6%). Our atmospheric monitoring demonstrated that the isotopic composition of locally emitted CO2approached the δ13C range of natural gas combustion in winter, correlating to natural gas power generation patterns at Cornell's Combined Heat and Power Plant located 600 m southeast of the monitoring site. Atmospheric CH4plumes were primarily of natural gas origin, were observed intermittently throughout the year, and were most frequent in winter and spring. No correlations between the timing of atmospheric natural gas CH4plumes and Cornell Plant gas use patterns could be drawn. However, elevated CH4and CO2concentrations were observed coincident with high winds from the southeast, and the plant is the only major emission source in that wind sector. Our results demonstrate pipeline leakage rates are low in cities with a low extent of leak prone pipe, and natural gas power facilities may be an important source of urban and suburban emissions.
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA. Electronic address: sdc84@cornell.edu.
authors.forename: Samuel D
authors.initials: SD
authors.lastname: Chamberlain
authors.affiliation: School of Civil and Environmental Engineering, Cornell University, Ithaca, NY, USA.
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Ingraffea
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA.
authors.forename: Jed P
authors.initials: JP
authors.lastname: Sparks
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000600:supply & distribution; D002245:Carbon Dioxide / Q000032:analysis* / Q000600:supply & distribution*; D002247:Carbon Isotopes; D002947:Cities; D004784:Environmental Monitoring; D017752:Greenhouse Effect; D015386:Hazardous Substances / Q000032:analysis; D006801:Humans; D008697:Methane / Q000032:analysis* / Q000600:supply & distribution*; D059206:Natural Gas / Q000032:analysis* / Q000600:supply & distribution; D009518:New York; D062211:Spatio-Temporal Analysis
chemical_list: D000393:Air Pollutants; D002247:Carbon Isotopes; D015386:Hazardous Substances; D059206:Natural Gas; D002245:Carbon Dioxide; D008697:Methane
keywords: Distribution pipelines; Fugitive emissions; Keeling plots; Natural gas; Stable isotope