In:
Elementa: Science of the Anthropocene, University of California Press, Vol. 3 ( 2015-01-01)
Abstract:
Understanding urban carbon cycling is essential given that cities sustain 54% of the global population and contribute 70% of anthropogenic CO2 emissions. When combined with CO2 concentration measurements ([CO2]), stable carbon isotope analyses (δ13C) can differentiate sources of CO2, including ecosystem respiration and combustion of fossil fuels, such as petroleum and natural gas. In this study, we used a wavelength scanned-cavity ringdown spectrometer to collect ∼2x106 paired measurements for [CO2] and δ13C values in Evanston, IL for August 2011 through February 2012. Evanston is located immediately north of Chicago, IL, the third largest city in the United States. The measurements represent one of the longest records of urban [CO2] and δ13C values thus far reported. We also compiled local meteorological information, as well as complementary [CO2] and δ13C data for background sites in Park Falls, WI and Mauna Loa, HI. We use the dataset to examine how ecosystem processes, fossil fuel usage, wind speed, and wind direction control local atmospheric [CO2] and δ13C in a midcontinent urban setting on a seasonal to daily basis. On average, [CO2] and δ13C values in Evanston were 16–23 ppm higher and 0.97–1.13‰ lower than the background sites. While seasonal [CO2] and δ13C values generally followed broader northern hemisphere trends, the difference between Evanston and the background sites was larger in winter versus summer. Mixing calculations suggest that ecosystem respiration and petroleum combustion equally contributed CO2 in excess of background during the summer and that natural gas combustion contributed 80%–94% of the excess CO2 in winter. Wind speed and direction strongly influenced [CO2] and δ13C values on an hourly time scale. The highest [CO2] and lowest δ13C values occurred at wind speeds & lt;3 m s−1 and when winds blew from the northwest, west, and south over densely populated neighborhoods.
Type of Medium:
Online Resource
ISSN:
2325-1026
DOI:
10.12952/journal.elementa.000052
DOI:
10.12952/journal.elementa.000052.f001
DOI:
10.12952/journal.elementa.000052.f002
DOI:
10.12952/journal.elementa.000052.f003
DOI:
10.12952/journal.elementa.000052.f004
DOI:
10.12952/journal.elementa.000052.f005
DOI:
10.12952/journal.elementa.000052.f006
DOI:
10.12952/journal.elementa.000052.f007
DOI:
10.12952/journal.elementa.000052.t001
DOI:
10.12952/journal.elementa.000052.t002
DOI:
10.12952/journal.elementa.000052.t003
DOI:
10.12952/journal.elementa.000052.t004
DOI:
10.12952/journal.elementa.000052.t005
DOI:
10.12952/journal.elementa.000052.s001
DOI:
10.12952/journal.elementa.000052.s002
DOI:
10.12952/journal.elementa.000052.s003
DOI:
10.12952/journal.elementa.000052.s004
Language:
English
Publisher:
University of California Press
Publication Date:
2015
detail.hit.zdb_id:
2745461-7
Bookmarklink