Seasonally varying contributions to urban CO2 in the Chicago, Illinois, USA region: Insights from a high-resolution CO2 concentration and δ13C record

• DOI: 10.12952/journal.elementa.000052
• Publication Date: 2015-06-05T13:22:18Z
• Authors: Joel Moore; Andrew D. Jacobson
• Keywords: atmospheric CO2; Environmental sciences; 13. Climate action; 11. Sustainability; urban carbon cycles; GE1-350; 15. Life on land; 01 natural sciences; 7. Clean energy; stable carbon isotopes; 0105 earth and related environmental sciences

Abstract Understanding urban carbon cycling is essential given that cities sustain 54% of the global population and contribute 70% anthropogenic CO2 emissions. When combined with concentration measurements ([CO2]), stable isotope analyses (δ13C) can differentiate sources CO2, including ecosystem respiration combustion fossil fuels, such as petroleum natural gas. In this study, we used a wavelength scanned-cavity ringdown spectrometer to collect ∼2x106 paired for [CO2] δ13C values in Evanston, IL August 2011 through February 2012. Evanston located immediately north Chicago, IL, third largest city United States. The represent one longest records thus far reported. We also compiled local meteorological information, well complementary data background sites Park Falls, WI Mauna Loa, HI. use dataset examine how processes, fuel usage, wind speed, direction control atmospheric midcontinent setting on seasonal daily basis. On average, were 16–23 ppm higher 0.97–1.13‰ lower than sites. While generally followed broader northern hemisphere trends, difference between was larger winter versus summer. Mixing calculations suggest equally contributed excess during summer gas 80%–94% winter. Wind speed strongly influenced an hourly time scale. highest lowest occurred at speeds <3 m s−1 when winds blew from northwest, west, south over densely populated neighborhoods.