Emission characteristics of atmospheric carbon dioxide in Xi'an, China based on the measurements of CO2 concentration, △14C and δ13C

Peng Wang; Weijian Zhou; Zhenchuan Niu; Peng Cheng; Shugang Wu; Xiaohu Xiong; Xuefeng Lu; Hua Du

doi:10.1016/j.scitotenv.2017.11.125

Emission characteristics of atmospheric carbon dioxide in Xi'an, China based on the measurements of CO₂ concentration, △¹⁴C and δ¹³C

Sci Total Environ. 2018 Apr 1:619-620:1163-1169. doi: 10.1016/j.scitotenv.2017.11.125. Epub 2017 Nov 29.

Authors

Peng Wang¹, Weijian Zhou², Zhenchuan Niu³, Peng Cheng³, Shugang Wu³, Xiaohu Xiong³, Xuefeng Lu³, Hua Du³

Affiliations

¹ State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China; Shaanxi Provincial Key Laboratory of Accelerator Mass Spectrometry Technology and Application, Xi'an AMS Center, Xi'an, China; University of Chinese Academy of Sciences, Beijing, China.
² State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China; Shaanxi Provincial Key Laboratory of Accelerator Mass Spectrometry Technology and Application, Xi'an AMS Center, Xi'an, China; Beijing Normal University, Joint Center For Global Changes Studies (JCGCS), Beijing, China. Electronic address: weijian@loess.llqg.ac.cn.
³ State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China; Shaanxi Provincial Key Laboratory of Accelerator Mass Spectrometry Technology and Application, Xi'an AMS Center, Xi'an, China.

PMID: 29734595
DOI: 10.1016/j.scitotenv.2017.11.125

Abstract

Given that cities contributed most of China's CO₂ emissions, understanding the emission characteristics of urban atmospheric CO₂ is critical for regulating CO₂ emissions. Regular observations of atmospheric CO₂ concentration, △¹⁴C and δ¹³C values were performed at four different sites in Xi'an, China in 2016 to illustrate the temporal and spatial variations of CO₂ emissions and recognize their sources and sinks in urban carbon cycles. We found seasonal variations in CO₂ concentration and δ¹³C values, the peak to peak amplitude of which was 80.8ppm for CO₂ concentration and 4.0‰ for its δ¹³C. With regard to the spatial variations, the urban CO₂ "dome" effect was the most pronounced during the winter season. The use of △¹⁴C combines with δ¹³C measurements aid in understanding the emission patterns. The results show that in the winter season, emissions from fossil fuel derived CO₂ (CO_2ff) contributed 61.8±10.6% and 57.4±9.7% of the excess CO₂ (CO_2ex) in urban and suburban areas respectively. Combining with the result of estimated δ¹³C value of fossil fuel (δ¹³C_ff=-24‰), which suggest coal burning was the dominant source of fossil fuel emissions. In contrast, the proportions of CO_2ff in CO_2ex varied more in the summer season than that in the winter season, ranging from 42.3% to >100% with the average contributions of 82.5±23.8% and 90.0±24.8%. Given the estimation of δ¹³C value of local sources (δ¹³C_s) was -21.9‰ indicates that the intensively biogenic activities, such as soil respiration and corn growth have significantly impacted urban carbon cycles, and occasionally played a role of carbon sink.

Keywords: Atmospheric CO(2); Sources and sinks; δ(13)C; △(14)C.