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.
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.
Sci Total Environ. 2018 Apr 1;619-620:1163-1169. doi: 10.1016/j.scitotenv.2017.11.125. Epub 2017 Nov 29.
Given that cities contributed most of China's CO emissions, understanding the emission characteristics of urban atmospheric CO is critical for regulating CO emissions. Regular observations of atmospheric CO concentration, △C and δC values were performed at four different sites in Xi'an, China in 2016 to illustrate the temporal and spatial variations of CO emissions and recognize their sources and sinks in urban carbon cycles. We found seasonal variations in CO concentration and δC values, the peak to peak amplitude of which was 80.8ppm for CO concentration and 4.0‰ for its δC. With regard to the spatial variations, the urban CO "dome" effect was the most pronounced during the winter season. The use of △C combines with δC measurements aid in understanding the emission patterns. The results show that in the winter season, emissions from fossil fuel derived CO (CO) contributed 61.8±10.6% and 57.4±9.7% of the excess CO (CO) in urban and suburban areas respectively. Combining with the result of estimated δC value of fossil fuel (δC=-24‰), which suggest coal burning was the dominant source of fossil fuel emissions. In contrast, the proportions of CO in CO 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 δC value of local sources (δC) 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.
鉴于城市贡献了中国大部分的 CO 排放，了解城市大气 CO 的排放特征对于调节 CO 排放至关重要。本研究于 2016 年在中国西安的四个不同地点进行了大气 CO 浓度、△C 和 δC 值的定期观测，以说明 CO 排放的时空变化，并认识到城市碳循环中的源汇。我们发现 CO 浓度和 δC 值存在季节性变化，其峰峰值分别为 80.8ppm 和 4.0‰。就空间变化而言，冬季城市 CO“穹顶”效应最为明显。利用△C 结合 δC 测量有助于理解排放模式。结果表明，在冬季，化石燃料衍生 CO（CO）的排放量分别占城市和郊区过量 CO（CO）的 61.8±10.6%和 57.4±9.7%。结合化石燃料估计的 δC 值（δC=-24‰），表明煤炭燃烧是化石燃料排放的主要来源。相比之下，CO 在 CO 中的比例在夏季比冬季变化更大，范围从 42.3%到>100%，平均贡献分别为 82.5±23.8%和 90.0±24.8%。鉴于本地源（δC）的 δC 值估计为-21.9‰，表明强烈的生物活动，如土壤呼吸和玉米生长，对城市碳循环有显著影响，偶尔发挥碳汇的作用。
