Search

Central China has been acting as a major convergence zone for sources and sinks in China, such that the climate change studies of Central China have taken on critical significance. The Jinsha atmospheric background station refers to the sole background monitoring site in Central China. It is noteworthy that the greenhouse gas attributes of the Jinsha atmospheric background station represent the greenhouse gas conditions of Central China. The seasonal and daily variations in CO2, CH4, and CO in the scope of time between October 2019 to April 2021 at the station were examined in this study. The effect of meteorological conditions on greenhouse gas concentrations at the site was evaluated. Furthermore, the primary transmission origins affecting the station were identified using the backward trajectory through potential source contribution function analysis. As indicated by the results, the background concentrations at the Jinsha station in 2020 for CO2, CH4, and CO reached 424.1 ± 0.1 ppm, 2046.2 ± 0.6 ppb, and 324.1 ± 1.1 ppb, respectively. CO2 varied on a daily basis with higher nighttime levels, which was affected by the boundary layer elevation, photosynthesis, and human activities. In autumn, CH4 levels peaked under the effect of agricultural activities in Central China. However, CO2 and CO concentrations reached the maximum in winter, majorly affected by the transmissions from the Beijing–Tianjin–Hebei region and Hubei. Under China’s comprehensive carbon neutrality, more attention should be paid to the emissions from winter heating and industrial activities in the Beijing–Tianjin–Hebei region, and effects exerted by transport in the monitoring process should be differentiated in depth.

Cities have multiple fugitive emission sources of methane (CH4) and policies adopted by China on replacing coal with natural gas in recent years can cause fine spatial heterogeneities at the range of kilometers within a city and also contribute to the CH4 inventory. In this study, a mobile observatory was used to monitor the real-time CH4 concentrations at fine spatial and temporal resolutions in Beijing, the most important pilot city of energy transition. Results showed that: several point sources, such as a liquefied natural gas (LNG) power plant which has not been included in the Chinese national greenhouse gas inventory yet, can be identified; the ratio “fingerprints” (CH4:CO2) for an LNG carrier, LNG filling station, and LNG power plant show a shape of “L”; for city observations, the distribution of CH4 concentration, in the range of 1940−2370 ppbv, had small variations while that in the rural area had a much higher concentration gradient; significant correlations between CO2 and CH4 concentrations were found in the rural area but in the urban area there were no such significant correlations; a shape of “L” of CH4:CO2 ratios is obtained in the urban area in wintertime and it is assigned to fugitive emissions from LNG sources. This mobile measurement methodology is capable of monitoring point and non-point CH4 sources in Beijing and the observation results could improve the CH4 inventory and inform relevant policy-making on emission reduction in China.