Atmospheric Monitoring of Methane in Beijing Using a Mobile Observatory

Abstract

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.

Observed decreases in on-road CO<sub>2</sub> concentrations in Beijing during COVID-19

“…The intake was linked/connected through a 2 m pipe with a particulate matter filter to Picarro (Figure 3A and 3B). The instruments characteristics and precision have been described by Sun et al(Sun et al, 2019). The CO 2 concentrations were collected every 2 seconds and then averaged into 1-minute intervals.…”

“…The global positioning system (GPS) data during BC and DC were collected by a GPS receiver (BS-70DU) (Sun et al, 2019).…”

The TRAX Light-Rail Train Air Quality Observation Project

“…In the last decade, the deployment of mobile urban pollution monitoring systems using different platforms (e.g., trains, bikes, other vehicles) have been demonstrated in many cities across the world, such as Brisbane, Australia [22], Ontario, Canada [23], Oakland, California [24], Beijing, China [25], Seoul, Korea [26], and Hong Kong [27]. A recent effort to outfit Google street cars across several US cities has also been successful in mapping fine-scale urban pollution gradients [24,25,28,29]. The importance of combining these mobile platforms with fixed-site platforms to derive highly resolved spatial pollution maps and related pollutant exposure metrics is a very active area of research [30][31][32].…”

Carbon Dioxide and Methane Emissions during the Composting and Vermicomposting of Sewage Sludge under the Effect of Different Proportions of Straw Pellets

“…CH 4 is radiatively stronger than CO 2 on a mass basis and it is reported that the current global warming potential of CH 4 is 25 times higher than that of CO 2 over a 100 year period [7]. Most previous studies on composting and vermicomposting have focused on the feasibility of different organic wastes and the factors affecting the growth and reproduction rate of earthworms as well as the quality of the compost and vermicompost [8]. However, little is known about the emissions of CO 2 and CH 4 during the composting and vermicomposting of sewage sludge.…”