资源环境科技发展态势分析平台

Atmospheric carbon monoxide (CO) was continuously measured from 2010/2011 to 2017 at Lin'an (LAN) and Shangdianzi (SDZ) background station in the economically developed region in China using cavity ring-down spectrometers. Diurnal variations of CO mixing ratio displayed a bimodal in all seasons, with the peak to trough amplitudes larger than 43.6 +/- 18.5 (95% CI) ppb at LAN and 80.5 +/- 47.0 ppb at SDZ, reflecting the influence of anthropogenic emissions. Seasonal variation at LAN was in accordance with those observed in the northern hemisphere. Due to the multiple influences of regional sources and meteorological transport, CO at SDZ displayed an abnormal pattern, with a maximum in summer and the minimum in autumn. CO levels decreased at a rate of 16.3 +/- 0.3 ppb yr(-1) at LAN and 1.3 +/- 0.4 ppb yr(-1) at SDZ during the six-year period. The 3-day back trajectory by the HYSPLIT model showed that high CO at LAN was mainly from the economically developed regions, including the North China Plain, the Middle-Lower Yangtze Plain and the eastern region of the station. The analysis by concentration-weighted trajectory (CWT) approach indicated that large-scale of strong source regions were uniformly distributed around the LAN site in all seasons. At SDZ, atmospheric CO was severely influenced by monsoons and air masses from the south-southeastern site. Major source areas were identified in megacities such as Beijing, Tianjin, and Tangshan, especially in summer. Consequently, most of the atmospheric CO mole fractions at SDZ could be defined into two subsets, with higher values associated with air masses from the south and lower ones from the north.