Analysis of atmospheric greenhouse gases in north Xinjiang.

Flask air samples were collected weekly at the Akedala (AKD) regional atmosphere station in north Xinjiang, China, and atmospheric carbon dioxide (CO 2) and methane (CH 4) mole fractions were measured using cavity-ring down spectroscopy. AKD station is under a typical temperate continental semiarid and arid monsoon climate with westerly air flow. This paper presents the long-term trends and seasonal variations in atmospheric CO 2 and CH 4 concentrations for the first time and discusses the possible influencing mechanisms. The CO 2 and CH 4 background mixing ratios were 412.1 ± 0.36 ppm and 1968.9 ± 0.95 ppb, respectively, in 2018. The growth rates were 2.62 ppm y−1 and 9.67 ppb y−1 for CO 2 and CH 4 , respectively, during 2010–2018, which were higher than the surface measurements at Waliguan Baseline Observatory at similar latitudes. The averaged CO 2 seasonal cycle showed a minimum in summer and a maximum in winter, and the annual amplitude was high at 18.7 ppm. The CH 4 seasonal cycle showed a rapid recovery in summer during July and August. Back-trajectory analysis showed that the atmospheric information at AKD station can provide some implications for uptake from Kazakhstan and Russia, as well as information about natural and anthropogenic emissions in northern Xinjiang. This study revealed that the long-term upward trend of the CO 2 concentration in AKD might be attributed to emissions from energy consumption of heavy industry. The comprehensive effects of livestock, geological micro seepage and oil and gas production, and vertical transport also enhanced the atmospheric CH 4 concentrations. The results of this study may improve our basic understanding of observed atmospheric CO 2 and CH 4 in China and Central Asia and the underlying fluxes to be used in atmospheric inversion models. • Anthropogenic activities strongly influenced the CO 2 background strongly in winter. • CO 2 and CH 4 growth rates were 2.62 ppm y−1 and 9.67 ppb y−1, respectively. • Eastern Kazakhstan could be a potential source region. • Higher CH 4 was attributed to enhanced regional sources and vertical transport. • Peak slopes of ΔCO/ΔCO 2 and ΔCO/ΔCH 4 occurred in winter and spring respectively. [ABSTRACT FROM AUTHOR]