Air samples were collected by flasks and analyzed via a Picarro G2401 gas analyzer for carbon dioxide (CO₂) and carbon monoxide (CO) at the Akedala Atmospheric Background Station in Xinjiang, China, from September 2009 to December 2019, to analyze the changes in the characteristics of atmospheric CO₂ and CO and determine the sources. The results show that the annual average CO₂ concentration showed an increasing trend (growth rate: 1.90 ppm year⁻¹), ranging from 389.80 to 410.43 ppm, and the annual average CO concentration also showed an increasing trend (growth rate: 1.78 ppb year⁻¹), ranging from 136.30 to 189.82 ppb. The CO₂ concentration and growth rate were the highest in winter, followed by autumn, spring, and summer. The CO concentration and growth rate were also the highest in winter due to anthropogenic emissions, ecosystem effects, and diffusion conditions. The main trajectories of CO₂ and CO determined by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model were parallel to the Irtysh River valley and then passed through the Old Wind Pass. Furthermore, the main source regions of CO₂ and CO at the Akedala Station were eastern Kazakhstan, southern Russia, western Mongolia, and the Xinjiang Tianshan North Slope Economic Zone of China. This study reflects the characteristics of long-term changes in CO₂ and CO concentrations at the Akedala station and provides fundamental data for the studies on environmental changes and climate change in Central Asia.

Field observations made with unmanned aerial vehicles of the particulate matter (PM) concentration from the ground to a height of 500 m were conducted at Xiaotang and Tazhong in the Taklimakan Desert (TD), China, from 7 to 15 November 2019. The vertical structures of the PM concentrations were studied. Pulsed lidar observations showed that dust aerosols in the TD can reach heights of 4 km. Within 500 m above the ground, the PM_1.0, PM_2.5, and PM₁₀ concentrations were <100, <201, and <764 µg∙m⁻³, respectively, in the TD. On days containing sand-blowing periods (e.g., at 18:00 on 11 November), the PM_1.0, PM_2.5, and PM₁₀ concentrations were 10–17.7 times higher than on clear days. The northern margin of the TD (Xiaotang) was dominated by fine particles, while the hinterland (Tazhong) was dominated by coarse particles, because there was sparse vegetation around Xiaotang and the surface was sand and clay, while there was no vegetation around Tazhong and the surface was sand. During floating dust periods, the boundary layer was dominated by fine particles. The average PM_1.0/PM_2.5 ratios were 0.25–0.65 and 0.40–0.80 at Tazhong and Xiaotang, respectively, while, during sand blowing periods, these ratios were 0.40–0.55 and 0.40–0.45, respectively. The critical condition in the atmospheric boundary layer for PM concentration was revealed with the enhanced momentum flux and sensible heat flux up to 0.52 kg∙m⁻¹∙s⁻², 0.69 m∙s⁻¹, and 6.7 W∙m², respectively, and the low mixed layer was high in the lower atmosphere.

Reactive gases (O₃, CO, NO₂, and SO₂) were collected hourly at the Akedala regional background station in northwestern China during September 2017 to August 2018. Wind rose, cluster analysis, potential source contribution function (PSCF), and concentration-weighted trajectory (CWT) methods were adopted for identifying the transport pathways and potential source regions of these atmosphere components at Akedala. The average O₃, CO, NO₂, and SO₂ mixing ratios detected were 29.65±11.44ppb, 123.78±73.35ppb, 3.79±0.98ppb, and 4.59±0.88ppb during the observation period, and the statistical results of the monthly mean values revealed that there were differences during the highest pollution period, with O₃ and CO mainly peaking in February, with mixing ratios of 38.03±7.10ppb and 208.50±106.50ppb, respectively. Meanwhile, NO₂ peaked in March (4.51±0.54ppb) and SO₂ in January (5.70±1.92ppb). The most obvious diurnal variation of CO and SO₂ was observed in the winter, with maximum levels reaching between 13:00 and 14:00. The diurnal variations of O₃ exhibited low values during the night and maximum values in the afternoon (16:0018:00). Diurnal variation was not significant in the case of NO₂. Cluster analysis showed that six main paths affected the Akedala atmosphere. In turn, the PSCF and CWT analysis results indicated that the Akedala reactive gas was affected by both local and foreign sources. The high PSCF value of the reactive gas potential source areas appeared in eastern Kazakhstan, northern Xinjiang, Western Mongolia, and Southern Russia. The WCWT (weighted concentration-weight trajectory) values of CO and SO₂ in winter were the highest, totaling 180240ppb and 56.5ppb, respectively. The WCWT value of O₃ in the spring and summer was higher than that in the autumn and winter. The main source area of O₃ was about 3236ppb in the spring and summer, and the main source area of NO₂ in the summer had a low WCWT value of 33.5ppb, whereas the NO₂ WCWT value was concentrated at 44.5ppb in the other seasons.