Spatio-temporal characteristics of air pollutants over Xinjiang, northwestern China

Characteristics and potential sources of wintertime air pollution in Linfen, China

“…The daily mean concentrations of PM 2.5 , PM 10 , NO 2 , SO 2 , and CO ranged from 6.3 to 313.7 μg m −3 , 14.7 to 370 μg m −3 , 8.1 to 95.2 μg m −3 , 3.5 to 142.5 μg m −3 , and 0.4 to 3.9 mg m −3 , respectively, with the highest concentration in January and the lowest in February. The mean PM 2.5 and PM 10 concentrations in January were the highest, at 158.1 μg m −3 and 193.4 μg m −3 , respectively, which were similar to that measured in Xinjiang (157.42 μg m −3 for PM 2.5 and 219.16 μg m −3 for PM 10 ) (Rupakheti et al, 2021) and exceeded the China NAAQS limit by 2.1 and 1.3 times. The mean SO 2 and CO concentrations were also highest in January, at 54.5 μg m −3 and 2.3 mg m −3 , respectively.…”

“…Qingdao (0.64) (Urumqi (0.70)). The PM 2.5 concentration level was higher than the 30.5 μg m −3 measured in Lhasa (Yin et al, 2019) and 82.0 μg m −3 in Beijing (Zhang et al, 2020) but lower than the 115.7 μg m −3 in Xi'an (Yang et al, 2019) and 144.6 μg m −3 in Urumqi (Rupakheti et al, 2021) during the winter. Pollution days with the daily concentration of PM 2.5 above 75 μg m −3 accounted for about 60% of the total monitored days, and heavily polluted days with the daily concentration of PM 2.5 above 150 μg m −3 accounted for more than 30%, reflecting severe air pollution in this region.…”

“…The mean concentrations of PM 2.5 , PM 10 , NO 2 , SO 2 , CO, and MDA8 O 3 during the entire study period were 106.2 μg m −3 , 139.4 μg m −3 , 47.2 μg m −3 , 41.0 μg m −3 ,1.8 mg m −3 , and 57.0 μg m −3 , respectively. The overall mean PM 2.5 /PM 10 ratio was 0.73, which was higher than the ratio observed in winter in Lhasa (0.48) (Yin et al, 2019), Beijing (0.67) (Li et al, 2017a), (Li et al, 2017b), (Rupakheti et al, 2021), demonstrating that PM 2.5 accounted for a relatively high proportion of PM 10 and mainly came from primary and secondary anthropogenic sources. PM 2.5 was the major pollutant causing air pollution and reduced visibility in Linfen in winter.…”

Characteristics and sources of atmospheric pollutants in typical inland cities in arid regions of central Asia: A case study of Urumqi city

“…Moreover, the west, east, and the south of Urumqi are bordered by Tianshan mountains, the north is resisted by northwest wind from Siberia carrying abundant dust (the northwest wind comes through the Gurbantunggut desert) [48]. Relevant studies have shown that the dust storms in Xinjiang usually occurred in spring and summer [49,50], and affect a large region downwind, such as the glaciers in the Tibetan Plateau [51], Eastern Asia [52], and across the Pacific, even influencing the air quality over North America [53]. The highest PM concentrations were recorded in cities surrounding the Taklimakan Desert during the spring season and the highest PM 2.5 /PM 10 ratio was recorded during the winter, indicating the influence of anthropogenic emissions in winter [50].…”

“…Relevant studies have shown that the dust storms in Xinjiang usually occurred in spring and summer [49,50], and affect a large region downwind, such as the glaciers in the Tibetan Plateau [51], Eastern Asia [52], and across the Pacific, even influencing the air quality over North America [53]. The highest PM concentrations were recorded in cities surrounding the Taklimakan Desert during the spring season and the highest PM 2.5 /PM 10 ratio was recorded during the winter, indicating the influence of anthropogenic emissions in winter [50]. However, the PM 2.5 /PM 10 ratio maintained around 0.1 during the two events occurred from November 25 th to December 2 nd (Fig 8), combined with the characteristics of the weather at the time of the pollution events that the local air humidity increased significantly, accompanied by precipitation and strong winds, indicated that the pollutants of the two events dominated by sandstorm.…”