Potential Source Regions and Transportation Pathways of Reactive Gases at a Regional Background Site in Northwestern China

Table 1

Reactive gases (O₃, CO, NO₂, and SO₂) mixing ratios from other sites in Asia (ppb).

Sampling site	Year	O3 mixing ratios	CO mixing ratios	NO2 mixing ratios	SO2 mixing ratios	Potential source regions	References
Seoul, Korea	2001 to 2014	—	619.10	37.00	5.34	Eastern and northeastern China	[9]
Wuhan, Central China	March 2013 to February 2014	29.11	559.79	26.78	11.33	Shanxi, Jiangxi, Anhui, Henan, Hebei, and Hunan provinces in China	[32]
Dinghushan background station, South China	January 2013 to December 2013	24.60 ± 23.90	348 ± 185	—	4.00 ± 4.80	Pearl river delta region	[33]
Gongga mountain, southwestern China	January 2017 to December 2017	34.91 ± 10.28	152.67 ± 101.78	0.83 ± 0.63	0.17 ± 0.21	Chongqing, Hubei, Hunan, Guizhou, Guangxi provinces in China, India, Pakistan	[34]
Menyuan, northwestern China	September 2013 to October 2013	56.59 ± 3.22	25.90 ± 27.74	1.95 ± 1.02	1.15 ± 0.70	Xining and Lanzhou in China	[35]
Shangdianzi background station, northern China	January 2006 to December 2006	30.9 ± 19.8	742 ± 558	11.5 ± 10.8	7.6 ± 10.2	The North China Plain region	[36]
An urban site (CSIR-NPL) of Delhi, India	January 2012 to December 2014	29.5 ± 7.3	1820 ± 520	—	—	The Indo-Gangetic Plain (IGP)	[37]
An urban city (Bhubaneswar) of Odisha, India	December 2009 to January 2011	20–85	—	—	—	Indo-Gangetic Plains (IGP) and western part of Indian peninsula	[38]
An urban site (IARI) of Delhi, India	January 2011 to December 2015	—	1800 ± 500	18.6 ± 4.6	—	NCR, Haryana, Punjab, Rajasthan, and Uttar Pradesh	[39]
A semiurban location (Patiala), India	December 2013 to November 2014	39	—	—	—	Parts of India such as Punjab, Haryana, and Rajasthan and parts of Pakistan	[40]
An island (Langkawi) of Andaman sea, Malaysia	January 1999 to December 2011	16.7 ± 12.8	494 ± 324	5.20 ± 3.60	1.50 ± 0.80	Northern Peninsular Malaysia, Sumatra, and Indochina	[41]
A background station (Jerantut) of Pahang, Malaysia	January 1997 to December 2011	12.6 ± 8.6	326.0 ± 32.0	2.4 ± 0.5	1.9 ± 0.1	Urbanized and industrial areas such as Kuala Lumpur city center and Jerantut city	[42]
A big city (Bursa), Turkey	January 2016 to December 2017	24.26 ± 11.98	335.57 ± 98.08	22.80 ± 8.08	2.66 ± 1.19	Industrial activities, combustion emissions, and traffic in the surrounding areas	[43]
An urban site (Kanpur), India	June 2009 to May 2013	27.9 ± 17.8	721 ± 403	—	3.0 ± 3.1	—	[44]
16 cites in Xinjiang, western China	January 2013 to June 2019	25.83–30.50	529.26–671.76	12.81–15.47	3.84–6.29	Xinjiang region and surrounding countries	[45]