Organic aerosol compositions and source estimation by molecular tracers in Dushanbe, Tajikistan

Pengfei Chen; Shichang Kang; Lanxin Zhang; Sabur F Abdullaev; Xin Wan; Huijun Zheng; Vladimir A Maslov; Salamat Abdyzhapar Uulu; Mustafo S Safarov; Lekhendra Tripathee; Chaoliu Li

doi:10.1016/j.envpol.2022.119055

Organic aerosol compositions and source estimation by molecular tracers in Dushanbe, Tajikistan

Environ Pollut. 2022 Jun 1:302:119055. doi: 10.1016/j.envpol.2022.119055. Epub 2022 Feb 25.

Authors

Affiliations

¹ State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
² State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; University of Chinese Academy of Sciences, Beijing, 100049, China. Electronic address: shichang.kang@lzb.ac.cn.
³ College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, 730000, China.
⁴ S.U.Umarov Physical Technical Institute of the National Academy of Sciences of Tajikistan, Dushanbe, 734063, Tajikistan.
⁵ Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100085, China.
⁶ State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
⁷ Research Center for Ecology and Environment of Central Asia (Bishkek), 720001, Kyrgyzstan; Geography Department, Geology Institute, National Academy of Sciences, 720001, Kyrgyzstan.
⁸ Research Center for Ecology and Environment of Central Asia (Dushanbe), 734063, Tajikistan.

PMID: 35227849
DOI: 10.1016/j.envpol.2022.119055

Abstract

To elucidate the molecular composition and sources of organic aerosols in Central Asia, carbonaceous compounds, major ions, and 15 organic molecular tracers of total suspended particulates (TSP) were analyzed from September 2018 to August 2019 in Dushanbe, Tajikistan. Extremely high TSP concentrations (annual mean ± std: 211 ± 131 μg m^-3) were observed, particularly during summer (seasonal mean ± std: 333 ± 183 μg m^-3). Organic carbon (OC: 11.9 ± 7.0 μg m^-3) and elemental carbon (EC: 5.1 ± 2.2 μg m^-3) exhibited distinct seasonal variations from TSP, with the highest values occurring in winter. A high concentration of Ca²⁺ was observed (11.9 ± 9.2 μg m^-3), accounting for 50.8% of the total ions and reflecting the considerable influence of dust on aerosols. Among the measured organic molecular tracers, levoglucosan was the predominant compound (632 ± 770 ng m^-3), and its concentration correlated significantly with OC and EC during the study period. These findings highlight biomass burning (BB) as an important contributor to the particulate air pollution in Dushanbe. High ratios of levoglucosan to mannosan, and syringic acid to vanillic acid suggest that mixed hardwood and herbaceous plants were the main burning materials in the area, with softwood being a minor one. According to the diagnostic tracer ratio, OC derived from BB constituted a large fraction of the primary OC (POC) in ambient aerosols, accounting for an annual mean of nearly 30% and reaching 63% in winter. The annual contribution of fungal spores to POC was 10%, with a maximum of 16% in spring. Measurements of plant debris, accounting for 3% of POC, divulged that these have the same variation as fungal spores.

Keywords: Carbonaceous aerosol; Central Asia; Levoglucosan; Organic molecular tracers; Source apportionment.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Carbon / analysis
Environmental Monitoring
Particulate Matter* / analysis
Seasons
Tajikistan

Substances

Aerosols
Air Pollutants
Particulate Matter
Carbon