Spatial distribution and temporal variation of atmospheric pollution in the South Gobi Desert, China, during 2016-2019.

The rapid pace of economic growth and urbanization in China affects both large and small cities of the country, causing an increase of pollutant concentrations in the air. The South Gobi is one of the main deserts and semidesert regions of the country; therefore, the study of air pollution near the potential source of natural aerosols is of great importance. Data obtained in the period from 1 January 2016 to 31 December 2019 was used to analyze spatial-temporal characteristics of atmospheric pollutants (PM, PM, SO, NO, and CO) in eight cities. Total mean concentrations of PM and PM were 36.1 ± 21.1 μg/m and 98.6 ± 108.7 μg/m. The occurrence rates of concentrations exceeding the Chinese National Ambient Air Quality Standard (CNAAQS) grade 1 and grade 2 were 40.1% and 5.4% for PM and 82.9% and 11.64% for PM in the region. Total concentrations of SO, NO, and CO did not exceed the CNAAQS standard and were 20.8 ± 23.6 μg/m, 22.6 ± 11.9 μg/m, and 0.72 ± 0.39 mg/m, respectively. The PM to PM ratio increased from 0.35 in spring to 0.46 in winter suggesting the predominance of coarse aerosol fractions in the atmosphere. Based on data on aerosol optical depth (AOD) and Ångström exponent (AE) ratio obtained from Moderate Resolution Imaging Spectroradiometer (MODIS), the predominant aerosol types in the region are Clean Сontinental and Mixed. Maximum concentrations of pollutants and the highest AOD values in the region air are observed in spring and winter. Results set forth in this article will be an important basis for further regional studies on air quality and distribution of sources.