Weakened black carbon trans-boundary transport to the Tibetan Plateau during the COVID-19 pandemic

• Published in: The Science of the total environment 2024-03, Vol.916, p.170208-170208, Article 170208
• Main Authors: Zhou, Ye, Yang, Junhua, Kang, Shichang, Hu, Yuling, Chen, Xintong, Xu, Mian, Ma, Mengmeng
• Format: Article
• Language: English
• Subjects: Air Pollutants - analysis; Carbon - analysis; Communicable Disease Control; COVID-19 - epidemiology; Emission reduction; Environmental Monitoring; Humans; Pandemics; Respiratory Aerosols and Droplets; Soot - analysis; South Asian black carbon; Tibet - epidemiology; Tibetan Plateau; Trans-boundary transport; Water - analysis; WRF-Chem
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.170208

The lockdowns implemented during the coronavirus disease 2019 (COVID-19) pandemic provide a unique opportunity to investigate the impact of emission sources and meteorological conditions on the trans-boundary transportation of black carbon (BC) aerosols to the Tibetan Plateau (TP). In this study, we conducted an integrative analysis, including in-situ observational data, reanalysis datasets, and numerical simulations, and found a significant reduction in the trans-boundary transport of BC to the TP during the 2020 pre-monsoon season as a result of the lockdowns and restrictive measures. Specifically, we observed a decrease of 0.0211 μgm−3 in surface BC concentration over the TP compared to the 2016 pre-monsoon period. Of this reduction, approximately 6.04 % can be attributed to the decrease in emissions during the COVID-19 pandemic, surpassing the 4.47 % decrease caused by changes in meteorological conditions. Additionally, the emission reductions have weakened the trans-boundary transport of South Asia BC to the TP by 0.0179 μgm−2s−1; indicating that the recurring spring atmospheric pollution from South Asia to the TP will be alleviated through the reduction of anthropogenic emissions. Moreover, it is important to note that BC deposition on glaciers contributes significantly to glacier melting due to its enrichment, posing a threat to the water sustainability of the TP. Therefore, urgent measures are needed to reduce emissions from adjacent regions to preserve the TP as the “Asian Water Tower.” [Display omitted] •Southwesterly winds dominate the cross-border pollution from South Asia to the TP.•Significant reduction of BC in South Asia and the TP due to the COVID-19 lockdown.•Emission reductions are crucial to reduce BC trans-boundary transport to the TP.