Measurement report: quantifying source contribution of fossil fuels and biomass-burning black carbon aerosol in the southeastern margin of the Tibetan Plateau

• Main Authors: H. Liu, Q. Wang, L. Xing, Y. Zhang, T. Zhang, W. Ran, J. Cao
• Format: Article
• Language: English
• Published: Copernicus Publications 2021-01-01
• Series: Atmospheric Chemistry and Physics
• Online Access: https://acp.copernicus.org/articles/21/973/2021/acp-21-973-2021.pdf

<p>Anthropogenic emissions of black carbon (BC) aerosol are transported from Southeast Asia to the southwestern Tibetan Plateau (TP) during the pre-monsoon; however, the quantities of BC from different anthropogenic sources and the transport mechanisms are still not well constrained because there have been no high-time-resolution BC source apportionments. Intensive measurements were taken in a transport channel for pollutants from Southeast Asia to the southeastern margin of the TP during the pre-monsoon to investigate the influences of fossil fuels and biomass burning on BC. A receptor model that coupled multi-wavelength absorption with aerosol species concentrations was used to retrieve site-specific Ångström exponents (AAEs) and mass absorption cross sections (MACs) for BC. An “aethalometer model” that used those values showed that biomass burning had a larger contribution to BC mass than fossil fuels (BC<span class="inline-formula">_biomass=57</span> % versus BC<span class="inline-formula">_fossil=43</span> %). The potential source contribution function indicated that BC<span class="inline-formula">_biomass</span> was transported to the site from northeastern India and northern Burma. The Weather Research and Forecasting model coupled with chemistry (WRF-Chem) indicated that 40 % of BC<span class="inline-formula">_biomass</span> originated from Southeast Asia, while the high BC<span class="inline-formula">_fossil</span> was transported from the southwest of the sampling site. A radiative transfer model indicated that the average atmospheric direct radiative effect (DRE) of BC was <span class="inline-formula">+</span>4.6 <span class="inline-formula">±</span> 2.4 W m<span class="inline-formula">⁻²</span>, with <span class="inline-formula">+</span>2.5 <span class="inline-formula">±</span> 1.8 W m<span class="inline-formula">⁻²</span> from BC<span class="inline-formula">_biomass</span> and <span class="inline-formula">+</span>2.1 <span class="inline-formula">±</span> 0.9 W m<span class="inline-formula">⁻²</span> from BC<span class="inline-formula">_fossil</span>. The DRE of BC<span class="inline-formula">_biomass</span> and BC<span class="inline-formula">_fossil</span> produced heating rates of 0.07 <span class="inline-formula">±</span> 0.05 and 0.06 <span class="inline-formula">±</span> 0.02 K d<span class="inline-formula">⁻¹</span>, respectively. This study provides insights into sources of BC over a transport channel to the southeastern TP and the influence of the cross-border transportation of biomass-burning emissions from Southeast Asia during the pre-monsoon.</p>