Anthropogenic dust: sources, characteristics, and impacts

Abstract:

Approximately 90% of people worldwide breathe air that contains high concentrations of particulate matter (PM) pollution. Anthropogenic dust (AD), as a crucial component of PM, can be interpreted as dust emitted by modifying or disturbing soil particles through direct (e.g., due to construction and driving of vehicles) and indirect (e.g., due to wind blowing over agricultural land and dry lakes) human activities. The compositions and properties of AD are more complex and variable than those of natural dust (ND), and thus, AD has a significant impact on environmental quality and climate systems. Direct and indirect AD emission fluxes over human disturbed land surfaces (e.g., urban, farmland, pastureland, etc.) are estimated globally from 2001~2018 in the study. Despite the widely scattered AD distribution, the total area of potential AD sources was found slightly higher than that of ND sources. The AD distribution area was 1.61×10⁷ km² in January and 1.54×10⁷ km² in July, respectively. The ND sources contributed 81.0% of the global dust emissions and the anthropogenic contributed 19.0% of the residual. The ND and AD emission flux was 6.34±0.31 μg m⁻² s⁻¹ and 1.01±0.07 μg m⁻² s⁻¹, respectively. Especially, ND and AD emissions situated in different climatic regions. ND emissions mainly located in hyper-arid and arid regions such as the Sahara, Arabian and Taklimakan Desert where dust emission fluxes range from 1 to 50 μg m⁻² s⁻¹, accounted for 97.3% of ND emissions at the global scale. While AD emissions concentrate in semi-arid, sub-humid and humid regions and generally fluctuated between 0.1 and 10 μg m⁻² s⁻¹. In addition, ND and AD proportions in semi-arid regions were the most complicated due to the complex land cover types, including grasslands, urban areas, croplands and open shrub lands, resulting in 42.99% of AD emissions in semi-arid regions. The complex interplay of ND and AD emissions contributing to the total dust loadings may be a crucial factor enhanced the warming over semi-arid regions. Moreover, taking urban Lanzhou in China as an example, the fugitive road dust PM_2.5 emission in urban Lanzhou was approximately 1141 ± 71 kg d⁻¹, accounting for 24.6% of total PM_2.5 emission. The estimated premature mortality burden induced by fugitive road dust PM_2.5 exposure was 234.5 deaths in Lanzhou in 2017. Reducing AD emissions are an important step forward to protect public health in many developing urban regions.