Quantifying the emission potentials of fugitive dust sources in Nanjing, East China

Abstract

Most cities in China have suffered severe atmospheric particulate matter (PM) pollution, with reduced visibility and worsened air quality. Fugitive dust that primarily originates from soils through the action of wind and anthropogenic activities is recognized to be a major source of urban PM. However, it remains challenging to quantify and parameterize fugitive dust emission from various sources due to a lack of observation data. In this study, a portable wind erosion system, PI-SWERL, was applied to characterize the dynamics and magnitude of PM10 and PM2.5 (particles smaller than 10 μm and 2.5 μm respectively) emissions from several possible sources in Nanjing, a typical large city in the Yangtze River Delta economic regions, East China. Results indicate that aerodynamic suspension and abrasion were two major physical mechanisms responsible for fugitive dust emissions, with varying characteristics by location. Changes of emission characteristics and quantities were primarily associated with differences in the supply of fine particles available for wind erosion, controlled by source-specific surface characteristics and anthropogenic disturbances. Construction sites and unpaved roads were identified as two significant sources, with total emission rates of 95.85 (56.97) and 57.22 (32.62) kg s−1 respectively for PM10 (PM2.5) at a friction velocity of 0.82 m s−1. These values were up to five times the amounts of PM emitted from arable lands and woodlands, and 1–2 orders of magnitude greater than those from paved roads, grasslands and bare lands. These data demonstrate the importance of construction sites and unpaved roads as local PM sources which might be significant in policy making for air quality management strategies and prioritization of emission control targets in an urban area.