Black carbon pollution for a major road in Beijing: Implications for policy interventions of the heavy-duty truck fleet

摘要

Increasing attentions have been attained to transportation air quality in developing countries. Multi-disciplinary models are useful to understand the relationship between traffic dynamics and air quality, however, which generate higher demand for input data regarding traffic and emission. In Beijing, the environmental impact from non-local heavy-duty trucks (HDTs) has not been evaluated yet, which may be an important reason for higher black carbon concentration at night. This study selected one link of the North Fourth Ring Road, a major urban traffic corridor, to characterize BC pollution for typical weekdays by coupling traffic data investigation, vehicle emission calculation and roadside concentration modelling. We found local meteorological conditions would play a more governing role than changes of vehicle emissions in elevating roadside BC concentration, in particular for the night hours when dispersion conditions were significantly worsened. AERMOD-modelled results were in a good agreement with simultaneously observed BC concentration data, which could be responsible for 17% of the total roadside BC concentration during the summer period. We further identified that approximately 30-40% of the total HDT fleet on the North Fourth Ring Road were non-local HDTs, which could increase total BC emissions by similar to 60% and roadside BC concentration by similar to 2 mu g m(-3) at night compared to a local HDTs exclusive scenario. In addition to stricter emission controls for non-local HDTs, policy-makers may consider allowing HDTs to drive within the urban area at noon under a delicate scheme based on fine-grained weather forecasting.