Source contributions to ambient concentrations of CO and NOX in the urban area of Beijing

An emission inventory based on GIS technology was developed in this study, and used to estimate the spatial distribution of the stationary and mobile sources in the urban area of Beijing. The stationary sources were divided i nto various types of finer classes depending on different usage, stack heig ht and emission factors. The mobile sources were treated as both line sourc es and area sources. It was shown that total anthropogenic CO and NOX emiss ions had reached 1.4 million and 233 thousand tons, respectively, and vehic le sources emissions of CO and NOX accounted for 76.8% and 40.2%, respectiv ely, of the total emissions in 1995. ISCST3, a Gaussian dispersion air qual ity model, was modified at low wind speed condition, and then used to facil itate the study of source contributions to ambient concentrations of CO and NOX in Beijing. The simulation results showed that emissions from the vehi cle sources had contributed 76.5% and 68.4% of the total CO and NOX concent rations in urban atmosphere of Beijing in 1995, and were even higher in the city core (86.3% of the CO and 72.0% of the NOX). Therefore, strategies fo r CO and NOX pollution control will of necessity need to focus on the vehic le sources.