Pollutant Transmission Research Articles

Integrated chemical species analysis with source-receptor modeling results to characterize the effects of terrain and monsoon on ambient aerosols in a basin

This study integrated estimated oxidation ratio of sulfur (SOR) and oxidation ratio of nitrogen (NOR) with source-receptor modeling results to identify the effects of terrain and monsoons on ambient aerosols in an urban area (north basin) and a rural area (south basin) of the Taichung Basin. The estimated results indicate that the conversion of sulfur mainly occurs in fine particles (PM₂.₅), whereas the conversion of nitrogen occurs in approximately equal quantities of PM₂.₅ and coarse particles (PM₂.₅-₁₀). The results show a direct relationship for PM₂.₅ between the modeling results with SOR and NOR. The high PM₂.₅ SOR, NOR, and secondary aerosol values all occurred in the upwind area during both monsoons; this shows that the photochemical reaction and the terrain effect on the pollutant transmission were significant in the basin. Additionally, the urban heat island effect on the urban area and the valley effect on the rural area were significant. The results show that secondary aerosol in PM₂.₅-₁₀ contributed approximately 10 % during both monsoons, and the difference in the contribution from secondary aerosol between both areas was small. Vehicle exhaust emissions and wind-borne dust were two crucial PM2.5-10 contributors during both monsoons; their average contributions in both areas were higher than 34 and 32 %, respectively.

Nonlinear estimation for PM2.5 transmission effects in Jefferson Co., Texas

AbstractUrban air pollution consists of emission and transmission of air pollutants. In this article, we discuss a complex valued nonlinear regression model to characterize the effect of pollutant transmission by estimating the direction and velocity of the spatial propagation at a fixed sequence of time intervals. In case the pollutant is transmitted from a distant source during a certain time period, the monitoring stations in the local network detect the signal with time delays, which are nonlinearly related to the velocity and angle of approach or azimuth. An observed vector time series in the monitoring network is modeled as the sum of a lagged or delayed stochastic signal and a zero mean stationary noise vector. The Fourier transformation is applied to the model, and the maximum likelihood estimation of the transmission parameters under such a model is considered. Those estimates can be used to identify the possible sources of local pollutants and for better understanding of spatial distribution of pollutants. Data used in this study are based on hourly PM2.5 records from three monitoring stations in the Beaumont‐Port Arthur area in Texas for April to December 2002. The results indicate that during the months May, November and December, PM2.5 transmission were significant, with the dominant direction from the east. The velocity estimates during the period range from 4 to 20 km/h. During the summer season (June to October) the transmission effect was not very evident except for the first week of August and the first week of September. The model well detects both consistent and momentary transmissions. The parameter estimates and their standard errors are given for each week separately. Copyright © 2004 John Wiley & Sons, Ltd.

Quantitative Prediction of Traffic Pollutant Transmission into Buildings

An integrated air quality model that combines a CFD model and multi-room pollutant transport model has been developed to study the effect of traffic pollution on indoor air quality of a multi-room building located in close proximity to busy roads. The CFD model conducts the large eddy simulation of the three-dimensional turbulent flows and pollutant transport processes in outdoor, whereas the multi-room pollutant transport model performs zonal airflow and pollutant transport in indoor. The integrated model is verified with available field measurement of traffic-induced CO concentrations. Twelve scenarios of numerical experiments for various configurations of window openness are carried out to study the effects of the air change rate and the outdoor pollutant dispersion on indoor air quality. It is concluded that the windward side opening is a significant factor contributing to indoor air quality. Using air inlets on the sideward and leeward envelopes simultaneously can effectively lower the daily mean and peak indoor levels of traffic pollutants and maintain a desirable air change rate.

Application of a knowledge- and geographical information-based system to the environmental impact assessment of an opencast coal mining project

ABSTRACT Environmental impact problems are assessed in two steps: scoping exercises (qualitative assessment) and technical assessment (quantitative). The scoping exercises use stored expertise to identify the source of environmental problems and then to analyse the propagation of pollutants and their impact on surrounding areas; when a significant adverse impact is identified, the system provides mitigation advice. Scoping exercises can be conducted repeatedly to assess the effects of different mitigalion measures and/or to assess properties in different locations. At the same time the scoping exercise gathers information that is subsequently used for the technical assessment. The technical assessment uses numerical models of pollutant transmission, together with a geographical model of the mine and surrounding area, to quantify impacts in neighbouring, environmentally sensitive areas. The results of the overall environmental impact assessment are presented as an environmental impact statement in text format and as geographical images.