Response of Atmospheric Particulate Matter to Changes in Precursor Emissions: A Comparison of Three Air Quality Models

Abstract

Three mathematical models of air quality (CMAQ, CMAQ-MADRID, and REMSAD) are applied to simulate the response of atmospheric fine particulate matter (PM2.5) concentrations to reductions in the emissions of gaseous precursors for a 10 day period of the July 1999 Southern Oxidants Study (SOS) in Nashville. The models are shown to predict similar directions of the changes in PM2.5 mass and component (sulfate, nitrate, ammonium, and organic compounds) concentrations in response to changes in emissions of sulfur dioxide (SO2), nitrogen oxides (NO(x)), and volatile organic compounds (VOC), except for the effect of SO2 reduction on nitrate and the effect of VOC reduction on PM2.5 mass. Furthermore, in many cases where the directional changes are consistent, the magnitude of the changes are significantly different among models. Examples are the effects of SO2 and NO(x) reductions on nitrate and PM2.5 mass and the effects of VOC reduction on organic compounds, sulfate and nitrate. The spatial resolution significantly influences the results in some cases. Operational model performance for a PM2.5 component appears to provide some useful indication on the reliability of the relative response factors (RRFs) for a change in emissions of a direct precursor, as well as for a change in emissions of a compound that affects this component in an indirect manner, such as via oxidant formation. However, these results need to be confirmed for other conditions and caution is still needed when applying air quality models for the design of emission control strategies. It is advisable to use more than one air quality model (or more than one configuration of a single air quality model) to span the full range of plausible scientific representations of atmospheric processes when investigating future air quality scenarios.

Quantifying the sources of ozone, fine particulate matter, and regional haze in the Southeastern United States

“…The performance of the model in 2002 simulations gives an indication of the uncertainties in future year simulations and sensitivity analysis results. It is generally assumed that the levels of the uncertainties in modeled responses would be similar to those in modeled concentrations (Pun et al, 2008). Therefore, the responses below are probably most accurate for O 3 while the uncertainties may be larger for PM 2.5 especially in winter.…”

A Case Study of the Relative Effects of Power Plant Nitrogen Oxides and Sulfur Dioxide Emission Reductions on Atmospheric Nitrogen Deposition

“…As a result, there is a net decrease in the particulate ammonium sulfate concentration and an increase in the particulate ammonium nitrate concentration. 4,6,30 In the case of the Plant Crist area, particulate nitrate concentrations are low compared with particulate sulfate concentrations; for example, in the Crist NO x and SO 2 control scenario, nitrate annual average surface concentrations range from 0.1 to 0.3 g/m 3 over Escambia Bay and from 0.3 to 0.9 g/m 3 over Escambia Bay watershed, whereas sulfate annual average surface concentrations range from 2.5 to 3.5 g/m 3 over the bay and watershed. Hence, the increase in particulate ammonium nitrate is small and the effect of SO 2 emission reduction is dominated by an increase in NH 3 concentrations and a corresponding decrease in particulate NH 4 ϩ concentrations.…”

“…Ansari and Pandis 4 and West et al 5 used thermodynamic equilibrium models of inorganic aerosol chemistry to demonstrate an increase in nitrate after reductions in SO 2 emissions because of the increased availability of gaseous NH 3 to react with nitric acid (HNO 3 ). Pun et al 6 report results from three three-dimensional (3-D) Eulerian air quality models that show that reductions in summer SO 2 emissions lead to increases in particulate nitrate concentrations in California and the eastern United States but also to some decreases in the Midwest. They attribute the increases to increased gaseous NH 3 concentrations and the decreases to a decrease in the particulate liquid water content, which leads to less dissolution of HNO 3 in the particles.…”

Major Source Contributions to Ambient PM2.5 and Exposures within the New South Wales Greater Metropolitan Region

“…This brute force method (BFM) or zero-out method has been widely used in source sensitivity studies of major pollutants worldwide (e.g., [13] and [17] ). While it is a popular tool for policy-maker to analyse the effects of emissions reduction on air quality, the non-linear effects between changes in emissions of SO 2 , NOx and VOC and changes in PM 2.5 mass and component (sulphate, nitrate, ammonium and organic compounds) concentrations is addressed [18]. And it is not always practical because computational cost increases linearly with the number of emissions scenarios to examine, and the smaller concentration changes between the simulations may be strongly influenced by numerical errors as noted in [19].…”