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This study investigates the dispersion patterns of oxides of nitrogen (NOx) emitted from major industrial and automobile sources in Nova Scotia, Canada. The study focuses on two modeling domains, Halifax (HFX) and Sydney (SYD), and examines the influence of chimney stacks and highways on NOx concentrations. The results show the highest concentrations near the refinery in HFX and negligible contribution from the Lingan station in SYD.
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Study of dispersion patterns for Oxides of Nitrogen (NOx) from major industrial and automobile sources in two modeling domains in Nova Scotia, Canada*Soumita Kundu, Satish Mysore & Mark Gibson *Corresponding Author: Soumita KunduDepartment of Civil and Resource Engineering Dalhousie University(sm256830@dal.ca)
Background • Air quality research in Nova Scotia • NOx is a criteria air contaminant • Nova Scotia emission inventory • Motivation for conducting the dispersion study
Oxides of nitrogen (NOx) dispersion study in Nova Scotia • Geographic location • Modeling domains • HFX location • SYD location SYD HFX
Sources of NOx-chimney stacks and highways • HFX domain • Chimney stacks-Dartmouth oil refinery, Tuft’s Cove generation station, Capital Health and Dalhousie University • Highways-101,102,103,107,111and 118 • SYD domain • Chimney stack-Lingan generation station • Highways-105 and 125
Dispersion Modeling • US-EPA regulatory model AERMOD VIEW v6.2 • Components-AERMET, AERMAP • Data requirements • Meteorological data • Land use • Terrain Data • Building downwash
Source characteristics • Chimney stacks • Geographical co-ordinates[Latitude & Longitude in UTM coordinates (m)] • Base Elevation • Release height (m) • Diameter (m) • Exit temperature(K) • Exit velocity(m/sec)
Source Characteristics continued • Highways • Section length (m/km) • Geographical co-ordinates of the starting and end point of a section[Latitude & Longitude in UTM co ordinates(m)] • Number of vehicles per section length (no per m/no per km) • Total emission data • Emission rate
Meteorological data • Surface air data • Halifax International Airport • Sydney station • Upper air data-station • Yarmouth station • Onsite data Halifax International Airport Yarmouth Sydney Station Yarmouth
Land use • Sectors-urban area, cultivated land, water bodies • Surface characteristics by month • Albedo • Bowen ratio • Surface Roughness length • Values suggested in AERMET
Terrain Data • Use of Geo-Tiff files • Process using AERMAP HALIFAX SYDNEY
Receptor Grid and output option • 2.450 km spacing on Uniform Cartesian receptor grid • HFX domain area = 44 km x 48 km • SYD domain area = 23 km x 23 km • Annual averaging - predict average NOx concentrations at receptor points
Conclusion - Halifax Domain • The chimney stacks and flare of Dartmouth Refinery had the most influence on the NOx dispersion pattern in the HFX domain • Highway 102 was the major linear emission source • During 2006 and 2007 the highest predicted NOx concentrations were at the intersection of highways 102 and 118 • During all four years (2004 – 2007) the maximum predicted NOx was observed within 2 km radius from the refinery
Conclusion - Sydney Domain • The NOx contribution to surface concentrations from Lingan station was predicted to be negligible when compared to the Canada Wide Standard • Highway 125 had a minor contribution to ground level NOx concentrations in the Sydney domain • In both model domains, the maximum annual NOx concentration predicted from line sources was within 100 m of the highways