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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