Characteristics of the Interactions Pattern of Surface Ozonewith its Precursors in the Fraser Valley, British Columbia

摘要

Hourly raw ambient data on air criteria pollutants of the Greater Vancouver Regional District(GVRD), British Columbia were analyzed to investigate the relationships of ozone with itsprecursors (NO, NO2, NOx, and Total Volatile Organic Compounds (TVOC)) and theirinteractions. Four monitoring sites of different land habitats, namely coastal DowntownVancouver, Industrial-commercial-residential mix (Burnaby) with low elevated topography (upto 400 m), inland industrial-commercial-residential mix (Surrey) with relatively plain land, andMountain-based urban (Chilliwack) sites were selected for analysis.Trends of ozone and its precursors were computed. Despite relatively higher concentrations ofNOx and TVOC, the coastal site of Downtown Vancouver experienced relatively lower levels ofozone than the other urban sites as fresh NO emissions scavenges the ozone concentrations inrelatively more quantity and also for possible meteorological effects on the precursor movements.Ozone production and destruction rates varied in different land habitats with highest rates inChilliwack (approximately 1.97 ppb/hr and 2.0 ppb/hr respectively) and lowest in the downtownVancouver site (approximately 1.11 ppb/hr and 1.15 ppb/hr respectively). Distinct interactionpatterns between ozone and NO2/NO were observed in different land habitats. Regressionanalysis showed that the ratio NO2/NO, photochemical process indicator, significantly influencesozone levels at all sites but varies with different land habitats (R2: 0.25 to 0.65) and withdifferent seasons (R2: 0.04 to 0.67). Stronger relationships between NOx and TVOC at downtownVancouver, Burnaby, and Surrey indicate potential contributions of TVOC in the ozoneproduction processes of those sites.