Pacific 2001 – Synthesis of Findings and Policy Implications Roxanne Vingarzan Pacific and Yukon Region

Pacific 2001 Study Previous large scale studies in the FV addressed ozone and visibility issues but a knowledge gap remained concerning fine PM Policy Relevant Questions 11 policy-relevant questions were identified in order to provide guidance with policy setting and air quality management in the region 11 policy-relevant questions were identified in order to provide guidance with policy setting and air quality management in the region Subject areas:  Aerosol Distribution & Transport  Particle Chemistry & Spatial Patterns  Particle Formation and Growth  Particle Events - causes  Sources  Addressing fine PM

Contributions Synthesis is based on a review of 20 papers 14 papers published in first special issue of AE 14 papers published in first special issue of AE 6 papers submitted for the second special issue 6 papers submitted for the second special issue Contribution of a large number of authors AQRB, Downsview AQRB, Downsview EC, PYR EC, PYR 9 Canadian universities 9 Canadian universities 3 US universities 3 US universities 1 UK universities 1 UK universities

Aerosol Distribution Night Concentrated aerosols in the tributary valleys Afternoon Concentrated aerosols in the eastern part of the LFV

WISE EFFECT WISE Wake Induced Stagnation Effect Build-up of pollutants over the Gulf & San Juan islands area High PM levels over the Strait of Georgia afternoon of August 26

Upslope flow of aerosol during the night Polluted layers were occasionally, entrained into clean air masses at the surface by the PBL. Polluted layers were occasionally, entrained into clean air masses at the surface by the PBL. PBL Studies PBL as found to be suppressed in height and occur several hours earlier during sea breeze conditions. Above ground aerosol layers at Harrison Lk. Above ground aerosol layers at Harrison Lk. Transport Mechanisms From Strawbridge and Snyder, 2004

Particle Chemistry - Inorganics From Pryor et al. 2004

Nitrate Chemistry Daytime Fine mode dominated by ammonium sulphate Coarse mode dominated by NaNO3 Cl- ion depletion from reaction of HNO3 with sea salt particles Nighttime Fine mode nitrate production from NO3-N2O5-HNO3 pathway Fine mode ammonium nitrate occurred almost always during the night. Sumas From, McLaren et al. 2004

The Ammonium Ion & Fine PM Ammonium ion excess What is the excess ammonium bound to?

Particle Chemistry - Organics Organic carbon was found to comprise approximately half of the particle composition Organic carbon was found to comprise approximately half of the particle composition A broad suite of organic substances were detected, including alkanes, aromatics and various oxidized hydrocarbons including fatty acids A broad suite of organic substances were detected, including alkanes, aromatics and various oxidized hydrocarbons including fatty acids Both anthropogenic and biogenic hydrocarbons were found to be photochemically reactive and contribute to SOA and ozone formation Both anthropogenic and biogenic hydrocarbons were found to be photochemically reactive and contribute to SOA and ozone formation Isoprenes and monoterpenes were the dominant biogenic hydrocarbons detected - their presence at all sites indicated the broad influence of biogenic organics throughout the FV Isoprenes and monoterpenes were the dominant biogenic hydrocarbons detected - their presence at all sites indicated the broad influence of biogenic organics throughout the FV

Particle Events Sulphate growth events were associated with photochemical production from advected SO2 from industrial sources in north-west Washington state. Sulphate growth events were associated with photochemical production from advected SO2 from industrial sources in north-west Washington state. Fine particle nitrate events were associated with advection of HNO3 from the urban core into the eastern FV reacting with local sources of ammonia. Fine particle nitrate events were associated with advection of HNO3 from the urban core into the eastern FV reacting with local sources of ammonia. Organic particle growth events were associated with stagnant conditions and advection of air over urban Vancouver. Organic particle growth events were associated with stagnant conditions and advection of air over urban Vancouver.

Sources - Highlights Primary sulphate in the FV is consistent with gasoline, diesel & gas combustion. Primary sulphate in the FV is consistent with gasoline, diesel & gas combustion. Approximately 30% of the sulphate in PM2.5 aerosols estimated to be derived from the oxidation of DMS. Approximately 30% of the sulphate in PM2.5 aerosols estimated to be derived from the oxidation of DMS. Organic aerosols were found to have significant contributions from terrestrial (plant material) sources during the summer months and from fossil fuel sources during the spring months. Organic aerosols were found to have significant contributions from terrestrial (plant material) sources during the summer months and from fossil fuel sources during the spring months. Hydrocarbon species indicated contributions of light and heavy-duty (diesel) traffic, meat cooking & biogenic sources. Hydrocarbon species indicated contributions of light and heavy-duty (diesel) traffic, meat cooking & biogenic sources. Biomass burning generally had a small but measurable impact on the composition of ambient aerosols in the FV. Biomass burning generally had a small but measurable impact on the composition of ambient aerosols in the FV.

Spatial Patterns Slocan  emission controlled regime  PM dominated by organics, both anthropogenic and biogenic  mobile sector emissions - gasoline and diesel combustion and fugitive emissions of petroleum fuels.  Biogenic organics important Langley  formation controlled regime  PM dominated by inorganics  Sulphate levels highest due to the influence of advected SO2 from oil refineries in north- west Washington state.  Elevated ammonia and biomass burning markers reflected the influence of agricultural sources. Sumas  Mixed emission/formation regime dominated by urban, agricultural and biogenic sources.  Fine mode nitrate important  The chemistry was most variable Golden Ears  PM dominated by biogenic organics  chemistry impacted by anthropogenic sources due to upslope flow  biogenically derived SOAs were transported into the FV by downslope flow.

Policy Implications – Addressing Fine PM in the FV Hypotheses for emission scenario modelling Ammonia Emissions  Ammonia was found not to be a limiting species  Limited ammonia reductions are not expected to offer a significant improvement in reducing fine PM levels but large reductions may be more effective  Reductions may result in secondary negative secondary effects, such as changes to the acidity of ambient aerosols and of atmospheric deposition SOx Emissons  Sulphate was a limiting species  SOx reductions may aid in partially reducing fine PM, however only if accompanied by NOx reductions (NH4NO3)  Contributions from biogenic sulphate during spring/summer may limit success

Policy Implications - continued NOx Emissions  Nitrate was a limiting substance  NOx reductions are expected to reduce NH4NO3 production in the eastern FV (esp. in wet season).  Reductions in NOx in the absence of VOC reductions may result in an increase in SOAs in urban areas (increase in oxidants) VOC Emissions  VOC reductions may provide some benefits to air quality  Benefits would be limited by the biogenic contribution to fine PM.  Targeting VOC reductions in the absence of NOx reductions may result in an increase nitric acid in NOx rich areas. Concurrent Emission Reductions in ammonia, SOx, NOx and VOC emissions may be required to reduce fine PM

PAC2001 Policy Relevant Findings Summary Identified mechanisms of aerosol transport: seabreeze-landbreeze flows, upslope-downslope flows and north-south valley flows Identified mechanisms of aerosol transport: seabreeze-landbreeze flows, upslope-downslope flows and north-south valley flows Identified areas of enhanced aerosol concentrations: eastern FV, north-south tributary valleys & the WISE zone Identified areas of enhanced aerosol concentrations: eastern FV, north-south tributary valleys & the WISE zone Confirmed the importance of organic carbon and biogenic organics in fine PM Confirmed the importance of organic carbon and biogenic organics in fine PM Characterized the chemistry of coarse & fine mode PM Characterized the chemistry of coarse & fine mode PM Identified both anthropogenic and biogenic sources contributing to secondary organic aerosol formation Identified both anthropogenic and biogenic sources contributing to secondary organic aerosol formation Identified geographical patterns in emission regimes, PM composition and aerosol processing Identified geographical patterns in emission regimes, PM composition and aerosol processing Provided hypotheses for testing out emission scenarios aimed at reducing fine PM Provided hypotheses for testing out emission scenarios aimed at reducing fine PM