Stories of Atmospheric Chemistry in the Lower Fraser Valley

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1 Stories of Atmospheric Chemistry in the Lower Fraser Valley Rob McLaren Dept. of Chemistry & Centre for Atmospheric Chemistry York University, Toronto, ntario yorku.ca Visibility Reduction View of Mount Baker looking south from Sumas Mountain Aug. 26, 2001 (~ 11:30 am) Aug. 29, 2001 (~12:30 am)

2 rganic Chemical Systems C 2, 2 hydrocarbons sources, N 3, 3, h ν, 2 N oxygenated hydrocarbons Wet and dry deposition Particulate matter acetophenone. N, 2 ethylbenzene glyoxal GAS PM Biogenic ydrocarbons Isoprene α-pinene β-pinene Limonene 3-carene Camphene α-terpinene γ τερπινενε Myrcene cimene α-phellandrene β-phellandrene

3 Suspected biogenic oxygenated hydrocarbons cis-3-hexen-1-ol cis-3-hexenyl acetate trans-2-hexenal 1-hexanol n-butanal n-hexanal 2-methyl-2-butanol 3-methyl-1-butanol acetone 2-butanone methanol? 2-methyl-3-buten-2-ol? PACIFIC 2001 The overall objective of Pacific 2001 is to provide a better understanding of, and reduce the uncertainty of the sources, formation and distribution of PM and ozone in the Lower Fraser Valley. To achieve this overall objective, specific goals are set to: determine the horizontal and vertical distribution of fine particulates and ozone in the LFV airshed. determine the physical and chemical characteristics of fine particulates in the Lower Fraser Valley airshed. identify the major physical and chemical processes in the formation of secondary aerosols and ozone. determine the roles of biogenic and anthropogenic (transportation sector) emissions in secondary organic aerosols and ozone formation provide an integrated data base for evaluation of regional PM and ozone computer models

4 Lower Fraser Valley Sites: PACIFIC 2001 N 3 Chemistry

5 Sumas Site 305m asl 3.3 km path DAS Receiver 200 m asl T33 Station DAS Transmitter 65m asl N 3 Absorption Absorption Cross section (cm2 ) 2E-17 1E-17 σ (λ) σ (λ) λ Wavelength (nm) λ1 σ '( λ) dλ

6 A' I' o = ln I' e = λ 2 ' A e λ 1 C = λ 2 ' L λ 1 σ DAS Measurement ( λ) σ' ( λ)cl ( λ) A e = differential absorbance I o (λ) = light intensity without absorption I (λ) = light intensity with absorption L = path length C = concentration σ (λ) = differential cross section ( λ) dλ ( λ)dλ Instrumental set-up for DAS

diffuser & fiber optic coupler laptop/ad interface DAS Receiver 8 x 1 m Newtonian reflector telescope cooled fiber optic CCD spectrometer Absorption Spectrum*, Aug 31, 4:00 am.

7 diffuser & fiber optic coupler laptop/ad interface DAS Receiver 8 x 1 m Newtonian reflector telescope cooled fiber optic CCD spectrometer Absorption Spectrum*, Aug 31, 4:00 am. λ 2 A λ 1 ' e ( λ)dλ Intensity (counts) N Absorbance Wavelength (nm) *reference spectrum is an early morning spectrum just after sunrise when N3 is at negligible levels but other atmospheric species (ie- 2) are still present.

8 N 3 Levels: Sumas N3 (ppt) N3 (ppt) Aug 15/16, :00 PM 12:00 PM 04:00 AM 08:00 AM Time (hour) Aug 29/30, :00 PM 12:00 PM 04:00 AM 08:00 AM Time (hour) N3 (ppt) N3 (ppt) Aug 20/21, :00 PM 12:00 PM 04:00 AM 08:00 AM Time (hour) Aug 30/31, :00 PM 12:00 PM 04:00 AM 08:00 AM Time (hour) Calculated N 2 5 Levels N 3 + N 2 N 2 5 K p (T) = P N25 / P N3 *P N N25 (ppt) :00 4:00 8:00 12:00 4:00 8:00 4:00 8:00 08/29 Time (hour) 08/30 08/31

9 Partitioning of No y N y [2*N25+N3]/[Ny] (fraction) = N + N 2 + N3 + PAN + o-n3 + + N N :00 4:00 8:00 12:00 4:00 8:00 4:00 8:00 08/29 Time (hour) 08/30 08/31 omogeneous Reaction N 2 5(g) + 2 (g) -> > 2 N 3(g) N 2 5 ydrolysis Dimitroulopoulou, Atmos.. Environ. 31, 1997, log k homo = T = 1 x cm 3 molecule - 1 sec 1 ) Range for 2 nights: (T = K, k = x cm 3 molecule - 1 sec 1 ) eterogeneous Reaction on moist particle surfaces N 2 5(g) -> > 2 N 3( 3(aq) k hetero ~ 0.25 ν γ S ; ν = mean molecular velocity γ = accomodation (uptake, sticking) coefficient S = particle surface area (ie( ie- cm 2 /cm 3 ) (S was calculated by Mozurkewhich using DMA/CNC particle distributions. For the 2 nights, k hetero = x 10-4 sec 1 assuming γ = 0.07 )

10 4.0 N 3- production N3- accumulation (ug/m3) :00 4:00 8:00 12:00 4:00 8:00 4:00 8:00 08/30 Time (hour) 08/31 N3-homo p-n3-hetero N3-het+homo N3- Production bservations for 2 nights vernight cumulative nitrate from N 2 5 hydrolysis omogeneous reaction, N 3(g) : eterogeneous reaction, p-n 3(aq) : verall N 3- : ug/m3 ( ppb) ug/m ug/m3 Uncertainties: - assumed γ = N 3 (measured) and N 2 5 (calculated) are lower limits. - S from DMA/CNC distributions are for d p < 650nm - N 3(g) + N 3(g) -> N 4 N 3(particulate) will re-equilibrate Significance: - this is a large source of both gaseous N 3 and/or particulate nitrate

11 Concentration (neq/m3) Sumas Aug.27 (10:46-19:10) Fine N 3 - = 0.08 ug/m 3 Course N 3 - = 1.54 ug/m 3 Moudi Data S4= N4+ Na+ Cl- N3- Cl- C22= K+ Concentration (neq/m3) Sumas 1941 Aug Aug 28 S4= 25.0 S4= S4= N3- N3- Cl- Cl- C22= 20.0 C22= Na+ Na+ N4+ N4+ K+ K N3- C22= Na+ N4+ Fine N3 - = 2.50 ug/m 3 Course N - 3 = 2.85 ug/m 3 K < particle size range (µm) > < particle size range (µm) >18 Sumas 0900 Aug Aug 29 Sumas 2009 Aug Aug 30 Concentration (neq/m3) Concentration (neq/m3) Fine N - 3 = 0.14 ug/m 3 Course N - 3 = 0.39 ug/m 3 Fine N - 3 = 0.99 ug/m Course N 3 - = 0.62 ug/m < > < >18 particle size range (µm) particle size range (µm) Sumas 0859 Aug Aug 30 Sumas 2027 Aug Aug 31 Concentration (neq/m3) Fine N 3 - = 0.09 ug/m S4= S4= N3- N3- Cl- Cl- C22= 20.0 C22= Na+ Na+ N4+ N4+ K+ K Concentration (neq/m3) 10.0 Course N - 3 = 0.13 ug/m 3 Fine N - 3 = 1.48 ug/m Course N 3 - = 0.41 ug/m < > < >18 particle size range (µm) particle size range (µm) N 3 Preliminary Conclusions significant levels of N 3 with night time max s of ppt, likely much higher than this in the elevated layer. N 2 5 and N 3 contribute 7-9% to total N y (lower estimate) in the elevated layer at night, with N 2 5 being the majority species. For 2 nights, we estimate N 2 5 hydrolysis to contribute ug/m3 of nitrate, dominated by the heterogeneous reaction. This compares qualitatively with Moudi data that shows significant fine particle N 3 appearance at night. N 3 plays a dominant role in oxidation of monoterpenes at this site.

Atmospheric Sources and Sinks Sources- any supply of gas or particulate to the atmosphere Primary sources - an identifiable direct source to the atmosphere Secondary source- a source of gas or

12 Atmospheric Sources and Sinks Sources- any supply of gas or particulate to the atmosphere Primary sources - an identifiable direct source to the atmosphere Secondary source- a source of gas or particulate that arises from some transformation (chemical or physical) of primary emissions. Anthropogenic sources- sources derived from the activities of mankind. Natural sources- sources not attributable to the actrivities of mankind including biogenic sources, windblown dust, oceanic emissions, geochemical sources. Biogenic Sources - Emissions from the biosphere. It has been known since the early 1960's that trees emit vast quantities of VC s. Many of these species are extremely reactive in the atmosphere since they contain unsaturated bonds. The success of N x /VC controls in controlling tropospheric ozone (smog) largely depends on the amount of natural VC s in the airshed of interest and the strategy. This was often overlooked in early ozone control strategies. The most important organic compounds emitted by vegetation in terms of mass include: isoprene, monoterpenes and oxygenated hydrocarbons. By far, the most ubiquitous species discovered to date is isoprene. These biogenic hydrocarbons are emitted from plants by two very general processes: 1) biosynthetic production in the presence of photosynthetic active radiation (PAR) followed by direct emission from the plant. example - isoprene from deciduous trees 2) biosynthetic production and storage in the plant, followed by evaporative emissions of the stored VC s. example - monoterpenes from pine trees In the former case, since the VC is not stored in the plant, the emission is dependent on the presence of sunlight. Emission will stop in the absence of sunlight.

13 Emission is dependent on temperature through the temperature dependence of enzymatically driven production. If the temperature becomes too high, emission stops due to plant damage... protein denaturization. In the case of monoterpenes and other oxygenated hydrocarbons, emission is dominated by temperature (light intensity to a lesser extent) since evaporative emissions from a pool of liquid hydrocarbon will increase with temperature. Temperature dependence follows a typical exponential Clausius-Clapeyron functionalit. P vap 1 1 ln = P o R To T where P is the partial pressure of the volatile at temperature T, P o is a reference pressure at temperature T o, ) vap is the enthalpy of vaporization of the liquid and R is the gas constant. Emission of monoterpenes can continue late into the night even after the sun has set, in contrast to isoprene. Biogenic ydrocarbons C 5 8 C (monoterpenes) Isoprene α-pinene β-pinene Limonene 3-carene Camphene α-terpinene γ τερπινενε Myrcene cimene α-phellandrene β-phellandrene

14 Suspected biogenic oxygenated hydrocarbons cis-3-hexen-1-ol cis-3-hexenyl acetate trans-2-hexenal 1-hexanol n-butanal n-hexanal 2-methyl-2-butanol 3-methyl-1-butanol acetone 2-butanone methanol? 2-methyl-3-buten-2-ol? ther Natural Emissions Soil Bacteria - both aerobic and anaerobic bacteria can produce volatile organics (formic acid, acetic acid, light alcohols), methane!! (methanogenesis from methanogenic bacteria) and nitrogen species (N 2, N 2, N x ). n a global scale most of the methane in the atmosphere is emitted from methanogenic bacteria, in wetlands, rice paddies, the stomach of termites and cattle. ceans ceans can be a source of some VC s including alkanes and alkenes, but more importantly dimethylsulphide. xidation products of dimethylsulphide are thought to play a role in aerosol formation in marine areas. The action of wind on the oceans can also initiate the formation of sea salt aerosols, containing significant quantities of dissolved cations and anions, Na +, K +, Ca 2+, Mg 2+, Cl -, Br -, I -, C 3-2, S 4-2.

Monoterpene and Sesquiterpene Emissions from Ponderosa Pine: Implications for Secondary Organic Aerosol Formation

Monoterpene and Sesquiterpene Emissions from Ponderosa Pine: Implications for Secondary Organic Aerosol Formation Anita Lee, Gunnar Schade, Allen Goldstein UC Berkeley GCEP Workshop: August 19, 2002 What