Long-term monitoring of VOCs in the free troposphere above the UK - PowerPoint PPT Presentation

Long-term monitoring of VOCs in the free troposphere above the UK Shalini Punjabi a , James R. Hopkins a,b , Alastair Lewis a,b a University of York, York b NCAS, University of York, York sp575@york.ac.uk

VOC monitoring : Aims • To characterize seasonal and inter annual trends • To capture important features related to transport, mixing and chemistry. • To utilise UK based research aircraft’s flying hours to the fullest for long-term study. 2

Sample collection • Silico-treated stainless steel canisters • Max. filling pressure 40psi • Altitude preferably : 2000 - 5000m 9000 2009-11 data 8000 The Whole Air Sampling System 7000 6000 altitude m 5000 •Sampling frequency : variable, typically 4000 once in a month 3000 2000 1000 0 0 500 1000 1500 2000 2500 3000 3500 Ethane pptv 3

Technique and analytical configuration York FGAM dc-gc-fid Dual channel gas chromatograph • Water removal – condensation trap maintained at - 30 o C • Preconcentration – Trapping temperature : Peltiers cooling -23 o C – Multi adsorbent bed: Carbopack B and carboxen 1000 • Thermal desorption 320 o C with carrier flow (helium) – • Separation – Two capillary columns 50 m PLOT and 10 m LOWOX • Detection – FID 1 and FID 2 • Calibration and standards: – National Physical Laboratory (NPL)- 30 component mix C 2 -C 8 Alkanes,C 2 -C 5 Alkenes – GAW-VOC standards Aromatics (BTEX), Acetylene C 2 -C 4 Oxygenated VOCs 4 Hopkins, J.R., Lewis, A.C. & Read, K.A. (2003) , J. Environ. Monit., 5 (1), pp. 8-13.

System performance with time NPL-30comp mix 2009 NPL GAW 28 comp mix NPL-30 comp mix 2008 CVO 0.3 0.25 0.2 PCRF (pptv) 0.15 0.1 0.05 0 Ethane Ethene Propane n-butane Propene Iso-butane Acetylene 1-butene cis-2-butene Iso-pentane n-pentane 1,3-butadiene 1-pentene n-hexane n-heptane Benzene octane toluene m+p-xylene o-xylene trans-2-butene 2+3-methylpentane Isoprene ethylbenzene trans-2-pentene Oct 2009 Jan 2011 5

WCC-VOC intercomparison 6

Seasonal trends : Ethane 3500 2009-11 all datapoints Ethane mean U.K free troposphere study North Atlantic study Pallas study 3000 2500 Ethane pptv 2000 1500 1000 500 0 Jan Feb Apr Jun Aug Oct Dec Feb Apr Jun Aug Oct Dec Feb Apr Jun 2009-2011 month U.K free troposphere,2009- 11 y=1318.32 + 539.34(2π/365(day+46.25) North Atlantic study,1989 y =1715 + 505(2π/365(day+46.25) Pallas ,Baltic sea ,1994 y=1425.00 + 683.34(2π/365(day+16.25) Laurila, T. and Hakola, H., 1996 ,Atmospheric Environment 30, pp. 1597–1607 S.A. Penkett, N.J. Blake, P. Lightman, A.R.W. Marsh and P. Anwyl, Journal of Geophysical Research 98 (1993), pp. 7 2865–2885

Seasonal trends: Acetylene 2009-11 all data ace avg U.K free troposphere study North Atlantic study 800 Pallas study 700 600 acetylene pptv 500 400 300 200 100 0 Jan Feb Apr Jun Aug Oct Dec Feb Apr Jun Aug Oct Dec Feb Apr Jun 2009-11 month U.K free troposphere study ,2009- 11 y = 223.67 + 137.47 (2π/365(day+56.25) North Atlantic study ,1989 y = 399.5 + 273.5 (2π/365(day+56.25) Pallas study ,1994 y = 388 + 305.33.5 (2π/365(day+26.25) Laurila, T. and Hakola, H., 1996 ,Atmospheric Environment 30, pp. 1597–1607 8 S.A. Penkett, N.J. Blake, P. Lightman, A.R.W. Marsh and P. Anwyl, Journal of Geophysical Research 98 (1993), pp. 2865–2885

Ratios and source profile variation 2009-11 data 1400 y = 2.334x - 52.151 1200 R 2 = 0.8231 1000 propane pptv ln[P]/{A] = (k P -k A /k P ) ln[P] + C 800 600 400 200 slope=rate constants 0 0 100 200 300 400 500 600 acetylene pptv 2009-11 data North Atlantic data 5.00 Where C = ln [P] 0 / [A] 0 -( k p -k a /k p ) ln[P] 0 y = 0.3925x + 0.3421 y = 0.3811x + 1.0777 ln [propane/acetylene] 4.00 R 2 = 0.3179 R 2 = 0.6566 3.00 intercept= source profile 2.00 1.00 0.00 Our study and intercept =1.07 -1.00 North Atlantic study and intercept =0.34 -2.00 -5.00 -4.00 -3.00 -2.00 -1.00 0.00 1.00 ln[propane] Goldan, P. D., D. D. Parrish, W. C. Kuster, M. Trainer, S. A. McKeen, J. Holloway, B. T. Jobson, D. T. Sueper, and F. C. 9 Fehsenfeld (2000), J. Geophys. Res. , 105(D7), 9091–9105, doi:10.1029/1999JD900429. Gong, Q., and K. Demerjian (1997), J. Geophys. Res., 102(D23), 28059-28069.

Ratios and aging pattern: another source 2009-11 data B458-60 June samples B457 June samples 0.00 8.0 -4.00 -3.50 -3.00 -2.50 -2.00 -1.50 -1.00 -0.50 0.00 y = 1.2993x + 8.3649 -1.00 7.0 ln[butane/ethane] R 2 = 0.9958 6.0 y = 1.4615x - 0.6902 -2.00 ln[propane] R 2 = 0.8232 5.0 -3.00 4.0 -4.00 3.0 y = 1.5475x + 7.8624 2.0 -5.00 R 2 = 0.9247 1.0 -6.00 0.0 2009-11 data B458-60 June samples -7.00 -4.00 -3.50 -3.00 -2.50 -2.00 -1.50 -1.00 -0.50 0.00 B457 June samples ln[propane/ethane] ln[propane/ethane] ln [butane/ethane] vs ln[propane/ethane] ln [propane/ethane] vs ln [propane] Flight B457 Atlantic ocean Flight B458 continental influence 10 Parrish, D. D., et al. (2004), J. Geophys. Res. , 109, D23S18, doi:10.1029/2004JD004978

Ratios : source characterization y = 0.297x + 0.8372 250 y = 0.3342x + 8.2283 R 2 = 0.9066 R 2 = 0.5623 200 Vehicular exhaust responsible for Benzene pptv benzene and acetylene emissions. 150 100 2009 data 2010-11 data 50 0 0 100 200 300 400 500 600 Acetylene pptv y = 6.9413x - 22.134 y = 6.7636x - 30.742 R 2 = 0.8722 1600 R 2 = 0.6991 1400 1200 Propane pptv 1000 Natural gas as a main source for 800 propane emission 2010-11 data 600 2009 400 200 0 0 50 100 150 200 250 Benzene pptv 11 Russo, R. S.; Zhou, Y.; White, M. L.; Mao, H.; Talbot, R.; Sive, B. C. Volume 10, Issue 1, 2010, pp.1083-1134

Hydrocarbon Processing and ozone 100 y = 28.463x + 114.34 LT data from other 90 R 2 = 0.8956 seasons July data 80 Low NO levels or mixing of polluted 70 air with clean marine air could be the ozone ppbv 60 reasons for ozone destruction. 50 40 30 20 10 0 -4.00 -3.00 -2.00 -1.00 0.00 ln propane/ethane 100 90 y = 0.8381x - 32.191 R 2 = 0.9304 80 70 ozone ppbv 60 50 40 30 July 2010 data 20 10 0 40 60 80 100 120 140 160 CO ppbv Helmig, D., D. M. Tanner, R. E. Honrath, R. C. Owen, and D. D. Parrish (2008), J. Geophys. Res. , 113 , D20S91, 12 doi:10.1029/2007JD008930.

Summary and further plans • Hydrocarbon ratios as a tracer • Free tropospheric study provides useful information on transport, mixing and chemistry • Continue to collect data over longer timescales and monitor instrument performance • Improve data coverage by collecting and analysing more samples. 13

Acknowledgements My supervisors Ally Lewis and Jim Hopkins University of York and NCAS for funding FGAM for dc-gc-fid Staff at FAAM ,Avalon and Directflight limited Research group people 14