UNIVERSITY OF CALIFORNIA, SAN DIEGO Triple Oxygen Isotope Measurement of Nitrate to Analyze Impact of Aircraft Emissions A Thesis submitted in partial satisfaction of the requirements for the degree Master of Science in Chemistry by Sharleen Chan Committee in charge: Professor Mark Thiemens, Chair Professor Timothy Bertram Professor William Trogler 2013 Copyright Sharleen Chan, 2013 All rights reserved. The Thesis of Sharleen Chan is approved and it is acceptable in quality and form for publication on microfilm and electronically: ___________________________________________ ___________________________________________ ___________________________________________ Chair University of California, San Diego 2013 iii DEDICATION To my family whose love, inspiration, and support made the completion of my degree possible. iv TABLE OF CONTENTS Signature Page………………………………………………..…………………………. iii Dedication……………………………………………………..………………..……….. iv Table of Contents…………………………………………………….………….….……. v List of Figures……………………………..………………………………………....…. vii List of Tables………………………………………………………………...………….. ix Acknowledgements………………………………………………..……….…………..… x Abstract………………………………………………………………...…......……....…. xi Chapter 1 Nitrate and the Nitrogen Cycle………………………………….………......… 1 1.1 The Nitrogen Cycle………………………………………………..........……...… 1 1.2 Atmospheric nitrogen species in the Troposphere………………………......…… 1 1.2.1 Leighton relationship…………………………………...…...…… 4 1.3 Consequences of anthropogenic nitrogen emissions……………….….………… 4 1.4 References……………………………………………………...………………… 6 Chapter 2 Isotopes…………………………………………………………....……...…… 7 2.1 Isotopes of Nitrogen……………………………………………………………… 7 2.2 Delta notation and mass-dependent isotopic fractionations…………………....… 9 2.3 Mass-independent fractionations………………………………………....…….. 12 2.4 References……………………………………………………………….....…… 14 Chapter 3 Triple oxygen isotope measurement of nitrate to analyze impact of aircraft emissions………………………………………………………………………….......… 15 3.1 Introduction………………………………………………………..………...….. 15 3.2 Experimental………………………………………………...……..…………… 22 v 3.2.1 Sample Collection…………………………………...……..…… 25 3.2.2 Nitrate Extraction and Analysis…………...…………...…..…… 26 3.3 Results and Discussion………………………………………..…………...…… 28 3.3.1 Palmdale, CA....………...………………………………………. 28 3.3.2 Los Angeles International Airport…………………………….... 36 3.4 Conclusions……………………………………………………………...……… 39 3.5 Appendix…………………………………………………….…..…....………… 41 3.6 References………………………………………………………..….……..…… 45 vi LIST OF FIGURES Figure 1: Diurnal variation of NO, NO2, and O3 showing the relationship between each species. [Finlayson-Pitts and Pitts, 2000]………………………………………...……… 3 Figure 2: Isotopic fractionation of ozone formation [Thiemens and Heidenreich, 1983]. At 0,0 ‰, the original oxygen isotopic composition exists. Molecular oxygen reservoirs are denoted by squares and the ozone product by circles. The dotted line is the mass fractionation line with slope = 0.52 passing through original isotopic composition at 0,0‰…………………………………………………………………………….………. 11 Figure 3: Overview of Fischer-Tropsch process. Carbon containing feedstock is processed into Syngas (mixture of CO and H2) and undergoes the Fischer Tropsch process through catalysts into hydrocarbon chains……………………………...……… 21 Figure 4: AAFEX campaign sampling sites located in Palmdale, CA at fixed distances from the exhaust. Distances of 1m, 30m, 145m were chosen to study the formation of particles……………………………………………………………………….…...……. 23 Figure 5: Map of the four sampling sites used in the LAX campaign. Site #1 was the closest to jet emissions situated at the east end of the south runway 25R, just behind the airfield’s southeast jet blast protection screen. Site #2 was at the northwest edge of LAX closest to incoming marine air during west wind conditions. Site #3 was intended to have the direct jet emission about 1km from the airport. Site #4 was northeast of LAX and closest to freeway traffic…………………………………………………...……...……. 24 vii Figure 6: Changes in ∆17O of nitrate with varying fuel types and distances (m)............. 29 Figure 7. Oxygen triple isotope plot showing the relationship between atmospheric oxygen and ozone with nitrate aerosol measurements from Palmdale, LAX, La Jolla and Coastal Antarctica…………………………………………………………….…...……. 30 Figure 8: Varying fuel types showing changes in ∆17O with respect to δ18O………….. 31 Figure 9: Seasonal representation of δ18O and ∆17O collected from LAX………….….. 37 viii LIST OF TABLES Table 1: Average comparison of properties from various fuel types and their mixtures. FT fuels contain minor amounts of sulfur and aromatic hydrocarbons, as conveyed through the higher hydrogen content and H/C ratio, compared to JP-8…...…… 20 Table 2: Palmdale Isotopic Measurements……………………………………….…….. 41 Table 3: LAX Fall 2009 Isotopic Measurements……………………………………….. 42 Table 4: LAX Winter 2010 Isotopic Measurements……………………………...…….. 43 Table 5: LAX Spring 2010 Isotopic Measurements…………………………...……….. 44 ix ACKNOWLEDGEMENTS I would like to acknowledge many individuals whose help and support have made this work possible. First, I would like to express my deepest gratitude to my thesis advisor, Professor Mark Thiemens, for his guidance, inspiration, patience and providing me with an excellent atmosphere for conducting research. I would also like to thank Dr. Robina Shaheen for her invaluable mentorship at the conclusion of my undergraduate career and throughout my graduate career. Teresa Jackson and Dr. Subrata Chakraborty for their input in experimental design, assistance in sample processing, and for collecting all aerosols used in this thesis. Also, many thanks also to members of my lab for their helpful discussions and words of wisdom. They are: Analisa Hill, Zhi-sheng Zhang (Sun Yat-Sen University- China), Jason Hill-Falkenthal, Morgan Nunn, and Dr. Antra Priyadarshi. Special thanks to Professor Bertram and Professor Trogler for participating in my thesis defense committee. Lastly, I would also like to thank my parents, my elder brother, and my friends for supporting and encouraging all my ambitions. Chapter 3, in part is currently being prepared for submission for publication of the material. R. Shaheen, A. Hill, T. Jackson, S. Chakraborty, The thesis author was the primary investigator and author of this material. x ABSTRACT OF THE THESIS Triple Oxygen Isotope Measurement of Nitrate to Analyze Impact of Aircraft Emissions by Sharleen Chan Master of Science in Chemistry University of California, San Diego, 2013 Professor Mark Thiemens, Chair With 4.9% of total anthropogenic radiative forcing attributed to aircraft emissions, jet engines combust copious amounts of fuel producing gases including: NOx (NO + NO2), SOx, VOC’s and fine particles [IPCC (1999), IPCC (2007), Lee et al., 2009]. The tropospheric non-linear relationships between NOx, OH and O3 contribute uncertainties in the ozone budget amplified by poor understanding of the NOx cycle. In a polluted urban environment, interaction of gases and particles produce various new compounds that are difficult to measure with analytical tools available today [Thiemens, 2006]. Using oxygen triple isotopic measurement of NO3 to investigate gas to particle formation and chemical transformation in the ambient atmosphere, this study presents xi data obtained from aerosols sampled at NASA’s Dryden Aircraft Operations Facility (DAOF) in Palmdale, CA during January and February, 2009 and Los Angeles International Airport (LAX) during Fall 2009, Winter 2010, and Spring 2010. The aerosols collected from jet aircraft exhaust in Palmdale exhibit an oxygen isotope anomaly (∆17O =δ17O -0.52 δ18O) increase with photochemical age of particles (-0.22 to 26.41‰) while NO3 concentration decreases from 53.76 - 5.35ppm with a radial distance from the jet dependency. Bulk aerosol samples from LAX exhibit seasonal variation with 17 ∆ O and NO3 concentration peaking in winter suggesting multiple sources and increased fossil fuel burning. Using oxygen triple isotopes of NO3, we are able to distinguish primary and secondary nitrate by aircraft emissions allowing new insight into a portion of the global nitrogen cycle. This represents a new and potentially important means to uniquely identify aircraft emissions on the basis of the unique isotopic composition of jet aircraft emissions. xii References: IPCC, 1999 - J.E.Penner, D.H.Lister, D.J.Griggs, D.J.Dokken, M.McFarland (Eds.) Prepared in collaboration with the Scientific Assessment Panel to the Montreal Protocol on Substances that Deplete the Ozone Layer. Cambridge University Press, UK. pp 373 IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Lee, D.S., Fahey, D.W., Forster, P.N., Newton, P.J., Wit, R., Lim, L.L., Owen, B., Sausen, R. Aviation and global climate change in the 21st century, Atmospheric Environment (2009),doi:10.1016/j.atmosenv.2009.04.024 Thiemens, M.H. 2006, History and Applications of Mass-Independent Isotope Effects. Annu. Rev. Earth Plnet. Sci. 34, 217-262. xiii Chapter 1 Nitrate and the Nitrogen Cycle 1.1 The Nitrogen Cycle Nitrogen is essential for the development of agricultural crops. When nitrogen is insufficient, plant growth and root systems become underdeveloped while older leaves turn yellow and