THESIS ESTIMATING CONTRIBUTIONS OF PRIMARY BIOMASS COMBUSTION TO FINE PARTICULATE MATTER AT SITES IN THE WESTERN UNITED STATES Submitted by Amanda S. Holden Department of Atmospheric Science In partial fulfillment of the requirements For the Degree of Master of Science Colorado State University Fort Collins, CO Fall, 2008 COLORADO STATE UNIVERSITY September 26, 2008 WE HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER OUR SUPERVISION BY AMANDA HOLDEN ENTITLED ESTIMATING CONTRIBUTIONS OF PRIMARY BIOMASS COMBUSTION TO FINE PARTICULATE MATTER AT SITES IN THE WESTERN UNITED STATES BE ACCEPTED AS FULFILLING IN PART REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE. Committee on Graduate work _______________________________________ Dr. Charles S. Henry (Outside Committee Member) _______________________________________ Dr. Sonia M. Kreidenweis (Committee Member) _______________________________________ Dr. Jeffrey L. Collett, Jr. (Adviser) _______________________________________ Dr. Richard H. Johnson (Department Head) ii ABSTRACT OF THESIS ESTIMATING CONTRIBUTIONS OF PRIMARY BIOMASS COMBUSTION TO FINE PARTICULATE MATTER AT SITES IN THE WESTERN UNITED STATES Biomass combustion occurs throughout the world and has many implications for human health, air quality and visibility, and climate change. To better understand the impacts of biomass combustion in the western United States, six-day integrated fine particle samples were collected during the winter and summer seasons of 2004-2006 at seven IMPROVE sampling sites using Hi-Vol samplers. These sites included both urban and rural locations. Filter samples were analyzed for organic and elemental carbon, levoglucosan, and a suite of particulate ions. Levoglucosan, a thermal degradation product of cellulose, is a widely used tracer for primary biomass combustion. Measurements of levoglucosan and other carbohydrates were made using a new approach involving aqueous filter extraction followed by direct analysis using High Performance Anion Exchange Chromatography. In this method carbohydrates are separated on a Dionex Carbopac PA-10 column and detected using pulsed amperometry. Source profiles for primary biomass combustion were applied to each of these samples to estimate the contributions of carbon from both residential wood burning (during the winter seasons) and wildland fires (during the summer seasons). Wildland fire source profiles were determined from FLAME (Fire Lab at Missoula Experiment) campaigns at the USFS/USDA Fire Science Lab in Missoula, MT, during which fine particle samples were collected from source burns of approximately 30 fuel types. Residential wood combustion source profiles were collected from the literature. iii Primary biomass combustion contributions to contemporary PM2.5 carbon, determined separately from carbon isotope measurements at Lawrence Livermore National Laboratory, ranged from 0.4% to more than 100%. Contributions of primary biomass combustion were higher at rural sites, while urban sites showed greater contributions of fossil carbon. Primary biomass combustion contributed a larger fraction of total carbon in the summer at southern sites, while northern sites had larger contributions during the colder winter months. Amanda S. Holden Department of Atmospheric Science Colorado State University Fort Collins, CO 80523 Fall 2008 iv ACKNOWLEDGEMENTS There are many people I need to thank for their love, support, feedback, constructive criticism, and sometimes just comic relief that helped me in this journey. I would first like to thank my adviser, Dr. Jeff Collett for all of his wonderful feedback and ideas, for always being available to talk, and for always knowing how to change words around to make them sound better. Thank you also to my committee members Drs. Sonia Kreidenweis and Chuck Henry for all their support and constructive criticism. I would also like to thank all the members of both the Collett and Kreidenweis groups. I owe special thanks to Dr. Amy Sullivan, for essentially being my un-official adviser #2, for always answering all my questions, and for teaching me much that I know about the wonderful world of lab work and field studies (and for having much better manual dexterity than me). I also want to thank Leigh Patterson, who helped analyze so many filter samples and compiled data on various source profiles in the literature. There are many people to thank outside of my research group. I thank former members of the Collett group Dr. Guenter Engling, Dr. Jenny Cox, Dr. Lynn Mazzoleni, and Rich Cullin for all of their help. Dr. Engling provided much insight on the HPAEC- PAD method and his previous work with it, continued by Drs. Cox and Sullivan. Many contributors at other research institutions also provided help, data, and constructive criticism. These include Drs. Bill Malm and Bret Schichtel at CIRA/NPS; Cyle Wold, Dr. Wei Min Hao, and their colleagues at the US Forest Service Fire Science Lab; Dr. Chuck McDade and his colleagues on the IMPROVE team; and Dr. Graham Bench at Lawrence v Livermore National Laboratory. Funding for this work was provided by the Joint Fire Science Program and the National Park Service. I need to thank my family, for supporting me long before I had the dream to become a scientist. Thank you to my parents for always pushing me to do my best and constantly reminding me how proud they were. I thank my little sister, Emily, for unknowingly helping me strive to become a better role model and big sister. I’d also like to thank my friends, especially my fellow graduate students for their support and being good listeners during stressful times. Special thanks go to Josh, my best friend, for always believing in me and reminding me of that, even when I didn’t think it myself. He has always given me support and love, even from the opposite side of the world. I also have to thank God for providing me with such wonderful opportunities in life and for the passion and drive to make it this far. I owe this all to you. vi TABLE OF CONTENTS LIST OF TABLES....................................................................................................................ix LIST OF FIGURES................................................................................................................... x LIST OF ACRONYMS..........................................................................................................xiii Chapter 1 Introduction ...................................................................................................... 1 1.1 Background and Motivation...............................................................................................1 1.1.1 Contribution of Fires to Atmospheric Aerosols and Environmental Effects ................................1 1.1.2 Biomass Combustion Chemistry...................................................................................................3 1.2 Current Analysis of Primary Biomass Burning................................................................6 1.2.1 Carbon Isotope Analysis...............................................................................................................6 1.2.2 Source Profiles..............................................................................................................................7 1.2.3 HPAEC-PAD Carbohydrate Analysis ..........................................................................................9 1.2.4 Results from Previous Studies ....................................................................................................10 1.2.4.1 Carbon Isotope Study..........................................................................................................10 1.2.4.2 Source Apportionment Studies............................................................................................13 1.3 Study Objectives ................................................................................................................17 Chapter 2 Experimental Methods ................................................................................... 20 2.1 FLAME Sampling..............................................................................................................20 2.1.1 Facility Description.....................................................................................................................20 2.1.2 Sampling and Handling...............................................................................................................21 2.1.2.1 Hi-vol ..................................................................................................................................22 2.1.2.2 URG ....................................................................................................................................24 2.2 IMPROVE Sampling and Handling ................................................................................26 2.3 Sample Extraction .............................................................................................................28 2.3.1 Hi-vol Filters...............................................................................................................................28 2.3.2 URG Filters.................................................................................................................................28 2.4 Analysis...............................................................................................................................29 2.4.1 High-Performance Anion Exchange Chromatography with Pulsed