PHYSICAL AND CHEMICAL WEATHERING PROCESSES AND ASSOCIATED CO2 CONSUMPTION FROM SMALL MOUNTAINOUS RIVERS ON HIGH-STANDING ISLANDS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Steven Todd Goldsmith, M.S. Geological Sciences Graduate Program The Ohio State University 2009 Dissertation Committee: Professor Anne E. Carey, Advisor Professor W. Berry Lyons Professor Michael Barton Professor Wendy Panero Copyright by Steven Todd Goldsmith 2009 ii ABSTRACT Recent studies of chemical weathering of on high standing islands (HSIs) have shown these terrains have some of the highest observed rates of chemical weathering and associated CO2 consumption yet reported. However, much remains unknown about controlling process. To determine the role these islands play on climate the following were evaluated: 1. dissolved, particulate and organic carbon fluxes delivered to the ocean from a small-mountainous river on an HSI during an intense storm event (i.e., typhoon); 2. relationship between physical and chemical weathering rates on an HSI characterized by ranges of uplift rates and lithology; 3. water and sediment geochemical fluxes and CO2 consumption rates on HSIs with andesitic-dacitic volcanism; and 4. the overall chemical weathering fluxes and CO2 consumption rates from andesitic-dacitic terrains on HSIs of the Pacific and the East and Southeast Asia region. Sampling of the Choshui River in Taiwan during Typhoon Mindulle in 2004 revealed a particulate organic carbon (POC) flux of 5.00x105 tons associated with a sediment flux of 61 million tons during a 96 hour period. The linkage of high amounts of POC with sediment concentrations capable of generating a hyperpycnal plume upon reaching the ocean provides the first known evidence for the rapid delivery and burial of POC from the terrestrial system. These fluxes, when combined with storm derived CO2 ii consumption of 1.65x108 moles from silicate weathering, elucidate the important role of these tropical cyclone events on small mountainous rivers as a global sink of CO2. Geochemical sampling of Taiwan rivers during spring 2004 and summer 2005 revealed carbonate weathering supplies a significant portion of the total cation yields (44–93%) while silicate weathering plays a lesser role. However, absolute silicate weathering rates are so high (5.8–149 tons km-2a-1) that they fall at the upper end of those previously determined from sedimentary and metamorphic terrains of HSIs. Comparisons of chemical weathering yields to potential controlling parameters revealed slightly positive correlations with basin average mean annual rainfall and average basin runoff as well as between silicate weathering rates with annual suspended sediment yields. However, the high p-value suggests more data are necessary to obtain an accurate determination. Silicate and carbonate weathering yields also had different relationships with post-uplift age of the landscape. H2SO4 weathering, originating from the dissolution of pyrite, accounts for 13–33 % of the total chemical weathering in these systems. After correction for H2SO4, calculated CO2 consumption from silicate weathering ranges from 236 to 2640 x 103 moles km-2 a-1 and is highly elevated over world average values. Such CO2 consumption likely represents the upper limit for a non-volcanic active margin setting. Sampling and stream gauging of Dominica rivers in July 2006 and March 2008 revealed distinct wet and dry season solute concentrations. A cluster analysis of the stream geochemical data shows the importance of parent material age on the overall delivery of solutes. Observed Ca:Na, HCO3:Na and Mg:Na ratios suggest crystallinity of iii the parent material may also play an important role in determining weathering fluxes. Observed chemical weathering yields (6–105 t km-2 a-1) were similar to those previously -2 -1 determined for basalt terrains. Silicate yields (3.1–58.4 t km a ) and associated CO2 consumption (143–2040 x 103 mol km-2 a-1) are amongst the highest determined to date. These chemical yields confirm the weathering potential of andesitic-dacitic terrains. Chemical weathering yields from two additional andesite terrains, Mt. Pinatubo in the Philippines and Volcán Barú in western Panama are combined with existing datasets in an attempt to calculate a regional CO2 drawdown value for this material. Annual chemical and silicate yields from both regions were some of the highest recorded to date 3 -2 -1 and corresponding CO2 consumption values (1532–2882 x10 moles km a ) are so high they fall in-line with those previously determined for basaltic terrains. A compilation of the new and existing datasets shows rivers draining andesite material are characterized by relatively high Na-normalized molar ratios and low Ca:Mg molar ratios compared to those draining continental silicates. No discernible relationship with material age was observed while runoff and temperature were shown to be the dominant controls on solute fluxes. From these relationships and a new highly-detailed lithology map, CO2 consumption from andesite weathering on HSIs of 0.49 x 1012 moles a-1 and for East and Southeast Asia of about 0.59 x 1012 moles a-1 were determined. These values represent between 5.7 and 6.8% of the annual CO2 consumption previously calculated from continental silicate weathering and between 16 and 19% of the value previously calculated from basaltic terrains worldwide thereby confirming the importance of iv andesite weathering as a CO2 sink. These terrains thus may play an important role on climate evolution over geologic time. This study is the first comprehensive evaluation of weathering processes on HSIs and provides valuable insights on the relationship of silicate weathering and global CO2 drawdown on various timescales. Weathering fluxes observed from the sedimentary and metamorphic terrains of Taiwan may represent the upper end of what may have occurred during the early stage collision of the Himalayas. Evaluation of CO2 drawdown from andesite terrains on HSIs shows the importance of this material as a weathering substrate and lends further support that andesite terrain be considered separately when calculating global CO2 sequestration from silicate weathering. Additional evaluation of andesite terrains worldwide is warranted in order to accurately delineate this annual value. v To Mom and Dad vi ACKNOWLEDGEMENTS I wish to thank my advisor, Dr. Anne Carey, for her help throughout the whole course of my Ph.D. and agreeing to take a chance on an environmental consultant in dire need of a career change. Her help was invaluable. Conversations with Dr. W. Berry Lyons regarding my data were both exciting and rewarding. Discussions on andesite volcanics with Dr. Michael Barton were extremely helpful as well. I also would like to thank Dr. Wendy Panero for agreeing to serve on my committee. I am indebted to the following members of the Carey and Lyons research groups for their valuable help at various intervals during the process: Sue Welch, Kathy Welch, Brent Johnson, Gregg McElwee, and Annette Trierweiler. I also wish to thank Dr. Shuh-Ji Kao of the Academia Sinica, Research Center for Environmental Changes, Taipei, Taiwan for serving as my host during my two summers (2004 and 2005) in the National Science Foundation East Asia and Pacific Summer Institute. A number of acknowledgements are required for specific help I received with this work: T.-Y. Lee, A.-J. Song, Jill Chien, Jack Hu, and S.-Y. Chou aided with sample collection of the Choshui River during Typhoon Mindulle (Chapter 2); Jean Chen and Jeff Owen for helping me to adjust to life in Taiwan while conducting my research (Chapters 2 and 3); Anne Carey, Jill Chien and T.-Y. Lee for their aide in sample collection of Taiwan rivers during the spring and summer of 2005; Jean Chen for providing help with field logistics and data analysis; T.-Y. Lee for accessing long-term vii gauging records of the Taiwan Water Resources Agency; Anthony Lutton for assistance with sample analysis on the ICP-OES (Chapter 3); Cecil Shillingsworth of the Office of Disaster Management for his help with field logistics and the people of Dominica for their kind access to streams for gauging and sampling; Anne Carey and Brent Johnson for their assistance with sampling and gauging of Dominica streams; Brent Johnson for aiding with watershed area determination (Chapter 4); Dr. Russell Harmon of the U.S. Army Research Office and Eric Nicoliasen and Alonzo Iglesias of TRAX-IAESA for their assistance with logistics and sample collection in Panama; Dr. Maria Luisa Tejada, Mark Lapus, Raymond Rodolfo, and Allan Salas of the National Institute of Geological Sciences, University of the Philippines – Diliman for their assistance with logistics and sample collection in the Philippines; Sue Welch for help with sample analysis on the ion chromatograph (Chapter 5). This work was also supported by the East Asia and Pacific Summer Institutes (OISE 0413475) and Hydrologic Sciences (EAR 0309564) programs of US National Science Foundation; the Geological Society of America Graduate Student Research Grant (2006), Friends of Orton Hall Fund; The Ohio State University Office of International Affairs Graduate Student Dissertation Research Travel Grant (2007); The Ohio State University Alumni Grants for Graduate Research and Scholarship (2007); and The Ohio State University Presidential Fellowship (2009). I am also grateful to Anne Carey for allowing me the opportunity to serve as a research mentor during my tenure at OSU. Assisting in the research projects of the following undergraduate students was extremely rewarding, kept me humble and viii confirmed my desire to teach: Christopher Gordon, Brent Johnson, Matthew Dugan, Justin Von Bargen, Lindsay Hannah, and Claire Mondro. I would also like to thank The Flying Pizza for providing the closest semblance to NY style pizza for this at times homesick New Yorker. I am also indebted to Mom, John and Irene for their support during this process.