Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada: A coupled organic-inorganic perspective by Britta Marie Voss B.S., University of Washington, 2009 Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY and the WOODS HOLE OCEANOGRAPHIC INSTITUTION September 2014 © 2014 Britta Marie Voss All rights reserved. The author hereby grants to MIT and WHOI permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part in any medium now known or hereafter created. Author……………………………………………………………………………………………… Department of Earth, Atmospheric, and Planetary Sciences, MIT & Department of Marine Chemistry and Geochemistry, WHOI August 25, 2014 Certified by………………………………………………………………………………………… Bernhard Peucker-Ehrenbrink Thesis Co-Supervisor Certified by………………………………………………………………………………………… Timothy I. Eglinton Thesis Co-Supervisor Accepted by………………………………………………………………………………………... Elizabeth B. Kujawinski Chair, Joint Committee for Chemical Oceanography 1 2 Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada: A coupled organic-inorganic perspective by Britta Marie Voss Submitted to the Department of Marine Chemistry and Geochemistry, MIT/WHOI Joint Program in Oceanography/Applied Ocean Science and Engineering on August 25, 2014 in partial fulfillment of the requirements for the degree of Doctor of Philosophy ABSTRACT The great geologic and climatic diversity of the Fraser River basin in southwestern Canada render it an excellent location for understanding biogeochemical cycling of sediments and terrigenous organic carbon in a relatively pristine, large, temperate watershed. Sediments delivered by all tributaries have the potential to reach the ocean due to a lack of main stem lakes or impoundments, a unique feature for a river of its size. This study documents the concentrations of a suite of dissolved and particulate organic and inorganic constituents, which elucidate spatial and temporal variations in chemical weathering (including carbonate weathering in certain areas) as well as organic carbon mobilization, export, and biogeochemical transformation. Radiogenic strontium isotopes are employed as a tracer of sediment provenance based on the wide variation in bedrock age and lithology in the Fraser basin. The influence of sediments derived from the headwaters is detectable at the river mouth, however more downstream sediment sources predominate, particularly during high discharge conditions. Bulk radiocarbon analyses are used to quantify terrestrial storage timescales of organic carbon and distinguish between petrogenic and biospheric organic carbon, which is critical to assessing the role of rivers in long-term atmospheric CO2 consumption. The estimated terrestrial residence time of biospheric organic carbon in the Fraser basin is 650 years, which is relatively short compared to other larger rivers (Amazon, Ganges-Brahmaputra) in which this assessment has been performed, and is likely related to the limited floodplain storage capacity and non-steady- state post-glacial erosion state of the Fraser River. A large portion of the dissolved inorganic carbon load of the Fraser River (>80%) is estimated to derive from remineralization of dissolved organic carbon, particularly during the annual spring freshet when organic carbon concentrations increase rapidly. This thesis establishes a baseline for carbon cycling in a largely unperturbed modern mid-latitude river system and establishes a framework for future process studies on the mechanisms of organic carbon turnover and organic matter-mineral associations in river systems. Thesis Supervisors: Bernhard Peucker-Ehrenbrink Senior Scientist, WHOI Timothy Eglinton Adjunct Scientist, WHOI Professor, ETH-Zürich 3 4 ACKNOWLEDGEMENTS The first words of thanks for all the diverse forms of support that contributed to this thesis belong to my advisors. Bernhard Peucker-Ehrenbrink and Tim Eglinton brought quite distinct but highly complementary contributions to this work. First, their unique areas of expertise allowed me to pursue questions spanning geologic applications of trace element isotope systems to molecular characterization of organic carbon. Over the past five years, I have enjoyed the freedom and support to take my thesis in the direction that excited me the most, and for that I am extremely grateful. Second, their different lab environments allowed me to work independently and search for my own solutions to challenges, but also to seek guidance when navigating unfamiliar territory. Starting from day one, Tim and Bernhard have encouraged me to present at countless scientific meetings and travel around the world for field and labwork. Their attention to scientific rigor and big-picture questions have significantly influenced how I think about the world and, I hope, made me a better scientist since I first stepped off the Peter Pan bus five years ago. I want to especially thank Bernhard for always making time to help me with new lab procedures, discuss fresh data, and provide feedback on countless fellowship and funding applications. His persistence and efficiency are probably the main reasons I was able to produce a thesis in these short years. And I credit his conscientious instruction for the fact that I never experienced a disfiguring lab accident (“Erst das Wasser, dann die Säure…”). I also want to thank Tim for opening his lab at ETH to me. The benefits of my visits to Zürich—scientifically as well as socially and culturally—were invaluable. In addition to being fabulous scientists, Bernhard and Tim are both tremendously thoughtful and kind human beings. I could not have asked for two more inspiring mentors. Valier Galy provided endless wisdom and guidance throughout my time in graduate school. I am forever grateful for the experience of doing field work on the Ganges-Brahmaputra in Bangladesh and Nepal, which both trained me to apply the “French” sampling methods to the Fraser and exposed me to a whole different world of culture and nature. Valier’s passion for river geochemistry is contagious and I owe a great deal of my enthusiasm for this research to his example. He has also been extremely generous with his scientific insights and lab facilities. Perhaps most importantly, and unbeknownst to them, Valier and Bernhard have been in an ongoing battle for the title of Quickest to Respond to Emails, which has also contributed greatly to this thesis. I thank Taylor Perron for embarking on a geochemical odyssey and offering his geomorphological insights to guide my thesis. The data within this thesis were largely made possible through the efforts of numerous individuals across the Fraser basin. Our collaboration with scientists and students at the University of the Fraser Valley not only generated a unique dataset, it also provided multiple generations of undergraduate students the opportunity to participate in scientific research both in the field and in the lab. This ongoing work is led by UFV professors Steven Marsh, Sharon 5 Gillies, and Alida Janmaat, who have mentored many students through individual research projects as part of this research. Students who have contributed significantly to this work include Jenna Fanslau, Bryce Downey, Garrett Macklam-Harron, Michelle Bennett, Helena Vankoughnett, Audrey Epp, Rosalie Luymes, Brayden Wiebe, Jillian Hansen-Carlson, Jocelyn Herbert, Reid Tucker, Amanda Hargreaves, Carissa England, Danielle Marcotte, Danyel Bourgeois, Jessica DaSilva, Jéssica Karyane, Kees Vanleeuwen, Mandy Alamwala, and Michelle Courtney. Professor Jonathan Hughes also provided support for field sampling in the Fraser Valley. Critical logistical support for sample shipment at UFV was provided by Pauleen Nuite, Ken Humbke, and Andy Gray. More recently, Prof. Jeremy Venditti at Simon Fraser University has greatly enhanced our sampling capabilities by allowing us to participate in his group’s suspended sediment research with the Water Survey of Canada. Graduate students Daniel Haught and Alex Gitto helped with field sampling on the CJ Walters, and Daniel has provided valuable data and insight on sediment transport in the Fraser. Field support was also provided by Curt Naumann, Trevor Mitchell, Alec Stalker, and Mathieu Beceulieu of the Water Survey of Canada. Logistical support at SFU was provided by B-Jae Kelly, Malcolm Little, and Joyce Chen. For our sampling campaigns in 2009-2011, Nelly François at Port Metro Vancouver facilitated sampling in the Fraser delta. We had the opportunity to use the boat Port Fraser, ably guided by captains Steve Davis, Feliks Rohraff, and Wayne Leslie and mates Norbert Simon, Asar (Jeffrey) Tengku, and Cathy McDonald. We also thank Lynne Campo and Amber Campbell of Environment Canada for providing rating curve information for the Harrison River. We gratefully acknowledge numerous groups and individuals who facilitated sampling at specific sites in the Fraser basin. Sampling was generously permitted by Wayne Mather and Peter Verschoor (Grant Narrows Regional Park), Telte Yet RV Campground (Hope), Fraser Cove Campground (Lillooet), Bridge River Band and Xwisten Tour operators (Bridge River), Stone Creek RV Park and Campground (Stoner), and Ann Hurley (Mt. Robson Provincial Park, Whitehorn Campground). We came to the Fraser basin as visitors and greatly appreciated the opportunity to take home water and sediments in order to learn about the river.