This electronic thesis or dissertation has been downloaded from Explore Bristol Research, http://research-information.bristol.ac.uk Author: Burford, Rory Title: Out of the Blue An investigation of two alternative sources of deep ice General rights Access to the thesis is subject to the Creative Commons Attribution - NonCommercial-No Derivatives 4.0 International Public License. A copy of this may be found at https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode This license sets out your rights and the restrictions that apply to your access to the thesis so it is important you read this before proceeding. Take down policy Some pages of this thesis may have been removed for copyright restrictions prior to having it been deposited in Explore Bristol Research. 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OUT OF THE BLUE: AN INVESTIGATION OF TWO ALTERNATIVE SOURCES OF DEEP ICE Rory Joshua Burford A dissertation submitted to the University of Bristol in accordance with the requirements for award of the degree of MSc by Research in the Faculty of Science School of Geographical Sciences, September 2018 Word count: 29,408 Abstract The direct sampling of deep ice is an invaluable tool for environmental research, however the logistical, technical and financial difficulties associated with many direct sampling approaches renders them unfeasible for all but the largest research collaborations. This thesis considers two alternative sampling approaches, both of which utilise deep ice that has been exposed for surface sampling by the natural flow of glaciers. Namely, it presents the biogeochemical analysis of terminal blue ice from the Marble Hills Blue Ice Area (Antarctica) and calved icebergs from Lago Steffen (Chilean Patagonia). These samples were collected and analysed using straightforward, low-cost methodologies, available to a large number of glaciological researchers. These approaches are evaluated in terms of the usefulness of the data that can be obtained and the availability of potential sample sites for future investigation. In doing so, this thesis sheds light on new methodologies that could be employed to answer questions concerning glacial processes. As well as exploring novel research approaches, this thesis offers original contributions to the knowledge of natural processes occurring within the vicinity of Horseshoe Valley Glacier (West Antarctic Ice Sheet) and Steffen Glacier (North Patagonian Icefield). The discussion of the Antarctic samples centres on the subglacial origin of the ice, which is indicated by the non-meteoric relationship between δ2H and δ18O and 2– the high concentrations of certain nutrients (CaCO3, SO4 , DOC) corresponding with subglacial environments. This also reveals the dominant chemical processes occurring at the bed. The discussion of iceberg samples employs similar techniques with a different focus: augmented by samples of local rivers and precipitation, it considers the impact of Steffen Glacier on downstream freshwater systems. This thesis therefore emphasises how readily-available deposits of deep ice can be utilised for a wide range of contemporary research questions. i ii Dedication and Acknowledgements I would like to dedicate this thesis to Susan, David, Zara and Tom – my family – without whom I would not have had the courage to make the jump to glaciology, let alone find the confidence to take myself seriously as an academic. To Zara and Tom in particular, I also owe thanks for their constant tips for my development as a postgraduate researcher. Along a similar vein, I would like to thank my supervisor, Professor Jemma Wadham, for offering me the opportunity to pursue this (fascinating) research and leaving me the space to grow as a scientist. I must also acknowledge the patience and support of Jon Hawkings and Matthew Marshall – my main mentors in the mysterious ways of planning and executing plans in the lab and field – and James Williams, who supported me enormously in bringing the water isotope analyser online against all odds. Lastly, I owe gratitude to Andy Hein, David Sugden and others at the University of Edinburgh involved in the sampling of the Marble Hills BIA with which I have been working, as well as Ale Urra Gallardo and the PISCES Project collaborators for their parts in organising the February 2017 field season at Lago Steffen. ¡Muchas gracias a todos! iii iv Author’s Declaration I declare that the work in this dissertation was carried out in accordance with the requirements of the University's Regulations and Code of Practice for Research Degree Programmes and that it has not been submitted for any other academic award. Except where indicated by specific reference in the text, the work is the candidate's own work. Work done in collaboration with, or with the assistance of, others, is indicated as such. Any views expressed in the dissertation are those of the author. SIGNED: .............. .................. DATE:..........................20/12/2018 v vi Table of Contents ABSTRACT ................................................................................................................................ I DEDICATION AND ACKNOWLEDGEMENTS ............................................................................... III AUTHOR’S DECLARATION ......................................................................................................... V TABLE OF CONTENTS.............................................................................................................. VII CHAPTER 1 – WHY DO WE NEED ALTERNATIVE SOURCES OF DEEP ICE? ..................................... 1 1.1 – OVERVIEW ................................................................................................................................. 1 1.2 – THE UTILITY OF DEEP ICE DATA ...................................................................................................... 2 1.2.1 – Paleoclimatic records ...................................................................................................................... 2 1.2.2 – Atmosphere and ecosystems .......................................................................................................... 3 1.2.3 – Subglacial processes ....................................................................................................................... 5 1.3 – DIFFICULTIES IN SAMPLING DEEP ICE ............................................................................................... 7 1.4 – AN ANTARCTIC SOLUTION: BLUE ICE AREAS ................................................................................... 10 1.5 – AN ALPINE SOLUTION: CALVED ICEBERGS ....................................................................................... 12 CHAPTER 2 – METHODOLOGY ................................................................................................ 14 2.1 – OVERVIEW OF FIELD SITES .......................................................................................................... 14 2.1.1 – Marble Hills BIA ............................................................................................................................ 14 2.1.2 – Subglacial Lake Ellsworth ............................................................................................................. 15 2.1.3 – Lago Steffen, Patagonia ............................................................................................................... 15 2.3 – WATER ISOTOPE ANALYSIS .......................................................................................................... 21 2.3.1 - Method .......................................................................................................................................... 21 2.3.2 – Quality control data ...................................................................................................................... 22 2.4 – ION CHROMATOGRAPHY (IC) ...................................................................................................... 24 2.4.1 – Method ......................................................................................................................................... 24 2.4.2 – Quality control data ...................................................................................................................... 25 2.5 – DISSOLVED ORGANIC CARBON (DOC) ........................................................................................... 29 2.5.1 – Method ......................................................................................................................................... 29 2.5.2 – Quality control data ...................................................................................................................... 29 2.6 – SUSPENDED DEBRIS ................................................................................................................... 30 CHAPTER 3 – WHAT CAN WE LEARN