Master’s thesis Recent environmental change as recorded in Godthåbsfjorden sediments, Western Greenland Elaina O’ Brien Advisor: Matthias Paetzel Ph.D Co-advisor: Diana Krawczyk Ph.D University of Akureyri Faculty of Business and Science University Centre of the Westfjords Master of Resource Management: Coastal and Marine Management Ísafjörður, May 2021 Supervisory Committee Advisor: Matthias Paetzel, Ph.D Co-advisor: Diana Krawczyk, Ph.D External Reader: Marit-Solveig Seidenkrantz, Ph.D Program Director: Verónica Méndez Aragón, Ph.D. Elaina O’ Brien Recent Environmental change as documented in Godtåbsfjorden sediments, Western Greenland 45 ECTS thesis submitted in partial fulfilment of a Master of Resource Management degree in Coastal and Marine Management at the University Centre of the Westfjords, Suðurgata 12, 400 Ísafjörður, Iceland Degree accredited by the University of Akureyri, Faculty of Business and Science, Borgir, 600 Akureyri, Iceland Copyright © 2021 Elaina O’ Brien All rights reserved Printing: Háskólaprent, Reykjavík, April 2021 Declaration I hereby confirm that I am the sole author of this thesis and it is a product of my own academic research. _________________________________________ Elaina O’ Brien Abstract Effects of environmental and climate change are evident from seven sediment cores taken in the Godthåbsfjord, West Greenland. Continuous smear slides taken from these sediment cores reveal signals of increasing fine mineral grain sizes (very fine silt and clay) and increasing concentrations of terrestrial organic matter throughout the last decades, especially at locations close to the glacier outlets from the Greenland ice sheet in the east and at locations taken at intermediate distance between the glacier outlets and the western fjord outlet at Nuuk, the capital of Greenland. Both signals were interpreted as originating from glacial retreat due to glacial melting (finer grain sizes), and from erosional processes occurring at newly exposed and more overgrown icefree land surfaces (terrestrial organic matter). Heavy metal, PAH, and PCB concentration were found at background or slightly elevated non-polluting levels, apart from polluting concentrations of nickel originating from the local rocks surrounding the Godthåbsfjord. Contaminant patterns in the middle and western parts of the fjord follow the distribution pattern of the fine mineral grain sizes and the terrestrial organic matter concentrations indicating contaminant sources from land deposits and settlements at Nuuk, Qoornoq, and Kapisillit. Contaminant pattern in the easternmost sediment core is related to coarse mineral grain sizes (coarse silt and fine sand) and the marine organic matter concentration, indicating their sources originating from glacial runoff of air transported contaminant that deposited on the Greenland ice sheet. The overall correlation of contaminants with sediment parameters over the last decades allows the conclusion that future contaminant scenarios might turn into pollution scenarios in the Godthåbsfjord sediments if global warming continues to increase the supply of sediment parameters related to the contaminant distribution, namley fine-grained and organic matter. v Útdráttur Umhverfis- og loftlagsáhrif eru bersýnileg úr sjö setkjörnum teknum í Góðvonarfirði (d. Godthåbsfjord) á vesturhluta Grænlands. Sýni (e. smear slides) úr setkjörnunum gefa til kynna hlutfallslega aukningu á minnstu kornastærðunum (silt og leir) sem og aukningu á lífrænum efnum upprunnum ofan af landi síðastliðna áratugi. Þetta á sérstaklega við um sýni tekin við jökultungur austur við Grænlandsjökul, og sýnum milli skriðjöklanna og fjarðarmynnis Góðvonarfjarðar við Nuuk. Breytingar í setkjarna eru upprunnin frá hörfandi jökli vegna bráðnunar hans og vegna rofs á berangri sem nýlega hefur komið undan jökli ásamt nýlegri gróðurþekju svæðisins. Þungmálmar, PAH og PCB mældust í litlu magni, að nikkeli undanteknu sem mældist yfir mengunarmörkum en það finnst náttúrulega í bergi umhverfis Góðvonarfjörð. Áhrif þungmálmamengunar í setkjarnasýnum fyrir miðju- og vesturhluta fjarðanna fylgir dreifingu minnstu kornastærða og lífrænum efnum af meginlandinu sem bendir til að uppruni mengunnar eru ættaður úr seti af meginlandinu og frá bæjarkjörnum Nuuk, Qoornoq og Kapisillit. Áhrif þungmálma í setkjörnum frá eystri hlutanum eru upprunnin úr grófari kornastærðum (silt og sandur) og lífrænum efnum úr sjávarvistkerfum, sem benda til uppruna frá loftbornu seti sem safnast hefur á Grænlandsjökli og borist með ísstraumum jökulsins til sjávar. Niðurstöður mælinga benda til mögulegrar þungmálmamengunar í setmyndun Góðvonarfjarðar í framtíðinni vegna hröðunar á setmyndunarferlum af völdum hlýnun jarðar. vi vii Table of Contents Abstract ............................................................................................................................ v Table of contents .......................................................................................................... viii List of figures ................................................................................................................... x List of tables .................................................................................................................. xiv Acknowledgments ......................................................................................................... xv 1. Introduction ................................................................................................................. 1 1.1 Thesis focus .................................................................................................. 1 2. Environmental Setting ................................................................................................ 7 2.1 Geological history and bedrock geology ...................................................... 7 2.2 Tertiary and Quaternary geology .................................................................. 9 2.3 Glacial geology of the Holocene ................................................................ 10 2.4 Geography ................................................................................................... 11 2.5 Fjord bathymetry and hydrography ............................................................ 12 2.6 Human impact of the last 100 years ........................................................... 16 2.6.1 Isua mining ..................................................................................... 16 2.6.2 Construction and tourism ............................................................... 16 3. Theoretical Framework ............................................................................................ 19 3.1 Environmental Change ............................................................................... 19 3.1.1 Natural environmental change: Climate Observations ................... 20 3.1.2 Natural environmental change: Sea ice cover and glacial runoff .. 23 3.1.3 Natural environmental change: Organic matter ............................ 24 3.1.4 Natural environmental change: Mineral matter ............................ 26 3.1.5 Human induced environmental change: Contaminants ................. 27 3.1.6 Human induced environmental change: Contaminants sources .... 30 3.2 Literature Review ....................................................................................... 32 viii 3.2.1 Fjord sediment literature ................................................................. 32 3.2.2 Hydrographic literature ................................................................. 34 3.2.3 Contaminant literature ................................................................... 34 3.2.4 Climate change literature ................................................................ 36 3.3 Scientific Contribution ................................................................................ 36 3.4 Practical Value ............................................................................................ 36 4. Methods ...................................................................................................................... 39 4.1 Sediment sampling in the field ................................................................... 39 4.1.1 Contaminant subsamples ................................................................ 40 4.1.2 Sediment cores and sediment fragments ....................................... 40 4.2 Dating and sedimentation rates ................................................................... 41 4.3 Smear slides ................................................................................................ 41 4.3.1 Smear slide preparation .................................................................. 42 4.3.2 Smear slide analysis ...................................................................... 45 4.4 Contaminant analysis .................................................................................. 49 5. Results ........................................................................................................................ 53 5.1 Sediment Sampling in the field ................................................................... 53 5.2 Dating and sedimentation rates ................................................................... 55 5.3 Smear slides ................................................................................................ 58 5.3.1 Mineral grain size ..........................................................................