Recent Environmental Change As Recorded in Godthåbsfjorden Sediments, Western Greenland

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

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.

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.

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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

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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 ...... 58

5.3.2 Organic matter fraction ...... 66

5.4 Contaminants ...... 75

5.4.1 Heavy metals ...... 76

5.4.2 Polycyclic aromatic hydrocarbon (PAH) ...... 84

5.4.3 Polychlorinated biphenyl (PCB) ...... 85

5.4.4 Organotin Compounds ...... 87

5.4.5 Pesticides ...... 87

5.4.6 Contaminant trends and correlations ...... 87

6. Discussion ...... 91

6.1 The sources of recent (0-100 year) contaminant variations in the Godthåbsfjord sediments ...... 91

6.1.1 Mineral grain size sources ...... 91

6.1.2 Organic matter sources ...... 92

6.2 The sources of recent (0-100 year) particulate matter variations in the Godthåbsfjord sediments ...... 95

6.3 Conclusions on the relationship between contaminant and particulate matter variations in the Godthåbsfjord sediments and their related sources ...... 98

6.4 Unexpected results ...... 100

6.5 Knowledge gaps, future research and management remarks ...... 101

7. Conclusion ...... 103

References ...... 104

Appendix A ...... 114

Appendix B ...... 115

Appendix C ...... 117

Appendix D ...... 121

Appendix E ...... 130

List of Figures

Figure 1: Map of Godthåbsfjord system including branch, settlements, glacier outlet names, baseline map by Mortensen et al, 2011 ...... 4

Figure 2: Geology of Greenland, including Iceland (Laurence Dyke (2014) ...... 8

Figure 3: Location of Isua Greenstone belt in the Godthåbsfjord region, Illustration from Moorbath (2009)...... 9

Figure 4: Bathymetry map of Godthåbsfjord system including major sills, depth range, settlements and continental shelf. Baseline map courtesy of Greenland Climate Change Research Centre ...... 14

Figure 5: Temperature, ice-melt simulation, precipitation, and runoff over the last 100 years taken from Nuuk station Source (Langen et al, 2015) ...... 21

Figure 6: Future projections of annual temperature and precipitation in Western Greenland from 2030 to 2100 including RCP 4.5 and RCP 8.5 (Boberg et al. (2018) ... 23

Figure 7: Map of coastal settlements in Western Greenland, including airport and heliport locations, and their proximity to the Greenland Ice Sheet. Image source https://www.greenlandbytopas.com/map-central-greenland ...... 31

Figure 8: Image of Van Veen box grab on location ...... 39

Figure 9: Equipment list for core opening ...... 42

Figure 10: Equipment list for smear slide preperation ...... 44

Figure 11: Microscope images of grain sizes from location 6 ...... 47

Figure 12: Microscope images of mineral versus organic matter at location 6 ...... 48

Figure 13: Microscope images of mineral versus organic matter and terrestrial versus marine organic matter at location 5 ...... 49

Figure 14: Bathymetry map from survey with samples in colour boxes indicating core samples or fragments ...... 54

Figure 15: Location of Greenland fjords where sedimentation rates were estimated ...... 56

Figure 16: Location 1 overview of the three grain sizes classifications; fine grains, medium grains and coarse grains ...... 59

Figure 17: Location 4 overview of the three grain sizes classifications; fine grains, medium grains and coarse grains ...... 60

Figure 18: Location 5 overview of the three grain sizes classifications; fine grains, medium grains and coarse grains ...... 61

Figure 19: Location 6 overview of the three grain sizes classifications; fine grains, medium grains and coarse grains ...... 62

Figure 20: Location 8 overview of the three grain sizes classifications; fine grains, medium grains and coarse grains ...... 63

Figure 21: Location 10 overview of the three grain sizes classifications; fine grains, medium grains and coarse grains ...... 64

Figure 22: Location 12 overview of the three grain sizes classifications; fine grains, medium grains and coarse grains ...... 65

Figure 23: Map illustrating decreasing and increasing trends in mineral matter content at all locations ...... 66

Figure 24: Location 1 overview of the mineral versus organic matter content and terrestrial versus marine organic content ...... 68

Figure 25: Location 4 overview of the mineral versus organic matter content and terrestrial versus marine organic content ...... 69

Figure 26: Location 5 overview of the mineral versus organic matter content and terrestrial versus marine organic content ...... 70

Figure 27: Location 6 overview of the mineral versus organic matter content and terrestrial versus marine organic content ...... 71

Figure 28: Location 8 overview of the mineral versus organic matter content and terrestrial versus marine organic content ...... 72

Figure 29: Location 10 overview of the mineral versus organic matter content and terrestrial versus marine organic content ...... 73

Figure 30: Location 12 overview of the mineral versus organic matter content and terrestrial versus marine organic content ...... 74

Figure 31: Maps illustrating decreasing and increasing trends in marine and terrestrial organic matter at all locations ...... 75

Figure 32: Graphs illustrating relation between heavy metals and medium grain sizes at all locations ...... 82

Figure 33: Graphs illustrating relation between heavy metals terrestrial organic matter at all locations ...... 83

Figure 34: Distribution of the sum of heavy metal concentrations (Σheavy metals) at the sediment sample sites (circles) in the Godthåbsfjord ...... 88

Figure 35: Distribution of the PAH16 concentrations at the sediment sample sites (circles) in the Godthåbsfjord...... 89

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Figure 36: Distribution of the PCB7 concentrations at the sediment sample sites (circles) in the Godthåbsfjord...... 90

Figure 37: Dependencies of sediment particulate matter and contaminant distribution in the Godthåbsfjord on their respective sources and source areas...... 100

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List of Tables

Table 1: List of elements analysed in this study, including their atomic number and density, signifying their classification as heavy metals accordingly (Podsiki, 2008).28

Table 2: Mineral grain sizes analysed in the smear slides of the Godthåbsfjord, according to the classification used in the Udden-Wentworth scale (Udden, 1914 and Wentworth, 1922)...... 46

Table 3: Sediment sampels analysed from the Godthåbsfjord, including location number, latitude and longitude position, water depth, core ID, sediment sequence and depth of subsamples ...... 55

Table 4: Arbitrary dating of the Godthåbsfjord sediments using sedimentation rate ..... 57

Table 5: Polluting levels of contaminants according to the Norwegian classification of contaminants in coastal marine sediments (Miljødirektoratet 2016) ...... 76

Table 6: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 1 ...... 76

Table 7: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 4 ...... 77

Table 8: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 5 ...... 78

Table 9: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 6 ...... 79

Table 10: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 8 ...... 79

Table 11: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 10 ...... 80

Table 12: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 12 ...... 81

Table 13: Contaminant levels of each PAH16 compound displayed for surface 0-2cm and subsurface 2-4cm sediments for all locations ...... 84

Table 14: PCB compounds at location 5, at surface 0-2cm and subsurface 2-4cm samples...... 86

Table 15: PCB compounds at location 10, at surface 0-2cm and subsurface 2-4cm samples ...... 86

Table 16: PCB compounds at location 12, at surface 0-2cm and subsurface 2-4cm samples ...... 87

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Acknowledgements

I would first like to thank Greenland Climate Research Centre for funding part of this thesis and for hosting me during my time in Nuuk. I want to express my sincere gratitude to my advisors, Dr. Matthias Paetzel and Dr Diana Krawczyk. Thank you for your time and attention throughout the year. Your envouragement, expertise and commitment to this project have been an invaluable asset to me and I am thankful to have met and worked with you both. I would also like to kindly thank Hafrannsóknarstofnun for the use of their laboratory facilities, and for allowing me drive to beautiful hafnarfjörður everyday. A sincere thank you to everyone at the University Centre of the Westfjords for the ongoing help over the last two years, and to my cohert who have gone through this journey with me, thank you for your advice and support which has gotten me to this point. Lastly, I would like to extend my deepest thanks to my family and friends, without you none of this would have been possible. Takk fyrir, a chairde, go raibh míle maith agaibh go léir.

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1 Introduction

1.1 Thesis focus

There has been an increasing concern amongst authorities and scientists about environmental and climate change in the Arctic over the last two decades, including the effects of global warming and polluting concentrations of contaminants (AMAP, 2018; Overland et al, 2019). This concern was derived from the findings such as contamination reflected in the microbrial metagenomes on the Greenland ice sheet (Hauptmann et al, 2017) and from the increasingly melting glaciers in the Arctic region (Mohan et al, 2018) and elsewhere (Bogdal et al, 2009). In Greenland, the signals from environmental and climate change are transported by runoff from the more and more melting glaciers into rivers, lakes, and ultimately into the Greenland fjords. While there have been extensive environmental investigations in Greenland on glacial mass balances (The IMBIE Team, 2019), fjord hydrography (Mortensen, Lennert, Bendtsen & Rysgaard, 2011), and even mammals (AMAP, 2018), there is a lack on such investigations on fjord sediments. It is the aim of this thesis to contribute to filling in parts of this gap by analyzing the sediments of the Godthåbsfjord, West Greenland, for signals from recent (0-100 years) environmental and climate change, following up the idea of Paetzel and Dale (2010) and Paetzel and Schrader (1991) who pointed out the importance of fjord sediment investigations for the temporal and spatial reconstruction of environmental and climate change in a glacially influenced fjord system in Norway.

To do so, this study will perform an assessment of sediment parameter composition and a contamination analysis in a grid of sediment cores across the Godthåbsfjord. The sediment parameters will include the organic matter fraction, mineral grain sizes, and the evidence of contamination, focusing on the following objectives:

• Objective 1: Has the composition of particulate matter in Godthåbsfjord sediments changed over the past 100 years?

• Objective 2: Is there any relationship between the variation in the particular matter composition and the respective sources?

• Objective 3: Are there significant contaminant concentrations in Godthåbsfjord sediments? Is there any relationship between the distribution of these contaminants and the variation in particulate matter and sources?

Explanation Objective 1: Has the composition of particulate matter in Godthåbsfjord sediments changed over the past 100 years?

The first objective of this study is to get a historical overview of the sediment deposition in the Godthåbsfjord by analyzing the sediment organic matter fraction (including a differentiation between terrestrial, land derived organic matter, and marine organic matter) and the mineral grain size (typically including sand, all silt sizes, and clay), using smear slide analysis, following the method of Rothwell (1989) and applied on hemipelagic historical fjord sediments by Paetzel and Schrader (1991). This will provide a frame for what kind of sediments form in the different fjord settings, including all individual fjord branches (Figure 1). After the spatial sediment analysis, it is essential to gain an understanding on the timing of the sediment variations throughout the entire fjord system. To do so, this thesis will adopt sedimentation rates from similar settings from the neighboring Ameralik fjord (Møller at al, 2006) and Qaumarujuk fjord (Perner et al, 2010), and three East Greenland fjords (Andrews, Milliman, Jennings, Rynes, and Dwyer, 1994), as the recent sedimentation rates in the Godthåbsfjord are not publicly available, yet (Ribeiro, personal communication, GEUS).

Explanation Objective 2: Is there any relationship between the variation in the particular matter composition and the respective source?

The second objective is to use the historical overview of the sediments to find out if it is possible to relate changes in the component composition to their respective sources. Such sources might include any local event and/or climatic variability in the area related to changes in runoff from glacial melt or precipitation, as well as prolonged summer seasons due to increased air temperatures and increased sea ice melting in the fjord. Thus, this objective will link the changes in sediment composition to the changes in climate conditions occurring over the same time period.

Explanation Objective 3: Are there significant contaminant concentrations in Godthåbsfjord sediments? Is there any relationship between the distribution of these contaminants and the variation in particulate matter and sources?

The third objective is to find out if there is contamination in Godthåbsfjord sediments and where these contaminants originate from. Contaminants in marine and fjord sediments are most often adsorbed on the sediment organic matter fraction and/or the fine grained (clay and silt) mineral grain sizes (Salomon et al, 1988; Syvitsky, Burrell, Skei, 1986). Thus, the sources of the contaminants should somehow be linked to the sources and source areas of the particulate matter fraction, as identified in the first and second objective. The source areas impacting the sediment composition will have a direct impact on the ability of the contaminants to bind to the sediment, and thus, sources of contaminants will be linked to the source of the sediment composition variability. The contaminants that are undergoing analysis are chosen based on previous studies in the Godthåbsfjord (Carlsson et al, 2012), and the neighbouring Affarlikassaa and Qaumarujuk fjords (Perner et al, 2010) and in arctic Svalbard fjords (Mohan et al, 2018), in addition to contamination research on the cryosphere of the Greenland ice sheet (Hauptmann et al, 2017). These contaminants include selected heavy metals (Cr, Ni, Cu, Zn, Cd, Sn, Hg, and Pb), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides (dichlorodiphenyltrichloroethane, i.e. DDT), and tributyltin (TBT). Classification of the polluting effects of the contaminants will follow the Norwegian quality standards for sediments (Miljødirektoratet 2016), as this is the only classification at hand that covers contamination in northern hemisphere fjord sediments, following European standards.

Figure 1: Location map of the Godthåbsfjord fjord system. Name code: Yellow – Settlements, with yellow stars pointing out the exact location. Pink – Glacier inlets, with pink arrows pointing in flow direction and indicating glacier front. White – Fjord branches. Light blue – Lake Tasersuaq. Light green – Isua region. Aerial photograph is public domain at https://commons.wikimedia.org/w/index.php?curid=2085117. Greenland outline map from Mortensen et al. (2011).

This thesis will first provide a theoretical overview of the geographic and historical setting of Godthåbsjord, including a brief synopsis on how Greenland and the Greenland ice sheet was formed throughout the geological history. Following this overview, a scientific setting will be provided, including relevant literature that is published regarding environmental change within marine sediments and a list of the most important papers used to support the study at hand. Beyond this, a summary of the methods that were used will provide relevant additional information into how the sediments in this thesis were retrieved and analysed. An overview of the smear slide preparation and microscope analysis will be explained as well as the methodology used by Eurofins Finland for the contaminant analyses on the sediment samples. Next will be the results of the analyses performed, including grain sizes, the organic matter content, and contaminant concentrations of the sediments. Lastly the discussion and conclusion will offer an interpretation of expected and unexpected results.

Theories for the trends found within the sediment samples will be explained, referring back to the three primary objectives of the thesis. The thesis at large will provide scientific knowledge into the understanding of environmental change within Godthåbsfjord sediments, relating that change to the sources and source areas within the region.

2 Environmental Setting

2.1 Geological history and bedrock geology

The geological history and bedrock geology of the Godthåbsfjord region provides background information to support the sediment framework of the Godthåbsfjord, to understand from which geological material the mineral particles of the sediment originate. Figure 2 represents an overview of the geology of Greenland, dating almost 4,000 million years back in time (Steinberger, Spakman, Japsen, Trond, Torsvik, 2014). The basement rocks of Greenland are composed of Archaean Gneiss (3900–3600my) primarily derived from metamorphized tonalite and granodiorite. The Archaic basement rocks are partly overlain by sedimentary and volcanic rocks, which formed the oldest of Greenland’s mountains from 3800 to 1600 million years ago (Henriksen, 2008). The remains of these Precambrian rocks are today located mostly in the northwest, central west, and south part of Greenland (Figure 2).

Since the Late Precambrian time about 650 my (million years) ago, Greenland has drifted due to plate tectonic movement from a location close to the Antarctic across the southern hemisphere into the northern hemisphere and the Arctic, thus experiencing a pole-to-pole journey via the tropics (Steinberger, Spakman, Japsen, Torsvik, 2014). While drifting, the central east and northeast part of Greenland (Figure 2) – at that time being part of the Laurentia continent in the east colliding with the Baltica continent in the west - were formed by the orogeny of the Caledonian mountain chain during the Silurian time (430 to 415my ago). The northeast part of Greenland (Figure 2) was in addition affected by the mountain building processes of the subsequent Variscan orogeny, occurring during the Late Devonian and Early Carboniferous time about 400 to 350 million years ago. From 60 to 55 million years ago, extensive volcanic activity occurred from the spreading of the tectonic plates that started the opening of the North Atlantic Ocean, today visible in Paleogene (Tertiary) basalts and intrusions in the north of Greenland and as a volcanic east-west stretching belt in central Greenland (Figure 2).

Figure 2: Geology of Greenland, including geographical position and Iceland in the Southeast. See legend for classification of colours and rock types. Cartography rights to Laurence Dyke (2014).

A special geological formation in the Godthåbsfjord area is the Isua Greenstone Belt (Figure 3), located in the northeastern main land extension of the Godthåbsfjord and stretching in east-west direction from the Isua peninsula (Figure 1) to the Greenland ice sheet. The belt consists of supracrustal amphibolitic rocks, holding in addition some of the oldest sedimentary and volcanic rock sequences known on the planet (Myers, 2001). The supracrustual Isua Greenstone Belt occurs within the Amitsoq orthogneisses formed through metamorphic crystal growth within the metasedimentary and metavolcanic rocks

(Henriksen, 2008) and dated to being of Archaean age about 3 to 3.7 billion years old (Moorbath, 2009; Myers, 2001).

Figure 3: Location of the Isua (Supracrustal) Greenstone Belt, northeast of the Godthåbsfjord fjord system. Illustration from Moorbath (2009).

2.2 Tertiary and Quaternary geology

In the beginning of the Tertiary time, 65 million years ago, the level of atmospheric carbon dioxide concentration was around 2000 ppm, which is about four times higher than CO2 levels of today (Rothman 2002). Global annual temperatures were up to 14°C higher than today, and highest surface water temperatures were 23°C at the North Pole (Funder, 1989). Due to these conditions, there was no evidence of permanent ice formation in Greenland. Upon this Paleocene Thermal Maximum (55 my ago), a cooling period followed, indicated

by coarser and more sandy particles in sediments from the Arctic Ocean (45 my ago). The coarser sediment material indicated ice rafting, and thus formation of glaciers, and was interpreted as a continuous increase in ice debris from northern regions, including Northern Greenland and Svalbard, especially from 14my to 3.2my ago. There is a lack of evidence of the glaciation input from Greenland at this time, but Miller, Fairbanks, and Mountain (1987) claimed that Greenland has supported glaciation since 38my ago. The climatic deterioration in Greenland was part of the global cooling that took place during the entire Tertiary time due to major changes in the global ocean current pattern, initiated by tectonic openings and closures of ocean water pathways, culminating in the Quaternary ice ages starting about 2 my ago (Miller et al, 1987).

Glacial deposits and erosional features give evidence for the effect of the Tertiary global cooling and the Quaternary buildup of the Greenland ice sheet (Henriksen, 2008). These features include mountain summits in the Godthåbsfjord area ranging from 500 to 1480 meters above sea level with numerous steep valleys, interconnected lakes, and multiple fjord branches and fjord outlets throughout the Godthåbsfjord system. The Quaternary cycles of warming and cooling over the last half a million years is characterized by eleven marine stable isotope stages (Alley et al, 2010). The ice age of the oxygen isotope stage 6 (about 188.000 to 130.000 years ago) may have produced the most extensive ice sheet in Greenland.

2.3 Glacial History of the Holocene

The current Marine Isotope Stage MIS 1 describes the last c. 10 ky, namely the Holocene period. Throughout the Quaternary, the Greenland ice sheet was shrinking during each warm, interglacial period, and growing during each cold, glacial period (Brink & Weidick, 1974). During the last glacial advance, the Greenland ice sheet reached its maximum extent between 24ky and 19ky ago. Through the following Holocene interglacial period, the Greenland ice sheet decreased by about 40%. Evidence of retreat from the Last Glacial Maximum is largely undocumented, as the relevant locations to study are today located below sea level (Alley et al, 2010; Funder, 1998).

Deposition of the major Holocene moraine systems in West Greenland was a consequence of glacial melting after periods of decreasing temperature and successive ice advance.

These periods did not affect the overall long-term retreat of the ice sheet during the Holocene (Brink & Weidick, 1974).

Today, the Greenland ice sheet has an area of approximately 1.7 million km2, a volume of 2.9 million km3, and stretches 2200 km from north to south. With the average thickness of the ice sheet at 1600m, it is predominantly above sea level. Throughout the 1980s and 1990s, the Greenland ice sheet has been in equilibrium. Since then it is in extensive retreat, producing 14% greater melt water discharge at a rate of 495 to 500 Gt yr−1 than during the previous observations from 1985 to 1999 (King et al, 2020). Between 1992 and 2018, the total mass loss of the Greenland ice sheet caused a mean sea level rise of 10.8 ± 0.9 millimetres (The IMBIE Team, 2019). In addition, these ice cores reveal signals of the glacial retreat through increased sea level rise since 1992. This thesis will try to link the Godthåbsfjord sediment signals of particulate matter and contaminants to the processes of recent glacial melt and the successively increasing runoff form the glacial outlets into the fjord.

2.4 Geography

The Godthåbsfjord is one of the largest fjord systems in the world, located at the southwest coast of Greenland, with the capital city Nuuk (latitude 64°10′N, longitude 51°44′W) situated at the western outlet of the fjord (Figure 1). The total surface area of the fjord is 2013km2 with a net volume of 525km3 (Mortensen, Lennert, Bendtsen, Rysgaard, 2011) and a total length of about 190km.

The eastern transition of the Greenland ice sheet into the Godthåbsfjord consists of three marine-terminating glacial outlets, Kangiata Nunâta Sermia, Akugdlerssûp Sermia, and Narssap Sermia (Figure 1). There are two land terminating outlet glaciers named Qamanârssûp Sermia and Kangilínguata Sermia that melt into the fjord, and a third land- terminating outlet glacier called Saqqap Sermersua that drains into the nearby Lake Tasersuaq, all illustrated in Figure 1. From the outlet glaciers, the Godthåbsfjord splits into three separate northeast-southwest trending fjord branches with a maximum width of 7km. These fjord branches are the Umánap Suvdlua, the Qôrnup Suvdlua, and the Nûp Kangerdlua. They are separated from the six glacial outlets by two northwest-southeast stretching fjord arms, the Kangersuneq and the Kapisillit Kangerdluat (Figure 1).

There are 18,000 inhabitants in Nuuk, and another 63 inhabitants in Kapisillit at the eastern termination of the Kapisillit Kangerdluat (Figure 1). According to Dzik (2016), the number of residents living in Kapisillit is steadily declining. There used to be another settlement at the north end of the middle fjord branch of Qôrnup Suvdlua, named Qoornoq (Figure 1). This was a larger settlement and with more inhabitants than Kapisillit in the past, peaking at 300 inhabitants in the 1960s (Dzik, 2016). According to local sources, Qoornoq has been uninhabited since the 1970s except for summerhouses (Personal communication with local people, 2020). This knowledge might add additional sources for the interpretation of the contaminant and organic matter distribution in the Godthåbsfjord.

The Godthåbsfjord is a prime location for studying environmental change by using marine sediments as a signal, because of its transitional location between the Greenland ice sheet and the North Atlantic Ocean. The fjord is an ideal marine study site due to its geographical position close to the Arctic, its accessibility, complex topography and its clear division into nearby but different morphological fjord settings.

2.5 Fjord bathymetry and hydrography

Bathymetry

The Godthåbsfjord is a subarctic sill fjord that is connected to six glacial outlets, as displayed in Figure 1 (Mortensen et al, 2011). Figure 4 shows the bathymetry of the Godthåbsfjord system. Beyond the coastline to the west, the continental shelf gets as shallow as 50m water depth, called the Fyllas Banke. East of the Fyllas Banke is the main sill at 170m water depth.

The westernmost northeast-southwest trending Nûp Kangerdlua (Figure 1) represents the main fjord branch. It is deepest of the three parallel branches with a maximum depth of 625m (Mortensen et al, 2011), as indicated in Figure 4. According to Mortensen et al (2013), the main water exchange in the Godthåpsfjord system occurs through this branch and its continuation into the northernmost up to 450m deep Kangersuneq fjord branch (Figure 4). The remaining parallel fjord branches of the middle Qôrnup Suvdlua and the eastern Ūmánap Suvdlua, as well as the Kapisillit Kangerdlua, that is located offshore Kapisillit (Figure 1), are of a more semi-enclosed character with shallow, 55m and 115m

deep sills (Figure 4). Maximum water depth is between 500m and 600m water depth in the parallel branches and between 500m and 600m in the Kapisillit Kangerdlua branch (Figure 4).

In addition to the water depth and the minor sills, Figure 4 illustrates the position and water depth of the major sills in the Godthåbsfjord system. Mortensen et al (2011) names the 170m deep sill offshore Nuuk the Main Sill, restricting water exchange into the Godthåbsfjord system. About 48km east of the Main Sill they locate another sequence of major sills, with Sill 1 (at 250m water depth) located directly at the fjord outlet at Nuuk, and Sill 2 (at 277m water depth) located about halfway northward into the Nûp Kangerdlua. A third major sill, Sill 3 (at 170m water depth) is located close to the junction of the northernmost Kangersuneq fjord branch and the Qamanârssûp Sermia glacial outlet (Figure 1 and 4).

With multiple branches in the fjord, there might also be variations in the fjord processes from branch to branch. In addition, the multiple sills found in each branch create more variation in the bathymetry and environmental setting of the fjord, suggesting variations in the sedimentation pattern that might be of relevance when interpreting the sediment record of the Godthåbsfjord.

Figure 4: Bathymetry of the Godthåbsfjord system according to survey done by the Climate Research Centre, Greenland Institute of Natural Resources. The colour code on the right indicates the water depth in meters. Sills and sill depth is indicated in black colour, including the names and depth of the major sills (Fyllas Banke, Main Sill, Sill 1, Sill 2, Sill 3), and the depth only for the minor sills. Sill location and depth after Mortensen et al (2011). The location of the maximum water depth is indicated for the main fjord branch (in dark blue colour) consisting of the Nûp Kangerdlua and its northern extension into the Kangersuneq fjord branch.

Hydrography

The West Greenland Current outside the Godthåbsfjord moves northward across the continental shelf west of the Fyllas Banke (Mortensen et al, 2011). Due to favorable topographic setting together with the Ekman transport in combination with the wind direction and the Coriolis force, these water masses are pushed in eastward direction during the summer season (Ekman, 1905), thus entering the Godthåbsfjord.

There are three principal water masses occurring in the Godthåbsfjord system. The first two water masses originate from the open oceanand it is the Sub Polar Mode Water (SPMW) originating from the Irminger Water mass of Atlantic origin (Mortensen et al, 2011) with average temperatures of 5°C, and a salinity of 35.0‰. The second water mass

is the coastal water that ranges from 0 to 6°C in the summer, and with summer salinities ranging from 33.0 to 32.0‰.

Inside the fjord, the third principal water mass is the freshwater supplied by precipitation, river runoff, and glacial runoff with average temperatures at 0°C and salinities of 0.0‰. This fresh water has two categories of supply. These are runoff to the surface water layer of the fjord (0°C and 0.0‰) and subglacial freshwater discharge from the tidal outlet glaciers (0.5°C and 0.0‰). The subglacial freshwater discharge is a major sedimentation source, pumping freshwater into the fjord at depth, creating an upwelling effect of the less dense, and slightly warmer waters that are enriched in glacially retrieved nutrients (Mortensen et al, 2011).

The intermediate baroclinic circular mode (Mortensen et al, 2011), and more generally estuarine circulation (Hansen & Rattay, 1965; Pritchard, 1952) transports sill water into the fjord from the outer Main sill region. This outer sill water mixes with the inner water masses of the Godthåbsfjord system. The predominant circulation pattern transfers the outer sill water into the main branch of the fjord during summer. Basin waters will then form inside Sill 2 and are defined as water that occurs at >277m water depth. Basin waters are made up of coastal water and Sub Polar Mode Water. These deep waters have an average mixed temperature of 0.0 to 2.8°C and a mixed salinity of 33.1 to 33.9‰. The deep-water inflow occurs once or twice a year over a period of three to six months (Mortensen et al, 2011).

In the Godthåbsfjord system, surface salinities range from 22.29 to 33.05‰, and surface temperatures vary between 0.91 and 8.61°C. Melt water trajectories studies show an out- fjord surface water transport, in agreement with a simple estuarine circulation paradigm. However, eddies and abrupt wind-driven reversals reveal complex surface transport pathways at time scales of hours to days (Carlson, Boone, Meire, Abermann, & Rysgaard, 2017). Within the Godthåbsfjord system, there are four primary circulation modes. These are the estuarine circulation mode, with the driving force primarily from freshwater runoff to the surface of the fjord. The second of these is the subglacial circulation, which relates to the estuarine circulation mode, along with the outlet glaciers and mixing of surrounding waters. The third circulation is the dense coastal advection from the open ocean that directs its way into the fjord, and lastly the intermediate baroclinic circulation mode, which is

forced by mixing of deep, dense bottom water starting in the Sill 1 area. These circulation patterns are significant contributors to glacial melting (Mortensen et al, 2011), thus influencing the local runoff entering the fjord. In addition, the circulation patterns will control whether the runoff material stays dissolved in the water column, settles on the fjord bottom, or gets transported to the open ocean.

2.6 Human impact of the last 100 years

2.6.1 Isua mining

Isua ore deposit occurs 150km northeast of Nuuk (London Mining EIA, 2013), located in the Qeqqata area (Figure 1 and Figure 3). The area lies within a 1200m altitudinal span from the Godthåbsfjord to the summit of Mount Isua. After the ore discovery in 1965, mining companies became interested in developing a mining project for iron ores in the area. In 2005, the UK based London Mining M/S were granted a license to explore the area, and although construction never went ahead, they did produce an environmental impact assessment (EIA) and a social impact assessment (SIA) of the area. According to their website, they were expected to produce 15 million tonnes a year of iron ore concentrate to the steel industry (SIA, Naalakkersuisut, 2009).

The Isua Greenstone Belt iron deposit in the area might impact the sediment minerology and contaminant distribution, especially that of associated heavy metals like nickel (Aoki, Kabashima, Kato, Hirata, Komiya, 2018). As seen by Perner et al (2010) in the Qaumarujuk Fjord, NW Greenland, heavy metal contamination connected to the adjecent Pb-Zn “Black Angel” Mine was found to have enriched the sediment material entering the fjord and depositing onto the sediments.

2.6.2 Construction and tourism

There has been an increase in construction and industrial development in Nuuk since the economic growth of 2015, according to economic reports (Theodora, 2020). Currently, construction is underway to expand the Nuuk international airport located six kilometres northeast of the harbour. The existing runway will be extended from 950m to 2220m length. This is one of three new airports under development in Greenland, together making

it the largest infrastructure investment (572 million Euro) made by Greenland in its history. The construction of Sikuki, the new harbour in the south of Nuuk was made in 2017. According to their website (Sikuki, 2015), rocks were blasted from the mountains in Nuuk and taken to the site areas. About 340,000m3 of rock were blasted in the nearby mountains, Qeqertat and Fyrø to construct the harbour. As well as this, underwater blasting was involved adding of a total of 21,000m3 rock to the harbour construction. There might thus be evidence of increased contamination in the Godthåbsfjord marine environment, relating to the increase in construction and industrial development seen since 2015.

Passengers travelling on cruise ships to the capital have steadily increased, from 30,271 in 2010 to 46,633 in 2019 (Lumholt, 2020). This implies that in addition to the construction of the airport and new harbour, another source of contamination could be from the combustion and exhausts of boats running in and out of the harbour (Sikuki Annual Reports, 2017), suggesting enhanced production and thus sedimentation of PAHs and associated contaminants in sediments deposited near Nuuk. The increasing number of passengers and cruise ships was also enhancing the need for harbour expansion and better infrastructure, and thus the building of Sikuki harbour and the extension of the airport (Lamprecht, Momberger, Ellis, 2020).

In addition to the construction activity, a surplus amount of unspecified contaminants originating from combustion, oil production, waste systems, and household products (Higueras, Sáez-Martínez, Reyes-Bozo, 2016) is expected to being supplied to the Godthåbsfjord sediments. At the same time, the sediments might be impacted by the local runoff in the area, causing larger amounts of coarse-grained material or impacting the organic matter content, especially as the amount of freshly broken rocks and thus larger grain sizes increased over the last five years due to the construction activity described above.

There is no sewage treatment in Nuuk, and the wastewater gets dumped into the ocean at multiple exit points around Nuuk. The ‘chocolate factory’ is the area aptly nicknamed due to the extent of sewage water that enters the ocean (Pedersen et al, 2020). This is relevant to the thesis at hand, because sewage supply is an additional factor to consider when interpreting the contaminant distribution in the Godthåbsfjord sediments, as illustrated in the Nordåsvannet fjord sediments in Norway (Paetzel, Schrader, and Croudace, 1994).

According to a study on waste management, 20,000 tons of waste is incinerated annually in Greenland (Eisted and Christensen, 2011). The lack of appropriate waste management in Nuuk might contribute to the contamination source linking to the signals of environmental change in the fjord sediments.

3 Theoretical Framework

3.1 Environmental Change

The central aim of this thesis is to understand the sediment processes in the Godthåbsfjord and relate these to natural and human induced environmental change and possible combinations of these. The sediment composition in marine and fjord areas changes over time in accordance with the effects of environmental change. The related sedimentary processes might not only allow the reconstruction of past environmental change, but they might also provide knowledge on the effects of future environmental change on the marine environment (Austin, Howe, Forwick, Paetzel, 2010).

Natural environmental change such as sea ice retreat and increased glacial melting can be related to changes in climate like increased precipitation and temperature. Such natural induced environmental change might consequently lead to prolonged growth seasons (Walsh, Overland, Groisman, Rudolf, 2012). These impacts will eventually leave signals in marine and fjord sediments through runoff from land and/or altered primary production in the marine environment. Paetzel and Dale (2010) state the relation between precipitation and sediment processes in two Norwegian fjords, when interpreting grain size variations and elevated organic matter concentrations as signals of naturally occurring environmental change.

Human induced environmental change has been observed in a variety of recent (0 to 100 years) marine and fjord sediment settings, usually related to the accumulation of contaminants (Austin et al, 2010; Salomons et al, 1988; Syvitski et al, 1987). In addition, Bodgal et al (2009) found increased fluxes of certain contaminants in sediments fed by Alpine glaciers in Switzerland in the 1950s, and interpreted these fluxes as originating from the release of glacially trapped contaminants into the aquatic (lake) environment, triggered by global warming. Graly, Humphrey, Landowski and Harper (2014) studied chemical weathering from the Greenland ice sheet. Carlsson et al (2012) documented contaminants in the Arctic, and in the air. It is yet unknown to what degree these contaminants are trapped in the Greenland ice sheet and surrounding glaciers, and how much of an influence the melting of the ice sheet has on contamination entering the fjords

that are connected to the Greenland ice sheet. These studies provide evidence for the connection between natural and human induced environmental change.

The following paragraphs will specify the most relevant natural and human induced environmental change processes as well as give an overview of supporting scientific research previously carried out in the Godthåbsfjord area.

3.1.1 Natural environmental change: Climate Observations

Monthly precipitation in Nuuk is approximately 100mm, which decreases extensively the further inland it travels (Koyama, Stroeve, 2019). Gale force winds are often evident in the area, mostly in the winter period and Föhn winds are also evident in the area, particularly near Isua at the north-eastern part of the Godthåbsfjord. The dry, warm Föhn winds form from adiabatic compression of the air that comes straight down from the Greenland ice sheet itself. The humidity falls to approximately 35%, and temperatures can rise approximately 17°C in as short as one hour. These elevated winds last for a couple of days and can be quite forceful, with strong hurricane gusts. The strong Föhn winds might impact the local runoff from the glacial outlets into the Godthåbsfjord, by enhancing the transporting of elevated amounts of eroded material in the direction of the fjord (EIA assessment, 2013).

Langen et al (2015) modelled the relationship between observed annual temperature, precipitation, and ice sheet variation in the Godthåbsfjord area over the last century (Figure 5). Figure 5a shows the average annual temperature (black line) over the past 100 years and the modelled enhanced ice sheet melt (red line) caused by increasing temperatures since 1990 until 2012. Figure 5b indicates the annual precipitation (black line) over the last 100 years, indicating more frequent precipitation since 1990, resulting in corresponding amounts of accumulated particulate matter transported by runoff (red line). Figure 5c illustrates the reconstructed Surface Mass Balance (SMB) of the ice sheet since 1950, which is rapidly declining since 1990. This decline is visible in both, the reconstructed graph (blue line) and the modelled graph (red line). A declining SMB leads to increasing surface runoff from the ice sheet, and an upward shift of the equilibrium line altitude (ELA). The ELA marks the altitude at which snow accumulation and snow melting

(=ablation) are at equilibrium (see Bakke & Nesje, 2014 for a review). An upward shift of the ELA means more melting and less snow/ice accumulation on the glacier.

Figure 5: Temperature, ice-melt simulation, precipitation, and runoff over the last 100 years taken from Nuuk station. The record is from 1890 to 2012 (black, left axis). The upper graph (a) represents temperature and total annual ice sheet melt in the Godthåbsfjord (model in red, right axis). The middle graph (b) represents total annual precipitation, and the resulting total annual accumulation rate of particulate matter transported by runoff (model in red, right axis). The lower graph (c) represents the reconstruction of SMB (Surface Mass Balance) of the ice sheet in grey and blue lines. The modelled SMB is in the red line and is modelled onto the observed temperature and precipitation data. Figure from Langen et al, 2015.

The graphs of Figure 5 indicate the effect of increasing temperature and greater ice sheet melt and thus more runoff and higher particulate matter transport into the Godthåbsfjord during the past decades. Glacial retreat, increasing freshwater runoff, and subglacial runoff from the Greenland ice sheet have thus increased over the last century (Langen et al, 2015).

While the observations and model simulations of Langen et al (2015) show past and present scenarios of the Greenland ice sheet in response to climate change (Figure 5), model simulations of Boberg, Langen, Mottram, Christensen, and Olesen, (2018) indicate the future fate of the Greenland ice sheet at given radiative forcing scenarios (Figure 6).

According to Boberg et al (2018), glacial retreat from the Qeqqata municipality was recorded, and Representative Concentration Pathway (RCP) models are applied, suggesting that ice caps in the Kangerlussuaq fjord, located about 300km north of Nuuk, will vanish before the turn of the century (Figure 6). RCP models (Van Vuuren et al, 2011) indicate scenarios of future climate impact on the environment (temperature; precipitation) based on combined radiative forcing in 20-year time increments until the year 2100.

Combined radiative forcing includes CO2 emissions, greenhouse gases, chemical compounds, and aerosols. The different model scenarios use successively stronger radiative forcing ranging from low forcing of 2.6W/m2, via 4.5W/m2 and 6W/m2 to strong forcing of 8.5W/m2, respectively.

Boberg et al (2018) illustrates the radiative forcing of 4.5W/m2 (RCP4.5) and 8.5W/m2 (RCP8.5) in their models (Figure 6). Their study suggests an increase in precipitation by 20%-30% for the RCP4.5 model scenario, and 30%-80% for RCP8.5 model scenario within this century. The models also imply an increase in mean annual temperature of 2.5– 3°C for the RCP4.5 model scenario and 4.8–6.0°C for the RCP8.5 model scenario.

Figure 6: Future projections of annual temperature and precipitation in Western Greenland. White line represents the Greenland ice sheet of today. Two representative concentration pathways are used. The first one (RCP) 4.5 is on the left, with the first scenario for from 2031 to 2050 (a, e). The second scenario is from 2081-2100 (b, f). The third scenario (c, g) is on (RCP) 8.5, from 2031 to 2050 and the last scenario (d, h) is on (RCP) 8.5 from 2081 to 2100. Each of these scenarios are relative to change from the period 1991-2010. The top right scale is for temperature change (ΔT in °C), and the bottom right scale is for delta precipitation change (ΔP in %). Figure source Boberg et al, 2018.

In addition, climate change has caused an increase in air and water temperatures, rapidly affecting the Arctic environment. “Arctic amplification” is a term describing the rapid effect of climate change in these less populated parts of the world (Dai, Luo, Song, Liu, 2019). The cryosphere is melting at a severe rate due to climate change, and Greenland is predicted to be ice-free within the millennium (Aschwanden et al, 2019).

3.1.2 Natural environmental change: Sea ice cover and glacial runoff

Changes in precipitation, temperature, and evaporation subsequently affect the runoff patterns and thus, sediment transport into fjords (Bianchi et al, 2020). Freshwater availability increases with glacial runoff (Citterio et al, 2017), and sediment transportation can be altered by the increasing freshwater influx from melting glaciers. Sediment yield may increase in relation to these processes, thus altering the grain sizes, organic matter and mineral content of the sediments. An understanding of ice cover and glacial runoff into the Godthåbsfjord is therefore a basic part of this study.

The sea ice cover in the Godthåbsfjord shows inter-annual variations with sea ice forming in November and covering most of the inner branches of the Godthåbsfjord until the end of April. There is sea ice evident in all parts of the fjord, with the most extensive distribution in the Kangersuneq fjord branch and around Kapisillit (Figure 1).

As illustrated in Figure 1, there are extensive glacial termini with a length of up to 6km, originating from the outlet glaciers. In the winter, there is a buildup of calved glacial ice seen in front of the Narssap Sermia glacial outlet (Figure 1). The floes range in sizes from 1m2 to 70m2 (Mortensen et al, 2011) and are stable until late spring, when the wind direction changes from out-fjord to in-fjord to start the breakup of the ice. The wind direction will keep the ice inside the fjord, where it eventually melts. Very little sea ice and glacial ice is seen exiting the fjord itself. From May onwards, the sea ice starts to decrease and melt until November, when it starts to build up once again (Mortensen et al, 2011).

The glacial runoff from land-terminating glacial outlets reaches the fjord surface waters through glacial rivers, while the runoff from marine-terminating outlets and areas of direct contact between the fjord and the glacier ice enters the fjord at deeper ranges, and thus creating density gradients in the water column. These nutrient rich subglacial inputs can trigger primary production in the fjord (Juul-Pedersen, 2020). Knowing the movement and pathways of the ice in the Godthåbsfjord provides useful information when investigating the fate of possible contaminants on their way from the glaciers into the fjord.

Indirect climate observations by local inhabitants confirmed the decreasing ice cover over the years throughout the fjords, and people can now access the inner fjord branch of the Kangersuneq via boat at times that were impossible due to the extended sea ice cover only a few decades ago (Lennert, 2017). Local people also documented less whales observed in the fjord, and hunting methods changed from whale hunting to terrestrial hunting, particularly foxes. Before that, during the 1920s to 1930s, local people adopted to hunting seals instead of whales after the whales stopped appearing (Lennert, 2017).

3.1.3 Natural environmental change: Organic matter

The primary causes of organic matter accumulation in marine sediments are from marine plankton, transport of terrestrial organic remains by runoff, and residual organic matter that is recycled and degraded over time within the sediments (Tissot & Pelet, 1981).

The input of terrestrial organic matter depends on its preservation and the conditions that affect its transport and formation processes such as runoff due to precipitation and glacial melting, or prolonged productivity seasons due to elevated annual temperatures inferred by global warming. Terrestrial organic matter is degraded, carried into the Godthåbsfjord by river currents, and is deposited in the sediment (Tissot & Pelet, 1981). In addition, terrestrial organic matter trapped in the Greenland ice sheet might get released during melting, influencing the overall input into the fjord (Wadham et al, 2019). The observed increasing precipitation and glacial melting in the Godthåbsfjord region (Langen et al, 2015) might therefore imply enhanced amounts of terrestrial organic matter entering the fjord.

The impact of marine organic matter depends on primary productivity and thus on the nutrient and light conditions in the aquatic environment of oceans (Redfield, 1934) and fjords (Syvitski, 1987). Light conditions in the upper water column will be reduced in the Godthåbsfjord during phases of sea ice cover. Globally rising temperatures would on the other hand keep the fjord free of ice for an increasingly longer time of the year (Langen et al, 2015), thus possibly leading to prolonged open water conditions that could enable increased primary productivity in the fjord. At the same time, rising temperatures would increase glacial melting and runoff, suggesting enhanced amounts of terrestrial particulate material (mineral grains and terrestrial organic matter) entering the fjord during summer seasons. Although enhanced melting and runoff would increase the amount of nutrients in the fjord (Juul-Pedersen, 2020), this process might counteract primary productivity as the particulate material might increase the turbidity in the water column and by this lowering the light conditions, leading to restrictions in primary productivity in the fjord (Syvitski et al, 1987).

Recycling of sedimented organic matter might be of less importance in the Godthåbsfjord as the succession of sills and the depth of the fjord basins (Mortensen et al, 2011) would reduce the probability for reworking the fjord sediments by water current activity (Syvitski et al, 1987). Overall, it might be expected that the Godthåbsfjord sediments reveal variations especially in the terrestrial organic matter fraction over time, in accordance with the changing climate.

3.1.4 Natural environmental change: Mineral matter

The primary causes of sedimentation deposition in arctic and subarctic fjords are from glacial runoff and land erosion (Gilbert, Nielsen, Desloges, Rasch, 1998). Due to the changes in climate and ocean warming, Polar regions are experiencing a shift in geological processes as well as the impact on the ice sheets and glaciers. The distribution of grain sizes and sedimentation rates can vary depending on the proximity to glaciers, with the coarser grain and silt material deposited closest to the glaciers. With the environmental changes to glaciers seen through ice retreat, increased melting and prolonged seasons (Langen et al, 2015) this influences the amount of material entering the fjord, as well as the mineral size. Glaciers only produce sizes of silt and larger, and with the continued retreat of glaciers documented this in turn affects the production of silt and how much is deposited into the fjord (Gilbert et al, 1998).

The contributing factors to climate change also affect the abiotic factors of the fjord such as temperature-salinity stratification and turbidity of the water column. With changes in glacier outflows, finer grain and clay material transportation from land deposits is forced to change (Syvitski et al, 1987). What binds together and what settles on the seafloor depends on the hydrodynamic conditions in the fjord, conditions that are changing due to environmental stress. Coarse grains are deposited into the fjord primarily through the release of icebergs as material melts off the ice and settles in the fjord or gets transported to the open ocean, of which icebergs are the main mechanism. With decreasing icebergs and an increasing distance of the galcier front to the fjord, one can therefore expect a decrease in coarse material (Drewnik et al, 2016).

Sedimentation processes are highly dependable on the distance to deltas that might build up in front of the glacial outlets (Syvitski et al, 1987). Gravity flows can also deposit in areas closer to the glaciers inside the fjord, and these gravity flows occur due to the morphology of the delta, and the relief. The closer to the delta the weaker the gravity flows tend to be, and this is another process of sediment deposition in fjords. These gravity flows and turbidity currents are the main cause of suspended material settling, with these processes being more evident in distal areas of the fjord (Gilbert et al, 1998). With the changing marine ecosystems due to environmental stress, sedimentation and sediment sizes

are altering over time, as documented by comparing them to fjord sediments throughout the Holocene (Gilbert et al, 1998).

Climate can change the sedimentation processes from different fjords in the same land area, as seen in a study comparing glacimarine environments between East and West Greenland (Desloges et al, 2001). Here we see that the primary source of sedimentation in West Greenland is from meltwater sources, as the climate on the west is not as harsh as that on the east. The West Greenland Current is also warmer water that contributes to this variability. It is an example of how warmer areas have more sedimentation deposition, and as climate change increases these processes and the climate gets warmer in arctic regions, this will have an overall impact on the sediment type and influx from the surrounding land and glaciers that are depositing sediment into the fjords. The parameters that are most sensitive to climate change are therefore glaciers and meltwater input (Gilbert et al, 1998).

3.1.5 Human induced environmental change: Contaminants

This investigation concentrates on the contaminant distribution pattern of heavy metals, Polycyclic aromatic hydrocarbons (PAH), Polychlorinated biphenyls (PCB), tributyltin (TBT), and Dichloro-diphenyl-trichloroethane (DDT) in Godthåbsfjord sediments. The reasons why these contaminants were analysed is because of their use in other contamination investigations in Arctic areas, allowing comparability. In addition, these contaminants are all considered to be harmful to human health and the environment at elevated amounts.

Definitions and terms: The use of the terms contamination and pollution will follow the definition of Chapman (2007). The term contamination thus includes any material in an environment that either occurs above background concentrations or that does not naturally occur in the respective area. Chapman (2007) further defines pollution as contamination at concentrations that have an unfavorable or harmful effect on the biological communities in that area.

Heavy metals: Heavy metals are naturally occurring elements that have an atomic weight of 23 or higher (Koller & Saleh, 2018), and a density that is minimum five times higher than water (Tchounwou, Clement, Patlolla, Sutton, 2012), thus corresponding to at least 5g/cm3. They are classified as human carcinogens and are toxic in the environment. The

term “heavy metals” should not be confused with the term “trace metals” that are metallic elements that naturally occur in concentrations between 5 and 15 mol/l in the environment (Robbins Mänd, Planavsky Alessi, Konhauser, 2019).

Table 1 shows a list of the elements analysed in this study, followed by their atomic number, and their density. According to the Occupational Safety and Health Administration USA, these elements are all classified as heavy metals in the environment (Podsiki, 2008).

Table 1: List of elements analysed in this study, including their atomic number and density, signifying their classification as heavy metals accordingly (Podsiki, 2008). Element Name Atomic number Density g/cm3 Classification

Cr Chromium 24 7.14g/cm3 heavy metal

Ni Nickel 28 8.908g/cm3 heavy metal

Cu Copper 29 8.92g/cm3 heavy metal

Zn Zinc 30 7.14g/cm3 heavy metal

Cd Cadmium 48 8.65g/cm3 heavy metal

Sn Tin 50 7.31g/cm3 heavy metal

Hg Mercury 80 13.534g/cm3 heavy metal

Pb Lead 82 11.34g/cm3 heavy metal

Heavy metals such as mercury, lead, cadmium, chromium, zinc, copper, and nickel can be extremely harmful to human health and to the ecosystem (Zhu, Bing, Yi, Wu, Sun, 2018). mercury as well as lead can cause damage to vital organs of both animals and humans, and to the environment itself (Jan et al, 2015). Just like mercury, lead is extremely hazardous to children and pregnant women and can affect multiple body systems. It is distributed through the liver, the brain, the kidneys, and the bones and during pregnancy it can be transported in the blood, where the fetus is exposed to it. It also bioaccumulates over time to some extent, and lead poisoning is a serious concern through possible pollutants of mining, manufacturing, smelting and heavy industry (Jan et al, 2015). Mercury (Hg) and

lead (Pb) are two of the most concerning trace metals found in studies worldwide (Jan et al, 2015).

PAHs: Polycyclic aromatic hydrocarbons are another form of anthropogenic contaminants. They are caused by incomplete combustion, which might be evident from cars, industry, and harbour activity (Zhu et al, 2018).

PCBs: Polychlorinated biphenyls (PCBs) have been proven to affect liver functions (Carpenter, 2006). They increase the rate of melanomas and various forms of cancer such as liver, breast, brain, kidney, and gastrointestinal cancer, as well as respiratory problems, dermal lesions and chloracne (Carpenter, 2006). Reproductive functioning is disturbed, and long exposure has serious effects on children. The origins for PCB are anthropogenic, although their transport pathways might be natural. This is why PCBs are listed as a chemical of emerging Arctic concern (AMAP, 2018) and are banned from use.

TBT: Tributyltin (TBT) is an organotin compound that is extremely hazardous to ecosystems and the environment. It can bioaccumulate in fish, mammals and causes severe and abnormal growth effects on sea-creatures, in particular mollusks, mussels, and oysters. It can lead to brittle shells, stunted growth, impaired nervous systems, and even death. TBT was used as anti-fouling paint on ship hulls worldwide, until it was formally banned in 2008 (Gipperth, 2009). Although banned, there is evidence of TBT in marine sediments from old ships that are still in use (Filipkowska, Kowalewska, Pavoni, 2014).

DDT: Dichloro-diphenyl-trichloroethane (DDT) is a synthetic insecticide that was first produced in the 1940s and was used to combat insects that would transfer diseases such as malaria and typhus. It is a carcinogen that bioaccumulates and is persistent in the environment. It can travel long distances in the air and it has negative implications on the reproductive system, the nervous system and can cause birth defects (NPIC, 1999).

Salomons, Bayne, Duursma, and Förstner (1988), and Syvitski, Burrell and Skei (1986) provide the first exhaustive reviews of human induced contaminant accumulation in marine and fjord sediments, respectively. In a first attempt, this thesis will try to find out if there is evidence of contamination in the Godthåbsfjord sediments, and if so to identify possible sources and reasons for their occurrence. This might provide policy makers and

local decision makers with scientific references to contamination distribution in the Godthåbsfjord.

3.1.6 Human induced environmental change: Contaminant sources

Anthropogenic activities in and around the Godthåbsfjord and the Sikuki harbour of Nuuk have a potential of introducing contaminants directly into the fjord, originating from combustion from cars and ongoing construction activity (since 2015). As the harbour was constructed through rock blasting, there is a possibility of PAHs being released into the fjord environment nearby. Another potential source of PAHs or diffused PAHs might be from the waste incinerator, the shipyard, or the metal yard that are all found in the western region of Nuuk. For verification, one of the sediment cores for contaminant analysis was taken in the marine sediments near the Sikuki harbour.

A chemical analysis of marine sediments from Sisimiut harbour in South West Greenland (Figure 7) showed evidence of high levels of trace metals and organic pollutants (Otteson &Villumsen, 2006). Concentrations of copper were at 200mg/kg, and cadmium was found up to 4.0 mg/kg. This is four times higher than the limiting concentration of toxicity for these chemicals (Otteson & Villumsen, 2006). PAHs were found directly adjacent to the shipping yard, and similar findings could also be evident near the shipping yard in Nuuk.

Figure 7: Map of coastal settlements in West Greenland, including Nuuk harbour, and Sisimiut harbour to the north. The encircled “A” represent airports, while encircled “H” display Heliports. Also included in this map is the settlement of Kapisillit, showing its proximity to the Greenland ice sheet. Source from https://www.greenlandbytopas.com/map-central-greenland/

In addition to the direct sources, a variety of contaminants are volatile compounds that are carried to the Arctic via long range transport in the air. Studies have found air-transported pollutants in marine and fjord sediments of Svalbard (Mohan et al, 2018). Melting glaciers like the Greenland ice sheet may redistribute compounds that are potentially trapped in the ice sheet and carry them into the glacial rivers (Padma, 2015). In this way, glacial contaminants could possibly enter the Godthåbsfjord system and the runoff through the six outlet glaciers might increase the probability that the increasing amount of meltwater carries contaminants into the different fjord branches (Mortensen et al, 2011).

According to Boutron and Görlach (1990), who were studying the Greenland ice sheet and Greenlandic case-specific projects, there is evidence of mercury and lead in glacier runoff. Cadmium (Cd), Hg and Pb are among the heavy metals that are transported via water currents (Gibbs, 1973). With the notably strong circulations and current systems in Godthåbsfjord (Mortensen, Bendtsen, Lennert, Rysgaard, 2014), this might influence the transportation of these chemical compounds and their spreading throughout the fjord.

Boutron, Candelone, and Hong (1999) found an increase in mercury, cadmium, zinc, and copper concentrations in Greenland ice from an ice core covering the past 220 years, which includes the industrial revolution. Lead was found to have increased the most out of these heavy metals, mainly due to the introduction of lead alkyl additives in gasoline (Boutron et al,1999).

McConnell and Edwards (2008) document the occurrence of contaminants within the Greenland ice sheet, suggesting that these contaminants were transported through the air, originating from emissions of industrial countries outside Greenland. As a possible consequence, the release of glacial contaminants into the Godthåbsfjord might occur when melting of the cryosphere discharges the glacially stored, air-transported contaminants into the meltwater that drains into glacier-fed river basins and flows into the downstream environments, ultimately settling in the fjord. Trace elements in glacier-fed rivers generally show clear diurnal variations with peaks related to periods of intense glacier melting of snow and ice (Kang et al, 2019), indicating substantial export of contaminants by melting glaciers.

While evidence of glacial contaminants and their transport pathways has been documented in ice covered regions of the Himalaya-Hindukush-Tibetian Plateau, the so called “Third Pole” (Yao et al, 2020) and places in the Arctic such as Svalbard (Bogdal et al, 2010), only a limited amount of data exists on the Greenland ice sheet and its possible pathways for contaminants into the connecting fjords. The thesis at hand will try to add on that information.

3.2 Literature review

3.2.1 Fjord sediment literature

A study by Ren et al (2009) confirms the relevance of studying marine sediments from West Greenland fjords, and using them as a climatic signal for environmental impacts. Ren et al (2009) used the Holocene Thermal Maximum as the climatic indicator and paleoenvironmental models on the sediment cores that were taken from the Ameralik fjord

(fig. 4). During the time period of 7800 to 7100 cal yrs B.P, there was a correlation in climate variations found in the Ameralik fjord and the North Atlantic region. Diatom assembleges were used as proxies to determine the shift in environmental impacts on the sediments. During this time period The Western Greenland Current was relativiely warm, which lead to an increase in meltwater production in the area. This in turn, enhanced the production of fine sediment deposition at the time (Ren et al, 2009). There was a documented shift in diatom composition from the Ameralik fjord that corresponded to a shift in surface water conditions, as seen by the warming of the Atlantic waters at approximately 7800-7600 cal. Yr BP.

A similar study was done by Seidenkrantz et al (2013) who took sediment cores from Disco bugt, Kangersuneq fjord, North Labrador Sea and Ameralik fjord where paleoecological and paleooceanographical models were made to determine the influence of melt water discharge, and Coastal Waters on the sedimentology of the case areas. Out of all cores the highest sedimentation rates were from the Ameralik fjord, which indicated a decrease in meltwater discharge over a time scale of 60 years, from c. 7760-7700 cal. Yr BP (Seidenkrantz et al, 2013). It was found that terrestrial derived minerals in the Ameralik fjord were supported by the grain sizes found within the sediment core, and that the main source of terrestrial sediments were from meltwater plumes. Seidenkrantz et al (2013) documented that by ca. 7700–7500 cal. yr BP, the produciton of meltwater plumes started to decrease and the Greenland ice sheet was retreating from the fjord area. This increased the deposition of coarse grains to enter the Ameralik fjord.

These studies are important supporting literature, because they use sedimentology and climate models to relate paleoclimatic records to changes in sedimentology in Western Greenlandic fjords. The Ameralik fjord is connected to the Godthåbsfjord system (fig. 1), and so similar patterns in the sedimentology could be expected.

In addition to these scientific studies on the sediment signals that are based in the Godthåbsfjord system, and their interaction with climate change, there are also other subarctic fjords with studies available that provide a sedimentary framework for this study. Paetzel and Schrader (1995) investigated the sewage history of fjord sediments in the Nordåsvannet close to Bergen, Western Norway. Paetzel and Schrader (1995) demonstrate the importance of analysing the organic matter fraction in sediments to assess the impacts

of human-induced environmental changes and climate signals on the fjord processes. In addition to smear slide investigations, they analysed the organic matter fraction instrumentally using the loss of ignition (LOI) method, C/N-ratios, and δ13C isotopic ratios. The instrumental organic matter analyses confirmed the results from the smear slide analysis, indicating that the smear slide analysis is a valid method for examining the organic matter fraction in fjord sediments.

In addition, smear slide analysis has proven to be a valid method for the determination of mineral grain sizes in hemipelagic and marine sediments (Rothwell, 1989). The validity of this method has been proven in sediments from various Norwegian fjord settings, including for example the Barsnesfjord (Paetzel & Schrader, 1992), the Nordåsvatnet (Paetzel & Schrader 1995), the Bergen harbour (Paetzel, Nes, Leifsen, Schrader, 2003), the Store Lungegårdsvatnet (Paetzel & Schrader, 2003), and the Sogndalsfjord area (Paetzel & Dale, 2010).

Thus, the study at hand will use the smear slide analysis for grain size determination and organic matter analysis including the identification of the terrestrial and marine organic matter fractions in the Godthåbsfjord sediments.

3.2.2 Hydrographic literature

There is a complex hydrographic system within Godthåbsfjord to consider, as described by Mortensen et al, (2011; 2014; Mortensen et al, 2020). This involves saline water masses reaching the deeper fjord basins from the open ocean, and their mixing with surficial freshwater outflow. Together with the tidal current, the estuarine circulation includes coastal surface and subsurface (and partly brackish) water masses, the intermediate baroclinic current and the saline and thus denser bottom water masses (Mortensen et al, 2014).

3.2.3 Contaminant literature

Their overview of the hydrography combined with the hydrographically linked pesticide investigation by Carlsson et al (2012) contribute to the understanding of the fjord system in terms of how the circulation pattern and freshwater inflow affects contaminants in the fjord. Research was conducted on the water column to find evidence of chlorinated

pesticides in Nup Kangerdlua. This report explains the importance of long-range transport of contaminants onto glaciers and the release of these contaminants into the fjord, and thus revealing an environmental signal to climate change. These contamination results were more predominant closer to the glaciers than in the local contaminant input from Nuuk, suggesting that the contaminants mainly originate from the glacier. This variance is critical to note, as it is part of the objectives of this project to investigate the primary sources of the contaminants. Rather than the water column, the sediments are the point of interest in the thesis at hand, indicating whether the contaminants registered in the water column also will settle in polluting concentrations in the Godthåbsfjord sediments.

In Maarmorilik, central West Greenland, a contaminant study was done by Perner et al (2010) that took sediment samples from Affarlikassaa and Qaumarujuk fjords. The aim of the study was to determine the evidence of heavy metals in the sediments adjacent to the lead and zinc mine, “Black Angel” (Perner et al, 2010). Although the mine has been closed for over 20 years, there was evidence of enriched heavy metals material in the samples, with maximum contents found at 12cm depth of the core sample from Affarlikassaa. Geochemical analysis and radioactive dating were performed on the sediments. The results found that surface layer of sediments (0-4cm) from the Affarlikassaa fjord show high- elevated levels of Cd, Fe, Hg, Pb, S, and Zn.

Paetzel et al (2003) conducted a study on surface and subsurface sediments in Bergen harbour, to investigate if there are correlations between the sediment pollution and human activity from the harbour, as well as erosion of the surrounding mountains and bedrock (Paetzel et al, 2003). This paper provides relevant scientific references for the study at hand. Both studies show similar research questions that include if there are polluting trace and heavy metals in the surface sediments, and to what extent. The sediment pollution of Ag, Cu, Hg, Pb, Sn, and Zn was directly related to the input of sewage into the inner part of the harbour. An interesting thing to note is that no correlation was found between the spatial distribution of these pollutants and the minerogenic grain size distribution. This will be taken under consideration when performing grain size analysis of the sediment samples in the Godthåbsfjord, to find out if there is any correlation between contaminants in the fjord, and the distribution of grain size, and the organic matter content.

3.2.4 Climate change literature

Paetzel and Dale (2010) investigated climate change proxies in sediments of the Sognefjord region of Western Norway, which has environmental conditions similar to the Godthåbsfjord, although being a subarctic fjord system. With similar objectives as the thesis at hand, sediment cores taken from the Sognefjord region underwent smear slide analysis to investigate the mineral grain sizes, the marine organic matter fraction, the terrestrial organic matter fraction, and the diatom composition. Sedimentation rates were established, and sediment parameter variations were correlated with meteorological data from the area. The methods they use for analysing the sediments and investigating inorganic climate proxies over the last 60 years are adopted for this study in the Godthåbsfjord.

3.3 Scientific Contribution

This study will contribute to the scientific knowledge on sediments of the Godthåbsfjord area relating to environmental changes, including effects of climate change and contaminant distribution. The study will link possible signals of climate change in Greenland with the results found in the Godthåbsfjord sediments. Besides the studies by Ren et al (2009) and Seidenkrantz et al (2013) on the Ameralik fjord, there has not been any studies investigating the sedimentology by means of recent environmental change and climate signals in the Godthåbsjford so this investigation will support existing knowledge on environmental impacts from the Greenland ice sheet and subarctic sill fjords. As Carlsson et al (2012) discovered there are contaminants found in the water column in Godthåbsfjord through long-range air transportation and glacial melting. Therefore, the further investigation of contamination in marine sediments in the same fjord will help to understand the fate of these contaminants.

3.4 Practical Value

Contamination investigations are vital for society due to the danger of contaminants and the damage they can cause to ecosystems and human health (AMAP 2016; 2018). Understanding the evidence of contaminants in Godthåbsfjord is important for the

inhabitants of Nuuk and Kapisillit, who are very dependent on fishing and hunting in the fjord (Lennett, 2017). If contaminants are found at polluting levels, environmental policy in the area should be revised, and locals need to be informed. The results of this study are vital for environmental indications of climate change and possible effects on the local inhabitants.

Knowing the composition variation of the sediments will also provide a framework for other sedimentary and geological research in the fjord, while also providing baseline information into sedimentary processes linked to environmental change. As the environment is always changing, scientists will continue to monitor the area in the future and this study will therefore provide practical value into future research.

In addition, understanding the source areas of contaminants into the fjord is important for policy makers, and knowing their possible fate and pathways will also contribute to scientific knowledge.

4 Methods

4.1 Sediment sampling in the field

Sediment sampling was done on board of the research vessel RV Sanna during a mapping survey of the Godthåbsfjord, lasting from the 4th to 9th September 2020. The cruise was organised by the Greenland Climate Research Centre, which is a department of the Greenland Institute of Natural Resources. A modified Van Veen box grab (Van Veen, 1933) with dimensions 20cm*20cm*20cm (Figure 8) was used to take the sediment samples.

The box grab was secured to a wire, hanging at a crane that lowered the box grab down to the seafloor at a speed of approximately one meter per second, using a speed adjustable winch. Once it reached the seafloor, the box grab was pressed into the sediment by its own weight and two sideways flaps closed the bottom of the open box grab, capturing the sediment. After that, the box grab began its ascent to the surface. Safely back on board of the vessel, the box grab was carefully opened so that the sediment surface and structure was not disturbed. Subsamples were taken from the open sediment for particulate matter and contaminant analysis using sterilized spatulas.

Figure 8: The Van Veen box grab ready to be deployed. Note the lead weight on each brace above the upper corners.

The sampling locations were spatially distributed in a grid starting from the western outlet of the Godthåbsfjord at Nuuk, where the cruise commenced, and continuing towards the northeast of the fjord near the glacier terminating outlets into the Kangersuneq fjord branch (Figure 1 and Figure 8). Three box grabs were taken at each location to get a statistically average sample taken from the area, and to assure the quality of the box grab, as there sometimes were large rocks or rock fragments in the box grab, or the box grab opened on ascent.

4.1.1 Contaminant subsamples

Subsamples for contaminant analysis were taken from the box grab sediment at each location at 0-2cm and 2-4cm sediment depth, using sterilised utensils. Contaminant subsample weight ranged from 1 to 2kg wet weight, ensuring enough sediment material for the required 200g sample dry weight for contaminant analysis at Eurofins Finland. The contaminant subsamples were scooped into plastic zip lock bags using a Teflon™ spoon and labelled with location number and subsample depth in the laboratory on board the research vessel. All contaminant subsample bags were put into a freezer immediately after subsampling. From these, another set of 200g subsamples per location was made after the cruise and sent to Eurofins Finland for contaminant analysis at their accredited dry laboratories.

4.1.2 Sediment cores and sediment fragments

Sediment cores were taken from the box grabs using 7cm diameter PVC (polyvinyl chloride) pipes of 20cm length. For core sampling, the PVC pipes were carefully pushed vertically into the sediment of the still unopened box grab in a slow, clockwise downward movement. Each sediment core was sealed using Oasis® floral foam at the bottom and top of the core and covered over with duct tape. The sediment cores were labelled with location number and a core ID and stored in a cool storage room on board the research vessel until analysis at the laboratory after the cruise.

At locations of water rich sediments, it was not possible to take sediment cores. Instead, 2cm thick sediment slices, here called sediment fragments were taken continuously from

top to bottom of the open box grab sediment, using a sterilized Teflon™ spoon and putting the sediment fragment into zip lock plastic bags. Each sediment fragment sample was labelled with location number and fragment depth and stored in a cool storage room along with the sediment cores. These samples went to the laboratories at the Marine and Freshwater Institute in Iceland for particulate matter analysis.

Each box grab was recorded using the data log from the survey and labelled according to the data log numbering. The data log included the time of sampling of each box grab in UTC (Coordinated Universal Time), their geographical location, the name of every sediment subsample including contaminant subsamples, sediment cores, and sediment fragments.

4.2 Dating and sedimentation rates

No dating was possible of the sediment cores of this study, as there is no published sedimentation or accummulation rates from the Godthābsfjord. Thus, existing dating information from neighbouring or similar glacier connected fjord settings was used and transferred to the Godthåbsfjord settings. Further detail on the applied dating method for this study is given in chapter 5.

4.3 Smear slides

Smear slide analysis is an effective way of analysing unconsolidated sediment samples using translucent light microscopy. The method allows to identify and determine concentrations of in situ sediment particles including mineral grain sizes and the different organic matter fractions, consisting of marine and terrestrial organic matter (Rothwell, 1989). In addition to looking at the complete sediment fractions as they occur in the sediment, smear slide analysis is cheap, fast, non-destructive, and can be applied in high resolution on a millimetre scale downcore hemipelagic sediments. Further, the microscope slides can be analysed repeatedly. The percent concentration of the single sediment parameters offers a first-hand valid and reliable overview over the sediment parameter composition. Although limited to concentrations, the smear slide technique is widely used for gaining an understanding of the respective sediment formation and providing the basis

for in-depth and more sophisticated instrumental and geochemical analyses (Rothwell, 1989). The entire smear slide preparation and smear slide analysis was carried out at the Marine and Freshwater Institute in Reykjavik, Iceland.

4.3.1 Smear slide preparation

Prior to making smear slides, the sediment cores needed to be opened. Figure 9 displays the equipment that was used to carry out the opening of the sediment cores. The PVC pipes were opened at two 180° opposite sides using a Festool Battery Versatile OSC 18 574848 electric cutter that was cutting firmly along the pipe sides. A tightened standard nylon fishing line (Figure 9b) was then drawn from bottom to top through the Oasis® floral foam and the sediment using the open side cuts as direction, dividing the sediment cores into two halves. The sediment surface of each core half was thereafter smoothened by drawing a standard cake spatula (Figure 9a) carefully across the sediment from one cut side to the other. Finally, the sediment core depth was labelled in centimetre steps below the cut sides using a permanent marker pen (Figure 9c).

Figure 9: Equipment used to open the sediment cores. Description of equipment (a) to (c) below the respective image.

Microscope smear slides were made continuously downcore at 1cm increments of the sediment core and from the 2cm increments of the sediment fragments. The resulting graphs were adjusted correspondingly. Figure 10 displays the equipment and material used for the smear slide preparation.

Figure 10: Equipment and material used to make microscope smear slides. Description of equipment (a) to (i) below the respective image.

To prepare the smear slides, a spatula with a 1cm wide tip (Figure 10a) was used to take 1cm3 sediment blocks from each centimetre continuously downcore of each sediment core. These sediment blocks were homogenised with a toothpick (Figure 10d). From each homogenised sediment sample, a subsample the size of a needle head was taken with a new, fresh toothpick. The sediment subsample was transferred to a microscope cover glass (Figure 10b) where the same toothpick was used to disintegrate the subsample in a drop of distilled water (Figure 10f) added by a pipette (Figure 10e). After disintegration, a drop of

Compard WAC Wetting Agent (Figure 10h) was added by another pipette to the disintegrated subsample for breaking down the surface tension of the water. Then, the long side of the toothpick was used to smear the sediment subsample evenly across the cover glass, leaving half a centimetre space at each short side of the cover glass, thus avoiding contact with the fingers holding the cover glass at these short sides. Following this, the cover glass with the smeared-out sample was transferred to a heat plate to dry at room temperature. While drying, a standard white adhesive paper label (Figure 10c) with core number and subsample depth was fastened at the short side of a standard microscope slide (Figure 10b) and put on the heat plate opposite the respective cover glass. Once the sediment subsample on the cover glass was dry, a stripe of Naphrax® Diatom Mountant (Figure 10g) with a high refractive index of >1.72 was added along the middle of the cover glass. Note that Naphrax® uses Toluene (Figure 10i) as solvent which is highly hazardous to human health. Thus, operating with Naphrax® must occur always in a ventilated foam cupboard. Upon adding Naphrax®, the microscope slide was placed firmly on the cover glass, turned, and the heat plate was warmed up to 100°C and heated until the Toluene had evaporated, normally after heating the slide twice for three minutes. After cooling, the smear slide was stored in a microscope slide box (Figure 10h), ready for analysis.

4.3.2 Smear slide analysis

Smear slide analysis after Rothwell (1989) included the determination of sediment particulate material, consisting of the percent mineral grain size distribution and the assessment of the organic matter fraction in terms of percent terrestrial organic matter and percent marine organic matter, using a Leica DMLB type 020-519.503 LB 30T. translucent light microscope at lenses of 10x and 40x magnification. The size determination of the single mineral grains in the smear slide was done using a 1mm micro scale.

The first step in smear slides analysis was to gain an overview of the material in the respective smear slide at low (10x) magnification. Based on this overview, three representative areas were defined in the slide and analysed separately for the mentioned sediment parameters at higher (40x) magnification. After analysis, the average of the single parameters within the three areas of that slide was used as the percentage distribution of these parameters.

Mineral grain size

The mineral grain size classification was done according to the Udden-Wentworth scale (Udden, 1914; Wentworth, 1922), including sand, the various (coarse, medium, fine, very fine) silt sizes, and the clay fraction as summarised in Table 2. Grain size analysis in smear slides is valid for hemipelagic sediments that seldom reveal mineral grains larger than the very fine sand fraction (63-125µm).

Table 2: Mineral grain sizes analysed in the smear slides of the Godthåbsfjord, according to the classification used in the Udden-Wentworth scale (Udden, 1914 and Wentworth, 1922).

Minerals grain size Scale in µm

Sand 63-2000

Coarse silt 31-63

Medium silt 16-31

Fine silt 8-16

Very fine silt 4-8

Clay <4

The method of Rothwell (1989) was used to estimate the mineral grain sizes on a percentage ratio towards each other. The total area covered by the mineral material within the largest grain size class got the fixed size number of “1”. All areas of the successively smaller mineral grain sizes were then each put in relation to this fixed largest grain size number, thus defining an area ratio number that was larger, as large as, or smaller than “1”. These ratios were then calculated into a percentage distribution. Figure 11 shows an example within the mineral grain size sand and silt in the smear slide of Location 6 sediment core FF, taken at 6-7cm sediment depth. The ratio determination can be illustrated in the example of Figure 11 that shows one single sand mineral grain in the middle of the smear slide area. This area got the fixed size number “1”. The area covered by the coarse silt fraction is three times as big as the fixed sand size number, thus getting an area ration number of “3”. In other words, the mineral grains of sand and coarse silt occur at a ratio of 1:3 in this slide. This process continues for the medium silt, fine silt,

very fine silt and clay fraction, resulting in a set of area ratios for this particular smear slide region. There is very little clay found in the given area of Figure 11.

Figure 11: Example of mineral grains of mainly sand and silt size in sediment core FF of Location 6 at 40x magnification. Red arrows point to examples of fine silt, coarse silt, and a small sand size. The scale on the bottom right is to 0.1millimeters (100 micrometers) numbered steps, corresponding to a total of 10*100 micrometers = 1mm across the entire scale.

Organic matter fraction

The ratios of the organic matter fractions were determined in the same way as the mineral grain size fractions. There were two ratios investigated: the organic matter versus mineral matter ratio, and the terrestrial organic matter versus marine organic matter ratio. Figure 12 illustrates an example from Location 4 of how the organic matter versus mineral matter ratio was determined. In the image on the left, the mineral matter fraction consists of two sand grains as well as smaller grains, in total set to a fixed size number of “1”. In comparison, the diffusive marine organic matter fraction contributes to a slightly smaller area than the total mineral matter fraction, resulting in an area ratio of “0.8”. The area distribution of organic versus mineral matter is thus 0.8:1. The right image shows

considerably less mineral matter, resulting in a ratio of 1:1.5 for the mineral versus organic matter fraction.

Figure 12: Examples of the mineral versus organic matter fraction in sediment core DD of Location 4 at 40x magnification. Red arrows point to examples of (marine) organic matter and mineral (sand) grains. The scale on the bottom right is to 0.1millimeters (100 micrometers) numbered steps, corresponding to a total of 10*100 micrometers = 1mm across the entire scale.

The same method was also used for comparing the marine organic matter versus terrestrial organic matter fraction. Distinguishing between the organic matter fractions followed the method described by Paetzel and Schrader (1992) in hemipelagic Barsnesfjord sediments. Terrestrial organic matter (from secondary production) describes all dark to black organic (or non-mineral) particles with distinctive shapes or fibre structures. Marine organic matter (from primary production) occurs in light brownish coloured diffusive aggregations of organic threads. The left image of Figure 13 shows a minor amount of dark terrestrial organic matter spots compared to a major amount of light brownish marine organic matter aggregates, occurring at a ratio of 0,5:1 in a sediment fragment of Location 4. The ratio terrestrial organic matter versus marine organic matter ratio is 0.3:1 in the right image of the same location. Note that the mineral fraction in both images varies greatly but does not play a role when the organic matter fractions are compared to each other.

Figure 13: Examples of the mineral versus organic matter fraction in a sediment fragment of Location 5 at 40x magnification. Red arrows point to examples of light marine organic matter and dark terrestrial organic matter. The scale on the bottom right is to 0.1millimeters (100 micrometers) numbered steps, corresponding to a total of 10*100 micrometers = 1mm across the entire scale.

All particle ratios described in the smear slides have in common that they are determined on a 100% scale, resulting in a percentage distribution of the single sediment components. After calculation of the percentage distribution of the single fractions, xy-graphs were made in Excel to visualise the different ratios.

Correlations were made using the Pearson correlation coefficient, indicating a negative correlation that was equal to -1, no correlation that was equal to 0, and a positive correlation that was equal to 1. All heavy metal trends correlate positively with the fine and/or medium mineral grain size trends and the trends of the terrestrial organic matter concentrations over the last decades. The correlation patterns were in the value of 1 that indicates a positive correlation, or a -1 that indicates a negative correlation. There were no correlations that resulted in 0, which would imply a lack of correlation.

4.4 Contaminant analysis

The methodology of contaminant analysis follows the Eurofins Finland protocol supplemented by information through personal communication. Dry matter samples of 100g were taken from the 200g subsampled sediment material of each location for contaminant analysis and examined independently. The dry matter content was determined by drying the sample to a constant mass of 105°C. The dry matter was then calculated from the difference in mass before and after the drying process.

Each sample was analysed in two separate laboratories, using the same methods. Gravimetry was used for all samples. Gravimetric analysis determines the mass of ions classified as a contaminant (Brescia, Meislich, Weiner, Arents, Turk, 1975). For heavy metals, the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) technique was used. This technique is often used to determine low range concentrations (µg/l) of various compounds. The sample is nebulised, and the resulting aerosol is transferred to the argon plasma. The elements then run through the plasma source and by means of high temperature they become ionized and atomised. The ions are then extracted, and a mass analyser can separate the ions through ion optics according to their mass. The method used in this analysis was based on the CEN/TS 16171 standard. Each sample was digested with nitric acid in a Hotblock (Eurofins report, 2021).

The Gas Chromatography/Mass Spectrometry (GC-MS) technique was used for PAHs of each sediment sample. The method was based on the ISO 18287 standard, and the SFS-EN 16181 standard. The PAH compounds were extracted from the sample, using acetone- hexane and then analysed with GC-MS. The GC-MS technique was also applied for the PCB analysis in the sediment samples. The standard method was based on the SFS ISO 10382 standard, and the ISO 13876 standard. PCB compounds were extracted using acetone-hexane, with the hexane layer purified with concentrated sulphuric acid and then analysed using GC-MS.

For the organic tin contaminant analyses, the GC-MS/MS technique was used for biocide analysis (TBT, TPT) applied on sediments. The method was based on the ISO 23161 standard. GC-MS/MS is a Gas Chromatography - Tandem Mass Spectrometry. The extra component in this technique is the second MS analysis. After the first analytical column, the analytes enter the tandem MS which has two scanning analysers, which are separated using a collision cell. The tandem MS provides detection of molecular ions, but the samples must be volatile to be used in this way (Eurofins Finland, 2020). The components are identified on a molecular level, thus indicating the presence of various organic contaminants and their volume in the sample. Through the first phase, the compounds are separated through heat using the GC. They are carried through a column and mixed with an inert gas before they continue into the MS for the second phase. Here, the MS identifies the compounds by finding the mass of the analyte molecule. This is a proven methodology that is commonly used for environmental analysis (Medeiros, 2018).

For pesticides, a similar method was used to that of organic tin with a standard ISO 10382. The sample was extracted with acetone-hexane, and analysed using GC-MS/MS.

5 Results

5.1 Sediment sampling in the field

Sediments are analysed from seven sampling locations in the Godthåbsfjord. Out of a total number of 13 locations, these seven locations were chosen strategically, representing at least one sample for each of the Godthåbsfjord branches (as named in Figure 1) at their deepest accessible location. Figure 14 illustrates the geographic distribution of the sampling locations:

• Contamination subsamples taken at all seven locations (numbered boxes). • Sediment cores taken at (white numbered boxes; total length in brackets) o Location 1 (3cm) – Outside Nuuk harbour o Location 4 (10cm) – Southern outlet Kangersuneq fjord branch o Location 6 (12cm) – Middle Qôrnup Suvdlua fjord branch o Location 10 (10cm)– Outside Kapisillit o Location 12 (9cm) – Southern outlet Umánap Suvdlua fjord branch • Sediment fragments taken at (purple numbered boxes; total length in brackets) o Location 5 (18cm) – Middle Nûp Kangerdlua fjord branch o Location 8 (12cm) – Middle Kapisillit Kangerdlua fjord branch

Figure 14: Bathymetry map taken from the 2020 survey including locations (boxes) of samples used for contaminant analysis and particulate matter analysis of the sediment. Contaminant subsamples were taken at all numbered locations. White boxes indicate location numbers that include sediment cores. The purple boxes indicate location numbers where sediment fragments were taken in continuous 2cm slices from top to bottom of the open box grab sediments.

Table 3 summarises the location coordinates from the sea chart (in latitude and longitude), water depth (in meter), and type of sediment sample taken (sediment core, sediment fragments, contaminant subsamples). Refer to the cruise report in Appendix A for a full overview of the sampling and sampling conditions.

Table 3: Sediment samples analysed from the Godthåbsfjord including location numbers, position in latitude (in degrees north) and longitude (in degrees west), water depth of the box grab sample (in meter), sediment core ID (double letter) and length (in cm), sediment fragment sequence (in cm), and the depth of the contaminant subsamples (in cm).

5.2 Dating and sedimentation rates

As it was not possible to date the sediments of this study, sedimention rate information was interpolated and transferred from neighbouring fjords such as Ameralik Fjord (Figure 15), which is the closest fjord to the Godthåbsfjord. According to Møller at al, (2006) the accumulation rate of sediments in Ameralik is 0.024 to 0.197cm/year. Andrews, Milliman, Jennings, Rynes, and Dwyer (1994) showed similar sedimentation rates in eastern Greenland fjords of 0.11 to 0.34cm/year over the last 1000 years in the Nansen Fjord and 0.01mm/year in the Kangerdlugssuaq Fjord (Figure 15).

A third sedimentation rate study was conducted in the western coast of Greenland, when Perner et al (2010) investigated contamination of heavy metals in sediments of the Qaumarujuk Fjord (Figure 15). According to their analysis the average sedimentation rate for Qaumarujuk Fjord is 0.62cm/year, with an accumulation rate of 3170g/m2/year.

Figure 15: Location of Greenland fjords where sedimentation rates were estimated. West Greenland: Qaumarujuk Fjord, Ameralik Fjord. East Greenland: Nansen Fjord, Kangerdlugssuaq Fjord. Godthåbsfjord as reference location. Outline map from Mortensen et al, 2015.

As the Ameralik Fjord and the Qaumarujuk Fjord of western Greenland are within the proximity of the Greenland ice sheet and have similar geographical setting as the Godthåbsfjord (Figure 15), those sedimentation rates were used as reference to set a rough estimate of sedimentation rates for the Godthåbsfjord sediments of this study.

The transferred data suggest minimum sedimentation rates of 0.024cm/year and maximum sedimentation rates of 0.62cm/year in Godthåbsfjord sediments, most probably decreasing with increasing distance to the Greenland ice sheet. Thus, 1cm of Godthåbsfjord sediment would correspond to a minimum of 1.61 years of sediment accumulation close to the Greenland ice sheet and 1cm of Godthåbsfjord sediment would correspond to a maximum of 41.7 years of sediment accumulation with increasing distance to the Greenland ice sheet.

Table 4 indicates the resulting arbitrary ages for the Godthåbsfjord sediment cores and fragments at the different sedimentation regimes, representing (a) the sediments taken at the fjord outlet distant to the glaciers (Location 1 in blue colour) at the lowest sedimentation rates of 0.024cm/year, (b) those sediments taken about midway between the coast and the glaciers (Locations 5, 6, 8, 10, and 12 in green colour) at intermediate sedimentation rates of 0.32cm/year, and (c) the sediments taken close to the glaciers (Location 4 in red colour) at highest sedimentation rates of 0,62cm/year. The arbitrary total core age would then range from 16 to 500 years. The arbitrary age of the contaminant samples would range from 3 to 83 years at the 0-2cm sediment surface samples, and from 6 to 125 years at the 2-4cm sediment subsurface samples.

Table 4: Arbitrary dating of the Godthåbsfjord sediments using sedimentation rates (a) Distant to the glaciers (Sediment cores 1 and 12): 0.024cm/year. (b) At intermediate distance to the glaciers (Sediment cores 5, 6, 8, and 10): 0,32cm/year. (c) Close to the glaciers (Sediment core 4): 0.62cm/year. Arbitrary ages are given for the total core length and corresponding to the contaminant sample sequences at 2 and 4 cm sediment depth of each sediment core.

Location Core/Fragments Core Age Age Age length number total core at 2cm at 4cm

Distant to glaciers 1 3cm 125 years 83 years 125 years

Midway to glaciers 5 18cm 56 years 6 years 12 years

Midway to glaciers 6 12cm 37 years 6 years 12 years

Midway to glaciers 8 12cm 37 years 6 years 12 years

Midway to glaciers 10 10cm 31 years 6 years 12 years

Midway to glaciers 12 12cm 37 years 6 years 12 years

Close to glaciers 4 10cm 16 years 3 years 6 years

A future determination of sedimentation rates would greatly improve the scientific knowledge of the Godthåbsfjord sediment regime and is a considerable factor when evaluating fjord processes. A study is underway at the Geological Survey of Denmark and Greenland (GEUS) with relevant sediment rate determination from dated sediment records in the Godthåbsfjord (Ribeiro, personal communication; two manuscripts in progress).

5.3 Smear slides

A total of 59 smear slides were made from the sediment samples of the Godthåbsfjord.

5.3.1 Mineral grain size

Appendix B summarises all raw data for the single mineral grain sizes, including single grain size graphs. Figure 16 to 22 present the mineral grain sizes according to their general appearance within grain size classes:

• Clay and very fine silt are combined into the mineral grain size class of Fine grain sizes. • Fine silt and medium silt are combined into the mineral grain size class of Medium grain sizes. • Coarse silt and sand are combined into the mineral grain size class of Coarse grain sizes.

These grain size classes were chosen as it was often not possible to determine the exact visual transition between clay and very fine silt, and between coarse silt and sand.

The stippled lines in each graph of Figure 16 to 22 indicate the statistical linear regression, suggesting either increasing or decreasing trends of the mineral grain sizes from the core bottom to the core top. The mathematic formula of the regression lines is shown below the graphs, with a red colour of the formula and graph indicating statistically increasing concentrations within the respective mineral grain size class, and with a blue colour of the formula and graph indicating statistically decreasing concentrations within the respective mineral grain size class.

In addition to the mineral grain size classes, Figures 16 to 22 show the lithology of the opened sediment cores. Note that no core images are available for the sediment fractions of Location 5 and Location 8, as only sediment fragments and not entire sediment cores were taken at these locations. Note also that the three grain size classes add up to 100%, thus not allowing a conclusion on the absolute distribution numbers of the individual grain size classes.

Figure 16 shows the sediment grain size classes in the sediment core of Location 1 (Outside Nuuk harbour) indicating an increasing trend of the fine mineral grain size class towards the sediment surface. The medium grain size class indicates a decreasing trend towards the sediment surface, while the coarse grain size class seems to be quite stable. Note that the statistic trend is based on only three subsamples.

Figure 16: Sediment core of Location 1, presenting the lithology along with the graphs of the three Fine, Medium, and Coarse grain size classes. Sediment depth is in cm; mineral grain size classes are presented as percentage concentrations. Weak stippled lines are statistic trend lines from linear regression, with the regression formulas indicated below the respective graphs. Red colour of formulas and graphs indicate an increasing statistical trend from core bottom to core top of the respective mineral grain size class. Blue colour of formulas and graphs indicate a decreasing statistical trend from core bottom to core top of the respective mineral grain size class.

Figure 17 shows the sediment grain size classes in the sediment core of Location 4 (Southern outlet Kangersuneq fjord branch) indicating an increasing trend of the Fine mineral grain size class towards the sediment surface. The Medium and the Coarse grain size classes indicate a decreasing trend towards the sediment surface.

Figure 17: Sediment core of Location 4, presenting the lithology along with the graphs of the three Fine, Medium, and Coarse grain size classes. Sediment depth is in cm; mineral grain size classes are presented as percentage concentrations. Weak stippled lines are statistic trend lines from linear regression, with the regression formulas indicated below the respective graphs. Red colour of formulas and graphs indicate an increasing statistical trend from core bottom to core top of the respective mineral grain size class. Blue colour of formulas and graphs indicate a decreasing statistical trend from core bottom to core top of the respective mineral grain size class.

Figure 18 shows the sediment grain size classes in the sediment fragments of Location 5 (Middle Nûp Kangerdlua fjord branch) indicating an increasing trend of the Fine mineral grain size class towards the sediment surface. The Medium grain size class indicates a decreasing trend towards the sediment surface, while the Coarse grain size class seems to increase.

Figure 18: Sediment fragments of Location 5, presenting the graphs of the three Fine, Medium, and Coarse grain size classes. No lithology image due to fragment sampling. Sediment depth is in cm; mineral grain size classes are presented as percentage concentrations. Weak stippled lines are statistic trend lines from linear regression, with the regression formulas indicated below the respective graphs. Red colour of formulas and graphs indicate an increasing statistical trend from core bottom to core top of the respective mineral grain size class. Blue colour of formulas and graphs indicate a decreasing statistical trend from core bottom to core top of the respective mineral grain size class.

Figure 19 shows the sediment grain size classes in the sediment core of Location 6 (Middle Qôrnup Suvdlua fjord branch) indicating an increasing trend of the Fine mineral grain size class towards the sediment surface. The Medium and the Coarse grain size classes indicate a decreasing trend towards the sediment surface.

Figure 19: Sediment core of Location 6, presenting the lithology along with the graphs of the three Fine, Medium, and Coarse grain size classes. Sediment depth is in cm; mineral grain size classes are presented as percentage concentrations. Weak stippled lines are statistic trend lines from linear regression, with the regression formulas indicated below the respective graphs. Red colour of formulas and graphs indicate an increasing statistical trend from core bottom to core top of the respective mineral grain size class. Blue colour of formulas and graphs indicate a decreasing statistical trend from core bottom to core top of the respective mineral grain size class.

Figure 20 shows the sediment grain size classes in the sediment fragments of Location 8 (Middle Kapisillit Kangerdlua fjord branch) indicating an increasing trend of the Fine mineral grain size class towards the sediment surface. The Medium and the Coarse grain size classes indicate a decreasing trend towards the sediment surface.

Figure 20: Sediment fragments of Location 8, presenting the graphs of the three Fine, Medium, and Coarse grain size classes. No lithology image due to fragment sampling. Sediment depth is in cm; mineral grain size classes are presented as percentage concentrations. Weak stippled lines are statistic trend lines from linear regression, with the regression formulas indicated below the respective graphs. Red colour of formulas and graphs indicate an increasing statistical trend from core bottom to core top of the respective mineral grain size class. Blue colour of formulas and graphs indicate a decreasing statistical trend from core bottom to core top of the respective mineral grain size class.

Figure 21 shows the sediment grain size classes in the sediment core of Location 10 (Outside Kapisillit) indicating an increasing trend of the Fine mineral grain size class towards the sediment surface. The Medium and the Coarse grain size classes indicate a decreasing trend towards the sediment surface.

Figure 21: Sediment core of Location 10, presenting the lithology along with the graphs of the three Fine, Medium, and Coarse grain size classes. Sediment depth is in cm; mineral grain size classes are presented as percentage concentrations. Weak stippled lines are statistic trend lines from linear regression, with the regression formulas indicated below the respective graphs. Red colour of formulas and graphs indicate an increasing statistical trend from core bottom to core top of the respective mineral grain size class. Blue colour of formulas and graphs indicate a decreasing statistical trend from core bottom to core top of the respective mineral grain size class.

Figure 22 shows the sediment grain size classes in the sediment core of Location 12 (Southern outlet Umánap Suvdlua fjord branch) indicating a decreasing trend of the Fine mineral grain size class towards the sediment surface. The Medium grain size class indicates an increasing trend towards the sediment surface, while the Coarse grain size class indicates an almost stable trend.

Figure 22: Sediment core of Location 12, presenting the lithology along with the graphs of the three Fine, Medium, and Coarse grain size classes. Sediment depth is in cm; mineral grain size classes are presented as percentage concentrations. Weak stippled lines are statistic trend lines from linear regression, with the regression formulas indicated below the respective graphs. Red colour of formulas and graphs indicate an increasing statistical trend from core bottom to core top of the respective mineral grain size class. Blue colour of formulas and graphs indicate a decreasing statistical trend from core bottom to core top of the respective mineral grain size class.

Figure 23 shows a map of the combined trends towards the sediment surface of all sediment records in a geographical distribution of the locations of the Godthåbsfjord. When comparing the overall results of increasing and decreasing trends of the three mineral grain size classes, it becomes obvious that the Fine grain size class is increasing towards the sediment surface, while the Medium and Coarse grain size classes are decreasing towards the sediment surface in the majority of the locations. These trends are especially visible for the eastern locations that are positioned closer to the Greenland ice sheet, while these trends are less clear towards the western outlet of the Godthåbsfjord at Nuuk.

Figure 23: Mineral grain size class statistical trend variations in the Godthåbsfjord sediment record. A: Fine grain size class; B: Medium grain size class; C: Coarse grain size class. Encircled numbers correspond to sampling locations. Blue circles indicate decreasing trends towards the sediment surface Red circles indicate increasing trends towards the sediment surface. Colour code to the right indicates water depth in meters. Trends are made using precentage distribution and the plotted graphs from fig,16-22.

5.3.2 Organic matter fraction

Appendix C summarises all raw data for the organic matter fractions, including single marine organic matter content, terrestrial organic matter content, and mineral versus organic matter content. Figure 24 to 30 present the comparisons of: mineral matter versus organic matter content, and marine organic matter versus terrestrial organic matter content.

The orange stippled lines in all graphs representing mineral matter versus organic matter of Figure 24 to 30 indicate the statistical linear regression, suggesting either increasing or decreasing trends of the organic matter content from the core bottom to the core top. Figures 24 to 30 also show the lithology of the opened sediment cores. Note that no core images are available for the sediment fractions of Location 5 and Location 8, as only

sediment fragments and not entire sediment cores were taken at these locations. As with the mineral grain sizes, the following graphs are also concentration graphs that add up to 100%, thus not allowing a conclusion on the absolute distribution numbers of the mineral matter content versus organic matter content, or marine organic matter versus terrestrial organic matter.

Figure 24 shows the organic matter versus mineral matter content in the sediment core of Location 1 (Outside Nuuk harbour) and the terrestrial versus marine organic matter towards the sediment surface. There is more concentration of organic matter compared to mineral matter at this location, and of the organic matter the terrestrial organic matter concentrations are slightly decreasing, meaning there is more marine organic matter evident when compared to terrestrial organic matter content concentrations. Note that the statistic trend is based on only three subsamples, and thus all trends might be interpreted as stable.

Figure 24: Sediment core of Location 1, presenting the lithology along with the graphs of the mineral vs organic matter content, and terrestrial vs marine organic matter content. Sediment depth is in cm; mineral and organic matter content are presented as percentage concentrations. Weak stippled line is a statistic trend line from linear regression. Orange colour in first graph (left) represent organic matter content, while blue colour represents mineral matter content. In the second graph (right) the orange colour represents terrestrial organic matter, while the blue colour represents marine organic matter. The depth is on the y-axis (0-18cm) and the total percentage is on the x-axis (100%).

Figure 25 shows the organic matter versus mineral matter content in the sediment core of Location 4 (Southern outlet Kangersuneq fjord branch) indicating higher organic matter concentrations compared to the mineral matter content at this location, and of the organic matter there is higher marine organic matter concentrations, and the terrestrial organic matter concentrations are increasing.

Figure 25: Sediment core of Location 4, presenting the lithology along with the graphs of the mineral vs organic content, and terrestrial vs marine organic matter content. Sediment depth is in cm; mineral and organic matter content are presented as percentage concentrations. Weak stippled line is a statistic trend line from linear regression. Orange colour in first graph (left) represent organic matter content, while blue colour represents mineral matter content. In the second graph (right) the orange colour represents terrestrial organic matter, while the blue colour represents marine organic matter. The depth is on the y-axis (0-18cm) and the total percentage is on the x- axis (100%).

Figure 26 shows the organic matter content in the sediment fragments of Location 5 (Middle Nûp Kangerdlua fjord branch). The organic matter and mineral matter content increase and decrease until approximately 5cm depth, until there is a clear decrease in organic matter and an increase in mineral matter content from here. Overall there is more organic matter evident at location 5. The increase of organic matter concentrations is terrestrial with the marine organic matter therefore decreasing at this location.

Figure 26: Sediment core of Location 5, presenting the lithology along with the graphs of the mineral vs organic content, and terrestrial vs marine organic matter content. Sediment depth is in cm; mineral and organic matter content are presented as percentage concentrations. Weak stippled line is a statistic trend line from linear regression. Orange colour in first graph (left) represent organic matter content, while blue colour represents mineral matter content. In the second graph (right) the orange colour represents terrestrial organic matter, while the blue colour represents marine organic matter. The depth is on the y-axis (0-18cm) and the total percentage is on the x- axis (100%).

Figure 27 shows the organic matter content the sediment core of Location 6 (Middle Qôrnup Suvdlua fjord branch) indicating an increase in organic matter when compared to mineral matter content. There is more marine organic matter evident with an increasing trend towards the surface when compared to terrestrial matter.

Figure 27: Sediment core of Location 6, presenting the lithology along with the graphs of the mineral vs organic content, and terrestrial vs marine organic matter content. Sediment depth is in cm; mineral and organic matter content are presented as percentage concentrations. Weak stippled line is a statistic trend line from linear regression. Orange colour in first graph (left) represent organic matter content, while blue colour represents mineral matter content. In the second graph (right) the orange colour represents terrestrial organic matter, while the blue colour represents marine organic matter. The depth is on the y-axis (0-18cm) and the total percentage is on the x- axis (100%).

Figure 28 shows the organic matter content in the sediment fragments of Location 8 (Middle Kapisillit Kangerdlua fjord branch) indicating an increase in organic matter content towards the surface but there is more mineral matter overall at this location. Of the organic matter content, terrestrial organic matter is increasing, while marine organic matter is therefore decreasing.

Figure 28: Sediment core of Location 8, presenting the lithology along with the graphs of the mineral vs organic content, and terrestrial vs marine organic matter content. Sediment depth is in cm; mineral and organic matter content are presented as percentage concentrations. Weak stippled line is a statistic trend line from linear regression. Orange colour in first graph (left) represent organic matter content, while blue colour represents mineral matter content. In the second graph (right) the orange colour represents terrestrial organic matter, while the blue colour represents marine organic matter. The depth is on the y-axis (0-18cm) and the total percentage is on the x- axis (100%).

Figure 29 shows the organic matter content in the sediment core of Location 10 (Outside Kapisillit) indicating an increase in organic matter content compared to mineral matter, although results show similar approximate numbers of both. Terrestrial organic matter is stable, with an increase from 9 cm depth at this location.

Figure 29: Sediment core of Location 10, presenting the lithology along with the graphs of the mineral vs organic content, and terrestrial vs marine organic matter content. Sediment depth is in cm; mineral and organic matter content are presented as percentage concentrations. Weak stippled line is a statistic trend line from linear regression. Orange colour in first graph (left) represent organic matter content, while blue colour represents mineral matter content. In the second graph (right) the orange colour represents terrestrial organic matter, while the blue colour represents marine organic matter. The depth is on the y-axis (0-18cm) and the total percentage is on the x- axis (100%).

Figure 30 shows the organic matter content in the sediment core of Location 12 (Southern outlet Umánap Suvdlua fjord branch) indicating a clear increase in mineral matter content from approximately 2.5cm depth. When comparing the total organic matter content, there is an increase in terrestrial organic matter and a decrease in marine organic matter towards the surface at this location.

Figure 30: Sediment core of Location 12, presenting the lithology along with the graphs of the mineral vs organic content, and terrestrial vs marine organic matter content. Sediment depth is in cm; mineral and organic matter content are presented as percentage concentrations. Weak stippled line is a statistic trend line from linear regression. Orange colour in first graph (left) represent organic matter content, while blue colour represents mineral matter content. In the second graph (right) the orange colour represents terrestrial organic matter, while the blue colour represents marine organic matter. The depth is on the y-axis (0-18cm) and the total percentage is on the x- axis (100%).

Figure 31 shows a map of the combined trends towards the sediment surface of all sediment records in a geographical distribution of the locations of the Godthåbsfjord. When comparing the overall results of increasing and decreasing trends of the marine organic matter and terrestrial organic matter content it becomes obvious that the marine matter is decreasing towards the sediment surface at locations closest to the glaciers, while the terrestrial organic matter are increasing towards the sediment surface in the locations closest to the glaciers. The opposite trends appear at location 1, furthest away from the glacier and closest to the open ocean. These trends are especially visible for the eastern locations that are positioned closer to the Greenland ice sheet, while these trends are less

clear towards the western outlet of the Godthåbsfjord at Nuuk. The opposite trends appear at location 1, furthest away from the glacier and closest to the open ocean.

Figure 31: Organic matter statistical trend variations in the Godthåbsfjord sediment record. A: Terrestrial organic matter; B: Marine organic matter. Encircled numbers correspond to sampling locations. Blue circles indicate decreasing trends towards the sediment surface. Red circles indicate increasing trends towards the sediment surface. Colour code to the right indicates water depth in meters.

5.4 Contaminants

Appendix D summarises all contamination raw data in the analysis report from Eurofins Finland. The pollution assessment of the contaminants follows the Norwegian Classification standard for quantification of contaminants in coastal marine sediments (Miljødirektoratet 2016); Appendix E shows the full list of the Norwegian coastal marine contaminant classification. Table 5 illustrates the colour code according to the five levels of pollution from this classification and their environmental effects. These colours will be used in the following results to indicate the degree of contamination found in the Godthåbsfjord sediment samples. Tin (Sn) is not included in the contaminant classification of the Godthåbsfjord sediment samples, as Tin is not classified according to the Norwegian standard for contaminants in coastal sediments.

Table 5: Polluting levels of contaminants ranging from a natural, non-polluting background level(blue colour) to a very polluted level with extensive toxic effects (red colour) according to the Norwegian classification of contaminants in coastal marine sediments (Miljødirektoratet 2016).

Classification Environmental effect Colour code

Natural background level non-polluting

Elevated pollution level minor effects

Polluted chronic effects

Polluted acute toxic effects

Very polluted extensive toxic effects

5.4.1 Heavy metals At Location 1 (Outside Nuuk harbour), heavy metal concentrations occur within natural background levels. Table 6 illustrates the levels of each heavy metal found in surface (0- 2cm) and subsurface (2-4cm) sediments, with the sum of all heavy metal concentrations on the right side of the table. The sum of all heavy metal concentrations reveals a decreasing trend across the upper 0-4cm of the sediment towards the sediment surface.

Table 6: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 1. (Outside Nuuk harbour). The sum of all heavy metal concentrations is indicated in the column to the right. All concentrations occur at background levels and are thus coloured blue. Tin is not classified as it not included.

Heavy Metals Cadmium Copper Chromium Lead Mercury Nickel Tin Zinc Sum

Location 1 mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg (mg/kg)

0-2 cm 0.070 6.6 15 4.4 0.013 9.9 0.20 15 51.2

2-4 cm 0.098 8.3 17 5.2 0.013 12 0.22 18 60.8

At Location 4 (Southern outlet Kangersuneq fjord branch), heavy metal concentrations occur within natural background levels for cadmium, lead, mercury and zinc, while copper

and chromium occur at slightly elevated polluted levels. Nickel as seen in yellow, occurs at polluting levels with chronic effects. Table 7 illustrates the levels of each heavy metal found in surface (0-2cm) and subsurface (2-4cm) sediments, with the sum of all heavy metal concentrations on the right side of the table. The sum of all heavy metal concentrations reveals an increasing trend across the upper 0-4cm of the sediment towards the sediment surface.

Table 7: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 4 (Southern outlet Kangersuneq fjord branch). The sum of all heavy metal concentrations is indicated in the column to the right. All blue classifications are concentrations that occur at background levels, while green classifies concentrations of elevated polluted levels with minor effects. Yellow concentrations are polluted levels with chronic effects. Tin is not classified.

Heavy Metals Cadmium Copper Chromium Lead Mercury Nickel Tin Zinc Sum

Location 4 mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg (mg/kg)

0-2 cm 0.053 32 77 15 0.015 53 0.69 66 243.8

2-4 cm <0.05 30 62 12 0.012 43 0.61 57 204.6

At Location 5 (Middle Nûp Kangerdlua fjord branch), heavy metal concentrations of cadmium, lead, mercury, zinc and the surface sample of chromium occur within natural background levels. The subsurface sample of chromium occurs at slightly elevated polluting levels along with copper and the surface sample of nickel. The subsurface sample of nickel occurs at polluted levels with chronic effects. Table 8 illustrates the levels of each heavy metal found in surface (0-2cm) and subsurface (2-4cm) sediments, with the sum of all heavy metal concentrations on the right side of the table. The sum of all heavy metal concentrations reveals a decreasing trend across the upper 0-4cm of the sediment towards the sediment surface.

Table 8: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 5 (Middle Nûp Kangerdlua fjord branch). The sum of all heavy metal concentrations is indicated in the column to the right. All blue classifications are concentrations that occur at background levels, while green classifies concentrations of elevated polluted levels with minor effects. Yellow concentrations are polluted levels with chronic effects. Tin is not classified.

Heavy Metals Cadmium Copper Chromium Lead Mercury Nickel Tin Zinc Sum

Location 5 mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg (mg/kg)

0-2 cm 0.12 26 57 12 0.022 40.0 0.68 54 189.8

2-4 cm 0.12 29 62 16 0.03 44.0 0.78 61 212.9

At Location 6 (Middle Qôrnup Suvdlua fjord branch), heavy metal concentrations of cadmium, lead, mercury and zinc occur within natural background levels. Copper and chromium concentrations occur at slightly elevated polluting effects, and nickel occurs at polluting levels with chronic effects. Table 9 illustrates the levels of each heavy metal found in surface (0-2cm) and subsurface (2-4cm) sediments, with the sum of all heavy metal concentrations on the right side of the table. The sum of all heavy metal concentrations reveals an increasing trend across the upper 0-4cm of the sediment towards the sediment surface.

Table 9: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 6 (Middle Qôrnup Suvdlua fjord branch). The sum of all heavy metal concentrations is indicated in the column to the right. All blue classifications are concentrations that occur at background levels, while green classifies concentrations of elevated polluted levels with minor effects. Yellow concentrations are polluted levels with chronic effects. Tin is not classified.

Heavy Metals Cadmium Copper Chromium Lead Mercury Nickel Tin Zinc Sum

Location 6 mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg (mg/kg)

0-2 cm 0.073 29 68 15 0.024 45.0 0.68 56 213.8

2-4 cm 0.073 28 66 15 0.025 44.0 0.78 55 208.9

At Location 8 (Middle Kapisillit Kangerdlua fjord branch), heavy metal concentrations occur within natural background levels. Table 10 illustrates the levels of each heavy metal found in surface (0-2cm) and subsurface (2-4cm) sediments, with the sum of all heavy metal concentrations on the right side of the table. The sum of all heavy metal concentrations reveals a decreasing trend across the upper 0-4cm of the sediment towards the sediment surface.

Table 10: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 8 (Middle Kapisillit Kangerdlua fjord branch). The sum of all heavy metal concentrations is indicated in the column to the right. All concentrations occur at background levels and are thus coloured blue. Tin is not classified.

Heavy Metals Cadmium Copper Chromium Lead Mercury Nickel Tin Zinc Sum

Location 8 mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg (mg/kg)

0-2 cm <0.05 17 33 8.4 0.011 23.0 0.34 31 112.8

2-4 cm 0.057 17 36 8.8 <0,010 25.0 0.37 33 120.2

At Location 10 (Outside Kapisillit), heavy metal concentrations of lead, mercury and zinc occur within natural background levels. copper and chromium occur at slightly elevated

concentrations, while nickel occurs in polluting concentrations with chronic effects at 2- 4cm sediment depth, decreasing to elevated concentrations at the surface 0-2cm of the sediment. Table 11 illustrates the levels of each heavy metal found in surface (0-2cm) and subsurface (2-4cm) sediments, with the sum of all heavy metal concentrations on the right side of the table. The sum of all heavy metal concentrations reveals a decreasing trend across the upper 0-4cm of the sediment towards the sediment surface.

Table 11: Contaminant concentration levels of each heavy metal found in surface 0-2cm and subsurface 2-4cm sediments of Location 10 (Outside Kapisillit). The sum of all heavy metal concentrations is indicated in the column to the right. All blue classifications are concentrations that occur at background levels, while green classifies concentrations of elevated polluted levels with minor effects. Yellow concentrations are polluted levels with chronic effects. Tin is not classified.

Heavy Metals Cadmium Copper Chromium Lead Mercury Nickel Tin Zinc Sum

Location 10 mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg (mg/kg)

0-2 cm 0.059 31 62 17 0.021 42.0 0.69 60 212.8

2-4 cm 0.081 31 68 18 0.022 45.0 0.68 62 224.8

At Location 12 (Southern outlet Umánap Suvdlua fjord branch), heavy metal concentrations of lead, mercury and zinc occur within natural background levels. copper and chromium occur at slightly elevated concentrations, while nickel occurs in polluting concentrations with chronic effects at 0-2cm and 2-4cm sediment depth. Table 12 illustrates the levels of each heavy metal found in surface (0-2cm) and subsurface (2-4cm) sediments, with the sum of all heavy metal concentrations on the right side of the table. The sum of all heavy metal concentrations reveals a decreasing trend across the upper 0- 4cm of the sediment towards the sediment surface.

Table 12: contamination levels of each trace metal found in surface 0-2cm and subsurface 2-4cm Comment [1]: Should be in bold for location 12. The total contamination is found at the right. The blue colour indicates natural background level of contaminants was found. Green indicates elevated pollutant, and yellow indicates polluted with chronic effects.

Heavy Metals Cadmium Copper Chromium Lead Mercury Nickel Tin Zinc Sum

Location 12 mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg (mg/kg)

0-2 cm 0.095 32 70 16 0.041 48.0 0.84 66 233.0

2-4 cm 0.093 31 75 17 0.044 50.0 0.82 66 240.0

Figure 32 indicates that there is a positive correlation between the trend in the sum of heavy metal concentrations across the upper 4cm of the sediment surface at each location and the mineral grain size concentrations within the Medium grains size class, except from Location 12, where there is a negative correlation.

Figure 32: The sum of heavy metal concentrations (blue squares) presented against the medium grain size class concentrations (green lines) of each location. The primary y-axis indicates the sum heavy metal concentrations in mg/kg; the secondary y-axis indicates the concentrations within the medium grain size class in percent.

In addition, there is a positive relationship between increasing trends of heavy metal concentrations across the upper 0-4cm of the sediment surface and increasing trends of terrestrial organic matter concentrations and vice versa, as illustrated in figure 33. The terrestrial organic matter and heavy metal concentrations are both decreasing towards the surface at location 1, 5, 8, 10 and 12, while they are increasing towards the sediment surface of Location 6. The trends are opposite at Location 4 with decreasing terrestrial organic matter concentrations and increasing heavy metal concentrations across the upper 0-4cm of the sediment towards the sediment surface.

Figure 33: The sum of heavy metal concentrations (blue squares) presented against the terrestrial organic matter fraction (blue lines) of each location. The primary y-axis indicates the sum heavy metal concentrations in mg/kg; the secondary y-axis indicates the concentrations of the terrestrial organic matter in percent.

5.4.2 Polycyclic aromatic hydrocarbon (PAH)

Along with heavy metals that were evident in the sediments, PAHs are also found in location 1, 5, 10 and 12 (table 13). They are decreasing towards the surface at all locations (figure 36). The levels range from not-detected levels, to elevated pollution levels at minor effects (in green), which are most evident in Location 10. The contamination at location 10 is decreasing across the upper 0-4cm of the sediment, towards the sediment surface.

Table 13: Contaminant levels of each PAH16 compound displayed for surface 0-2cm and subsurface 2-4cm sediments for all locations. Included is the colour code indicating level of pollution, which ranges from not-detected levels, to natural background in blue and elevated pollution at minor effects in green.

PAH16 compounds Location Location Location Location Location Location Location 1 4 5 6 8 10 12 mg/kg dm

Acenaphthene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

Acenaphthylene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

Anthracene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

Benz[a]anthracene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 0,004 <0,003

Benzo[a]pyrene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 0,004 <0,003

Benzo[b]fluoranthene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 0,004

<0,003 <0,003 0,003 <0,003 <0,003 0,004 0,005

Benzo[ghi]perylene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 0,005

<0,003 <0,003 0,003 <0,003 <0,003 0,003 0,004

Benzo[k]fluoranthene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

Chrysene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 0,004 <0,003

Dibenz[a,h]anthracene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

Fluoranthene <0,003 <0,003 <0,003 <0,003 0,004 0,003 <0,003 <0,003 <0,003 <0,003 <0,003 0,004 0,003 0,001

Fluorene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

Indeno[1,2,3-cd]pyrene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

Naphthalene <0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 <0,003 <0,003

Phenanthrene <0,003 <0,003 <0,003 <0,003 <0,003 0,003 <0,003

0,003 <0,003 <0,003 <0,003 <0,003 0,004 <0,003

Pyrene <0,003 <0,003 <0,003 <0,003 <0,003 0,007 <0,003

<0,003 <0,003 <0,003 <0,003 <0,003 0,008 <0,003

Sum 0.003 0.006 0.014 0,012 0.041 0,013

5.4.3 Polychlorinated biphenyl (PCB)

Along with the PAH concentrations, also PCB concentrations were found in at locations 5, 10 and 12, decreasing across the upper 0-4cm of the sediment towards the sediment

surface, summarised in Table 14 to 15. The PCB concentrations of all other locations are not displayed, as the concentrations of the analysed PCBs were belowe detection limit <0.0005mg/kg.

Location 5 is situated in the main branch, and is recording background levels of PCB7 contaminants, although decreasing towards the surface (Table 14).

Table 14: PCB compounds at location 5, at surface 0-2cm and subsurface 2-4cm samples. Measured in mg/kg of dry matter, all results are below detection limit. Total PCB7 are seen on the right.

PCB7 compounds mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

Location 5 PCB52 PCB28 PCB118 PCB101 PCB138 PCB153 PCB180 PCB 7

0-2cm <0,0005 <0,0005 <0,0005 <0,0005 <0,0005 <0,0005 <0,0005 <0,0005

2-4cm <0,0005 <0,0005 0.0006 <0,0005 <0,0005 <0,0005 <0,0005 0.0006

Location 10 is situated near Kapisillit, and is the second location to have recorded background levels of PCB7 contaminants, although these are also decreasing towards the surface (Table 15).

Table 15: PCB compounds at location 10, at surface 0-2cm and subsurface 2-4cm samples. Measured in mg/kg of dry matter Results show below background levels, which are indicated without colour coding. PCB118 is in green, indicating polluting levels at minor effects. Total PCB7 are seen on the right

PCB7 compounds mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

Location 10 PCB52 PCB28 PCB118 PCB101 PCB138 PCB153 PCB180 PCB 7

0-2cm <0,0005 <0,0005 <0,0005 <0,0005 <0,0005 <0,0005 <0,0005 <0,0005

2-4cm <0,0005 <0,0005 0.0015 <0,0005 <0,0005 <0,0005 <0,0005 0.0015

Location 12 is situated at the southern end of Ûmánap Suvdlua, and is the third location to have recorded background levels of PCB7 contaminants, of which are also decreasing towards the surface (Table 15).

Table 16: PCB compounds at location 12, at surface 0-2cm and subsurface 2-4cm samples. Measured in mg/kg of dry matter Results show below background levels, which are indicated without colour coding. PCB118 is in green, indicating polluting levels at minor effects. Total PCB7 are seen on the right.

PCB7 compounds mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

Location 12 PCB52 PCB28 PCB118 PCB101 PCB138 PCB153 PCB180 PCB 7

0-2cm <0,0005 <0,0005 <0,0005 <0,0005 <0,0005 <0,0005 <0,0005 <0,0005

2-4cm <0,0005 <0,0005 0.0006 <0,0005 <0,0005 <0,0005 <0,0005 0.0006

5.4.4 Organotin Compounds

The organic tin compounds that were tested in the assessment by Eurofins Finland consisted of Tributyltin (TBT), Dibutyltin (DBT), Monobutyltin (MBT) and Tetrabutyltin (TTBT). The results are not displayed as all concentrations were below the instrumental detection limit of <1µg/kg.

5.4.5 Pesticides

Along with all organic tin compounds, pesticides (DDT) also showed results that were below the detection limit of of 0.020mg/kg dry matter at all locations. Thus, these results are not displayed.

5.4.6 Contaminant trends and correlations

As seen in Figure 34, the sum of all heavy metals (presented as Σheavy metals) shows decreasing concentration trends towards the sediment surface in all locations, except for location 6 in the Qôrnup Suvdlua fjord branch and location 4 at the outlet of the Kangersuneq fjord branch, where the concentrations are increasing towards the sediment surface.

Figure 34: Distribution of the sum of heavy metal concentrations (Σheavy metals) at the sediment sample sites (circles) in the Godthåbsfjord. A blue circle and a blue location number indicate decreasing of heavy metal concentration trends towards the sediment surface. A red circle and a red location number indicate increasing heavy metal concentration trends towards the sediment surface. The dating for contamination corresponds to the last decades as indicated in Table 4. The boxes outside the map indicate the correlation factors of the sum heavy metals with the particulate matter fraction for each site. These correlation factors include the coarse, medium, and fine grain size classes, and marine and terrestrial organic matter concentrations. A negative correlation with the sum of trace metals results in -1 (white boxes), and a positive correlation results in 1 (red boxes). OM stands for organic matter. Pearsons correlation coefficient was used for all correlations.

As seen in Figure 35, evidence of elevated PAH16 concentrations was found at locations 1, 5, 10 and 12. The blue colour of in all locations signifies a decreasing PAH16 trend towards the sediment surface. Similar to the heavy metal correlations, a positive correlation was found for the PAH16 with medium and/or fine grain size classes and terrestrial organic matter. The correlation patterns were in the value of 1 that indicates a positive correlation, or a -1 that indicates a negative correlation. There were no correlations that resulted in 0, which would imply a lack of correlation.

Figure 35: Distribution of the PAH16 concentrations at the sediment sample sites (circles) in the Godthåbsfjord. A blue circle and a blue location number indicate decreasing of PAH16 concentration trends towards the sediment surface. A red circle and a red location number indicate increasing PAH16 concentration trends towards the sediment surface. The dating for contamination corresponds to the last decades as indicated in Table 4. The boxes outside the map indicate the correlation factors of the PAH16 concentrations with the particulate matter fraction for each site. These correlation factors include the coarse, medium, and fine grain size classes, and marine and terrestrial organic matter concentrations. A negative correlation with PAH16 concentrations results in -1 (white boxes), and a positive correlation results in 1 (red boxes). OM stands for organic matter.

The pattern of the PCB7 contamination (Figure 36) is similar to the pattern of the PAH16 contamination, in that PCB7 concentrations decrease towards the surface in the sediments of location 5, 10 and 12. The correlation patterns are the same as for PAH16 and the heavy metal concentrations, showing a positive correlation with terrestrial organic matter concentrations and the fine and/or medium grain size classes. The correlation patterns were in the value of 1 that indicates a positive correlation, or a -1 that indicates a negative correlation. There were no correlations that resulted in 0, which would imply a lack of correlation.

Figure 36: Distribution of the PCB7 concentrations at the sediment sample sites (circles) in the Godthåbsfjord. A blue circle and a blue location number indicate decreasing of PCB7 concentration trends towards the sediment surface. A red circle and a red location number indicate increasing PCB7 concentration trends towards the sediment surface. The dating for contamination corresponds to the last decades as indicated in Table 4. The boxes outside the map indicate the correlation factors of the PCB7 concentrations with the particulate matter fraction for each site. These correlation factors include the coarse, medium, and fine grain size classes, and marine and terrestrial organic matter concentrations. A negative correlation with the PCB7 concentrations results in -1 (white boxes), and a positive correlation results in 1 (red boxes). OM stands for organic matter.

6 Discussion

6.1 The sources of recent (0-100 year) particulate matter variations in Godthåbsfjord sediments

6.1.1 Mineral grain size sources

According to the arbitrary sedimentation rates estimated from neighbouring and other Greenlandic fjords, the sediment cores of the Godthåbsfjord represent a maximum time span of about the last 125 years (Table 4). The fine mineral grain size concentrations, including clay and very fine silt, increase in the entire Godthåbsfjord over the last 125 years, and especially over the last 12 years in the surface sediments of the sediment cores taken at intermediate distance to the glaciers and those taken close to the glaciers of the Greenland ice sheet, while the medium and coarse mineral grain sizes decrease.

According to Haldorsen (1981), glacial erosion mainly produces mineral grain sizes of silt or larger, implying that only minor concentrations (less than 5%) of mineral clay or very fine silt particles would be expected to occur in sediments dominated by material from glacial runoff (Boulton, 1996). Thus, the decreasing concentration of medium and coarse grain sizes over the last decades might indicate a retreat of the glaciers that feed into the Godthåbsfjord. Due to increased glacial melt throughout the last 30 years (Langen et al, 2015) the Greenland ice sheet would successively loose volume and the glacier outlets would retreat from locations close to the fjord into locations further inward their glacial valleys. In this way, the distance of the source areas of the glacially derived mineral matter to the fjord would successively increase. The resulting fjord sediments would then consist of gradually less glacially derived silt and coarse-grained mineral matter and receive more fine-grained mineral particles through local runoff triggered by erosion of newly exposed land areas, possibly enhanced by the increased frequency of precipitation during the last 30 years (Langen et al, 2015). The measurements of Auger, Birkel, Maasch, Mayewski, and Schuenemann (2017) confirm the future expectations of increased precipitation as modelled by Langen et al (2015) suggesting that enhanced land erosion increases the production of finer non-glacial produced mineral grains entering the fjord through runoff initiated by increasing amounts of precipitation. The increase in coarse grain sizes

particularly found at location 1, illustrate a change in mineral grain sources at this area which is closest to the open ocean, thus having direct influence from The West Greenland Current and the coastal waters. The strong influx of water directed from the open ocean that enters the Godthåbsfjord at this area, could be the reason for a clear increase in coarse grain sizes. Another source of coarse grains are deposited from icebergs that release material as they melt. The coarse grains then get transported to the open ocean through the circulation pattern and water current activity (Zaborska, Pempkowiak, Papucci, 2006).

A recent and more detailed investigation at individual glacier outlets from the Godthåbsfjord illustrates glacial retreat and ice melting over the last decades (Motyka et al, 2017). A total ice loss of 43.8 ± 0.2km3 is recorded in the area, (Motyka et al, 2017). The glacial outlet of Narsap Sermia (Figure 1) retreated 3.3km between 2010-2014, while the Kangiata Nunâta Sermia glacial outlet (Figure 1) has retreated 0.8km since 1985. Motyka et al, (2017) calculated that the total runoff from all glaciers into the Godthåbsfjord had an annual average of 22.1km3 between the years 2004 and 2012 and was steadily increasing. Adhikari and Delaney (2020) came to a similar result as Motyka et al (2017) when calculating mass balances of sediment supply from subglacial outlet glaciers and relating these to global warming.

The evidence from Motyka et al (2017), Adhikari and Delaney (2020), and the model data of Langen et al (2015) on climatically forced glacial retreat, increasing melting, and increasing runoff into the fjord triggered by enhanced precipitation validate the interpretation regarding the influence of the variation in these glacial sources on the observed changes of mineral grain sizes in the Godthåbsfjord sediments. Consequently, climate warming and subsequent glacial retreat could account as reasons for the decreasing medium and coarse grain sizes in the Godthåbsfjord sediments proximal and at intermediate distance to the glaciers.

6.1.2 Organic matter sources

While mineral grain sizes generally decrease from subsurface towards the surface, the terrestrial organic matter fraction generally increases in the Godthåbsfjord sediments towards the sediment surface over the last decades. The marine organic matter fraction decreases correspondingly (Figure 31b), as the two organic matter fractions are determined

on a 100% scale. There are two general possibilities to explain the organic matter pattern, either related to turbidity variations that affect the marine organic matter fraction, or to larger exposed land areas and prolonged summer seasons that would affect the terrestrial organic matter fraction. Both solutions are related to climate change and glacial retreat, and therefore both solutions can be seen as environmental signals in the fjord relating to climate change.

The decreasing marine organic matter fraction: Yoshihiko, Takahiro, Shin, Shigeru, (2016) documented enhanced water turbidity due to increased glacial melting in the Uummannap Kangerlua Fjord off the Thule region in northeast Greenland. Increased glacial melting and increased precipitation in the Godthåbsfjord area are modelled by Langen et al (2015) and enhanced glacial melting is observed by Mortensen et al (2011) and Van As et al (2017). These turbidity related processes could be responsible for the decreasing marine organic matter fraction as increased turbidity would limit the light conditions in the fjord and decrease marine primary productivity (see Sigman and Hain, 2012 for a review). Thus, higher turbidity input due to the observed snow in the water column, glacial melting and runoff from newly exposed land areas triggered by enhanced precipitation (Langen et al, 2015) could lead to a deterioration of the light conditions in the Godthåbsfjord, leading to a limited primary productivity, and by this explaining the decreasing marine organic matter fraction over the last decades.

On the other hand, Tissot and Pelet (1981) documented high productivity of phytoplankton close to the glacial outlets into the Kangersuneq fjord branch (Figure 1) due to the upwelling system that occurs there. The subglacial release of freshwater (Adhikari & Delaney, 2020) creates an upwelling of glacially derived mineral nutrients, allowing for optimal conditions for organic matter to grow (Tissot & Pelet, 1981). In addition, Plante and Conant (2014) document that the increasing precipitation discharges higher amounts of carbon nutrients from land, thus triggering marine productivity.

While the overall trend in marine organic matter is decreasing towards the surface, location 1 shows the opposite trend and is seen to have an increase in marine organic matter towards the surface. This shift could be due to the difference in sources of organic matter, and grain sizes near the entrance of the fjord as previously explained. This is the furthest location from the glacier outlets, and therefore the furthest away from influence of newly

exposed land area too. The sedimentation rate towards the glaciers is higher, and the material discharged by the glaciers is a very important factor that influences the organic matter content in the sediments. The finer grains sizes and turbidity of the water column can block sunlight from entering the fjord, and therefore limit primary production. However at location 1, there is less influence of fine grain material, and so more sunlight can enter the fjord allowing primary production to occur (Zaborska et al, 2006). This could explain the increase in marine organic matter at this location.

The proposed increase in primary productivity and thus enhanced marine organic matter concentration is not seen in the surface sediment cores of the Godthåbsfjord locations. One reason could be that no sediment cores were taken in the Kangersuneq fjord branch and that the released nutrients are used up before entering the more westerly Godthåbsfjord areas where the sediment cores were taken, thus missing the productivity areas in front of the glaciers. Another reason might be that the marine and terrestrial organic matter fractions were determined at a 100% scale, not allowing a quantification of the organic material. If the marine organic matter fraction would increase, the marine fraction could still appear as a decrease on a 100% scale if the terrestrial organic matter fraction would increase at the same time on a higher degree than the marine organic matter fraction. This should be investigated further by measuring the absolute amount of the organic matter fractions in the sediment in future research, such as using the loss on ignition technique for analysing weight percentage of total organic matter, or by C/N ratios and δ13 isotopic ratios for identifying the terrestrial and marine organic matter fractions as done by Paetzel and Schrader (1995).

The increasing terrestrial organic matter fraction: Alternatively, the glacial retreat in the Godthåbsfjord area over the last 30 years (Langen et al, 2015) would expose the freshly deglaciated land masses to prolonged biologic growing seasons and thus to enhanced terrestrial organic matter growth, as summarized in the review on global glacial settings by Hågvar (2012). The additionally increasing precipitation over the last 30 years (Langen et al, 2015) would then lead to an enhanced runoff of this newly produced terrestrial organic matter, leading to an increased supply of this terrestrial fraction into the Godthåbsfjord and its settling in the fjord surface sediments.

The increase in terrestrial organic matter can also be related to the increase in fine grain sizes, as elevated amounts of finer mineral particles in the surface waters are favourable for binding (terrestrial and marine) organic matter into fast sinking aggregates in the aquatic environments (Tissot & Pelet, 1981). As stated by Tissot and Pelet (1981) terrestrial higher plants are one of the main sources for organic matter in semi-enclosed basins.

Paetzel and Dale (2010) investigated the impact of climate change and how it interferes with sediment deposition in the inner Sognefjord region of Norway. They found a dependency of the transport of lake and river produced freshwater diatoms and terrestrial organic matter on the local precipitation pattern, indicating a similar relationship between precipitation and terrestrial organic matter supply as suggested here for the Godthåbsfjord. To further support this theory, a study on the diatoms found in Godthåbsfjord sediments could confirm an enhanced terrestrial impact if the freshwater diatom concentration would dominate the marine diatom concentration.

In summary, the distribution pattern of particulate matter in the Godthåbsfjord sediments allows to define variations of environmental change over the last decades, where the increasing fine mineral grain size concentrations and the increasing terrestrial organic matter concentrations imply enhanced terrestrial runoff and enhanced glacial melting over the last decades as possible sources.

6.2 The sources of recent (0-100 year) contaminant variations in Godthåbsfjord sediments

The total volume of organic and inorganic contaminant concentrations evident in the Godthåbsfjord sediments is below detection limits (most PAHs, and most PCBs), at natural background levels (Cu, Cr), or they occur at slightly elevated (but not polluting) levels (Hg, Pb, Zn, few PAHs, and few PCBs) according to the classification of Miljødirektoratet (2016). The exemptions are the nickel concentrations that are at polluting levels (with chronic effects) at all locations but Location 1 and 8 (Table 6 and 10). Nickel is known to occurring at higher concentrations in Archean tholeiitic rocks, especially at the west coast of Greenland (Aoki, 2018). During investigations of gold potential, elevated nickel concentrations were frequently found in the Archean rocks surrounding the Godthåbsfjord

and especially within the rocks of the Isua province (Møller, Rasmussen, Steenfelt, 2006). Increasing runoff from Ni-bearing Archaen rocks should thus occur as a plausible explanation for the elevated nickel concentrations in the surface sediments of the entire Godthåbsfjord area, supported by the generally increasing precipitation and thus possible nickel enriched runoff over the last 30 years (Langen et al, 2015).

The non-polluting nickel concentrations of Location 8 might be attributed to its position at the junction of three fjord branches and subsequent dilution due to associated water current activity. Location 1 (outside Nuuk) sediments show in addition to the low nickel concentrations the generally lowest contaminant concentrations of all sediment cores. These sediments are exposed directly to The West Greenland Current across the shallow outer sill. This exposure is thought to be responsible for the increasing coarse grain sizes and lower organic matter concentrations at this location over the last century, which is a process generally observed in silled fjords (Syvitski et al, 1987). This is confirmed by the results of this study, where coarse grain sizes were found to be increasing towards the surface at location 1, closest to the open ocean. The current activity across the shallow Outer sill would thus erode those fractions from the sediment (Mortensen et al, 2011). According to Salomons (1988), the remaining coarse grained and organic matter poor sediment should hold less contaminants. In addition, the building activities around Nuuk harbour should have supplied a surplus coarse mineral grain size fraction to the sediments of Location 1.

Wherever organic or inorganic contaminants are found in Godthåbsfjord sediments, their concentrations decrease over the last decades, except at Location 4 and Location 6 where the total concentration of heavy metals increases over the same period. Both, the decreasing and increasing effect might be attributed to the observed glacial retreat (Milner et al, 2017). The decreasing contaminant concentrations occur at locations of intermediate distance to the glaciers of the Greenland ice sheet. As indicated above, the glacial retreat would increase the distance of the glacier fronts to these locations. Possible contaminants released from the Greenland ice sheet (Boutron & Görlach, 1990) into the meltwater of the retreating glaciers might thus increasingly aggregate and settle on land or in the eastern parts of the Kangersuneq fjord branch (Figure 1) before reaching the more western areas of the Godthåbsfjord. This idea is confirmed by the increasing concentrations of heavy metals in the sediments of Location 4 over the past decades. Location 4 is located directly at the

outlet of the Kangersuneq fjord branch and is thus the only location that might be influenced directly by the glacial meltwater discharge, thus indicating the proposed increasing supply of contaminants from the melting Greenland ice sheet (Milner et al, 2017). Location 6 is positioned in the direct extension of the Kangersuneq fjord branch and could probably still be influenced by the direct meltwater supply from the glaciers, leading also at this location to increasing heavy metal concentrations over the last decades. The periodic intensive use of summerhouses at the nearby settlement of Qoornoq might have triggered an additional release and subsequent sedimentation of heavy metals at Location 6 in the Qôrnup Suvdlua fjord branch over the last 30 years.

At all locations but Location 4, the total heavy metal concentration trends seem to correlate with the trends of terrestrial organic matter in the sediments deposited over the last decades. The correlation with the terrestrial organic matter fraction suggests that the main influence on the contaminant transport is related to land derived sources and runoff variations due to the local precipitation pattern in the Godthåbsfjord area. The nature of these land derived sources is probably from local rocks and local deposits, as the concentrations of the single heavy metals do not exceed natural background levels (Miljødirektoratet 2016). Especially Location 1 and 10 show a similar correlation of the organic contaminants PAH16 and PCB7 with the terrestrial organic matter concentrations, suggesting that also the organic contaminants are coming from land. As Locations 1 and 10 are located close to the settlements of Nuuk and Kapisillit respectively, human impact could possibly be one of the sources of organic contamination here. This is confirmed by the fact that the most significant, though non-polluting, elevation of PAH16 and PCB7 occurs in the sediments of location 10, close to the settlement of Kapisillit.

This situation is different at Location 4, with increasing heavy metal concentrations (Table 7) correlating with increasing marine oganic matter concentrations over the last decades. This can be explained by the position of Location 4 closest to the glacier outlets into the Godthåbsfjord and would suggest that the increasing contamination might originate from glacial runoff. This idea is strengthened by the observation of Tissot and Pelet (1981), on elevated primary production in nutrient rich glacial upwelling waters from subglacial melt in the Kangersuneq fjord branch. Contaminants in marine environments attach favourably to finer grain sizes and to marine organic matter (Salomons, 1988), as observed at Location 4. The parallel increasing concentrations of coarser grain sizes might contradict this theory,

though. On the other hand, the concentration of coarser grain sizes might increase independently due to increased precipitation and glacial runoff in the area close to the glaciers (Langen et al, 2015). Thus, Location 4 remains the only sediment core indicating direct contaminant supply from the Greenland ice sheet.

6.3 Conclusions on the relationship between contaminant and particulate matter variations in the Godthåbsfjord sediments and their related sources

Figure 37 summarises the dependencies of the changes in the major particulate matter composition in the Godthåbsfjord sediments on their respective sources and source areas throughout the last decades. The increasing sedimentary fine mineral grain sizes and enhanced terrestrial organic matter concentrations seem to relate to a rather complex combination of land-based source variations. The main trigger of these land-based variations appears to be of atmospheric origin, namely climate variability with steadily increasing global temperatures and parallel increasing precipitation over the last 30 years. These meteorological conditions are identified as the causes of land-based changes, represented in the Godthåbsfjord area by glacial retreat and subsequent greater aerial exposure of land masses that were formerly covered by glacier ice. These new land masses are now subjected to enhanced plant growth due to prolonged growth seasons, and to increasing erosion due to the elevated runoff levels caused by the precipitation.

This suggests a shift from a more glacially derived supply of sediment material to a particulate matter supply that is more based on runoff originating from rain and snow. The shift results in glacially derived coarse mineral grain sizes being deposited on land and only in less degree distributed into the eastern fjord areas, due to glacier retreat and thus an increasing distance between the glaciers and the fjord. These coarse grain sizes are instead replaced by fine mineral grain sizes and terrestrial organic matter that are increasingly exposed to erosion from precipitation, getting distributed into the entire Godthåbsfjord area due to their over-regional appearance and their low weight.

This new runoff pattern could open also for an increasing supply of mineral nutrients into the fjord that generally would trigger enhanced primary productivity in the fjord. However, the process of enhanced erosion from land could counteract primary productivity in the

Godthåbsfjord, as the surplus fine grained mineral matter increases the turbidity in the fjord waters, thus deteriorating light conditions and thereby effectively hindering the primary production of marine organic matter in the fjord.

In addition, Figure 37 indicates that he contaminant pathways into the fjord sediments seem to originate from atmospheric supply onto the glaciers of the Greenland ice sheet and subsequent glacial runoff, as well as from direct dispersal into the Godthåbsfjord from settlements and industrial activity. Correlation analysis shows that the contaminants enter the fjord waters and sediments together with the fine-grained mineral matter and the marine and mostly the terrestrial organic matter fraction. Sediment contamination levels are low, though increasing to slightly elevated levels within the inner parts of the Godthåbsfjord over the past decades. The shown dependency of the contaminant distribution on the particulate matter supply suggests that sedimentary contaminant levels in the Godthåbsfjord might rise in time if global temperatures, and thus glacial retreat and land runoff continue to increase in the future.

Figure 37: Dependencies of sediment particulate matter and contaminant distribution in the Godthåbsfjord on their respective sources and source areas. The symbol “⊕” in front of a parameter indicates an increase in this parameter. The symbol “!” in front of a parameter indicates a decrease in this parameter. Grey boxes describe atmospheric processes, green boxes describe land-based processes including glaciers, blue boxes describe fjord water processes, and orange boxes describe fjord sediment processes. The pink colour and arrows follow the contaminant pathways in the Godthåbsfjord.

6.4 Unexpected Results

Carlsson et al (2012) found pesticides in the water column of the Nûp Kangerdlua fjord branch. Similar results were expected in the sediment samples from the Godthåbsfjord, which is why DDT was included in the contaminant analysis. However, there was no evidence of DDT found in any of the sediment samples. The causes might be that DDT compounds are volatile (Spencer and Cliath, 1972) and thus might not attach to the sediment particles as easily as the other contaminants that were found. Another reason

100

might be the strong freshwater influx and the related estuarine circulation pattern that might transport the DDT compounds out of the fjord into the shelf and open ocean regions. This idea is strengthened by Mortensen et al (2011), who documented a strong circulation pattern the fjord as well as strong winds coming from the Greenland ice sheet. This could be the reason why not only DDT was not evident, but why the contamination concentration in general were quite low and even below detection limits (for most PAHs and PCBs) in the Godthåbsfjord sediments.

Another unexpected result is from the organotins (TBT, DBT, MBT, TTBT) that all together were at levels below the detection limit. Organotin compounds have been widely exploited over the last 60 years in agriculture, industry, and used as antifouling paint for shipping (Filipkowska, Kowalewska, and Pavoni, 2014). Due to the increased shipping and industry development in Nuuk organotin compounds were expected in the sediments. Although TBT is not as common in arctic marine sediments compared to sediments from lower latitudes with higher shipping activity, a study did confirm their evidence in coastal waters in Greenland, close to shipping lanes and harbours including Sisimiut harbour (Ottosen & Villumsen 2006). The organotins could have been transported to areas outside the Godthåbsfjord of the same current activity that was attributed to the non-deposition of the pesticides (Mortensen et al, 2011). Another theory might be that the organotins cannot bind to the coarse-grained sediment in the area they are most likely to occur, which is at Location 1 at Nuuk harbour.

6.5 Knowledge gaps, future research and management remarks

Although there are studies done on contaminants in the water column (Carlsson et al, 2012) and on contaminants found in marine sediments in Greenland (Ottosen & Villumsen 2006), there are few studies done to date that focus on the evidence and distribution of contaminants on and from the Greenland Ice Sheet. Having a better understanding of the range of contamination that is found on the Greenland ice sheet originating from precipitation and long-way atmospheric transport would support any research in contaminant studies in Greenland, as melting contaminants from the Greenland ice sheet are inevitably entering the surrounding fjords. Gaining knowledge in sedimentation rates

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(in cm/year) and mass accumulation rates (in g/m2/year) would also assist with furthering the research and quantifying the contaminant levels available from the Godthåbsfjord area.

Another recommendation is to investigate sediments of additional fjords connected to the Greenland ice sheet for similar parameters. As the Godthåbsfjord has deep sills and oxic sediments, doing a similar investigation in a neighbouring fjord with shallow sills and more anoxic sediments would improve the understanding of the particulate matter composition, contaminant distribution and the sources relating to their variations.

Although the contamination results in this thesis show low concentrations, heavy metals are found to be increasing towards the sediment surface, and as they are related to melting glaciers, this means that continued climate change and increased glacial melting might also increase the influx of contaminants, and particularly heavy metals into the fjord. Environmental monitoring is important for this reason, and a continued Environmental Impact Assessment (EIA) of contaminants in the fjord will give a better understanding of possible effects of the registered contaminants in the future. If the contaminants continue to increase, this might cause more serious pollution in the fjord and thus restrict traditional and recreational hunting and fishing.

An additional investigation in the Godthåbsfjord could be done on the effect of environmental and/or climate change on micro-organisms like diatoms (from the existing smear slides) or foraminifera.

Policy might need to be adapted to adhere to regulations if contamination progresses, such as precautions in fishing areas and hunting grounds. An important aspect of science communication is community outreach and engagement, so involving local stakeholders and people is vital for environmental studies. Having the local people and authorities informed of the contamination in the fjord and any on-going investigations is therefore strongly advised.

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7 Conclusion

The composition of particulate matter in Godthåbsfjord sediments has changed from a more coarse-grained composition to a more fine-grained composition with elevated terrestrial organic matter concentrations over the last decades.

This change in the sedimentary particulate matter composition is related to a shift in sources from more glacial runoff to more terrestrial runoff over the past decades.

Contaminant concentrations in the Godthåbsfjord sediments appear at slightly elevated but mainly non-polluting levels. The contaminant distribution varies in dependence of the particulate matter composition. The results indicate that contaminant concentration might rise to higher and even polluting levels if the particulate matter composition continues to change due to the described consequences of rising temperatures and precipitation.

This prediction suggests that the Godthåbsfjord sediments should be monitored continuously over the next decades to increase the awareness towards a possible future scenario of elevated contamination in this subarctic marine environment.

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References

Alley, R. B., Andrews, J. T., Brigham-Grette, J., Clarke, G. K. C., Cuffey, K. M., Fitzpatrick, J. J., Funder, S., Marshall, S. J., Miller, G. H., Mitrovica, J. X., Muhs, D. R., Otto-Bliesner, B. L., Polyak, L., & White, J. W. C. (2010). History of the Greenland Ice Sheet: paleoclimatic insights. Quaternary Science Reviews, 29(15–16), 1728–1756. https://doi.org/10.1016/j.quascirev.2010.02.007

AMAP, 2016. Chemicals of Emerging Arctic Concern Summary for Policy-makers (CEAC). CEAC Scientific Assessment Report, Programme (AMAP), Tromsø, Norway. vii+84pp (https://www.amap.no/documents/download/2890/inline)

AMAP, 2018. AMAP Assessment 2018: Biological Effects of Contaminants on Arctic Wildlife and Fish. Arctic Monitoring and Assessment Programme (AMAP), Tromsø, Norway. vii+84pp (https://www.amap.no/documents/download/3080/inline)

Andrews, J. T., Milliman, J. D., Jennings, A. E., Rynes, N., & Dwyer, J. (1994). Sediment thicknesses and Holocene Glacial Marine sedimentation rates in Three EAST Greenland Fjords (CA. 68°N). The Journal of Geology, 102(6), 669-683. doi:10.1086/629711

Ann Eileen Lennert, PhD 2017, A Millennium of Changing Environments in the Godthåbsfjord, West Greenland, Bridging cultures of knowledge. 10.13140/RG.2.2.16091.36640Arndt, N.T. (1991): High Ni in Archean tholeiites. Technophysics 187 (4), 411-419. https://doi.org/10.1016/0040-1951(91)90479-C

Aoki, S., Kabashima, C., Kato, Y., Hirata, T., & Komiya, T. (2018). Influence of contamination on banded iron formations in the Isua supracrustal belt, West Greenland: Reevaluation of the Eoarchean seawater compositions. Geoscience Frontiers, 9(4), 1049–1072. https://doi.org/10.1016/j.gsf.2016.11.016

Aschwanden, A., Fahnestock, M. A., Truffer, M., Brinkerhoff, D. J., Hock, R., Khroulev, C., … Khan, S. A. (2019, June 1). Contribution of the Greenland Ice Sheet to sea level over the next millennium. Retrieved from https://advances.sciencemag.org/content/5/6/eaav9396

Auger, J. D., Birkel, S. D., Maasch, K. A., Mayewski, P. A., & Schuenemann, K. C. (2017). Examination of Precipitation variability in southern Greenland. Journal of Geophysical Research: Atmospheres, 122(12), 6202-6216. doi:10.1002/2016jd026377

Austin, W. E., Howe, J. A., Forwick, M., & Paetzel, M. (2010). Fjord systems and archives: An introduction. Geological Society, London, Special Publications, 344(1), 1-3. doi:10.1144/sp344.1

Bakke, J., Nesje, A. (2011) Equilibrium-Line Altitude (ELA). In: Singh V.P., Singh P., Haritashya U.K. (eds) Encyclopedia of Snow, Ice and Glaciers. Encyclopedia of Earth Sciences Series. Springer, Dordrecht. https://doi.org/10.1007/978-90-481-2642-2_140

Bendtsen, J., Mortensen, J., Lennert, K., & Rysgaard, S. (2015). Heat sources for glacial ice melt in a west Greenland TIDEWATER outlet glacier fjord: The role of SUBGLACIAL

104

freshwater discharge. Geophysical Research Letters, 42(10), 4089-4095. doi:10.1002/2015gl063846

Bianchi, T.S., Arndt, S., E.N, W., Douglas, A, I., Benn, Bertrand, S., Cui, X., Faust, J, C., Koziorowska-Makuch, K., Moy, C, M., Savage, C., Smeaton, C., Smith, R, W., Syvitski, J. Fjords as Aquatic Critical Zones (ACZs), Earth-Science Reviews,Volume 203, 2020, 103145, ISSN 0012-8252, https://doi.org/10.1016/j.earscirev.2020.103145.

Blasting. (2017). Retrieved March 2020, from https://www.sikuki.com/expansion/blasting/ Boberg, F., Langen, P., Mottram, R., Christensen, J., Olesen, M. (2018). 21st Century Climate Change around Kangerlussuaq, West Greenland: From the Ice Sheet to the Shores of Davis Strait. (Figure 5, Map figure) Arctic Antarctic and Alpine Research. 50. 10.1080/15230430.2017.1420862. Bogdal, C., Schmid, P., Zennegg, M., Anselmetti, F. S., Scheringer, M., & Hungerbühler, K. (2009). Blast from the Past: Melting Glaciers as a relevant source for persistent organic pollutants. Environmental Science & Technology, 43(21), 8173-8177. doi:10.1021/es901628x

Boulton, G. (1996). Theory of glacial erosion, transport and deposition as a consequence of subglacial sediment deformation. Journal of Glaciology, 42(140), 43-62. doi:10.3189/S0022143000030525 Boutron C.F., Görlach U. (1990) The occurrence of heavy metals in Antarctic and Greenland ancient ice and recent snow. In: Broekaert J.A.C., Güçer Ş., Adams F. (eds) Metal Speciation in the Environment. NATO ASI Series (Series G: Ecological Sciences), vol 23. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-74206-4_9 Boutron, C. F., Candelone, J.-P., & Hong, S. (1999, December 27). Greenland snow and ice cores: unique archives of large-scale pollution of the troposphere of the Northern Hemisphere by lead and other heavy metals. Retrieved from https://www.sciencedirect.com/science/article/pii/0048969795043599

Brescia, F. (1975). Fundamentals of chemistry laboratory studies. In Fundamentals of chemistry laboratory studies. New York: Academic Press.

Briner, J.P., Cuzzone, J.K., Badgeley, J.A. et al. Rate of mass loss from the Greenland Ice Sheet will exceed Holocene values this century. Nature 586, 70–74 (2020). https://doi.org/10.1038/s41586-020-2742-6

Carlson, D. F., Boone, W., Meire, L., Abermann, J., & Rysgaard, S. (2017). Bergy Bit and Melt Water Trajectories in Godthåbsfjord (SW Greenland) Observed by the Expendable Ice Tracker. Frontiers in Marine Science, 4. doi:10.3389/fmars.2017.00276

Carlsson, P., Cornelissen, G., Rysgaard, S., Bøggild, C., Mortensen, J., Kallenborn, R. (2012). Hydrology-linked spatial distribution of pesticides in a fjordsystem in Greenland. Journal of Environmental Monitoring. 10.1039/c2em30068k.

105

Carpenter D. O. (2006). Polychlorinated biphenyls (PCBs): routes of exposure and effects on human health. Reviews on environmental health, 21(1), 1–23. https://doi.org/10.1515/reveh.2006.21.1.1

Chapman, P.M. (2007): Determining when contamination is pollution — Weight of evidence determinations for sediments and effluents. Environment International 33 (4), 492-501.

Chart of heavy metals, their salts and other compounds. (n.d.). Retrieved March 13, 2021, from https://www.culturalheritage.org/docs/default-source/resource-guides/chart-of-heavy- metals-their-salts-and-other-compounds-nbsp-.pdf

Citterio, M., Sejr, M.K., Langen, P.L. et al. Towards quantifying the glacial runoff signal in the freshwater input to Tyrolerfjord–Young Sound, NE Greenland. Ambio 46, 146–159 (2017). https://doi.org/10.1007/s13280-016-0876-4

Dai, A., Luo, D., Song, M., & Liu, J. (2019, January 10). Arctic amplification is caused by sea-ice loss under increasing CO 2. Retrieved from https://www.nature.com/articles/s41467-018- 07954-9

Delaney, I., & Adhikari, S. (2020). Increased subglacial sediment discharge in a warming climate: Consideration of ice dynamics, glacial erosion, and fluvial sediment transport. Geophysical Research Letters, 47, e2019GL085672. https://doi.org/10.1029/2019GL085672

Desloges, J. R., Gilbert, R., Nielsen, N., Christiansen, C., Rasch, M., & Øhlenschläger, R. (2002). Holocene glacimarine sedimentary environments In fiords of Disko Bugt, West Greenland. Quaternary Science Reviews, 21(8-9), 947-963. doi:10.1016/s0277- 3791(01)00049-x

Drewnik, A., Węsławski, J.M., Włodarska-Kowalczuk, M. et al. From the worm’s point of view. I: Environmental settings of benthic ecosystems in Arctic fjord (Hornsund, Spitsbergen). Polar Biol 39, 1411–1424 (2016). https://doi.org/10.1007/s00300-015-1867-9

Duarte, P., Weslawski, J. M., & Hop, H. (2019). Outline of an Arctic fjord Ecosystem Model for Kongsfjorden-Krossfjorden, Svalbard. The Ecosystem of Kongsfjorden, Svalbard, 485– 514. https://doi.org/10.1007/978-3-319-46425-1_12

Dyke, L.M., Hughes, L.C. A., Murray, T., Hiemstra, J.F., Andresen, C.S., Rodés, Á. Evidence for the asynchronous retreat of large outlet glaciers in southeast Greenland at the end of the last glaciation, Quaternary Science Reviews, Volume 99, 2014, Pages 244-259, ISSN 0277-3791, https://doi.org/10.1016/j.quascirev.2014.06.001.

Dzik, T, January 2-17 Settlement closure or persistence: A comparison of Kangeq and Kapisillit, Greenland. Researchgate publications. DOI: 10.19188/01JSSP022016

Eisted, R., & Christensen, T. H. (n.d.). Waste management in Greenland: current situation and challenges - Rasmus Eisted, Thomas H. Christensen, 2011. Retrieved from https://journals.sagepub.com/doi/abs/10.1177/0734242x10395421

Ekman, V.W. (1905) On the influence of the earth’s rotation on ocean-currents. Arkiv för Matematik, Astronomi och Fysik 2 (11), 1-53.

106

Eurofins Report, (2021) Analytical Methods. https://www.eurofins.fi/environmentandindustry/exploration-and-mining/analytical- methods/

Evidence for the asynchronous retreat of large outlet glaciers in southeast Greenland at the end of the last glaciation (geology map). Quaternary Science Reviews, Volume 99, 2014, Pages 244-259, ISSN 0277-3791, https://doi.org/10.1016/j.quascirev.2014.06.001.

Filipkowska, A., Kowalewska, G., & Pavoni, B. (2014). Organotin compounds in surface sediments of the Southern Baltic coastal zone: a study on the main factors for their accumulation and degradation. Environmental science and pollution research international, 21(3), 2077–2087. https://doi.org/10.1007/s11356-013-2115-x

Funder, S., 1989d. Sea level history. In: Fulton, R.J. (Ed.), Quaternary Geology of Canada and Greenland. Geological Survey of Canada (Chapter 13), Geology of Canada, no. 1, 839 pp.; also Geological Society of America, the Geology of North America K-1, pp. 772e774.

Gibbs R. J. (1973). Mechanisms of trace metal transport in rivers. Science (New York, N.Y.), 180(4081), 71–73. https://doi.org/10.1126/science.180.4081.71

Gilbert, R., Nielsen, N., Desloges, J. R., Rasch, M. (1998). Contrasting glacimarine sedimentary environments of two arctic FIORDS on Disko, West Greenland. Marine Geology, 147(1- 4), 63-83. doi:10.1016/s0025-3227(98)00008-5

Gipperth L. (2009). The legal design of the international and European Union ban on tributyltin antifouling paint: Direct and indirect effects, Journal of Environmental Management https://doi.org/10.1016/j.jenvman.2008.08.013 Graly, J. A., Humphrey, N. F., Landowski, C. M., & Harper, J. T. (2014). Chemical weathering under the Greenland ice sheet. Geology, 42(6), 551-554. doi:10.1130/g35370.1 Greenland Economy 2020. (2020). Retrieved January 2020, from https://theodora.com/wfbcurrent/greenland/greenland_economy.html Hågvar, S. (2012): Primary succession in glacial forelands: How small animals conquer new land around melting glaciers. In: SS Young & SE Silvern (eds) International Perspectives of Global Environmental Change. Intech Open Access Publisher, 151-172. DOI: 10.5772/26536 Haldorsen, S. (1981): Grain-size distribution of subglacial till and its relation to glacian crushing and abrasion. Boreas 10, 91-105. DOI: 10.1111/j.1502-3885.1981.tb00472.x

Hansen, D.V., & Rattray, M., (1965): Gravitational circulation in straits and estuaries. Journal of Marine Research 23, 104-122. https://digital.lib.washington.edu/researchworks/bitstream/handle/1773/16068/M66- 76.pdf?sequence=1&isAllowed=y

Hauptmann, A. L., Sicheritz-Pontén, T., Cameron, K. A., Bælum, J., Plichta, D. R., Dalgaard, M., & Stibal, M. (2017). Contamination of the ARCTIC reflected in microbial metagenomes from the Greenland ice sheet. Environmental Research Letters, 12(7), 074019. doi:10.1088/1748-9326/aa7445

107

Henriksen, N. (2008). Geological history of Greenland: Four billion years of earth revolution. Copenhagen: GEUS.

Higueras, P.L., Sáez-Martínez, F.J. & Reyes-Bozo, L. Characterization and remediation of contamination: the influences of mining and other human activities. Environ Sci Pollut Res 23, 5997–6001 (2016). https://doi.org/10.1007/s11356-016-6388-8

ISUA iron Ore project oil and chemicals and assessment of ... (n.d.). Retrieved March 13, 2021, from https://naalakkersuisut.gl/~/media/Nanoq/Files/Hearings/2012/London%20Mining%20ISU A/Bilag%206%20engelsk.pdf

Jan, A. T., Azam, M., Siddiqui, K., Ali, A., Choi, I., & Haq, Q. M. (2015). Heavy Metals and Human Health: Mechanistic Insight into Toxicity and Counter Defense System of Antioxidants. International journal of molecular sciences, 16(12), 29592–29630. https://doi.org/10.3390/ijms161226183

Juul-Pedersen, T., Arendt, K., Mortensen, J., Blicher, M., Søgaard, D., & Rysgaard, Søren. (2015). Seasonal and interannual phytoplankton production in a sub-Arctic tidewater outlet glacier fjord, SW Greenland. (basemap) Marine Ecology Progress Series. 524. 10.3354/meps11174.

Juul-Pedersen. T, (2020). Nuup Kangerlua – Exploration of an Arctic fjord. Greenland Climate Research Centre, Greenland Institute of Natural Resources.

Kang, S., Zhang, Q., Qian, Y., Ji, Z., Li, C., Cong, Z., . . . Qin, D. (2019). Linking atmospheric pollution to cryospheric change in the third POLE region: Current progress and future prospects. National Science Review, 6(4), 796-809. doi:10.1093/nsr/nwz031

King, M.D., Howat, I.M., Candela, S.G. et al. Dynamic ice loss from the Greenland Ice Sheet driven by sustained glacier retreat. Commun Earth Environ 1, 1 (2020). https://doi.org/10.1038/s43247-020-0001-2

Koller, M., Saleh, H.M., (June 27th 2018). Introductory Chapter: Introducing Heavy Metals, Heavy Metals, HS, RA, (Saleh & Aglan), Heavy Metals, chapter 1. IntechOpen, DOI: 10.5772/intechopen.74783. Available from: https://www.intechopen.com/books/heavy- metals/introductory-chapter-introducing-heavy-metals

Koyama, T., & Stroeve, J. (2019). Greenland monthly PRECIPITATION analysis from the ARCTIC SYSTEM REANALYSIS (ASR): 2000–2012. Polar Science, 19, 1-12. doi:10.1016/j.polar.2018.09.001

Krawczyk, D.W. 2019 hydrographic survey of Godthåbsfjord system (baseline bathymetry map) Greenland Climate Research Centre, Greenland Institute of Natural Resources.

Krawczyk, D.W. 2020 hydrographic survey of Godthåbsfjord system (bathymetry map) Greenland Climate Research Centre, Greenland Institute of Natural Resources.

Lamprecht, M., Paul Ellis, P. (March, 2020). Manfred Momberger, Airport Development International News. Retrieved March 11, 2021, from http://www.mombergerairport.info/file.aspx?id=385cbf00-a3c0-4fff-86cd-a4c7ede4aed8

108

Langen, P. L., Mottram, R. H., Christensen, J. H., Boberg, F., Rodehacke, C. B., Stendel, M., . . . Cappelen, J. (2015). Quantifying energy and MASS fluxes Controlling Godthåbsfjord Freshwater input in a 5-km SIMULATION (1991–2012) (graphs). Journal of Climate, 28(9), 3694-3713. doi:10.1175/jcli-d-14-00271.1

Lumholt M., Visit Greenland, (May 2020). Tourism Statistics Report 2019 Capital Region, Tourism Statistics, Visit Greenland. Retreived from: http://www.tourismstat.gl/resources/reports/en/r31/Tourism%20Statistics%20Report%20G reenland%202019.pdf

McConnell, J. R., Edwards, R. (2008). Coal burning leaves toxic heavy Metal legacy in the Arctic. Proceedings of the National Academy of Sciences, 105(34), 12140-12144. doi:10.1073/pnas.0803564105

Medeiros P.M. (2018) Gas Chromatography–Mass Spectrometry (GC–MS). In: White W.M. (eds) Encyclopedia of Geochemistry. Encyclopedia of Earth Sciences Series. Springer, Cham. https://doi.org/10.1007/978-3-319-39312-4_159

Miljødirektoratet (2016), Grenseverdier for klassifisering av vann, sediment og biota – revidert 30.10.2020. VEILEDER, M-608 | 2016.

Miller, K.G., Fairbanks, R.G,, Mountain, G.S. (1987): Tertiary oxygen isotope synthesis, sea level history, and continental margin erosion. Paleoceanography and Paeoclimatology 2 (1), 1- 19.

Milner, A. M., Khamis, K., Battin, T. J., Brittain, J. E., Barrand, N. E., Füreder, L., . . . Brown, L. E. (2017). Glacier shrinkage driving global changes in downstream systems. Proceedings of the National Academy of Sciences, 114(37), 9770-9778. doi:10.1073/pnas.1619807114

Mohan, M., Sreelakshm, U., Sagar, V., Gopikrishna, V.G., Pandit, G., Sahu, S., Tiwari, M., Ajmal, P.Y., Kannan, V.M., Shukkur, M., & Krishnan, K.P.. (2018). Rate of sediment accumulation and historic metal contamination in a tidewater glacier fjord, Svalbard. Marine Pollution Bulletin. 131. 10.1016/j.marpolbul.2018.04.057.

Møller, H. S., Jensen, K. G., Kuijpers, A., Aagaard-Sørensen, S., Seidenkrantz, M., Prins, M., . . . Mikkelsen, N. (2006). Late-Holocene environment and climatic changes IN Ameralik fjord, Southwest Greenland: Evidence from the sedimentary record. The Holocene, 16(5), 685-695. doi:10.1191/0959683606hl963rp

Moorbath, S. (2009): The discovery of the Earth's oldest rocks. Notes and Records of The Royal Society, 63 (4), 381-392. https://doi.org/10.1098/rsnr.2009.0004

Mortensen, J., Bendtsen, J., Lennert, K., & Rysgaard, S. (2014): Seasonal variability of the circulation system in a west Greenland tidewater outlet glacier fjord, Godthåbsfjord (64°N). Journal of Geophysical Research: Earth Surface 119, 2591–2603. doi:10.1002/2014JF003267

Mortensen, J., Lennert, K., Bendtsen, J., & Rysgaard, S. (2011). Heat sources for glacial melt in A Sub-arctic fjord (GODTHÅBSFJORD) in contact with the Greenland ice sheet. Journal of Geophysical Research, 116(C1). doi:10.1029/2010jc006528

109

Mortensen, J., Rysgaard, S., Bendtsen, J., Lennert, K., Kanzow, T., Lund, H., & Meire, L. (2020). Subglacial discharge and its down‐fjord transformation in West Greenland fjords with an ice mélange. Journal of Geophysical Research: Oceans, 125, e2020JC016301. https://doi.org/10.1029/2020JC016301

Motyka, R. J., Cassatto, R., Truffer, M., Kjeldsen, K. K., Van, AS, D., Korsgaard, N. J., . . . Rysgaard, S. (2017). Asynchronous behavior of outlet glaciers feeding godthåbsfjord (Nuup KANGERLUA) and the triggering OF NARSAP Sermia's retreat in SW Greenland. Journal of Glaciology, 63(238), 288-308. doi:10.1017/jog.2016.138

Myers, S. J. (2001). Protoliths of the 3.8–3.7 Ga Isua greenstone belt, West Greenland, Precambrian Research, (map) Volume 105, Issues 2–4. Pages 129-141, ISSN 0301-9268, https://doi.org/10.1016/S0301-9268(00)00108-X.

NPIC, (1999). DDT Fact Sheet. http://npic.orst.edu/factsheets/ddtgen.pdf

Offentlig høring om rapporterne Vurdering af Virkninger på Miljøet og Vurdering af Samfundsmæssig Bæredygtighed, som er udarbejdet i forbindelse med London Mining Greenland A/S' ansøgning om udnyttelsestilladelse til et jernmineprojekt ved Nuuk. (n.d.). Retrieved January 07, 2021, from https://naalakkersuisut.gl/da/H%c3%b8ringer/Arkiv- over-h%c3%b8ringer/2012/London-Mining-ISUA

Ottosen, L. M., Villumsen, A. (2006). High cu and Cd pollution in sediments from Sisimiut, Greenland. ADSORPTION to organic matter and fine particles. Environmental Chemistry Letters, 4(4), 195-199. doi:10.1007/s10311-006-0045-2

Overland, J., Dunlea, E., Box, J.E., Corell, R., Forsius, M., Kattsov, V., Olsen, M.S., Pawlak, J., Reiersen, L.O., Wang, M.(2019). The urgency of Arctic change, Polar Science,Volume 21, 2019, Pages 6-13, ISSN 1873-9652, https://doi.org/10.1016/j.polar.2018.11.008.

Padma, T. V. (2015, December 28). Pollutants buried under glaciers surface to haunt India. Retrieved from https://www.thethirdpole.net/en/2015/09/22/pollutants-buried-under- glaciers-surface-to-haunt-india/

Paetzel, M., Nes, G., Leifsen, L., Schrader, H. (2003). Sediment pollution in The vågen, BERGEN HARBOUR, NORWAY. Environmental Geology, 43(4), 476-483. doi:10.1007/s00254- 002-0662-4

Paetzel, M., & Schrader, H. (1992). Recent environmental changes recorded in anoxic Barsnesfjord sediments: Western Norway. Marine Geology, 105(1-4), 23–36. https://doi.org/10.1016/0025-3227(92)90179-l

Paetzel, M., Schrader, H., & Bjerkli, K (1994a): Do decreased trace metal concentrations in surficial Skagerrak sediments over the last 15-30 years indicate decreased pollution? Environmental Pollution 84, 213-226.

Paetzel, M., Schrader, H., Croudace, I. (1994b): Sewage history in the anoxic sediments of the fjord Nordåsvatnet, western Norway: (I) dating and trace-metal accumulation. The Holocene 4 (3), 290-298.

110

Pedersen, K.B., Lejon, T., Jensen, P.E. et al. Chemometric Analysis for Pollution Source Assessment of Harbour Sediments in Arctic Locations. Water Air Soil Pollut 226, 150 (2015). https://doi.org/10.1007/s11270-015-2416-4

Perner, K., Leipe, T.H., Dellwig, O., Kuijpers, A., Mikkelsen, N., Andersen, T.J., Harff, J. Contamination of arctic Fjord sediments by Pb–Zn mining at Maarmorilik in central West Greenland, Marine Pollution Bulletin, Volume 60, Issue 7, 2010, Pages 1065-1073, ISSN 0025-326X, https://doi.org/10.1016/j.marpolbul.2010.01.019. (https://www.sciencedirect.com/science/article/pii/S0025326X10000378)

Plante, A., & Conant, R. T. (2014). Soil organic Matter dynamics, climate change effects. Global Environmental Change, 317-323. doi:10.1007/978-94-007-5784-4_3

Pritchard, D.W. (1952): Salinity distribution and circulation in the Chesapeake Bay estuaries system. Journal of Marine Research 11, 106–123. https://images.peabody.yale.edu/publications/jmr/jmr11-02-02.pdf

Redfield, A.C (1934) On the proportions of organic derivates in sea water and their relation to the composition of plankton. James Johnstone Memorial Volume, University Press Liverpool, 176-192.

Ren, J., Jiang, H., Seidenkrantz, M.-S., & Kuijpers, A. (2009). A diatom-based reconstruction of Early Holocene hydrographic and climatic change in a southwest Greenland fjord. Marine Micropaleontology, 70(3-4), 166–176. https://doi.org/10.1016/j.marmicro.2008.12.003

Robbins L.J., Mänd K., Planavsky N.J., Alessi D.S., Konhauser K.O. (2020) Trace Metals. In: Gargaud M. et al. (eds) Encyclopedia of Astrobiology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-27833-4_5422-1

Rothman, H.D., (2002): Atmospheric carbon dioxide levels for the last 500 million years. Proceedings of the National Academy of Science (PNAS USA) 99 (7), 4167-4171.

Rothwell, R.G. (1989) Chp 2, pg 21/22, Minerals and Mineraloids in Marine Sediments An Optical Identification Guide. https://www.springer.com/gp/book/9789401070027

Salomons, W. (1988). Pollution of the North Sea: An assessment. Berlin: Springer-Verlag. 200pp- 220pp ISBN 978-3-642-73709-1. https://www.springer.com/gp/book/9783642737114

Seidenkrantz, M.-S., Ebbesen, H., Aagaard-Sørensen, S., Moros, M., Lloyd, J. M., Olsen, J., Knudsen, M. F., & Kuijpers, A. (2013). Early Holocene large-scale meltwater discharge from Greenland documented by foraminifera and sediment parameters. Palaeogeography, Palaeoclimatology, Palaeoecology, 391, 71–81. https://doi.org/10.1016/j.palaeo.2012.04.006

Sigman, D.M., & Hain, M.P. (2012): The Biological Productivity of the Ocean. Nature Education 3 (6), 1-16. https://www.nature.com/scitable/knowledge/library/the-biological- productivity-of-the-ocean-section-70631438/

Spencer, W. F., Cliath, M. M. (1972). Volatility of ddt and related compounds. Journal of Agricultural and Food Chemistry, 20(3), 645-649. doi:10.1021/jf60181a057

111

Steinberger, B., Spakman, W., Japsen, P., & Torsvik, T. H. (2015). The key role of GLOBAL solid-Earth processes IN preconditioning greenland's GLACIATION since the Pliocene. Terra Nova, 27(1), 1-8. doi:10.1111/ter.12133

Syvitski, J., Burrell, D., & Skei, J., (1986): Fjords – processes and products. Springer Verlag New York, 379pp. https://www.springer.com/gp/book/9781461246329

Tchounwou, P. B., Yedjou, C. G., Patlolla, A. K., & Sutton, D. J. (2012). Heavy metal toxicity and the environment. Experientia supplementum (2012), 101, 133–164. https://doi.org/10.1007/978-3-7643-8340-4_6

The IMBIE Team., Shepherd, A., Ivins, E. et al. Mass balance of the Greenland Ice Sheet from 1992 to 2018. Nature 579, 233–239 (2020). https://doi.org/10.1038/s41586-019-1855-2

Yao, T., Thompson, L., Chen, D., Zhang, Y., et al. Third pole climate warming and cryosphere system changes. (2020, April 23). Retrieved March 11, 2021, from https://public.wmo.int/en/resources/bulletin/third-pole-climate-warming-and-cryosphere- system-changes

Tissot, B., Pelet, R., (1981). Sources and fate of organic matter in ocean sediments. Institut Français du Pétrole. 1 ct 4, Ivenue de Bois-Préau . 92506 Rueil-Malmaison Cedex. France. https://archimer.ifremer.fr/doc/00246/35680/34188.pdf

Topas. (2018, December 13). Map central greenland. Retrieved March 14, 2021, from https://www.greenlandbytopas.com/map-central-greenland/

Udden, J.A. (1914) Mechanical composition of clastic sediments. Bulletin of the Geological Society of America 25, 655-744

Van As, D., Andersen, M., Petersen, D., Fettweis, X., Van Angelen, J., Lenaerts, J., Steffen, K. (2014). Increasing meltwater discharge from the Nuuk region of the Greenland ice sheet and implications for mass balance (1960–2012). Journal of Glaciology, 60(220), 314-322. doi:10.3189/2014JoG13J065

Van Veen, J. (1933) Onderzoek naar het zandtransport van rivieren. De Ingenieur 48 (27), 151- 159.

Van Vuuren, D. P., Edmonds, J., Kainuma, M., Riahi, K., Thomson, A., Hibbard, K., Rose, S. K. (2011). The representative concentration pathways: An overview. Climatic Change, 109(1- 2), 5-31. doi:10.1007/s10584-011-0148-z

Wadham, J.L., Hawkings, J.R., Tarasov, L. et al. Ice sheets matter for the global carbon cycle. Nat Commun 10, 3567 (2019). https://doi.org/10.1038/s41467-019-11394-4

Walsh, J. E., Overland, J. E., Groisman, P. Y., & Rudolf, B. (2011). Ongoing Climate Change in the Arctic. Ambio, 40(Suppl 1), 6–16. https://doi.org/10.1007/s13280-011-0211-z

Wang, Lu, Mao, Boyu, Huixin, Yu, … Jing. (2018, October 26). Comparison of hepatotoxicity and mechanisms induced by triclosan (TCS) and methyl-triclosan (MTCS) in human liver hepatocellular HepG2 cells. Retrieved from https://academic.oup.com/toxres/article/8/1/38/5553383

112

Wentworth, C.K. (1922) A scale of grade and class terms for clastic sediments. The Journal of Geology 30, 377–392

Yoshihiko, O., Takahiro, I., Shin, S., & Shigeru, A. (2016): Spatial and temporal variations in high turbidity surface water off the Thule region, northwestern Greenland. Polar Science 10, 270-277. https://doi.org/10.1016/j.polar.2016.07.003.

Zhu, H., Bing, H., Yi, H., Wu, Y., Sun, Z. (2018). Spatial distribution and CONTAMINATION assessment of heavy metals in Surface sediments of THE caofeidian adjacent sea after the land Reclamation, Bohai Bay. Journal of Chemistry, 2018, 1-13. doi:10.1155/2018/2049353

Zaborska, Agata & Pempkowiak, Janusz & Papucci, Carlo. (2006). Some Sediment Characteristics and Sedimentation Rates in an Arctic Fjord (Kongsfjorden, Svalbard). Annu Environ Prot. 8.

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Appendix A

Table A: Original report from survey from the Godthåbsfjord includingtime (UTC) location numbers, position in latitude (in degrees north) and longitude (in degrees west), sediment type, water depth of the box grab sample (in meter), sediment core ID (double letter) and length (in cm), sediment fragment sequence (in cm), and the depth of the contaminant subsamples (in cm) with additional comments on the right.

UTC Station Latitude Longitude Sample Sediment depth Core sample comments time no. taken type 11.35 8b 64˚27’024 50˚40’473 8b1 muddy 180m 0-2cm

8b2 2-4cm 11.48 8c 64˚26’813 50˚39’733 8c1 muddy 180m 0-2cm

8c2 2-4cm 12.46 9a 64˚24’451 50˚24’963 Surface 260m GG mixed 0-10cm 13.03 9b 64˚24’432 50˚25’254 9b1 Gravel 262m 0-2cm mud

9b2 2-4cm 13.17 9c 64˚24’562 50˚24’755 9c1 257m 0-2cm

9c2 2-4cm 15.24 10a 64˚24’900 50˚18’263 10a1 0- muddy 234m HH 2cm 0-15cm

10a2 2- 4cm 15.40 10b 64˚24’916 50˚18’350 10b1 0- muddy 233m 2cm

10b2 2- 4cm 15.55 10c 64˚24’907 50˚18’399 10c1 muddy 235m 0-2cm

10c2 2-4cm Day5 114 9.38 11a 51˚16’997 51˚04’187 11a1 0- Gravelly 229m 11,1-11,7 2cm mud 2cm fragments 11a2 2- 4cm

Appendix B

The following figure (B) displays single graphs plotting all individual grain sizes for mineral matter content including sand, coarse silt, medium silt, fine silt, very fine silt and clay. Each graph also includes trend lines using linear regression with the regression formula included. The order is location 1, 4, 5 ,6 8, 10 and 12.

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Figure B: Sediment grain sizes of all locations presenting the graphs of the all individual grain sizes used in this investigation. Sediment depth is in cm; mineral grain size classes are presented as percentage concentrations. Weak stippled lines are statistic trend lines from linear regression, with the regression formulas indicated within the respective graphs.

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Appendix C

The figure below (C1) represents contamination graphs for all locations. Each location starts with mineral grains grouped in two: medium and fine silt, and very fine silt and clay versus heavy metals. The second graph is of sand mineral versus heavy metals, and the third graph is of heavy metals versus organic matter. The last three graphs are of PCB and PAH comparisions from location 10. The first two graphs compare marine organic matter, terrestrial organic matter, PAH16 and PCB7. The last graph displays PAH16 and PCB7 alone.

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Figure C1: Contamination graphs the Godthåbsfjord sediment record at all locations. First comparision (per location) is of medium grains, fine grains and heavy metals. Second graph (per location) is a comparison of sand grains versus heavy metals. Third graph (per location) is a comparison of heavy metals versus organic matter. The last three graphs are comparisons of PAH16 and PCB7 found at location 10. These comparisons are made together with marine organic matter and terrestrial organic matter for the first two graphs, with the last graph comparing PAH16 and PCB7. Sediment depth is in cm; mineral grain size classes are presented as percentage concentrations. Weak stippled lines are statistic trend lines from linear regression, with the regression formulas indicated within the respective graphs. Red and blue squares represent heavy metals, green squares represent PCB7, purple triangles represent PAH16, orange lines represnt medium and fine grain sizes, or organic matter, green line represents sand.

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Figure C2: graphs plotting different parameters together starting with mineral grain sizes (medium silt and fine silt) and fine grain size (very fine silt and clay) with heavy metals. Orange line represents grain sizes, red boxes represents heavy metals. Graphs are for all locations. Next is terrestrial organic matter plotted against marine organic matter, PAH and PCB7 at location 10. PAH is in purple triangle, and PCB is in green squares. After that is marine organic matter versus terrestrial organic matter graphs, marine matter is in blue with terrestrial organic matter in orange.

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Figure C3: PCB compounds at all locations, at surface 0-2cm and subsurface 2-4cm samples. Measured in mg/kg of dry matter Results that are in white show levels under detection limit, which are indicated without colour coding. Green indicates polluting levels at minor effects. Total PCB7 are seen on the right

Table C4 shows the levels of each heavy metal found in surface (0-2cm) and subsurface (2-4cm) sediments, with the sum of all heavy metal concentrations on the right side of the table. All locations are included in this figure. No colour code represents concentrations that were below detection limit, blue colour indicates natural background level, green indicates elevated pollutant, and yellow indicates polluted with chronic effects.

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Table C4: contamination levels of each heavy metals found in surface 0-2cm and subsurface 2-4cm for all locations. The total contamination is found at the right. The blue colour indicates natural background level of contaminants was found. Green indicates elevated pollutant, and yellow indicates polluted with chronic effects.

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Figure C5 displays the results for organic tin at each sediment location, with measurements of microgram per kilogram of dry matter. All results show values that are under detection limit, and thus no colour coding is necessary.

Figure C5: organic tin compounds at all locations, at surface 0-2cm and subsurface 2-4cm samples. Measured in µg/kg of dry matter Results show below background levels, which are indicated without colour coding.

Pesticides (DDT) are displayed below (Table C6) showing all results that were found. Results are under the detection limit at all locations. This is represented in the colour coding, as there are no colours from the contamination colour code above.

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Table C6: pesticides compounds at all locations, at surface 0-2cm and subsurface 2-4cm samples. Measured in mg/kg of dry matter Results show below background levels, which are indicated with no colour coding. All pesticide compounds are listed on the left, with values according to each location to the right of them. Location numbers listed at the top.

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Appendix D

The figure below (D) is a copy of the Eurofins Finland contamination report.

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Figure D: analytical contamination report from Eurofins Finland including laboratories information, overview of methods, overview of subsamples and results of contaminants.

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Appendix E

The following figure (E) is of the Norwegian classification of contaminants formarine sediments.

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Figure E: Norwegian classification of contaminants in marine sediments according to Miljødirektoratet (2016).

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