Release of dissolved organic carbon from coastal erosion into the southern Canadian Beaufort Sea Master thesis to attain the academic degree Master of Science in Geography Submitted by George Tanski born on the 10th of July 1986 in Potsdam, Germany Freie Universität Berlin Institute for Geographical Science Berlin, June 2013 1. Gutachter Prof. Dr. Karl-Tilman Rost Freie Universität Berlin Institut für Geographische Wissenschaften Malteserstr. 74-100, 14195 Berlin 2. Gutachter Prof. Dr. Hans-Wolfgang Hubberten Alfred-Wegener-Institut für Polar- und Meeresforschung Telegrafenberg A43, 14473 Potsdam Für meine Familie. „Was wir wissen ist ein Tropfen, was wir nicht wissen ein Ozean.“ Isaac Newton Contents List of figures.................................................................................................... I List of tables ................................................................................................... III Abbreviations and nomenclature .................................................................. IV Abstract............................................................................................................ 1 Kurzfassung .................................................................................................... 3 1 Introduction ................................................................................................. 5 1.1 State of the Art ....................................................................................... 5 1.2 Aims & Objectives ................................................................................ 11 1.3 Project framework ................................................................................ 11 2 Geographical and geological background .............................................. 12 2.1 The periglacial environment ................................................................. 12 2.2 Permafrost ........................................................................................... 12 2.3 Ground ice ........................................................................................... 14 2.4 Thermokarst and coastal erosion ......................................................... 16 2.5 Dissolved organic carbon and the Arctic organic carbon cycle ............. 19 2.6 Study area and regional setting ............................................................ 21 2.6.1 Yukon Coastal Plain ................................................................. 21 2.6.2 Permafrost and geomorphology ................................................ 22 2.6.3 Climate ..................................................................................... 24 2.6.4 Vegetation ................................................................................ 25 2.6.5 Study sites ................................................................................ 26 3 Methods ..................................................................................................... 27 3.1 Field Work ............................................................................................ 28 3.1.1 Preprocessing at the Cold lab ................................................... 29 3.1.2 Hydrochemical analyses ........................................................... 29 3.1.3 pH measurement ...................................................................... 30 3.1.4 Electrical conductivity measurement ......................................... 30 3.1.5 Determination of DOC .............................................................. 30 3.2 Ice content ........................................................................................... 34 3.3 Mapping and spatial distribution of massive ground ice ........................ 35 3.3.1 Volume of ice wedges ............................................................... 37 3.3.2 Volume of massive ice bodies .................................................. 38 3.4 Estimation of dissolved organic carbon stocks ..................................... 39 3.5 Calculation of DOC fluxes .................................................................... 40 4 Results ....................................................................................................... 41 4.1 Permafrost profiles and hydrochemical characteristics ......................... 41 4.1.1 Ice wedge TSA12-IW ................................................................ 41 4.1.2 Ice wedge TSC12-IW ................................................................ 43 4.1.3 Ice wedge TSD12-IW1 .............................................................. 45 4.1.4 Ice wedge TSD12-IW2 .............................................................. 47 4.1.5 Massive ice body TSD12-MI ..................................................... 49 4.1.6 Massive ice body HIWCS12-MI ................................................ 52 4.1.7 Ice wedge series RB12-IW ....................................................... 54 4.1.8 Massive ice body KP12-MI ....................................................... 57 4.1.9 Ice wedge KP12-IW .................................................................. 60 4.2 Synthesis hydrochemistry .................................................................... 62 4.3 Massive ground ice contents ................................................................ 64 4.4 Coastal erosion rates ........................................................................... 66 4.5 Coastline height ................................................................................... 68 4.6 DOC stocks .......................................................................................... 69 4.7 DOC fluxes .......................................................................................... 72 5 Discussion ................................................................................................ 75 5.1 Origin of massive ground ice and sources of DOC ............................... 75 5.1.1 Massive ice bodies ................................................................... 75 5.1.2 Ice wedges ............................................................................... 80 5.1.3 Comparison between massive ice bodies and ice wedges........ 81 5.2 DOC fluxes from coastal erosion .......................................................... 82 5.2.1 DOC fluxes and its control factors ............................................. 82 5.2.2 Possible sources of error .......................................................... 88 5.3 DOC fluxes and the arctic carbon budget ............................................. 89 5.3.1 DOC fluxes from coastal erosion .............................................. 89 5.3.2 Coastal erosion vs. River discharge .......................................... 92 5.3.3 Incorporation of DOC fluxes into the Arctic carbon budget ........ 95 5.4 Fate of DOC in the near shore zone ..................................................... 97 6 Conclusions and Outlook ....................................................................... 100 References ................................................................................................... 102 Appendix ...................................................................................................... 122 Danksagung ................................................................................................. 129 Selbständigkeitserklärung .......................................................................... 130 I List of figures Figure 2.1: Permafrost map of the Northern Hemisphere ................................ 13 Figure 2.2: Idealized latitudinal distribution of permafrost ................................ 14 Figure 2.3: Classification of massive ground ice .............................................. 15 Figure 2.4: Idealized scheme of the evolution of an ice wedge ........................ 16 Figure 2.5: Scheme of a retrogressive thaw slump .......................................... 17 Figure 2.6: Coastal processes and responses at arctic permafrost coasts ....... 18 Figure 2.7: Continuum of dissolved organic carbon in natural waters .............. 19 Figure 2.8: Dissolved organic carbon as part of the Arctic carbon budget........ 21 Figure 2.9: Map showing the Yukon Coastal Plain and study sites .................. 22 Figure 2.10: Distribution of sediments along the Yukon Coastal Plain ............. 23 Figure 2.11: Temperature and precipitation data of Komakuk Beach ............... 25 Figure 2.12: Divisions of the Yukon Coastal Plain and study sites ................... 26 Figure 3.1: Flow chart illustrating the work flow used in the thesis ................... 27 Figure 3.2: Flow chart of the dissolved organic carbon measurement ............. 33 Figure 3.3: Dissolved organic carbon measurement procedure ....................... 34 Figure 3.4: Terrain units along the Yukon Coastal Plain .................................. 35 Figure 4.1: Cryostratigraphic profile of ice wedge TSA12-IW ........................... 42 Figure 4.2: Cryostratigraphic profile of ice wedge TSC12-IW ........................... 44 Figure 4.3: Cryostratigraphic profile of ice wedge TSD12-IW1 ......................... 46 Figure 4.4: Cryostratigraphic profile of ice wedge TSD12-IW2 ......................... 48 Figure 4.5: Cryostratigraphic profile of massive ice body TSD12-MI ................ 51 Figure 4.6: Cryostratigraphic profile of massive ice body HIWCS12-MI ........... 53 Figure 4.7: Cryostratigraphic profile of ice wedge series RB12-IW .................