Project

GReenland Analogue Surface Project (GRASP)

Goal: The objectives are to better understand biogeochemical and hydrological processes during permafrost conditions.

Date: 1 August 2010 - 1 January 2021

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Tobias Lindborg
added a research item
Climate change is predicted to have far reaching consequences for the mobility of carbon in arctic landscapes. On a regional scale, carbon cycling is highly dependent on interactions between terrestrial and aquatic parts of a catchment. Despite this, studies that integrate the terrestrial and aquatic systems and study entire catchments using site-specific data are rare. In this work, we use data partly published by Lindborg et al. (2016a) to calculate a whole-catchment carbon mass-balance budget for a periglacial catchment in West Greenland. Our budget shows that terrestrial net primary production is the main input of carbon (99% of input), and that most carbon leaves the system through soil respiration (90% of total export/storage). The largest carbon pools are active layer soils (53% of total carbon stock or 13 kg C m-2), permafrost soils (30% of total carbon stock or 7.6 kg C m-2) and lake sediments (13% of total carbon stock or 10 kg C m-2). Hydrological transport of carbon from the terrestrial to aquatic system is lower than in wetter climates, but the annual input of 4100 kg C yr-1 (or 3.5 g C m-2 yr-1) that enters the lake via runoff is still three times larger than the eolian input of terrestrial carbon. Due to the dry conditions, the hydrological export of carbon from the catchment is limited (5% of aquatic export/storage or 0.1% of total export/storage). Instead, CO2 evasion from the lake surface and sediment burial accounts for 57% and 38% of aquatic export/storage, respectively (or 0.8% and 0.5% of total export/storage), and Two-Boat Lake acts as a net source of carbon to the atmosphere. The limited export of carbon to downstream water bodies make our study system different from wetter arctic environments, where hydrological transport is an important export pathway for carbon.
Tobias Lindborg
added a research item
Emma Lindborg
added a research item
The cycling of water in the landscape is influenced by climate change on different time scales and in different directions regarding warming or cooling trends. Along with a changing climate, also the landscape and subsurface conditions, such as permafrost extent, may change in a long-term perspective. Permafrost and hydrology are intimately connected but the interactions between them are poorly understood, and the hydrological response to climate change is complex. The first part of this thesis investigates the effects of different drivers of future changes in hydrological flow and water storage components in the present day temperate Forsmark catchment in Sweden. The role of taliks and their influence on the exchange of deep and shallow groundwater in permafrost environments are also studied. This is done by a simulation sequence where the site is exposed to the landscape, climate and permafrost changes expected from site-specific numerical modeling. In the second part of this thesis, present day periglacial hydrological processes are studied in the Two Boat Lake catchment in western Greenland by field and model investigations of the site. The presence of a through talik below the Two Boat Lake, and data from a deep bedrock borehole into the talik, enable studies of the hydrological interactions between the lake and the talik. The spatial and temporal variability of the different water balance components of the catchment are quantified and the interactions between the surface water and the supra- and sub-permafrost groundwater are analyzed. The results show that the investigated changes in climate and permafrost influence hydrology more than the investigated landscape changes. Under permafrost conditions, the general direction of the exchange between deep and shallow groundwater may change relative to unfrozen conditions. The simulation studies of Forsmark show that the relative topography between taliks governs the recharging and discharging conditions, which is consistent with results from Two Boat Lake. The lake is located at high altitude relative to other taliks and hydraulic measurements indicate recharging conditions. The talik recharge is small compared to other water balance components and does not influence the lake level, which instead is found to be controlled by evapotranspiration and water inflow from the active layer. This is concluded from numerical simulations that take into account and combine evapotranspiration with other surface and subsurface hydrological processes. This thesis highlights the need to integrate surface and subsurface process modelling in order to quantitatively understand and represent the dynamics and complexity of hydrological interactions in periglacial catchments.
Tobias Lindborg
added a research item
Earth has experienced many glacial cycles over the ̴ 2.5 million year long Quaternary period. During the latter part of the Quaternary, roughly the last 800,000 years, each cycle has been of duration ̴ 100,000 years and has included extended periods of glacial conditions, with ice sheets in the northern hemisphere. In-between those periods, intervals with periglacial or temperate conditions in northern latitudes have occurred. Global sea level has, as a response to the formation and melting of ice sheets, fluctuated over 120 meters. Thus, the global climate cycles have been the main driver for the location of continental coastlines, environmental changes in the past as well as the resulting present-day landscapes. Recent human-induced climate change is now also affecting the landscape. In this thesis, I examine the use of global climate models as input to exploring local landscape evolution over glacial cycles. An approach is proposed for landscape description that is designed for use in long-term safety assessments related to landscape development into the far future. The approach is illustrated by results of work that shows methods applied to a site-specific landscape development model using climate and climate-related data. Site-specific data is utilised to gain site understanding from which conceptual ecosystem models are developed for present day conditions, and to inform landscape narratives. Concentrations of elements are used to infer the characteristics of transport processes in the landscape over time. The results from the above studies are discussed in relation to the general hypothesis in this thesis; that by considering a few well-defined climate-related processes and using site understanding on local properties and processes, it is possible to reduce the uncertainties in future landscape developments for a specific site. Uncertainties include the abundance and distribution of ecosystems and associated properties related to processes governing the transport of matter. I conclude that relevant examples of historical and future landscape evolution for specific sites can be given that are useful for long-term assessments.
Jens-Ove Näslund
added a research item
The geometries of a catchment constitute the basis for distributed physically based numerical modeling of different geoscientific disciplines. In this paper results from ground-penetrating radar (GPR) measurements, in terms of a 3D model of total sediment thickness and active layer thickness in a periglacial catchment in western Greenland, are presented. Using the topography, thickness and distribution of sediments are calculated. Vegetation classification and GPR measurements are used to scale active layer thickness from local measurements to catchment scale models. Annual maximum active layer thickness varies from 0.3 m in wetlands to 2.0 m in barren areas and areas of exposed bedrock. Maximum sediment thickness is estimated to be 12.3 m in the major valleys of the catchment. A method to correlate surface vegetation with active layer thickness is also presented. By using relatively simple methods, such as probing and vegetation classification, it is possible to upscale local point measurements to catchment scale models, in areas where the upper subsurface is relatively homogenous. The resulting spatial model of active layer thickness can be used in combination with the sediment model as a geometrical input to further studies of subsurface mass-transport and hydrological flow paths in the periglacial catchment through numerical modelling. The data set is available for all users via the PANGAEA database, https://doi.pangaea.de/10.1594/PANGAEA.845258.
Tobias Lindborg
added a research item
Global warming is expected to be most pronounced in the Arctic where permafrost thaw and release of old carbon may provide an important feedback mechanism to the climate system. To better understand and predict climate effects and feedbacks on the cycling of elements within and between ecosystems in northern latitude landscapes, a thorough understanding of the processes related to transport and cycling of elements is required. A fundamental requirement to reach a better process understanding is to have access to high-quality empirical data on chemical concentrations and biotic properties for a wide range of ecosystem domains and functional units (abiotic and biotic pools). The aim of this study is therefore to make one of the most extensive field data sets from a periglacial catchment readily available that can be used both to describe present-day periglacial processes and to improve predictions of the future. Here we present the sampling and analytical methods, field and laboratory equipment and the resulting biogeochemical data from a state-of-the-art whole-ecosystem investigation of the terrestrial and aquatic parts of a lake catchment in the Kangerlussuaq region, West Greenland. This data set allows for the calculation of whole-ecosystem mass balance budgets for a long list of elements, including carbon, nutrients and major and trace metals.
Emma Lindborg
added 3 research items
Global warming is expected to be most pronounced in the Arctic where permafrost thaw and release of old carbon may provide an important feedback mechanism to the climate system. To better understand and predict climate effects and feedbacks on the cycling of elements within and between ecosystems in northern latitude landscapes, a thorough understanding of the processes related to transport and cycling of elements is required. A fundamental requirement to reach a better process understanding is to have access to high quality empirical data on chemical concentrations and biotic properties for a wide range of ecosystem domains and functional units (abiotic and biotic pools). The aim of this study is therefore to make one of the most extensive field data sets from a periglacial catchment readily available that can be used both to describe present day periglacial processes and to improve predictions of the future. Here we present the sampling and analytical methods, field and laboratory equipment and the resulting biogeochemical data from a state-of-the-art whole-ecosystem investigation of the terrestrial and aquatic parts of a lake catchment in the Kangerlussuaq region, West Greenland. This dataset allows for the calculation of whole-ecosystem mass balance budgets for long list of elements, including carbon, nutrients as well as major and trace metals. The dataset is freely available and can be downloaded from PANGAEA: https://doi.pangaea.de/10.1594/PANGAEA.860961
Few hydrological studies have been made in Greenland with focus on permafrost hydrology rather than on the glacial hydrology associated with the Greenland ice sheet. Understanding permafrost hydrology, and its reflection and propagation of hydroclimatic change and variability, however, can be a key to understand important climate change effects and feedbacks in arctic landscapes. This paper presents a new extensive and detailed hydrological dataset, with high temporal resolution of main hydrological parameters, for a permafrost catchment with a lake underlain by a talik close to the Greenland ice sheet in the Kangerlussuaq region, western Greenland. The paper describes the hydrological site investigations and data collection, and their synthesis and interpretation to develop a conceptual hydrological model. The catchment and lake water balances and their intra-annual variability, and uncertainty intervals for key water balance components, are quantified. The study incorporates all relevant hydrological processes within the catchment and, specifically, links the surface water system to both supra-permafrost and sub-permafrost groundwater. The dataset enabled water balance quantification with high degree of confidence. The measured hydraulic gradient between the lake and the groundwater in the talik shows this to be a groundwater recharging talik. Surface processes, dominated by evapotranspiration during the active flow period, and by snow dynamics during the frozen winter period, influence the temporal variation of groundwater pressure in the talik. This shows the hydrology in the catchment as being rather independent from external large-scale landscape features, including those of the close-by ice sheet.
This study simulates and quantifies the exchange and the pathways of deep and shallow groundwater flow and solute transport under different climate and permafrost conditions, considering the example field case of the coastal Forsmark catchment in Sweden. A number of simulation scenarios for different climate and permafrost condition combinations have been performed with the three-dimensional groundwater flow and transport model MIKE SHE. Results show generally decreasing vertical groundwater flow with depth, and smaller vertical flow under permafrost conditions than under unfrozen conditions. Also the overall pattern of both the vertical and the horizontal groundwater flow, and the water exchange between the deep and shallow groundwater systems, change dramatically in the presence of permafrost relative to unfrozen conditions. However, although the vertical groundwater flow decreases significantly in the presence of permafrost, there is still an exchange of water between the unfrozen groundwater system below the permafrost and the shallow groundwater in the active layer, via taliks. ‘Through taliks’ tend to prevail in areas that constitute groundwater discharge zones under unfrozen conditions, which then mostly shift to net recharge zones (through taliks with net downward flow) under permafrost conditions.
Emma Lindborg
added 2 research items
Few hydrological studies have been made in Greenland, other than on glacial hydrology associated with the ice sheet. Understanding permafrost hydrology and hydroclimatic change and variability, however, provides key information for understanding climate change effects and feedbacks in the Arctic landscape. This paper presents a new extensive and detailed hydrological and meteorological open access dataset, with high temporal resolution from a 1.56 km**2 permafrost catchment with a lake underlain by a through talik close to the ice sheet in the Kangerlussuaq region, western Greenland. The paper describes the hydrological site investigations and utilized equipment, as well as the data collection and processing. The investigations were performed between 2010 and 2013. The high spatial resolution, within the investigated area, of the dataset makes it highly suitable for various detailed hydrological and ecological studies on catchment scale.
Few hydrological studies have been made in Greenland, other than on glacial hydrology associated with the ice sheet. Understanding permafrost hydrology and hydroclimatic change and variability, however, provides key information for understanding climate change effects and feedbacks in the Arctic landscape. This paper presents a new extensive and detailed hydrological and meteorological open access dataset, with high temporal resolution from a 1.56 km2 permafrost catchment with a lake underlain by a through talik close to the ice sheet in the Kangerlussuaq region, western Greenland. The paper describes the hydrological site investigations and utilized equipment, as well as the data collection and processing. The investigations were performed between 2010 and 2013. The high spatial resolution, within the investigated area, of the dataset makes it highly suitable for various detailed hydrological and ecological studies on catchment scale. The dataset is availble for all users via the PANGAEA database, http://doi.pangaea.de/10.1594/PANGAEA.836178. Please note this dataset is under review and recommended not to be used before the final version of the manuscript is accepted for publication.
Emma Lindborg
added 4 research items
Few hydrological studies have been conducted in Greenland, other than on glacial hydrology associated with the ice sheet. Understanding permafrost hydrology and hydroclimatic change and variability, however, provides key information for understanding climate change effects and feedbacks in the Arctic landscape. This paper presents a new, extensive, and detailed hydrological and meteorological open access data set, with high temporal resolution from a 1.56 km2 permafrost catchment, with a lake underlain by a through-talik close to the ice sheet in the Kangerlussuaq region, western Greenland. The paper describes the hydrological site investigations and utilized equipment, as well as the data collection and processing. The investigations were performed between 2010 and 2013. The high spatial resolution, within the investigated area, of the data set makes it highly suitable for various detailed hydrological and ecological studies on catchment scale. The data set is available for all users via the PANGAEA database, http://doi.pangaea.de/10.1594/PANGAEA.836178.
This study investigates annual water balance conditions and their spatiotemporal variability under a wide variety of atmospheric driving conditions in the periglacial permafrost catchment of Two Boat Lake in Western Greenland. The study uses and combines a comprehensive hydrological multi-parameter dataset measured at the site with site conceptualization and numerical model development, application and testing. The model result reproduces measured lake and groundwater levels, as well as observations made by time-lapse cameras. The results highlights the importance of numerical modeling that takes into account and combines evapotranspiration with other surface and subsurface hydrological processes at various depths, in order to quantitatively understand and represent the dynamics and complexity of the interactions between meteorology, active layer hydrology, lakes, and unfrozen groundwater below permafrost in periglacial catchments. Regarding these interactions, the water flow between the studied lake and a through talik within and beneath it is found to be small compared to other water balance components. The modeling results show that recharge and discharge conditions in the talik can shift in time, while the lake and active layer conditions in the studied catchment are independent of catchment-external landscape features, such as the unfrozen groundwater system below the permafrost and the nearby continental-scale ice sheet.
Tobias Lindborg
added a project goal
The objectives are to better understand biogeochemical and hydrological processes during permafrost conditions.
 
Tobias Lindborg
added 3 research items
In proglacial landscapes, such as western Greenland, eolian transport plays an important role for the influx of particulate material to lakes. On the basis of an analysis of a sediment profile and surface sediments from several lakes, we show that eolian activity has a strong influence on sediment deposition in time and space. Principal component analysis revealed that sediments that accumulated during periods with high eolian activity were enriched in zirconium-originating from coarse silt and sand fractions preferentially transported by wind-and depleted in rubidium. In addition, zirconium to rubidium ratios in the surface sediment of four additional lakes decreased with distance from the ice sheet. Finally, previously published data show that pH and alkalinity tend to be higher in lakes close to the front of the ice sheet, which we speculate is coupled to a larger supply of fresh eolian material. These findings demonstrate that lakes in proglacial landscapes may receive a substantial part of their sediment load through eolian deposition, and that this is especially true close to the glacial outwash plains along the ice margin.
The geometries of a catchment constitute the basis for distributed physically based numerical modeling of different geoscientific disciplines. In this paper results from ground-penetrating radar (GPR) measurements, in terms of a 3-D model of total sediment thickness and active layer thickness in a periglacial catchment in western Greenland, are presented. Using the topography, the thickness and distribution of sediments are calculated. Vegetation classification and GPR measurements are used to scale active layer thickness from local measurements to catchment-scale models. Annual maximum active layer thickness varies from 0.3 m in wetlands to 2.0 m in barren areas and areas of exposed bedrock. Maximum sediment thickness is estimated to be 12.3 m in the major valleys of the catchment. A method to correlate surface vegetation with active layer thickness is also presented. By using relatively simple methods, such as probing and vegetation classification, it is possible to upscale local point measurements to catchment-scale models, in areas where the upper subsurface is relatively homogeneous. The resulting spatial model of active layer thickness can be used in combination with the sediment model as a geometrical input to further studies of subsurface mass transport and hydrological flow paths in the periglacial catchment through numerical modeling. The data set is available for all users via the PANGAEA database, doi:10.1594/PANGAEA.845258.
Knowledge about biotic and abiotic features and processes in ecosystems influenced by a periglacial climate is limited and long term effects on mass balances and transport processes when climate switches between temperate and permafrost conditions is not well understood . Furthermore, there is limited consensus on the hydrological response to long-term climate change during a glacial cycle and its influence on transport and accumulation (fluxes and pools) of matter within an ecosystem in a changing environment; thus, further studies are needed. The main aim of the present work, which is a four-year project, is to increase the understanding of how ecosystem processes and features are affected by a periglacial climate. Hydrological and biogeochemical investigations in a lake catchment in Western Greenland has been performed and a conceptual model has been developed that can be used in assessments of periglacial conditions. The core hypothesis is that ecosystems in cold climate conditions compared to temperate ones show a different pattern in process rates and transport related features. The hydrological investigations have focused on monitoring water flows and storage in the catchment in order to better understand when and how main hydrological events that influence the transport of matter in the ecosystem appear during the year. By monitoring soil temperature and soil water content, as well as ground- and surface water levels, the dynamics of the active layer and the interactions between groundwater and surface water have been analysed. The interactions between i) deep and shallow groundwater via taliks and ii) groundwater in the active layer and surface water in the lake are key aspects for transport and accumulation of matter in ecosystems in a periglacial climate. Surface water, groundwater, soil and sediment sampling has been carried out to establish site-specific knowledge on major chemical pools and fluxes of elements in the terrestrial and aquatic ecosystems of the catchment. Samples were analysed using ICP-MS techniques as well as by stable isotope analysis. In combination with hydrological modelling, the chemical sampling was used to develop mass balance models for carbon at both ecosystem and catchment levels. The results are discussed and compared to relevant studies in other regions.
Tobias Lindborg
added an update
Swedish Nuclear Fuel and Waste Management Co (SKB) have since 2009 been conducting research in the Kangerlussuaq area in West Greenland in cooperation with Stockholm University (SU) and Swedish University of Agricultural Sciences (SLU). The objectives are to better understand biogeochemical and hydrological processes during permafrost conditions. The tasks contains: measurements and sampling of soils, water and biota in a lake centred catchment, and to build distributed and numerical models, conceptual modelling and mass balance calculations on elements (including carbon). So far the project have produced five articles describing site specific hydrological data and models, lake sediment profiles, geometrical models of topography and bathymetry and biogeochemical data for the catchment.
 
Tobias Lindborg
added a research item
Global warming is expected to be most pronounced in the Arctic where permafrost thaw and release of old carbon may provide an important feedback mechanism to the climate system. To better understand and predict climate effects and feedbacks on the cycling of elements within and between ecosystems in northern latitude landscapes, a thorough understanding of the processes related to transport and cycling of elements is required. A fundamental requirement to reach a better process understanding is to have access to high-quality empirical data on chemical concentrations and biotic properties for a wide range of ecosystem domains and functional units (abiotic and biotic pools). The aim of this study is therefore to make one of the most extensive field data sets from a periglacial catchment readily available that can be used both to describe present-day periglacial processes and to improve predictions of the future. Here we present the sampling and analytical methods, field and laboratory equipment and the resulting biogeochemical data from a state-of-the-art whole-ecosystem investigation of the terrestrial and aquatic parts of a lake catchment in the Kangerlussuaq region, West Greenland. This data set allows for the calculation of whole-ecosystem mass balance budgets for a long list of elements, including carbon, nutrients and major and trace metals. The data set is freely available and can be downloaded from PANGAEA: doi:10.1594/PANGAEA.860961.