Modern Aeolian dust deposition on Arctic soils in South West Greenland: linkages between geomorphology and ecosystem dynamics in space and time
thesisposted on 12.04.2021, 07:47 by Maud Van-Soest
In parts of the Arctic, Aeolian (wind) processes are thought to play a substantial role in the development of soils, although the influence of high latitude aeolian processes and the magnitude of dust deposition on the formation of soils has not been extensively studied. There is also a lack of understanding around the impact of climate change on arctic soils, particularly in relation to the extent of permafrost conditions and soil carbon stocks. This thesis, aims to quantify the importance of contemporary dust inputs to modern arctic soil development and consider how these soils contribute to the regional carbon cycle. The research focuses on the Kangerlussuaq region of South West Greenland within which soils have been developing along a gradient of ice-retreat during the Holocene. The area is diverse in terms of its geomorphology and ecology. A variety of complementary methods were used to investigate soil and ecosystem processes at a range of spatial and temporal scales. Contemporary seasonal and annual dust inputs to soils were quantified using passive dust traps (April 2017 to April 2019). Annual dust deposition is estimated to have been 65.7 g m-2 yr-1 in 2017/18 and 14.6 g m-2 yr-1 in 2018/19 reinforcing studies from other Arctic regions that suggest annual dust deposition can vary substantially. Overall, the dustiest season was spring 2017/18 and summer 2018/19. Spatial variability in dust deposition investigated along a gradient west from the Greenland Ice Sheet suggests that there is no consistent and systematic trend in dust deposition. This is likely to be because the regional wind regime is bidirectional, the terrain within the study area is complex and importantly there are multiple dust sources that could contribute to the soils. Particle-size analysis of the dust with main modes of ~20–30 µm indicates that sources are local. A detailed dataset of soil characteristics is provided over a transect of 42 km and covers the widest area in Kangerlussuaq studied to date. Variations in soil characteristics are mainly influenced by microtopography and the degree of soil development is not substantially different with distance from the Greenland Ice Sheet. Particle size analysis confirms that there is a strong aeolian component to all soils examined. The carbon stock in the top 30 cm of the soil surface grouped by landcover type ranges between 9.78–13.88 kg m-2, which is in the same order of magnitude as found in comparable arctic studies. Using a multidisciplinary approach, this study highlights the importance of soil profiles (past) in combination with the quantification of seasonal & annual dust deposition (present), which help to elucidate how arctic ecosystems developed since deglaciation, and how they might change under future climate change.
- Social Sciences and Humanities
- Geography and Environment