Ecological effects of glacial dust deposition on remote Arctic lakes

The Arctic is changing rapidly as a result of climate warming and other global environmental change processes. One of the most obvious effects of altered Arctic heat budgets is the thinning of the Greenland ice sheet and the retreat of outlet glaciers. However, the increased fluvio-glacial output from glaciers is also laden with silt and there is growing evidence that such output from the Greenland ice sheet is increasing with enhanced seasonal melting. Some of this glacially-derived material is lost to the marine system but a significant part is deposited on glacial outwash plains from where the finer particles are deflated and transported to nearby terrestrial and aquatic ecosystems. Importantly this silt and the deflated dust is not inert. Because of its high nutrient content (carbon, phosphorus, nitrogen, silica and micronutrients), this silt/dust may be ecologically important because of the low nutrient status of adjacent aquatic and terrestrial ecosystems. There is now considerable evidence that dust stimulates microbiological activity on glacial ice and in cryoconite holes (meltwater holes caused by particle deposition which increases heat uptake) on the ice surface. However, there are no comparable studies on how glacially-derived dust influences lakes within terrestrial areas adjacent to the ice margin, despite the knowledge that lakes are hotspots of carbon processing.

The vast majority of lakes adjacent to the Greenland ice sheet are not hydrologically connected to it by meltwater channels, and so aerially-delivered dust might be an important or even predominant lake nutrient source. Fertilization of lakes by nutrients associated with dust stimulates primary production and hence carbon dynamics. Dust inputs to lakes at lower latitudes is known to have major impacts on lake biogeochemical cycling. There has, however, been limited consideration of these processes in the Arctic where lakes are important for regional carbon cycling although they are not well integrated into regional and global carbon budgets. Arctic lakes are numerous (their abundance is highest between 65-75 degrees N) and generally very nutrient poor and if dust increases lake productivity as an indirect effect of changing climate, this will be a positive result. This is due to the disproportional effect on increased carbon burial which removes carbon from the terrestrial carbon cycle and hence can offset warming. Conversely, increasing organic matter input to aquatic ecosystems may enhance microbial decomposition in lakes and stimulate lake CO2 emissions. In this study we will compare the ecological effects of glacially-derived dust on lakes along a gradient of dust deposition rates in SW Greenland and assess its role in regional carbon and aquatic community dynamics at a range of temporal (annual to centennial) and spatial scales (lake to regional landscape).

The primary beneficiaries of this research are detailed below, together with details of how they will benefit:

Local residents in Kangerlussuaq. There are around 550 permanent residents of Kangerlussuaq with an intense interest in and respect for the natural environment. There are around 70 local school children (6-16 years old), who have expressed an interest in the educational opportunities we could offer through this (and previous) work. Specifically, our conversations with local residents revealed a desire to raise aspirations of children in Kangerlussuaq through greater engagement with the scientists who work there. The first aim of the impact plan will therefore be to engage in educational exchange with local residents and schoolchildren with reciprocal benefits for the investigators on this project.

Health workers and agencies: This study will provide baseline data which could be used to ascertain whether glacially-derived dust might be a human health risk for Arctic communities in paraglacial regions. Such work is likely to be directly important to the Ministry of Health, the Government of Greenland but also has relevance for health workers and researchers in other regions. Dust-related health effects including respiratory and lung conditions have been observed elsewhere, but to date there is no published work investigating such linkages in Greenland. Discussions with one local resident revealed complaints that dust appeared to be finer recently and was causing lung problems, which had not been previously experienced. The local council in Kangerlussuaq are encouraging the sowing of grass seeds in an attempt to trap dust, indicating that it is an issue of growing concern. Therefore the second focus of this impact plan will be to gather and disseminate pilot data on the potential links between health and air quality in this region to identify possible areas for further research and to assist with local healthcare planning.

Ecotourism companies, tourist agencies and tourists: The national tourist board Visit Greenland http://www.greenland.com/en/ strongly focuses on ecotourism and the natural wilderness environment for marketing Kangerlussuaq and other regions in Greenland. There are several thousand seasonal visitors to Kangerlussuaq, which is the only international transport hub into Greenland and it is rapidly developing as an eco-tourism destination. Tour operators, such as World of Greenland- Arctic Circle http://wogac.com/, offer environmental-related activities and tours.

Ecotourism and "climate change tourism" are growth areas http://www.tourismstat.gl. The benefits of this (and of our previous) work to these groups is to provide a sound science base to inform tourist guides and package tour operators leading to better educational outcomes for visitors. Therefore, this work has relevance to the ecotourism industry and so to the Greenland Ministries of Nature, Environment & Justice, and of Industry, Labour and Trade.

Meteorological agencies: The Danish Meteorological Institute (DMI) has maintained the weather station at Kangerlussuaq airport since 1973, and has a remit to conduct research activities. Measurements at Kangerlussuaq include dust codes (a semi-quantitative indication of emissions since 1941) which we will compare with our dust measurements. The linkages between meteorological datasets and aerosols investigated in our study will be of interest to DMI and meteorologists in general.

Members of the UK public and next-generation scientists: Public interest in the Arctic continues to grow, and the proposed work provides attractive material for education, outreach and dissemination through public lectures, school visits, social media and other media. The benefit of engaging with this stakeholder group is to encourage next-generation scientists and increase environmental awareness and responsibility.