| 1. |
- Keuschnig, Christoph, et al.
(författare)
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Selection processes of Arctic seasonal glacier snowpack bacterial communities
- 2023
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Ingår i: Microbiome. - : BioMed Central (BMC). - 2049-2618. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundArctic snowpack microbial communities are continually subject to dynamic chemical and microbial input from the atmosphere. As such, the factors that contribute to structuring their microbial communities are complex and have yet to be completely resolved. These snowpack communities can be used to evaluate whether they fit niche-based or neutral assembly theories.MethodsWe sampled snow from 22 glacier sites on 7 glaciers across Svalbard in April during the maximum snow accumulation period and prior to the melt period to evaluate the factors that drive snowpack metataxonomy. These snowpacks were seasonal, accumulating in early winter on bare ice and firn and completely melting out in autumn. Using a Bayesian fitting strategy to evaluate Hubbell’s Unified Neutral Theory of Biodiversity at multiple sites, we tested for neutrality and defined immigration rates at different taxonomic levels. Bacterial abundance and diversity were measured and the amount of potential ice-nucleating bacteria was calculated. The chemical composition (anions, cations, organic acids) and particulate impurity load (elemental and organic carbon) of the winter and spring snowpack were also characterized. We used these data in addition to geographical information to assess possible niche-based effects on snow microbial communities using multivariate and variable partitioning analysis.ResultsWhile certain taxonomic signals were found to fit the neutral assembly model, clear evidence of niche-based selection was observed at most sites. Inorganic chemistry was not linked directly to diversity, but helped to identify predominant colonization sources and predict microbial abundance, which was tightly linked to sea spray. Organic acids were the most significant predictors of microbial diversity. At low organic acid concentrations, the snow microbial structure represented the seeding community closely, and evolved away from it at higher organic acid concentrations, with concomitant increases in bacterial numbers.ConclusionsThese results indicate that environmental selection plays a significant role in structuring snow microbial communities and that future studies should focus on activity and growth.
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| 2. |
- Krecl, Patricia, et al.
(författare)
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A feasibility study of mapping light-absorbing carbon using a taxi fleet as a mobile platform
- 2014
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Ingår i: Tellus. Series B, Chemical and physical meteorology. - : Stockholm University Press. - 0280-6509 .- 1600-0889. ; 66, s. 23533-
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Tidskriftsartikel (refereegranskat)abstract
- Carbon-containing particles are associated with adverse health effects, and their light-absorbing fractions were recently estimated to be the second largest contributor to global warming after carbon dioxide. Knowledge on the spatiotemporal variability of light-absorbing carbon (LAC) particles in urban areas is relevant for air quality management and to better diagnose the population exposure to these particles. This work reports on the first mobile LAC mass concentrations (M-LAC) measured on-board four taxis in the Stockholm metropolitan area in November 2011. On average, concentrations were higher and more variable during daytime (median of 1.9 mu g m(-3) and median absolute deviation of 2.3 mu g m(-3)). Night-time (21:00-05:00) measurements were very similar for all road types and also compared to levels monitored at an urban background fixed site (median of 0.9 mu g m(-3)). We observed a large intra-urban variability in concentrations, with maxima levels inside road tunnels (median and 95th percentile of 7.5 and 40.1 mu g m(-3), respectively). Highways presented the second ranked concentrations (median and 95th percentile of 3.2 and 9.7 mu g m(-3), respectively) associated with highest vehicle speed (median of 65 km h(-1)), traffic rates (median of 62 000 vehicles day(-1) and 1500 vehicles h(-1)) and diesel vehicles share (7-10%) when compared to main roads, canyon streets, and local roads. Multiple regression modelling identified hourly traffic rate and M-LAC concentration measured at an urban background site as the best predictors of on-road concentrations, but explained only 25% of the observed variability. This feasibility study proved to be a time-and cost-effective approach to map out ambient M-LAC concentrations in Stockholm and more research is required to represent the distribution in other periods of the year. Simultaneous monitoring of other pollutants, closely correlated to M-LAC levels in traffic-polluted environments, and including video recording of road and traffic changes would be an asset.
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| 3. |
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| 4. |
- Ruppel, Meri M., et al.
(författare)
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Do contemporary (1980-2015) emissions determine the elemental carbon deposition trend at Holtedahlfonna glacier, Svalbard?
- 2017
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 17:20, s. 12779-12795
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Tidskriftsartikel (refereegranskat)abstract
- The climate impact of black carbon (BC) is notably amplified in the Arctic by its deposition, which causes albedo decrease and subsequent earlier snow and ice spring melt. To comprehensively assess the climate impact of BC in the Arctic, information on both atmospheric BC concentrations and deposition is essential. Currently, Arctic BC deposition data are very scarce, while atmospheric BC concentrations have been shown to generally decrease since the 1990s. However, a 300-year Svalbard ice core showed a distinct increase in EC (elemental carbon, proxy for BC) deposition from 1970 to 2004 contradicting atmospheric measurements and modelling studies. Here, our objective was to decipher whether this increase has continued in the 21st century and to investigate the drivers of the observed EC deposition trends. For this, a shallow firn core was collected from the same Svalbard glacier, and a regional-to-meso-scale chemical transport model (SILAM) was run from 1980 to 2015. The ice and firn core data indicate peaking EC deposition values at the end of the 1990s and lower values thereafter. The modelled BC deposition results generally support the observed glacier EC variations. However, the ice and firn core results clearly deviate from both measured and modelled atmospheric BC concentration trends, and the modelled BC deposition trend shows variations seemingly independent from BC emission or atmospheric BC concentration trends. wet-deposited at this Svalbard glacier, indicating that meteorological processes such as precipitation and scavenging efficiency have most likely a stronger influence on the BC deposition trend than BC emission or atmospheric concentration trends. BC emission source sectors contribute differently to the modelled atmospheric BC concentrations and BC deposition, which further supports our conclusion that different processes affect atmospheric BC concentration and deposition trends. Consequently, Arctic BC deposition trends should not directly be inferred based on atmospheric BC measurements, and more observational BC deposition data are required to assess the climate impact of BC in Arctic snow.
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| 5. |
- Spolaor, Andrea, et al.
(författare)
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Climate change is rapidly deteriorating the climatic signal in Svalbard glaciers
- 2024
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Ingår i: CRYOSPHERE. - 1994-0416 .- 1994-0424. ; 18:1, s. 307-320
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Tidskriftsartikel (refereegranskat)abstract
- The Svalbard archipelago is particularly sensitive to climate change due to the relatively low altitude of its main ice fields and its geographical location in the higher North Atlantic, where the effect of Arctic amplification is more significant. The largest temperature increases have been observed during winter, but increasing summer temperatures, above the melting point, have led to increased glacier melt. Here, we evaluate the impact of this increased melt on the preservation of the oxygen isotope ( delta 18 O) signal in firn records. delta 18 O is commonly used as a proxy for past atmospheric temperature reconstructions, and, when preserved, it is a crucial parameter to date and align ice cores. By comparing four different firn cores collected in 2012, 2015, 2017 and 2019 at the top of the Holtedahlfonna ice field (1100 m a.s.l.), we show a progressive deterioration of the isotope signal, and we link its degradation to the increased occurrence and intensity of melt events. Our findings indicate that, starting from 2015, there has been an escalation in melting and percolation resulting from changes in the overall atmospheric conditions. This has led to the deterioration of the climate signal preserved within the firn or ice. Our observations correspond with the model's calculations, demonstrating an increase in water percolation since 2014, potentially reaching deeper layers of the firn. Although the delta 18 O signal still reflects the interannual temperature trend, more frequent melting events may in the future affect the interpretation of the isotopic signal, compromising the use of Svalbard ice cores. Our findings highlight the impact and the speed at which Arctic amplification is affecting Svalbard's cryosphere.
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| 6. |
- Spolaor, Andrea, et al.
(författare)
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Editorial: Pan-Arctic snow research
- 2023
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Ingår i: Frontiers in Earth Science. - 2296-6463. ; 11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Zdanowicz, Christian, 1966-, et al.
(författare)
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An agenda for the future of Arctic snow research : the view from Svalbard
- 2024
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Ingår i: Polar Research. - : Norwegian Polar Institute. - 0800-0395 .- 1751-8369. ; 42
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic region is warming at over twice the mean rate of the Northern Hemisphere and nearly four times faster than the globe since 1979. The local rate of warming is even higher in the European archipelago of Svalbard. This warming is transforming the terrestrial snow cover, which modulates surface energy exchanges with the atmosphere, accounts for most of the runoff in Arctic catchments and is also a transient reservoir of atmospherically deposited compounds, including pollutants. Improved observations, understanding and modelling of changes in Arctic snow cover are needed to anticipate the effects these changes will have on the Arctic climate, atmosphere, terrestrial ecosystems and socioeconomic factors. Svalbard has been an international hub of polar research for many decades and benefits from a well-developed science infrastructure. Here, we present an agenda for the future of snow research in Svalbard, jointly developed by a multidisciplinary community of experts. We review recent trends in snow research, identify key knowledge gaps, prioritize future research efforts and recommend supportive actions to advance our knowledge of present and future snow conditions pertaining to glacier mass balance, permafrost, surface hydrology, terrestrial ecology, the cycling and fate of atmospheric contaminants, and remote sensing of snow cover. This perspective piece addresses issues relevant to the circumpolar North and could be used as a template for other national or international Arctic research plans.
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| 8. |
- Zdanowicz, Christian, 1966-, et al.
(författare)
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Strategies and Best Practices for Monitoring Seasonal Snow Cover Composition
- 2019
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Seasonal snow covers up to 45 million km^2 every winter. As such, it represents a major interface between the Earth's surface and atmosphere. It also offers a convenient sampling medium to monitor water isotopes in solid precipitation and the net deposition of a wide variety of atmospheric species, including nutrients, organic compounds (OCs), trace metals, dust, black carbon (BC), and many others. Impurities such as dust and BC are light-absorbing and as such can modify the radiative properties of snow, while other atmospheric species such as OCs or certain metals can adversely affect the aquatic environment and drinking water quality in meltwater-fed basins. Systematic monitoring of seasonal snowpack composition may therefore offer a way of supplementing direct observations of air and precipitation chemistry. It may also lend itself well to certain "citizen science" activities, provided a set of standardized protocols can be adopted, and an adequate platform for data collection and sharing be established. In recent years, some recommendations to this effect were made by the snow science community through the IASC Cryosphere Working Group, the WMO Global Cryosphere Watch and EU Harmosnow initiative. The purpose of this presentation is to stimulate a continued discussion of the merits, challenges and caveats of establishing a network of coordinated snowpack composition observations. Examples of existing or recently-developed monitoring protocols for snowpacks in Arctic and montane regions will be presented and discussed.
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