scholarly journals Supplementary material to "Microbial dynamics in a High-Arctic glacier forefield: a combined field, laboratory, and modelling approach"

2016 ◽  
Author(s):  
James A. Bradley ◽  
Sandra Arndt ◽  
Marie Šabacká ◽  
Liane G. Benning ◽  
Gary L. Barker ◽  
...  
Keyword(s):  
High Arctic ◽  
Microbial Dynamics ◽  
Glacier Forefield ◽  
Field Laboratory ◽  
Supplementary Material ◽  
Arctic Glacier ◽  
Modelling Approach

scholarly journals Microbial dynamics in a High-Arctic glacier forefield: a combined field, laboratory, and modelling approach

2016 ◽  
Author(s):  
James A. Bradley ◽  
Sandra Arndt ◽  
Marie Šabacká ◽  
Liane G. Benning ◽  
Gary L. Barker ◽  
...  
Keyword(s):  
Microbial Community ◽  
Numerical Model ◽  
Microbial Communities ◽  
Community Dynamics ◽  
Heterotrophic Bacteria ◽  
High Arctic ◽  
Soil Development ◽  
Arctic Soils ◽  
Field Laboratory ◽  
Modelling Approach

Abstract. Modelling the development of soils in glacier forefields is necessary in order to assess how microbial and geochemical processes interact and shape soil development in response to glacier retreat. Furthermore, such models can help us predict microbial growth and the fate of Arctic soils in an increasingly ice-free future. Here, for the first time, we combined field sampling with laboratory analyses and numerical modelling to investigate microbial community dynamics in oligotrophic proglacial soils in Svalbard. We measured low bacterial growth rates and growth efficiencies (relative to estimates from Alpine glacier forefields), and high sensitivity to soil temperature (relative to temperate soils). We used these laboratory measurements to inform parameter values in a new numerical model and significantly refined predictions of microbial and biogeochemical dynamics of soil development over a period of roughly 120 years. The model predicted the observed accumulation of autotrophic and heterotrophic biomass. Genomic data indicated that initial microbial communities were dominated by bacteria derived from the subglacial environment, whereas older soils hosted a mixed community of autotrophic and heterotrophic bacteria. This finding was validated by the numerical model, which showed that active microbial communities play key roles in fixing and recycling carbon and nutrients. We also demonstrated the role of allochthonous carbon and microbial necromass in sustaining a pool of organic material, despite high heterotrophic activity in older soils. This combined field, laboratory and modelling approach demonstrates the value of integrated model-data studies to understand and quantify the functioning of the microbial community in an emerging High-Arctic soil ecosystem.

scholarly journals Distribution of soil nitrogen and nitrogenase activity in the forefield of a High Arctic receding glacier

2018 ◽  
Vol 59 (77) ◽  
pp. 87-94 ◽  
Author(s):  
Thomas Turpin-Jelfs ◽  
Katerina Michaelides ◽  
Joshua J. Blacker ◽  
Liane G. Benning ◽  
James M. Williams ◽  
...  
Keyword(s):  
Nitrogenase Activity ◽  
Soil Formation ◽  
High Arctic ◽  
N Fixation ◽  
N Availability ◽  
N Accumulation ◽  
Glacier Forefield ◽  
Biological N Fixation ◽  
Arctic Glacier ◽  
Emerging Ecosystems

ABSTRACTGlaciers retreating in response to climate warming are progressively exposing primary mineral substrates to surface conditions. As primary production is constrained by nitrogen (N) availability in these emerging ecosystems, improving our understanding of how N accumulates with soil formation is of critical concern. In this study, we quantified how the distribution and speciation of N, as well as rates of free-living biological N fixation (BNF), change along a 2000-year chronosequence of soil development in a High Arctic glacier forefield. Our results show the soil N pool increases with time since exposure and that the rate at which it accumulates is influenced by soil texture. Further, all N increases were organically bound in soils which had been ice-free for 0–50 years. This is indicative of N limitation and should promote BNF. Using the acetylene reduction assay technique, we demonstrated that microbially mediated inputs of N only occurred in soils which had been ice-free for 0 and 3 years, and that potential rates of BNF declined with increased N availability. Thus, BNF only supports N accumulation in young soils. When considering that glacier forefields are projected to become more expansive, this study has implications for understanding how ice-free ecosystems will become productive over time.

scholarly journals Consumption of CH<sub>3</sub>Cl, CH<sub>3</sub>Br, and CH<sub>3</sub>I and emission of CHCl<sub>3</sub>, CHBr<sub>3</sub>, and CH<sub>2</sub>Br<sub>2</sub> from the forefield of a retreating Arctic glacier

2020 ◽  
Vol 20 (12) ◽  
pp. 7243-7258 ◽  
Author(s):  
Moya L. Macdonald ◽  
Jemma L. Wadham ◽  
Dickon Young ◽  
Chris R. Lunder ◽  
Ove Hermansen ◽  
...  
Keyword(s):  
Methyl Chloride ◽  
High Arctic ◽  
The Arctic ◽  
Emission Rates ◽  
Cyanobacterial Mats ◽  
Small Surface ◽  
Glacier Forefield ◽  
Land Surfaces ◽  
Arctic Glacier ◽  
The Impact

Abstract. The Arctic is one of the most rapidly warming regions of the Earth, with predicted temperature increases of 5–7 ∘C and the accompanying extensive retreat of Arctic glacial systems by 2100. Retreating glaciers will reveal new land surfaces for microbial colonisation, ultimately succeeding to tundra over decades to centuries. An unexplored dimension to these changes is the impact upon the emission and consumption of halogenated organic compounds (halocarbons). Halocarbons are involved in several important atmospheric processes, including ozone destruction, and despite considerable research, uncertainties remain in the natural cycles of some of these compounds. Using flux chambers, we measured halocarbon fluxes across the glacier forefield (the area between the present-day position of a glacier's ice-front and that at the last glacial maximum) of a high-Arctic glacier in Svalbard, spanning recently exposed sediments (<10 years) to approximately 1950-year-old tundra. Forefield land surfaces were found to consume methyl chloride (CH3Cl) and methyl bromide (CH3Br), with both consumption and emission of methyl iodide (CH3I) observed. Bromoform (CHBr3) and dibromomethane (CH2Br2) have rarely been measured from terrestrial sources but were here found to be emitted across the forefield. Novel measurements conducted on terrestrial cyanobacterial mats covering relatively young surfaces showed similar measured fluxes to the oldest, vegetated tundra sites for CH3Cl, CH3Br, and CH3I (which were consumed) and for CHCl3 and CHBr3 (which were emitted). Consumption rates of CH3Cl and CH3Br and emission rates of CHCl3 from tundra and cyanobacterial mat sites were within the ranges reported from older and more established Arctic tundra elsewhere. Rough calculations showed total emissions and consumptions of these gases across the Arctic were small relative to other sources and sinks due to the small surface area represented by glacier forefields. We have demonstrated that glacier forefields can consume and emit halocarbons despite their young age and low soil development, particularly when cyanobacterial mats are present.

scholarly journals Microbial dynamics in a High Arctic glacier forefield: a combined field, laboratory, and modelling approach

2016 ◽  
Vol 13 (19) ◽  
pp. 5677-5696 ◽  
Author(s):  
James A. Bradley ◽  
Sandra Arndt ◽  
Marie Šabacká ◽  
Liane G. Benning ◽  
Gary L. Barker ◽  
...  
Keyword(s):  
Microbial Community ◽  
Numerical Model ◽  
Microbial Communities ◽  
Bacterial Growth ◽  
Growth Rates ◽  
High Arctic ◽  
Soil Development ◽  
Field Laboratory ◽  
Bacterial Growth Rates ◽  
Modelling Approach

Abstract. Modelling the development of soils in glacier forefields is necessary in order to assess how microbial and geochemical processes interact and shape soil development in response to glacier retreat. Furthermore, such models can help us predict microbial growth and the fate of Arctic soils in an increasingly ice-free future. Here, for the first time, we combined field sampling with laboratory analyses and numerical modelling to investigate microbial community dynamics in oligotrophic proglacial soils in Svalbard. We measured low bacterial growth rates and growth efficiencies (relative to estimates from Alpine glacier forefields) and high sensitivity of bacterial growth rates to soil temperature (relative to temperate soils). We used these laboratory measurements to inform parameter values in a new numerical model and significantly refined predictions of microbial and biogeochemical dynamics of soil development over a period of roughly 120 years. The model predicted the observed accumulation of autotrophic and heterotrophic biomass. Genomic data indicated that initial microbial communities were dominated by bacteria derived from the glacial environment, whereas older soils hosted a mixed community of autotrophic and heterotrophic bacteria. This finding was simulated by the numerical model, which showed that active microbial communities play key roles in fixing and recycling carbon and nutrients. We also demonstrated the role of allochthonous carbon and microbial necromass in sustaining a pool of organic material, despite high heterotrophic activity in older soils. This combined field, laboratory, and modelling approach demonstrates the value of integrated model–data studies to understand and quantify the functioning of the microbial community in an emerging High Arctic soil ecosystem.

scholarly journals Solute in high arctic glacier snow cover and its impact on runoff chemistry

1998 ◽  
Vol 26 ◽  
pp. 156-160 ◽  
Author(s):  
Richard Hodgkins ◽  
Martyn Tranter
Keyword(s):  
Chemical Composition ◽  
Atmospheric Transport ◽  
Total Concentration ◽  
High Arctic ◽  
Sea Salt ◽  
Acidic Ph ◽  
Sea Salt Aerosol ◽  
Wet Snow ◽  
Potential Contributor ◽  
Arctic Glacier

The chemical composition of snow and meltwater in the 13 km2 catchment of Scott Turnerbreen, Svalbard, was investigated during the spring and summer of 1993. This paper assesses the provenance of solute in the snowpack and its impact on runoff chemistry. Dry snow contains 420μeql-1 of solute, is slightly acidic (pH 5.4) and is dominated by Na+ and Cl-. Wet snow is more dilute (total concentration 340μeql-1), and less acidic (pH 5.9). This is consistent with the elution of ions from the snowpack by meltwater. Snowpack solute can be partitioned into the following fractions: sea-salt aerosol, acid aerosol and crustal. About 98% of snowpack solute is sea salt, yielding 22000 kg km-2a-1. The behaviour of snowpack-derived Cl- in runoff is distinctive, peaking at over 800 μeql-1 early in the melt season as runoff picks up, before declining quasi-exponentially. This represents the discharge of snowmelt concentrated by elution within the snowpack which subsequently becomes relatively dilute. A solute yield of 140 kg km-2 a-1 can be attributed to anthropogenically generated acid aerosols, representing long-range atmospheric transport of pollutants, a potential contributor to Arctic runoff acidification.

scholarly journals Effects of substrate differences on water availability for Arctic lichens during the snow-free summers in the High Arctic glacier foreland

Polar Science ◽  
2014 ◽  
Vol 8 (4) ◽  
pp. 397-412 ◽  
Author(s):  
Takeshi Inoue ◽  
Sakae Kudoh ◽  
Masaki Uchida ◽  
Yukiko Tanabe ◽  
Masakane Inoue ◽  
...  
Keyword(s):  
Water Availability ◽  
High Arctic ◽  
Glacier Foreland ◽  
Arctic Glacier

scholarly journals Intra-annual and intra-seasonal flow dynamics of a High Arctic polythermal valley glacier

2003 ◽  
Vol 37 ◽  
pp. 181-188 ◽  
Author(s):  
Robert G. Bingham ◽  
Peter W. Nienow ◽  
Martin J. Sharp
Keyword(s):  
Drainage System ◽  
High Arctic ◽  
Ablation Zone ◽  
Accumulation Zone ◽  
Seasonal Flow ◽  
Excess Surface ◽  
Velocity Response ◽  
Spatio Temporal ◽  
June July ◽  
Arctic Glacier

AbstractMeasurements of surface dynamics on polythermal John Evans Glacier, Nunavut, Canada, over two winter periods and every 7–10 days throughout two melt seasons (June–July 2000, 2001) provide new insight into spatio-temporal patterns of High Arctic glacier dynamics. In the lower ablation zone, mean annual surface velocities are 10–21 m a–1, but peak velocities up to 50% higher are attained during late June/early July. In the upper ablation zone and lower accumulation zone, mean annual surface velocities are typically 10–18 m a–1, and peak velocities up to 40% higher occur during late July. In the upper accumulation zone, mean annual surface velocities are 2–9 m a–1, and motion in mid- to late July exceeds this by up to 10%. Rapid drainage of ponded supraglacial water in the upper ablation zone to an initially distributed subglacial drainage system in mid-June may force excess surface motion in the warm-based lower glacier. The data indicate that the duration of the velocity response may be related to the rate of channelization of the basal drainage, and the velocity response may be transmitted up-glacier by longitudinal coupling. An increase in surface velocities in the middle glacier in late July occurs in conjunction with the opening of two further moulins in the accumulation zone.

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