Search results for "GLACIER"

Microbial succession of nitrate-reducing bacteria in the rhizosphere of Poa alpina across a glacier foreland in the Central Alps

2006

International audience; Changes in community structure and activity of the dissimilatory nitrate-reducing community were investigated across a glacier foreland in the Central Alps to gain insight into the successional pattern of this functional group and the driving environmental factors. Bulk soil and rhizosphere soil of Poa alpina was sampled in five replicates in August during the flowering stage and in September after the first snowfalls along a gradient from 25 to 129 years after deglaciation and at a reference site outside the glacier foreland (> 2000 years deglaciated). In a laboratory-based assay, nitrate reductase activity was determined colorimetrically after 24 h of anaerobic inc…

L'Arctique en mutation

2016

International audience; AVANT-PROPOS..........................................Daniel JOLYCHAPITRE 1 - Fluctuations climatiques récentes en Arctique : l’exemple du Spitsberg occidental, Madeleine GRISELIN, Christelle MARLIN et Jean-Michel FRIEDTCHAPITRE II - Évolution contemporaine des glaciers arctiques ; exemple de l’Austre Lovénbreen (79°N), Eric BERNARD et Florian TOLLECHAPITRE III - Géomorphologie des côtes rocheuses arctiques, SAMUEL ETIENNE, Jim HANSOM et Donald L. FORBESCHAPITRE IV - L’Arctique face aux crises géomorphologiques paraglaciaires, Denis MERCIERCHAPITRE V - Distribution multi-scalaire de la végétation en Arctique, Martha RAYNOLDCHAPITRE VI - Distribution de la végétation …

HIGH-RESOLUTION SURFACE AND BED TOPOGRAPHY MAPPING OF RUSSELL GLACIER (SW GREENLAND) USING UAV AND GPR

2020

Abstract. This study presents the detailed survey of the northern marginal part of Russell Glacier, SW Greenland using the combination of unmanned aerial vehicle (UAV) photogrammetry and low-frequency ground penetrating radar (GPR) measurements. Obtained digital elevation model (DEM) and ice thickness data from GPR data allowed the generation of high precision subglacial topography model. We report uncertainties arising from GPR, GPS, and DEM suggesting sufficient accuracy for the reconstruction of glacier bed topography. GPR data and generated subglacial topography model does not reveal any possible Nye channel that could be incised into the bedrock, however, we were able to detect englaci…

Terrestrial Inputs Drive Seasonality in Organic Matter and Nutrient Biogeochemistry in a High Arctic Fjord System (Isfjorden, Svalbard)

2020

Climate-change driven increases in temperature and precipitation are leading to increased discharge of freshwater and terrestrial material to Arctic coastal ecosystems. These inputs bring sediments, nutrients and organic matter (OM) across the land-ocean interface with a range of implications for coastal ecosystems and biogeochemical cycling. To investigate responses to terrestrial inputs, physicochemical conditions were characterized in a river- and glacier-influenced Arctic fjord system (Isfjorden, Svalbard) from May to August in 2018 and 2019. Our observations revealed a pervasive freshwater footprint in the inner fjord arms, the geochemical properties of which varied spatially and seaso…

Discrete element model for viscoelastic materials with brittle fracture : applications on glacier dynamics

2017

Rétro-observation des processus de décrue glaciaire à partir de peintures. Apports de la mono-photogrammétrie

2019

Alpine landscapes are indicators of climatic variations recognized through their geomorphological and glacial dynamics. Inthis field, the old documents (photographs, engravings, paintings…) constitute important data sources, used for the purposesof retro-observations. The classical methods consist, most often, to exploit them in descriptive works then being the subject ofnaturalistic cartographic retranscriptions. Today the contribution of innovative methods of treatment, such as mono-photogrammetry,offer new perspectives. It is thus possible to extract quantitative information from qualitative archives. This approachallows, in addition to a conventional landscape analysis, to project the i…

Evolution of Seismicity During a Stalled Episode of Reawakening at Cayambe Volcano, Ecuador

2021

Cayambe Volcano is an ice-capped, 5,790 m high, andesitic-dacitic volcanic complex, located on the equator in the Eastern Cordillera of the Ecuadorian Andes. An eruption at Cayambe would pose considerable hazards to surrounding communities and a nationally significant agricultural industry. Although the only historically documented eruption was in 1785, it remains persistently restless and long-period (LP) seismicity has been consistently observed at the volcano for over 10 years. However, the sparse monitoring network, and complex interactions between the magmatic, hydrothermal, glacial, and tectonic systems, make unrest at Cayambe challenging to interpret. In June 2016 a seismic “crisis” …