Glaciers are decaying due to global warming. Svalbard is a very sensitive area within the European High Arctic and studies on glacier changes and evolutions are representative for the Arctic. The present work aims glaciers at Spitsbergen; we investigated meltwater supplied by glacierized basins in introducing radioactive isotope measurements in combination with classical parameters. Among the natural radioactive elements, the most promising is the noble gas radon, more precisely the isotope 222 Rn, with a short half life of 3.8 days and the possibility of automated continuous measurements. Measurements of radon in glacier meltwater showed surprisingly high concentrations thus enabling investigations with radon as valuable tracer. Only meltwater in contact with rock or sediments has the possibility to be charged with radon. Varying radon concentrations can be linked to changes in mixing meltwater from different origins, roughly the surface of glaciers (supraglacial), within (englacial) and under ice (subglacial). We are able to collect information on the glacier drainage system and its evolution over time and thus contribute to the study of glacier dynamics.Results from three sampling periods on Werenskioldbreen glacier, covering different glaciological seasons, are presented and discussed in this study. The potential results of further continuous measurements will give supplementary information on drainage footpaths and the style and system of the draining of glaciers. Our study intends also a better understanding of the response of glaciers to environmental parameters and, on a longer term, to make a contribution to climate change studies.
In low-nutrient ecosystems such as forests developed on acidic soil, the main limiting factor for plant growth is the availability of soil nutrients. The aim of this study was to investigate in a temperate forest: 1) the influence of the rhizosphere processes on the availability of nutrients and trace elements during one year period and 2) the seasonal evolution of this rhizosphere effect. Bulk soil and rhizosphere were collected in organo-mineral and mineral horizons of an acidic soil during autumn, winter, and spring under Norway spruce (Picea abies Karst) and beech (Fagus sylvatica). Soil solutions were extracted by soil centrifugation. Rhizosphere solutions were enriched in K, and in Ca, Mg, and Na (principally in spring) compared to those of the bulk soil. Our study reveals seasonal variations of the rhizosphere effect for Ca, Mg, and Na under both species, i.e., higher enrichment of the rhizosphere solution in spring as compared with that in autumn and winter. An enrichment of the rhizosphere solutions was also observed for trace elements regardless of the season under both species in the mineral horizon, only. In contrast, seasonal variations of the rhizosphere effect for the trace elements were observed in the solutions of the organo-* Corresponding author. C. Calvaruso et al. 324 mineral horizon under beech, i.e., enrichment in autumn and depletion in winter. This study demonstrates that rhizosphere biological activities significantly increase nutrient bioavailability during the growth period. These complex interactions between roots, microbial communities and soils are a key-process that supports tree nutrition in nutrient-poor forest soils. This research also reveals that rhizosphere processes a) occur throughout the year, even in winter, and b) influence differently the dynamics of nutrients and trace elements in the root vicinity of the organo-mineral horizon.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.