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Cryoconite is an organomineral sediment on the surface of glaciers. It has predominantly an eolian origin, demonstrates high microbial activity, and contains a relatively large pool of nutrients. When glaciers retreat, the cryoconite material is translocated to the periglacial zone, where it serves as a nutrient-rich fine-textured parent rock component that promotes establishment of initial soils. Here we examine the spatial patterns of cryoconite on the surface of Aldegonda Glacier (Svalbard) and investigate the further pedogenic transformation of cryoconite material in periglacial environments of this rapidly retreating glacier. The data on micromorphology, composition of carbon and nitrogen stable isotopes, and radiocarbon age of different organic matter fractions in cryoconite and cryoconite-influenced periglacial soils are discussed. We demonstrate that soils formed on cryoconite material partially inherit its properties, and the soil formation processes can be accelerated by an order of magnitude compared to the surrounding nutrient-poor and coarse-textured till. [ABSTRACT FROM AUTHOR]

Birds can be an important agent of environmental change in High Arctic ecosystems, particularly due to the role of seabirds as a vector transferring nutrients from the marine to terrestrial realms. The soils of bird nesting sites are known to host distinct plant communities but the consequences of bird modification for microorganisms are much less clear. Our focus here is testate amoebae: a widely-distributed group of protists with significant roles in many aspects of ecosystem functioning. We compared the testate amoeba assemblages of a site on Spitsbergen (Svalbard archipelago) affected by nesting birds, with nearby control sites. We found differences in assemblage between sites, typified by reduced relative abundance of Phryganella acropodia and Centropyxis aerophila in bird-modified soils. These changes may reflect a reduced availability of fungal food sources. We found no evidence for differences in assemblage diversity or test concentration between bird-modified and control soils. Our dataset is small but results provide the first evidence for the potential effect of bird modification of soils on testate amoebae in the Arctic. Results show only limited similarity to experimental studies of nutrient addition, implying that response mechanisms may be more complicated than simply additional nutrient supply. [ABSTRACT FROM AUTHOR]

Abstract For the first time, lithospheric temperatures, strength, and effective elastic thickness (Te) distributions are estimated for the Arctic region north of 68°. To this aim, we use ArcCRUST, a recent model of the Arctic crust, which includes the thickness and density of the crust and sediments, the boundaries between the continental and oceanic crust, and the age of the oceanic lithosphere. We estimate the temperature variations in the continental lithosphere assuming steady-state conditions, for a constant surface heat flow of 50 mWm−2 and 62 mWm−2 for the onshore and offshore regions, respectively. In the oceanic domain, the temperature variations are estimated adopting a global depth and heat flow model. We discuss the robustness of the results by comparing the new thermal field with temperatures obtained from inversion of a regional seismic velocity model. The results are used as input for estimating integrated strength and Te , assuming a mafic crustal rheology. Our models predict a sharp transition between cratonic areas, characterized by high strength and Te , and tectonically active areas with a weaker lithosphere, corresponding to the continental shelves and the oceanic spreading ridges. The significant lateral change in our modeled strength and Te at the edges of Greenland and Canadian Arctic and along the active mid-ocean ridge in the NE Atlantic corresponds to increased observed seismic activity. Highlights • Lithospheric temperature and strength are estimated for the Arctic region • At shallow depth in the Arctic region, temperature spans in a large range • A sharp strength variation between cratons and tectonically active areas exists • Seismicity is concentrated in correspondence of lateral changes in strength [ABSTRACT FROM AUTHOR]