Chemical element distribution in Arctic soils: Assessing vertical, spatial, animal and anthropogenic influences in Elsa and Ebba Valleys, Spitsbergen, Svalbard.

The Arctic region is threatened by climate change and pollution caused by human activities which potentially influence the elemental concentrations available to and from the biota. To better understand this delicate balance, it is crucial to investigate the role of several factors. Therefore, we quantified the level of 43 chemical elements in soils from Elsa and Ebba Valleys, Petunia Bay, Spitsbergen, a region that has experienced lasting environmental impacts from historical mining activities. We evaluated the a) vertical sampling influence by examining the variation in element distribution between the soil upper and deeper layers, b) animal influence by verifying the role of native animals, particularly vertebrates, in introducing thought faeces elements to the soil and c) anthropogenic influence by studying the spatial geographical differences in element distribution based on the degree of human pressure between the valleys. Our analysis also includes data on soil organic matter (SOM) and mineral composition. Both valleys exhibited similar mineralogical composition, but Elsa Valley had higher concentrations of most analyzed elements compared to Ebba Valley. Despite the contribution of vertebrate feaces, no increase in element concentrations was observed in the animal-influenced soils. The sampled soil layers had similar chemical element profiles for most elements. SOM content tended to be higher in superficial soils and showed a strong positive correlation with most quantified elements. The higher concentrations in Elsa Valley reflect its past mining and mineral exploration, making this area more significantly impacted than Ebba Valley. Surprisingly, vertebrate animals do not appear to influence the concentrations of chemical elements or organic matter in soils. Our findings provide valuable insights into the legacy of past mining activities and mechanisms driving environmental change in the Arctic.

Cryoconite - From minerals and organic matter to bioengineered sediments on glacier's surfaces.

Cryoconite is a mixture of mineral and organic material covering glacial ice, playing important roles in biogeochemical cycles and lowering the albedo of a glacier surface. Understanding the differences in structure of cryoconite across the globe can be important in recognizing past and future changes in supraglacial environments and ice-organisms-minerals interactions. Despite the worldwide distribution and over a century of studies, the basic characteristics of cryoconite, including its forms and geochemistry, remain poorly studied. The major purpose of our study is the presentation and description of morphological diversity, chemical and photoautotrophs composition, and organic matter content of cryoconite sampled from 33 polar and mountain glaciers around the globe. Observations revealed that cryoconite is represented by various morphologies including loose and granular forms. Granular cryoconite includes smooth, rounded, or irregularly shaped forms; with some having their surfaces covered by cyanobacteria filaments. The occurrence of granules increased with the organic matter content in cryoconite. Moreover, a major driver of cryoconite colouring was the concentration of organic matter and its interplay with minerals. The structure of cyanobacteria and algae communities in cryoconite differs between glaciers, but representatives of cyanobacteria families Pseudanabaenaceae and Phormidiaceae, and algae families Mesotaeniaceae and Ulotrichaceae were the most common. The most of detected cyanobacterial taxa are known to produce polymeric substances (EPS) that may cement granules. Organic matter content in cryoconite varied between glaciers, ranging from 1% to 38%. The geochemistry of all the investigated samples reflected local sediment sources, except of highly concentrated Pb and Hg in cryoconite collected from European glaciers near industrialized regions, corroborating cryoconite as element-specific collector and potential environmental indicator of anthropogenic activity. Our work supports a notion that cryoconite may be more than just simple sediment and instead exhibits complex structure with relevance for biodiversity and the functioning of glacial ecosystems.