Aluminium in glacial meltwater demonstrates an association with nutrient export (Werenskiöldbreen,Svalbard)     

&#x;ukasz Stachnik  Jacob C. Yde  Adam Nawrot  &#x;ukasz Uzarowicz  Elbieta &#x;epkowska  Katarzyna Kozak 《水文研究》2019,33(12):1638-1657

The aluminium (Al) cycle in glacierised basins has not received a great deal of attention in studies of biogeochemical cycles. As Al may be toxic for biota, it is important to investigate the processes leading to its release into the environment. It has not yet been ascertained whether filterable Al (passing through a pore size of 0.45 μm) is incorporated into biogeochemical cycles in glacierised basins. Our study aims to determine the relationship between the processes bringing filterable Al and glacier‐derived filterable nutrients (particularly Fe and Si) into glacierised basins. We investigated the Werenskiöldbreen basin (44.1 km², 60% glacierised) situated in SW Spitsbergen, Svalbard. In 2011, we collected meltwater from a subglacial portal at the glacier front and at a downstream hydrometric station throughout the ablation season. The Al concentration, unchanged between the subglacial system and proglacial zone, reveals that aluminosilicate weathering is a dominant source of filterable Al under subglacial conditions. By examining the Al:Fe ratio compared with pH and the sulphate mass fraction index, we found that the proton source for subglacial aluminosilicate weathering is mainly associated with sulphide oxidation and, to a lesser degree, with hydrolysis and carbonation. In subglacial outflows and in the glacial river, Al and Fe are primarily in the forms of Al(OH)₄^‐ and Fe(OH)₃. The annual filterable Al yield (2.7 mmol m^‐2) was of a magnitude similar to that of nutrients such as filterable Fe (3.0 mmol m^‐2) and lower than that of dissolved Si (18.5 mmol m^‐2). Our results show that filterable Al concentrations in meltwater are significantly correlated to filterable and dissolved glacier‐derived nutrients (Fe and Si, respectively) concentrations in glaciers worldwide. We conclude that a potential bioavailable Al pool derived from glacierised basins may be incorporated in biogeochemical cycles, as it is strongly related to the concentrations and yields of glacier‐derived nutrients.  相似文献   

Aspects of the Clay/Electrolyte/Water System with Special Reference to the Geotechnical Properties of Clays     

Ewa T. St  epkowska 《Engineering Geology》1990,28(3-4):249-267

The solid phase of the clay/electrolyte/water system is composed of platy clay particles (of variable thickness, δ, and variable specific surface, S) and of crystal phase (hygroscopic) water, wherefrom δ and S may be estimated. Diffuse layer water between parallel particles and other structural elements at the mutual distance 2d, W_d = d S ρ_w, and macropore water form the liquid phase. Particles are arranged in domains and and clusters, these in aggregates in an “aggregate lattice” with vacancies (macropores) and further superstructures are formed. Contact bonds may develop and long-range forces exist between structural elements, which govern the clay geotechnical behaviour. Cohesion is usually due to van der Waals attraction, friction component–to contact bonds and particle delamination, swelling and suction–to diffuse layer repulsion. Most phenomena may be explained in terms of the equilibrium condition between attraction and repulsion. Heat dissipation must be considered in mechanical processes. The angle of effective stress env envelope is correlated with particle thickness, thus therefrom clay strength may be estimated.  相似文献