Application of first-arrival tomography to characterize a quick clay landslide site in Southwest Sweden

First-arrival traveltime tomography was applied to high-resolution seismic data acquired over a known quick-clay landslide scar near the Göta River in southwest Sweden in order to reveal the geometry and physical properties of clay-related normally consolidated sediments. Investigated area proved to be a challenging environment for tomographic imaging because of large P-wave velocity variations, ranging from 500 to 6000 m/s, and relatively steeply-dipping bedrock. Despite these challenges, P-wave velocity models were obtained down to ca. 150 m for two key 2D seismic profiles (each about 500-m long) intersecting over the landslide scar. The models portrait the sandwich-like structure of marine clays and coarse-grained consolidated sediments, but the estimated resolution (20 m) is too small to distinguish thin layers within this structure. Modelled velocity structures match well the results of reflection seismic processing and resistivity tomography available along the same profiles.     

Distribution of thallium and accompanying metals in tree rings of Scots pine (Pinus sylvestris L.) from a smelter-affected area

Distribution of Tl, Zn, Cd, Pb, K, Ca, Mg and Mn and Pb isotopic composition in tree rings of Scots pine (Pinus sylvestris L.) from an area affected by primary Zn smelting (Olkusz, southern Poland) were investigated. Elevated concentrations of Tl (up to 0.8 mg kg⁻¹) in pine trees imply that conifers tend to accumulate this metal to some extent. A generally positive relationship between soil and tree-ring Tl levels was identified. The Tl patterns in stem wood did not correspond to changes in Tl deposition; the lateral translocation of Tl in the sapwood and its accumulation at the sapwood-heartwood boundary (i.e., in the inner sapwood) is suggested. It is probable that the specific behavior of Tl in trees results from its biogeochemical analogy with K. In contrast, tree-ring patterns of Zn and Cd significantly correlated with their deposition; nevertheless, a partial shift of these metals towards the stem center cannot be excluded. The isotopic composition of Pb (²⁰⁶Pb/²⁰⁷Pb ~ 1.172–1.184) in trees and underlying soils revealed the predominant influence of smelter emissions (²⁰⁶Pb/²⁰⁷Pb ~ 1.17) on Pb contamination. Analysis of main nutrients (Ca, Mg and Mn) in wood reflected environmental changes related to acid deposition.     

Kinetic study of abstraction of ethyl xanthate ions by oxidized chalcocite surface

The results of potassium ethyl xanthate (EtXK) consumption measurements by synthetic chalcocite (Cu₂S grain-sized classes of 60–75 μm and 120–200 μm, respectively) are presented. These measurements were done in a modified circulation apparatus in an argon or oxygen atmosphere at pH=9.5. The experimental results were compared with theoretical results predicted by a mathematical model based on the assumption that the EtX^? ions were immobilized as a result of a chemical reaction (or reactions), e.g., of an ion-exchange type, taking place within the oxidation product layer (OPL), formed on the Cu₂S surface.The experimental and theoretical results are in good agreement especially for small values of Q₀ (Q₀ is the initial mass of the EtX^? in solution per mass unit of Cu₂S). In this case both the theoretical and experimental results show that the EtX^? concentration in solution decays exponentially with time.