Velocity and Density Heterogeneities of the Tien-Shan Lithosphere

—The Tien-Shan orogene is a region in which the earth’s crust undergoes considerable thickening and tangential compression. Under these conditions the lithosphere heterogeneities (composi tion, rheological) create the prerequisites for the development of various phenomena of tectonic layering (lateral shearing, different deformation of layers). To study the distribution of velocity, density and other elastic parameters, the results from a seismic tomography study on P-wave as well as S-wave velocities were used. Using empirical as well as theoretical formulas on the relationship between velocity, density and silica content in rocks, their distribution in the Tien-Shan’s lithosphere has been calculated. In addition, other elastic parameters, such as Young’s modulus, shear modulus, Poisson’s ratio and coefficient of general compressions have been determined. Zoning of different types of crust was carried out for the region investigated. The characteristics of the "crust-mantle" transition have been investi gated. Large blocks with different types of the earth’s crust were distinguished. Layers with inverse values of velocity, density and shear and Young modulus are revealed in the Tien-Shan lithosphere. All of the above described features open new ways to solve geodynamics problems.     

Analysis of mutations in the p53 tumor suppressor gene and Ki- and Ha-ras proto-oncogenes in hepatic tumors of European flounder (Platichthys flesus).

DNA from five tumors, three other-injured livers and two normal liver tissue samples from the European flounder were analyzed for mutations in exons 5-8 of the tumor suppressor gene p53 and at codons 12, 13 and 61 of Ha- and Ki-ras proto-oncogenes. No tumor-specific mutations were identified by direct sequencing and single-strand conformation polymorphism of these genes. A number of silent polymorphisms were noted in p53. In addition to a need for more extensive analyses of flounder liver tumor samples for ras or p53 mutations, other cancer-related genes should be investigated.     

Impact of Sea-level Rise and Storm Surges on a Coastal Community

A technique to evaluate the risk of storm tides (the combination of a storm surge and tide) under present and enhanced greenhouse conditions has been applied to Cairns on the north-eastern Australian coast. The technique combines a statistical model for cyclone occurrence with a state-of-the-art storm surge inundation model and involves the random generation of a large number of storm tide simulations. The set of simulations constitutes a synthetic record of extreme sea-level events that can be analysed to produce storm tide return periods. The use of a dynamic storm surge model with overland flooding capability means that the spatial extent of flooding is also implicitly modelled. The technique has the advantage that it can readily be modified to include projected changes to cyclone behaviour due to the enhanced greenhouse effect. Sea-level heights in the current climate for return periods of 50, 100, 500 and 1000 years have been determined to be 2.0 m, 2.3 m, 3.0 m and 3.4 m respectively. In an enhanced greenhouse climate (around 2050), projected increases in cyclone intensity and mean sea-level see these heights increase to 2.4 m, 2.8 m, 3.8 m and 4.2 m respectively. The average area inundated by events with a return period greater than 100 years is found to more than double under enhanced greenhouse conditions.     

Alteration processes in the CV chondrite parent body based on analysis of NWA 2086 meteorite

Analysis of the NWA 2086 CV3 chondrite showed a matrix/chondrule ratio of 52%, similar to Bali, Mokoia, and Grosanaja. Nearly twice as many chondrule fragments as intact ones demonstrate that an early fragmentation phase occurred prior to final accretion. After this event, no substantial mechanical change or redeposition is evident. Rims with double‐layered structures were identified around some chondrules, which, in at least one case, is attributed to an accretionary origin. The rim's outer parts with a diffuse appearance were formed by in situ chemical alteration. During this later process, Mg content decreased, Fe content increased, and olivine composition was homogenized, producing a rim composition close to that of the matrix. This alteration occasionally happened along fractures and at confined locations, and was probably produced by fluid interactions. Iron oxides are the best candidate for a small grain‐sized alteration product; however, technical limitations in the available equipment did not allow exact phase identification. These results suggest that NWA 2086 came from a location (possible more deeply buried) in the CV parent body than Mokoia or Bali, and suffered less impact effects—although there is no evidence of sustained thermal alteration. This meteorite may represent a sample of the CV parent asteroid interior and provide a useful basis for comparison with other CV meteorites in the future.     

The use of acidimetric titration as a novel approach to study particulate trace metal speciation and mobility: Application to sediments of the Scheldt estuary

The study of trace metal speciation has benefited from a great deal of interest leading to the development and the diversification of sequential extraction schemes (SES), which triggered the need for harmonization by the standard, measurements and testing programme (SM & T). However, some uncertainties still persist in the application of the harmonized 3-step protocol, because of the difficulty in conceptualizing a technique that can be applied to environmental samples irrespective of their nature. The alternative method proposed in this study is based on the solubility of the sample components progressively dissolved during the course of an acidimetric titration by 1 mol L⁻¹ HCl. The major HCl-reactive mineralogical components are identified using mass balance calculation of H⁺ consumed by their dissolution together with the amount of major elements released into solution. The speciation of minor and trace elements is investigated by comparing their titrations to those of the major elements. This approach is much simpler than SES because it uses simple non-selective H⁺ at room temperature instead of a complex experimental design of so-called specific reagents. The different mineral components of the solid are no longer operationally defined and the problem of selectivity is irrelevant to the titration approach. The method was applied to several sediment samples from the Scheldt estuary and the particulate phase was further examined by Scanning Electron Microprobe and X-ray Diffraction techniques. The nearly complete consumption of H⁺ in the suspension is balanced by the total dissolution of carbonates and Fe-oxyhydroxides. In contrast to the speciation inferred from the Tessier SES, the acidimetric titration has demonstrated that the carbonate phase does not significantly contain trace metals with the exceptions of 40% of the Mn and 30% of the Co. In contrast, the Fe-oxyhydroxides seem to play a major role and account for 70% of Pb and 20% of Cr, in addition to 60% of P and additional amounts of 20% Co and 40% Mn. 70% of the Cu also occur in the oxyhydroxide phase, more likely coprecipitated with gibbsite. 90% of the Cd and 85% of Zn can be attributed to the Acid Volatile Sulfide (AVS) phase as evidenced from S titration. The acidimetric titration method not only provides information on the speciation of trace metals but also allows the quantification of their reactivity and mobility, if one considers that the titration roughly mimics pH changes that may occur as a result of chemical disequilibrium in the environment. The results demonstrate the potential of the acidimetric titration as an alternative to SES protocols in geochemical and environmental regulation studies. This method is applicable to a wide variety of environmental materials with little or minor adjustments.