Assessment of mercury mobility and bioavailability by fractionation method in sediments from coastal zone inundated by the 26 December 2004 tsunami in Thailand

The 26 December 2004 tsunami covered significant portion of a coastal zone with a blanket of potentially contaminated sediments. In this report are presented results on mercury concentrations in sediments deposited by the tsunami in a coastal zone of Thailand. Since the total mercury concentrations are insufficient to assess mercury mobility and bioavailability in sediment, its fractionation was applied. Sediments were sampled within 50 days after the event and analyzed by sequential extraction method. The procedure of sequential extraction involved five subsequent stages performed with solutions of chloroform, deionized water, 0.5 M HCl, 0.2 M NaOH, and aqua regia. The mean concentration of total mercury in sediments was 119 ± 50 ng g⁻¹ dry mass (range 66–230). The fractionation revealed that mercury is mainly bound to the least bioavailable sulphides 75 ± 6% (range 62–86), organomercury compounds 14 ± 7% (range 4–26), and humic matter 9 ± 7% (range 1–27). The lowest contributions bring fractions of water-soluble mercury 0.8 ± 1.0% (range 0.1–3.6) and acid soluble mercury 0.9 ± 0.5% (range 0.2–2.1). Although, the total mercury content is similar in a reference sample and in the tsunami sediments, the highly toxic organomercury fraction contribution is higher in the latter. The results were compared with chemical and sedimentological properties of the sediments but no significant correlations were obtained between them.     

Taxonomic analysis of the Quaternary archaeofauna found at The Lapa do Santo site,Lagoa Santa region,Brazil

The Lapa do Santo archaeological site, located in the Lagoa Santa region, Brazil, represents an important hunter-gatherer occupation dated from the Early and Middle Holocene. Prior studies of archaeofauna dating to this period are few and most of them only provide basic faunal identification with limited information on taphonomic processes. The main goal of this study is to identify the archaeofauna, record the taphonomic processes, and make inferences about its natural (interpreted as the death of the animal in the rockshelter area due to natural causes or due to predation) or anthropic origins. No extinct species (including megamastofauna) were identified. Taxonomic analysis indicated that most faunal remains consist of taxa that may be of mixed origin (natural or anthropic), such as microvertebrates and carnivorous mammals. The Cervidae are the main vertebrate family found in the studied material and these are likely the result of hunting. The Cervidae Ozotoceros support the presence of a fauna that is typical of savannah environments, although the assemblage contains mostly generalist fauna that can thrive in a variety of environments. Very few remains showed clear evidence for taphonomic processes related to human interaction, such as burnt bones.     

The accuracy of standard enthalpies and entropies for phases of petrological interest derived from density-functional calculations

The internal energies and entropies of 21 well-known minerals were calculated using the density functional theory (DFT), viz. kyanite, sillimanite, andalusite, albite, microcline, forsterite, fayalite, diopside, jadeite, hedenbergite, pyrope, grossular, talc, pyrophyllite, phlogopite, annite, muscovite, brucite, portlandite, tremolite, and CaTiO₃–perovskite. These thermodynamic quantities were then transformed into standard enthalpies of formation from the elements and standard entropies enabling a direct comparison with tabulated values. The deviations from reference enthalpy and entropy values are in the order of several kJ/mol and several J/mol/K, respectively, from which the former is more relevant. In the case of phase transitions, the DFT-computed thermodynamic data of involved phases turned out to be accurate and using them in phase diagram calculations yields reasonable results. This is shown for the Al₂SiO₅ polymorphs. The DFT-based phase boundaries are comparable to those derived from internally consistent thermodynamic data sets. They even suggest an improvement, because they agree with petrological observations concerning the coexistence of kyanite?+?quartz?+?corundum in high-grade metamorphic rocks, which are not reproduced correctly using internally consistent data sets. The DFT-derived thermodynamic data are also accurate enough for computing the P–T positions of reactions that are characterized by relatively large reaction enthalpies (>?100 kJ/mol), i.e., dehydration reactions. For reactions with small reaction enthalpies (a few kJ/mol), the DFT errors are too large. They, however, are still far better than enthalpy and entropy values obtained from estimation methods.     

Factors controlling the development of prism faces in granite zircons: a microprobe study

Based on microprobe work, we present arguments that the size relations of the two common prisms {100} and {110} of accessory granite zircons are strongly influenced by chemical factors. Magmatic growth zoning patterns, which we have studied by means of backscattered electron imaging in special zircon sections orientated perpendicular to the c-axis, do not support previous models which assumed temperature or the degree of ZrSiO₄ supersaturation to be the primary prism-form-directing factors. The element U, which usually occupies the Zr-sites of granite zircoms to some degree, is strongly suspected of producing an (adsorptive) growth-blocking effect for {110}-type faces thus creating crystals with {110}-dominated prism morphology. A second independent mechanism that is likely to form zircons with large {110} prisms is the common substitution Zr⁴⁺+Si⁴⁺ versus Y(REE) and P contents (relative to Zr) are, according to our model, predestinated to produce zircons with large {100} prisms and vice versa.Dedicated to Prof. Günther Frasl on the occasion of his seventieth birthday     

Stochastic response of rigid foundations

While the study of kinematic interaction (i.e. the dynamic response of massless foundations to seismic loads) calls, in general, for advanced analytical and numerical techniques, an excellent approximation was proposed recently by Iguchi.^1,2 This approximation was used by the authors to analyse embedded foundations subjected to spatially random SH-wave fields, i.e. motions that exhibit some degree of incoherence. The wave fields considered ranged from perfectly coherent motions (resulting from seismic waves arriving from a single direction) to chaotic motions, resulting from waves arriving simultaneously from all directions. Additional parameters considered were the shape of the foundation (cylindrical or rectangular) and the degree of embedment. It was found that kinematic interaction usually reduces the severity of the motions transmitted to the structure, and that incoherent motions do not exhibit the frequency selectivity (i.e. narrow valleys in the foundation response spectra) that coherent motions do.     

Icequakes and glacier motion: The hans glacier,spitsbergen

The recording of glacier icequakes has been carried out on the Hans glacier, Spitsbergen. The icequakes have been connected with the formation of open cracks. The energy of the main group of icequakes has ranged from 0.01 J to 6 J, their seismic moment being from 0.5 · 10¹⁴ dyne · cm to 26 · 10¹⁴ dyne · cm. The nonelastic volume increase corresponding to each crack has ranged from 0.2 · 10⁻² m³ to 8.8 · 10⁻² m³. The stresses released due to extensional faulting ranged from 25N/m² to 500 N/m²; these values are so small that they suggest an incomplete release of the medium. The contribution into the glacier flow rate of the deformation in the surface glacier layer due to extensional faulting is lower by 2 to 3 orders of magnitude than the total plastic deformation associated with the ice creeping.     

Thermodynamic mixing behavior of synthetic Ca-Tschermak–diopside pyroxene solid solutions: II. Heat of mixing and activity–composition relationships

The heat of mixing for the binary solid solution diopside–Ca-Tschermak was investigated at T = 980 K by lead borate solution calorimetry. A new statistical technique was applied to overcome the problem of using experimental data of various precisions. A two-parameter Margules model was fitted to the calorimetric data leading to W _CaTs–Di^H = 31.3 ± 3.4 kJ mol⁻¹ and W ^H _Di–CaTs = 2.4 ± 4.3 kJ mol⁻¹. The results are in good agreement with calorimetric data given in the literature. They agree also with enthalpy data that were extracted from phase equilibrium experiments. With configurational entropy values taken from the literature, the volume and the vibrational entropy, presented in Part I of this work, and the enthalpy data of this study, the activity–composition relationships of the diopside–Ca-Tschermak binary were calculated.     

The heat capacity of two natural chlorite group minerals derived from differential scanning calorimetry

The heat capacity of natural chamosite (X_Fe=0.889) and clinochlore (X_Fe=0.116) were measured by differential scanning calorimetry (DSC). The samples were characterised by X-ray diffraction, microprobe analysis and Mössbauer spectroscopy. DSC measurements between 143 and 623?K were made following the procedure of Bosenick et?al. (1996). The fitted data for natural chamosite (CA) in J?mol^?1?K^?1 give: C _p,CA = 1224.3–10.685?×?10³?×?T ^??0.5???6.4389?× 10⁶?×T ^??2?+?8.0279?×?10⁸?×?T ^??3 and for the natural clinochlore (CE): C _p,CE = 1200.5–10.908?×?10³?×T ^??0.5?? 5.6941?×?10⁶?×?T ^??2?+?7.1166?×?10⁸?×?T ^??3. The corrected C _p-polynomial for pure end-member chamosite (Fe₅Al)[Si₃AlO₁₀](OH)₈ is C _p,CAcor = 1248.3–11.116?× 10³?×?T ^??0.5???5.1623?×?10⁶?×?T ^??2?+?7.1867?×?10⁸×T ^??3 and the corrected C _p-polynomial for pure end-member clinochlore (Mg₅Al)[Si₃AlO₁₀](OH)₈ is C _p,CEcor = 1191.3–10.665?×?10³?×?T ^??0.5???6.5136?×?10⁶?×?T ^??2?+ 7.7206?×?10⁸?×?T ^??3. The corrected C _p-polynomial for clinochlore is in excellent agreement with that in the internally consistent data sets of Berman (1988) and Holland and Powell (1998). The derived C _p-polynomial for chamosite (C _p,CAcor) leads to a 4.4% higher heat capacity, at 300?K, compared to that estimated by Holland and Powell (1998) based on a summation method. The corrected C _p-polynomial (C _p,CAcor) is, however, in excellent agreement with the computed C _p-polynomial given by Saccocia and Seyfried (1993), thus supporting the reliability of Berman and Brown's (1985) estimation method of heat capacities.     

Geology, coal quality, and resources of the Antaramut–Kurtan–Dzoragukh coal field, north-central Armenia

The Antaramut–Kurtan–Dzoragukh (AKD) coal deposit is a previously unrecognized coal field in north-central Armenia. Coal has been known to exist in the general vicinity since the turn of the century, but coal was thought to be restricted to a small (1 km²) area only near the village of Antaramut. However, through detailed field work and exploratory drilling, this coal deposit has been expanded to at least 20 km², and thus renamed the Antaramut–Kurtan–Dzoragukh coal field, for the three villages that the coal field encompasses. The entire coal-bearing horizon, a series of tuffaceous sandstones, siltstones, and claystones, is approximately 50 m thick. The AKD coal field contains two coal beds, each greater than 1 m thick, and numerous small rider beds, with a total resource of approximately 31,000,000 metric tonnes. The coals are late Eocene in age, high volatile bituminous in rank, relatively high in ash yield (approximately 40%, as-determined basis) and moderate in sulfur content (approximately 3%, as-determined basis). The two coal beds (No. 1 and No. 2), on a moist, mineral-matter-free basis, have high calorific values of 32.6 MJ/kg (7796 cal/g) and 36.0 MJ/kg (8599 cal/g), respectively. Coal is one of the few indigenous fossil fuel resources occurring in Armenia and thus, the AKD coal field could potentially provide fuel for heating and possibly energy generation in the Armenian energy budget.