Performance of structures in the rural area during the March 8, 2010 Elazığ-Kovancılar earthquake

Numerous studies demonstrated the possibility of utilizing fly ash in the construction of embankments, road subgrades and stabilization of a wide range of soils. The present investigation aims at determining the optimum fly ash (OFA) for mechanical stabilization of expansive soils. Four different soils were tested for compaction characteristics and unconfined compressive strength with and without the addition of fly ash to determine the OFA. The liquid limit (LL) and the fraction coarser than 425 μ (CF) of these soils range from 50 to 120 and 25 to 70%, respectively. An experimental strategy called two-factor factorial design was adopted in the conducting experiments. LL and CF present in the soil are the two factors considered to influence the OFA content. Factorial experimentation enables relative quantification of the effect of each factor as well as their interaction with the OFA. The OFA was found to range from 5 to 40% depending upon the two factors. The LL and the CF were found to have dominating influence on OFA content in that order, whereas the interaction effect of these two factors was marginal to fair. A statistical regression model was developed for determination of the OFA in terms of the influencing factors. The validity of the model developed was verified by conducting laboratory tests on two more soils that were not used in the development of the model. Swell potential and swelling pressure of expansive soils were reduced to non-critical levels when treated with OFA.     

Validation of a field filtration technique for characterization of suspended particulate matter from freshwater. Part II. Minor, trace and ultra trace elements

A field filtration method for the concentration and separation of suspended particulate matter (SPM) from freshwater systems and the subsequent determination of minor, trace and ultra trace elements (As, Ba, Be, Cd, Co, Cr, Cs, Cu, Ga, Hf, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Sn, Sr, Ta, Th, Tl, U, V, W, Zn and Zr) is validated with respect to detection limits, precision and bias. The validation comprises the whole procedure including filtration, sample digestion and instrumental analysis. The method includes two digestion procedures (microwave acid digestion and alkali fusion) in combination with inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). Total concentrations of these 27 trace and minor elements have been determined in suspended particulate matter (SPM) from lake and river water with low levels of suspended solids (<2 mg L⁻¹ DW), and a wide range of element concentrations. The precision of the method including filtration, digestion and instrumental determination ranges between 8% and 18% RSD for most elements on a dry weight basis. Higher recovery after acid digestion is found for some elements, probably because of volatilization or retention losses in the fusion procedure. Other elements show higher recovery after fusion, which is explained by more efficient decomposition of refractory mineral phases relative to the non-total acid digestion. Non-detectable concentrations of some elements are reported due to small differences between blank filter levels and the amounts of elements present on the filters after sampling. The method limits of detection range between 0.7 ng and 2.65 μg, as estimated from the blank filter samples. These detection limits are 10–550 times higher compared to the corresponding instrumental limits of detection. The accuracy and bias of the overall analytical procedure was assessed from replicate analysis of certified reference materials. A critical evaluation of the instrumental capabilities of the ICP-QMS instrumentation in comparison with a double focusing sector field plasma mass spectrometry technique (ICP-SFMS) is also included. It was found that a modified microwave acid digestion procedure in combination with ICP-SFMS could replace ICP-AES determinations and fusion digestions for most of the investigated elements. Guidelines and limitations for this time- and labour- efficient procedure, offering accurate results for the majority of elements studied are discussed.     

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Mollusc-based paleoecological investigations of the Late Copper — Early Bronze Age earth mounds (kurgans) on the Great Hungarian Plain

The malacological material of the mound bodies (kurgans) of the Great Hungarian Plain indicates a mixed vegetation of dry and humid environments, developed on a mosaic of alkaline and chernozem soils in the period of the construction of the kurgan. The malacofauna that evolved in the upper soil horizon of the mound indicates the extremely dry environmental conditions of steppes, charaterized by the dominance of thermoxerophilous species. Dominant species of this kurgan are Chondrula tridens, Helicopsis striata, Granaria frumentum and Cepaea vindobonensis. The species composition shows that there are differences in the malacofauna of the Danube-Tisa Interfluves region compared to that of the lowlands east of River Tisza, indicated by the higher dominance of Granaria frumentum and Helicopsis striata in the former region. Following the construction of the kurgans an island-like, dry habitat developed on their surface, covered by black soil and populated by a steppe fauna, the composition of which is comparable mostly with the mollusc fauna of loess steppes and forest steppe, irrespectively of the floodplain or wind-blown sand character of the original surface.     

Tachylyte in Cenozoic basaltic lavas from the Czech Republic and Iceland: contrasting compositional trends

Mineralogy and Petrology - Tachylytes from rift-related volcanic rocks were recognized as: (i) irregular veinlets in host alkaline lava flows of the Kozákov volcano, Czech Republic, (ii)...     

Holocene salt‐marsh sedimentary infilling and relative sea‐level changes in West Brittany (France) using foraminifera‐based transfer functions

In order to reconstruct former sea‐levels and to better characterize the history of Holocene salt‐marsh sedimentary infillings in West Brittany (western France), local foraminifera‐based transfer functions were developed using weighted‐average‐partial‐least‐squares (WAPLS) regression, based on a modern data set of 26 and 51 surface samples obtained from salt‐marshes in the bay of Tresseny and the bay of Brest, respectively. Fifty cores were retrieved from Tresseny, Porzguen, Troaon and Arun salt‐marshes, which were litho‐ and biostratigraphically analysed in order to reconstruct palaeoenvironmental changes. A total of 26 AMS ¹⁴C age determinations were performed within the sediment successions. The Holocene evolution of salt‐marsh environments can be subdivided into four stages: (i) a development of brackish to freshwater marshes (from c. 6400 to 4500 cal. a BP); (ii) salt‐marsh formation behind gravel barriers in the bay of Brest (from 4500 to 2900 cal. a BP); (iii) salt‐marsh erosion and rapid changes of infilling dynamics due to the destruction of coastal barriers by storm events (c. 2900?2700 cal. a BP); (iv) renewed salt‐marsh deposition and small environmental changes (from 2700 cal. a BP to present). From the application of transfer functions to fossil assemblages, 14 new sea‐level index points were obtained, indicating a mean relative sea‐level rise of around 0.90±0.12 mm a^?1 since 6300 cal. a BP.