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The ∼100 m-long Laguna Potrok Aike sediment sequence yielded a record spanning the Last Glacial period to the Holocene. This paper presents and discusses two aspects of the mineralogy of the lake. The first aspect is based on a semi-quantitative X-ray diffraction analysis of bulk and clay mineralogical assemblages. Minor mineralogical changes are observed throughout the glacial section suggesting relatively uniform sediment sources. The transition into the Holocene is characterized by increasing fluxes of endogenic calcite thought to relate to lower lake levels. The second aspect is based on analysis of uranium-series disequilibria in diagenetic vivianite from the glacial section. U-series ages were expected to yield minimum ages for the host-sediment. Unfortunately, very little authigenic U is present in vivianite grains. The low primary productivity of the lake and thus low organic carbon fluxes might have prevented the development of strong redox gradients at the water-sediment interface and thus reduced diagenetic U-uptake into the sediment. One vivianite sample, at a 56.9 m composite depth, yielded enough authigenic uranium to calculate a 230Th-age of 29.4 ± 5.9 ka (±2σ). This age is younger than the one indicated by the radiocarbon chronology. It is thus concluded that a relatively late diagenetic evolution of the U–Th system characterizes the recovered vivianite minerals. The authigenic U displays a very high excess in 234U (over 238U) with an activity ratio of 4.58 ± 0.58 (±2σ). It suggests that it originates from the transfer of highly fractionated U from surrounding detrital minerals through very low U-content pore waters. [ABSTRACT FROM AUTHOR]

The corrosion product films that were formed on industrial, low-carbon concentration Fe–C steel after immersion in diluted ammoniac solutions were investigated by 57Fe Mössbauer spectroscopy. The amorphous Fe3+ oxyhydroxide was the major constituent of the corrosion layers. Layer thickness increased as NH3 concentration changed from 10-1 to 10-4 N. All CEMS spectra indicated a magnetic anisotropy on the surface of the samples. [Copyright &y& Elsevier]

Carbamazepine microparticles were produced by the rapid expansion of supercritical carbon dioxide solutions (RESS) method. The characteristics of the resulting particles were studied by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and image analysis. X-ray diffractograms and SEM photomicrographs revealed that the crystalline nature of the produced carbamazepine microparticles depended on operating pressure and temperature conditions. Different polymorphs were obtained under various operating conditions. Under certain temperature (below 40 °C) and pressure (below 240 bar) conditions, it was possible to form primarily the carbamazepine polymorph stipulated by US Pharmacopeia. A significant reduction was observed in the particle size and size distribution range of carbamazepine produced by RESS. The processed particles had a mean diameter smaller than 3 μm and a size distribution range between 0.5 and 2.5 μm compared to unprocessed starting material with a mean diameter of approximately 85 μm and a size distribution range between 15 and 336 μm. Thus, this study demonstrates that the polymorphic characteristics of carbamazepine microparticles produced by the RESS method can be controlled by varying operating pressure and temperature parameters. [Copyright &y& Elsevier]

Abstract The aim of study was to assess the effectiveness of organic and inorganic amendments to immobilize cadmium (Cd), lead (Pb) and zinc (Zn) in soil and reduce their availability in a contaminated soil. We present the results of a field experiment organised in the Copșa Mica area in which different types of amendments were applied: Na-bentonite, dolomite, natural zeolite and manure. The effectiveness of applied amendments was assessed using single extraction of metals from soil (using DTPA-CaCl 2 -TEA at pH 7.3 or NH 4 NO 3) and metal accumulation in plants. All treatments produced significant increases of soil pH, but the best results were observed after applications of dolomite and Na-bentonite. After two years from applications all amendments decreased the metal (Cd, Pb or Zn) availability compared to the control, but the magnitude of effects depends on each metal and amendment. The addition of dolomite and Na-bentonite reduced significantly the concentrations of Pb and Zn in plants, but this reduction is not enough to produce healthy food or fodder. The application of manure led to a significant increasing of biomass yield comparing with control, even if the extractability of metals in manure treated plots was moderate. The results demonstrate the high potential of Na-bentonite and dolomite to reduce the availability and possible toxicity of heavy metals in contaminated soils but more attention should be paid to the transitory liming effect and metal remobilizing over time. Highlights • Copsa Mica is one of the most polluted area from Romania. • Soil amendment addition increased pH and enhances the metal immobilization in soil. • Long-term monitoring of soils and crops quality is compulsory in contaminated area. [ABSTRACT FROM AUTHOR]

Abstract: The accumulation, enrichment and provenance of selected trace metals (Ag, As, Cd, Cr, Cu, Hg, Ni, Pb, V and Zn) were studied in sediment cores collected from three lakes located in the Central Mexican Plateau, selected on the basis of their contrasting degree of urbanization: Santa Elena Lake, in a rural and remote area; El Tule Lake, in a rural and slightly urbanized area; and Chapala Lake, in a highly urbanized area. Grain size, magnetic susceptibility and sedimentary constituents such as organic carbon, calcium carbonate, as well as major (Al, Fe, Mn) and minor (Ca, Li, Rb, Sr, Th) elements were analyzed to explain the concentration trends of trace metals. Factor analysis (FA) was used to assess the provenance of the trace elements. The highest metal enrichment factor (EF) above natural concentration levels was found at Chapala Lake for Ag (EF=3.9), although other trace element EF in all lakes was <2.0, indicating slight contamination. However, the concentration levels of Cr and Ni in all lakes, Hg and Zn in Chapala Lake, Cu in El Tule Lake and As in Santa Elena Lake were above international benchmarks for which adverse effects are expected to occur frequently, even for those metals only slightly enriched (e.g. As, Cr). Through FA, the terrigenous contribution was identified as the most important source of trace metals to the three lakes, most likely related to deforestation and erosion of the surrounding areas, followed by atmospheric transport of volcanic ashes, rather than to direct sources. [Copyright &y& Elsevier]

Abstract: The inhibiting effect of N-ciclohexil-benzothiazole-sulphenamida (NCBSA) on the corrosion of carbon-steel in diluted ammonia solution at room temperature has been studied by Mössbauer spectroscopy, electrochemical measurements, weight loss and surface microscopic analysis. A decrease in the corrosion spot concentration with the increase of the NCBSA concentration indicates a good adsorbability of NCBSA on the metal surface. Mössbauer spectrometry shows the formation of a layer at the surface of the corroded sample, which is interpreted in terms of the formation of complexes between NCBSA and the metal cations present in the carbon-steel structure. [Copyright &y& Elsevier]

Abstract: A sedimentary sequence from the Espejo de los Lirios lake in the Metropolitan Zone of Mexico City (MZMC) was analyzed in detail for 210Pb and 137Cs activities, allowing to assess the evolution of the accretion rates in the lake during the last ∼84±4 years. The core revealed the deposition of contemporaneously indigenous lake sediments to the site interspersed with eroded bedrock from the catchment, evidencing episodic increases in sediment accretion which varied from 0.14 to 0.93 cm year−1. Increasing trends in sedimentation rates were found to be closely related to demographic expansion of the Metropolitan Zone of Mexico City and explained on the basis of the erosive processes produced as a result of deforestation created as a consequence of the urban and industrial development of the MZMC. [Copyright &y& Elsevier]

The ΣΣ intermediate-energy reference spectrum irradiation facility, operated until 1998 at the VVR-S Reactor from Bucharest, was put into operation at the Romania TRIGA Reactor. This paper presents the experimental devices developed for the ΣΣ system operating at the Steady State Reactor (SSR)-TRIGA core, including the monitoring system, and preliminary neutron characterization results. These results show that the spectrum characteristics are slowly deviating from those for the recommended ΣΣ spectrum. The high-energy neutron tail is slowly increasing, compared with the recommended ΣΣ spectrum and other similar facilities. [Copyright &y& Elsevier]