Abstract: This article reviews the different methods used for the determination of selenium species in all types of environmental waters. Basic difficulties are discussed and the efficiency of the methods is explained in view of the sub-μg/1. concentration levels. Special attention is paid to preconcentration steps. Published data on speciation and concentration levels in various water samples are critically reviewed.

Abstract: By using a polyester sailboat as sampling platform, a series of duplicate aerosol samples was collected by cascade impactors on a trip from Panama to Tahiti in 1979. Elemental analysis mainly by particle-induced X ray emission (PIXE) indicated, in the samples collected between Panama and the Galapagos Islands, the presence of a substantial crustal component (∼0.4 μg/m3), fine Cu (∼0.4 ng/m3) and Zn (∼0.6 ng/m3), and excess fine S and K (∼100 and ∼2.4 ng/m3, respectively) in addition to the major sea salt elements. The crustal component and fine Cu and Zn are suggested to result from natural continental sources (i.e., eolian dust transport from the American continents and perhaps geothermal emissions). Samples collected west of the Galapagos Islands in the southern trades showed significantly lower concentrations for the nonseawater components. The average Si and Fe levels were as low as 4.8 and 3.3 ng/m3, corresponding to a maximum of 0.066 μg/m3 for an assumed mineral dust component, whereas heavy metal concentrations were all below the detection limits (typically ranging from 0.05 to 0.15 ng/m3 for V, Cr, Mn, Ni, Cu, Zn, and Se). Excess fine S decreased to a mean of 46 ng/m3, a level similar to those reported for other remote marine and continental locations. This all indicates that the marine atmosphere west of the Galapagos was little influenced by natural continental source processes or by anthropogenic emissions. Under these truly marine conditions, several concentration ratios of the major seawater elements were significantly different from those in bulk seawater. Ca, Sr, and S in >1 μm diameter particles were enriched relative to K and Na, with the enrichment being substantially more pronounced (up to 50% or higher) for l4-μm diameter particles than for particles >4 μm. Comparison of these data with a similar data set from samples collected over the Atlantic indicates that the departures from seawater composition are significantly larger for the Pacific. Differences in sea-to-air fractionation processes, probably involving binding of divalent cations to organic matter in the oceanic surface microlayer, are suggested as being responsible for these observations.

Abstract: A remote site in the Namib Desert was selected for sampling background aerosols in southern Africa, as one of a wide network of stations spanning the Southern Hemisphere in a programme designed to measure the background concentrations of trace elements in the atmosphere. A series of samples was collected over a 6-month period using a single-orifice cascade impactor, which fractionated the particles into six size groups. Analysis was performed using particle-induced X-ray emission (PIXE), yielding results for S, Cl, K, Ca, Ti, Mn, Fe, Br and Sr, and occasionally also for V, Cr, Ni, Cu, Zn and Pb. No direct correlations with wind direction were observed excluding strong local or regional sources of particles. K, Ca, Ti, Mn and Fe can be identified with a dust dispersion source. Cl, large particle S and Br, and part of the K and Sr are derived from sea spray. Relative to the soil components small particle K is not enriched as it normally is in regions with less scarce vegetation. Cr, V, Ni, Cu, Zn and Pb concentrations and enrichments in the aerosol are lower than practically all values measured at any other location hitherto. The concentration of the small particle sulphur, 200 ng m−3, is believed to be related to anaerobic conditions and plankton blooms in the ocean upwelling zones off Namibia.

Abstract: An automated electron microprobe, equipped with an energy-dispersive X-ray spectrometer and an additional backscattered electron signal digitalization system, can allow rapid sizing and major element analysis on numerous particles. A software package has been developed to exploit the particle size and shape information to achieve quantitative analysis of single particles, and to compare the performance of the different matrix correction procedures.

Abstract: Individual aerosol particles from the remote marine atmosphere were investigated by scanning electron microscopy and electron microprobe analysis. A large fraction of the silicate mineral component of the aerosol was found to be internally mixed with sea-salt aerosol particles. This observation explains the unexpected similarity in the size distributions of silicates and sea salt that has been observed in remote marine aerosols. Reentrainment of dust particles previously deposited onto the sea surface and collision between aerosol particles can be excluded as possible source mechanisms for these internally mixed aerosols. The internal mixing could be produced by processes within clouds, including droplet coalescence. Cloud processes may also be responsible for the observed enrichment of excess (nonsea-salt) sulfate on sea-salt particles.

Abstract: Bilayers of carbon, consisting of a layer of natural carbon and a second layer highly enriched in 13C, were investigated with the LAMMA 500-® instrument. When such a bilayer is perforated by the laser beam, comparable amounts of 12C and 13C are evaporated and partly ionized so that geometry effects and recombination reactions during laser-induced ionization can straightforwardly be studied.

Abstract: Aerosols were sampled in the Amazon Basin, as part of the Global Tropospheric Experiment (GTE), during the Amazon Boundary Layer Experiment (ABLE 2A) in JulyAugust 1985. Fine- and coarse-particle fractions were analyzed for 22 elements by particle-induced X ray emission. Gravimetric mass, black carbon, sulfate, and nitrate concentrations were also determined. Morphological and trace element measurements of individual particles were carried out by automated electron probe X ray microanalysis. Various receptor models, including multivariate methods and a chemical mass balance model, were employed in the interpretation of the bulk trace element concentrations. Three factors explained over 85% of the variability of fine- and coarse-mode variables. On the basis of the elemental composition of the factors, two could be identified as plant related, and the third was a soil dust component. Of the coarse-mode aerosol mass concentration (of 7.6±1.6 μg/m3), 62% could be attributed to aerosols released by the vegetation and 11% to soil dust. In the fine mode, soil dust accounted for less than 10% of the measured mass concentration (of 6.8±3.9 μg/m3). The variables related to the plant component were K, P, S, Ca, Mg, Cl, Rb, and the gravimetric mass. The elemental profile of the plant component resembled the bulk plant composition. By single-particle analysis coupled with hierarchical cluster analysis, six to nine different biogenic-related particle groups could be identified in the fine- and coarse-aerosol modes. Almost all particle types consisted predominantly of carbonaceous material, with trace amounts of K, S, Ca, P, Cl, and Na. Only one group, comprising less than 11% of the total number of particles, consisted of soil dustrelated aerosol.

Abstract: The aim of the present work is to study the radiation damage induced in LYSO and LuYAP crystals by the gamma radiation and the secondary electrons/positrons generated. The displacements per atom (dpa) distributions inside each material were calculated following the Monte Carlo assisted Classical Method (MCCM) introduced by the authors. As gamma sources were used Sc-44, Na-22 and V-48. Also the energy of gammas from the annihilation processes (511 keV) was included in the study. This procedure allowed studying the in-depth dpa distributions inside each crystal for all four sources. It was also possible to obtain the separate contribution from each atom to the total dpa. The LYSO crystals were found to receive more damage, mainly provoked by the displacements of silicon and oxygen atoms.

Abstract: Hidden, sub-surface paint layers and features contain valuable information for the art-historical investigation of a painting's past and for its conservation for coming generations. The number of techniques available for the study of these features has been considerably extended in the last decades and established techniques have been refined. This review focuses on mobile non-destructive subsurface imaging and depth profiling techniques, which allow for the in-situ investigation of easel paintings, i.e. paintings on a portable support. Among the techniques discussed are: X-ray radiography and infrared reflectography, which are long established methods and are in use for several decades. Their capabilities of element/species specific imaging have been extended by the introduction of energy/wavelength resolved measurements. Scanning macro-X-ray fluorescence analysis made it for the first time possible to acquire elemental distribution images in-situ and optical coherence tomography allows for the non-destructive study the surface paint layers in virtual cross-sections. These techniques and their variants are presented next to other techniques, such as Terahertz imaging, Nuclear Magnetic Resonance depth profiling and established techniques for non destructive testing (thermography, ultrasonic imaging and laser based interference methods) applied in the conservation of historical paintings. Next to selected case studies the capabilities and limitations of the techniques are discussed. (C) 2013 Elsevier B.V. All rights reserved.

Abstract: The most successful binding kinetics analysis systems at this moment include surface plasmon resonance (SPR), quartz microcrystal balance (QMB) and surface acoustic wave (SAW). Although these are powerful methods, they generally are complex, expensive and require the use of monolayers. Here, we report on potentiometric sensors as an inexpensive and simple alternative to do binding kinetics analysis between small molecules in solution and biomolecules (covalently) attached in a biopolymer sensor coating layer. As an example, dopamine and an anti-dopamine aptamer were used as the small molecule and the biomolecule respectively. Binding between both follows a Langmuir adsorption type model and creates a surface potential. The system operates in Flow Injection Analysis mode (FIA). Besides being an interesting new binding kinetics tool, the approach allows systematic design of potentiometric biosensors (in the present study a dopamine sensor), and gives new insights into the functioning of ion-selective electrodes (ISEs).

Abstract: Bed sediments were collected from the entire region of the Ganges basin and some parts of the Brahmaputra. In addition, selected stations were sampled for suspended sediments as well. The samples were analysed for a number of heavy metals (Fe, Mn, Ni, Cr, Cu, and Zn) by the thin-film energy dispersive X-ray fluorescence technique. There are pronounced temporal and spatial variations in the heavy metals distributions. Suspended sediments are 510 times richer than the bed sediments. None of the tributaries contribute significant heavy metal load, but around urban areas in Yamuna (tributary of Ganges), very high levels due to the distribution from the drainage network are observed. Compared to the Brahmaputra, the distribution and fractionation of heavy metals in the Ganges sediments are more erratic and highly variable. All the metals considered show high correlation among themselves. Given the high flux of suspended sediments from the Himalayan rivers (nearly 20% of the global flux), the worldwide budget for heavy metal transport may need to be suitably revised.

Abstract: The alkaline aluminate waste, of which 10002000 tonnes are dumped a few times a year off the Belgian coast in the Southern Bight of the North Sea, contains 5·4% NaCl, 1·8% dissolved Al and 7·4% NaOH, in addition to traces of heavy metals and some aniline- and phenol-derivatives. The pH rises locally to 8-5 and the total Al-concentration reaches 120niglitre−1(corresponding to an initial waste dilution factor of only 150) in the 10-m wide track just beyond the discharging barge, but these decay quickly to pH 8·1 and 1 mg litre-1 in the 30-m wide track, 500m behind the barge. The relation between the waste concentration and seawater pH was studied. The white precipitate that forms immediately in the sea was identified as Mg6Al2CO3(OH)164H20 (hydrotalcite-manasseite like). No trace of it was found in the local sediments.