Colloidal mobilization of arsenic from mining-affected soils by surface runoff

Received 2 June 2015, Revised 2 September 2015, Accepted 24 September 2015, Available online 23 October 2015Scorodite-rich wastes left as a legacy of mining and smelting operations pose a threat to environmental health. Colloids formed by the weathering of processing wastes may control the release of arsenic (As) into surface waters. At a former mine site in Madrid (Spain), we investigated the mobilization of colloidal As by surface runoff from weathered processing wastes and from sediments in the bed of a draining creek and a downstream sedimentation-pond. Colloids mobilized by surface runoff during simulated rain events were characterized for their composition, structure and mode of As uptake using asymmetric flow field-flow fractionation coupled to inductively plasma mass spectrometry (AF4-ICP-MS) and X-ray absorption spectroscopy (XAS) at the As and Fe K-edges. Colloidal scorodite mobilized in surface runoff from the waste pile is acting as a mobile As carrier. In surface runoff from the river bed and the sedimentation pond, ferrihydrite was identified as the dominant As-bearing colloidal phase. The results from this study suggest that mobilization of As-bearing colloids by surface runoff may play an important role in the dispersion of As from metallurgical wastes deposited above ground and needs to be considered in risk assessment.The Spanish Ministry of Economy and Competitiveness (research project CGL 2010-17434) supported this study.A. Gomez-Gonzalez was supported by the Ph.D. Spanish FPI fellow-ship (BES-2011-046461) and by graduate students (EEBB-I-14-08063) programs.Peer reviewe

Formation of Zn-rich phyllosilicate, Zn-layered double hydroxide and hydrozincite in contaminated calcareous soils

Recent studies demonstrated that Zn-phyllosilicate- and Zn-layered double hydroxide-type (Zn-LDH) precipitates may form in contaminated soils. However, the influence of soil properties and Zn content on the quantity and type of precipitate forming has not been studied in detail so far. In this work, we determined the speciation of Zn in six carbonate-rich surface soils (pH 6.2 to 7.5) contaminated by aqueous Zn in the runoff from galvanized power line towers (1322 to 30090 mg/kg Zn). Based on 12 bulk and 23 microfocused extended X-ray absorption fine structure (EXAFS) spectra, the number, type and proportion of Zn species were derived using principal component analysis, target testing, and linear combination fitting. Nearly pure Zn-rich phyllosilicate and Zn-LDH were identified at different locations within a single soil horizon, suggesting that the local availabilities of Al and Si controlled the type of precipitate forming. Hydrozincite was identified on the surfaces of limestone particles that were not in direct contact with the soil clay matrix. With increasing Zn loading of the soils, the percentage of precipitated Zn increased from {approx}20% to {approx}80%, while the precipitate type shifted from Zn-phyllosilicate and/or Zn-LDH at the lowest studied soil Zn contents over predominantly Zn-LDH at intermediate loadings to hydrozincite in extremely contaminated soils. These trends were in agreement with the solubility of Zn in equilibrium with these phases. Sequential extractions showed that large fractions of soil Zn ({approx}30% to {approx}80%) as well as of synthetic Zn-kerolite, Zn-LDH, and hydrozincite spiked into uncontaminated soil were readily extracted by 1 M NH{sub 4}NO{sub 3} followed by 1 M NH{sub 4}-acetate at pH 6.0. Even though the formation of Zn precipitates allows for the retention of Zn in excess to the adsorption capacity of calcareous soils, the long-term immobilization potential of these precipitates is limited

Distinction between Pore Assembly by Staphylococcal α-Toxin versus Leukotoxins

The staphylococcal bipartite leukotoxins and the homoheptameric α-toxin belong to the same family of β-barrel pore-forming toxins despite slight differences. In the α-toxin pore, the N-terminal extremity of each protomer interacts as a deployed latch with two consecutive protomers in the vicinity of the pore lumen. N-terminal extremities of leukotoxins as seen in their three-dimensional structures are heterogeneous in length and take part in the β-sandwich core of soluble monomers. Hence, the interaction of these N-terminal extremities within structures of adjacent monomers is questionable. We show here that modifications of their N-termini by two different processes, using fusion with glutathione S-transferase (GST) and bridging of the N-terminal extremity to the adjacent β-sheet via disulphide bridges, are not deleterious for biological activity. Therefore, bipartite leukotoxins do not need a large extension of their N-terminal extremities to form functional pores, thus illustrating a microheterogeneity of the structural organizations between bipartite leukotoxins and α-toxin

Exiles in British sociology

We have all seen them, foreheads wrinkled like a ploughed field, pastel-shaded check summer shirts worn in winter, desks festooned with yellowed index cards covered in hieroglyphics, books like yours only in plainer covers and read more carefully, filthy cigarettes, an accent growing thicker with age. But we have all seen them too, the luxuriant thatch at seventy, the jacket and tie, the tidy desk, the London club and the house in the country, the pipe, the disdain for small talk made all the more intimidating by an English acquired somewhere between grammar school and Oxford. Self-contained in a way only the uprooted can be, mysterious because you never knew what questions to ask them, emissaries from worlds they have lost and you have never known: the Polish gentry, the central European peasantry, Jewish merchants, German workers and, most puzzling of all, the continental European middle class

Sounds too true to be good: diegetic infidelity–the case for sound in virtual reality

This is a pre-copyedited, author-produced version of an article accepted for publication in Journal of Media Practice following peer review. The version of record McArthur, A., et al. (2017). "Sounds too true to be good: diegetic infidelity – the case for sound in virtual reality." Journal of Media Practice 18(1): 26-40. is available online at:https://doi.org/10.1080/14682753.2017.1305840© 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. Cinematic virtual reality (VR) elicits new possibilities for the treatment of sound in space. Distinct from screen-based practices of filmmaking, diegetic sound–image relations in immersive environments present unique, potent affordances, in which content is at once imaginary, and real. However, a reductive modelling of environmental realism, in the name of ‘presence’ predominates. Yet cross-modal perception is a noisy, flickering representation of worlds. Treating our perceptual apparatus as stable, objective transducers, ignores the inter-subjective potential at the heart of immersive work, and situates users as passive spectators. This condescends to audiences and discounts the historic symbiosis of sound–image signification, which comes to constitute notions of verisimilitude. We understand the tropes; we willingly suspend disbelief. This article examines spatial sound rendering in virtual environments, probing at diegetic realism. It calls for an experimental, aesthetic approach, suggesting several speculative strategies, drawing from theories of embodied cognition and acousmatic practice (amongst others) which necessarily deal with space and time as contingencies of the immersive. VR affords a development of the dialectic between sound and image which distinctively involves our spatial attention. The lines between referent and signified blur; the mediation between representations invoked by practitioners, and those experienced by audiences, suggest new opportunities for co-authorship.The authors wish to acknowledge support from the EPSRC and AHRC Centre for Doctoral Training in Media and Arts Technology through Queen Mary University of London

Social Change and Progress in the Sociology of Robert Nisbet

The final publication is available at Springer via http://dx.doi.org/10.1007/s12115-015-9908-

Mutual intelligibility between West and South Slavic languages

In the present study we tested the level of mutual intelligibility between three West Slavic (Czech, Slovak and Polish) and three South Slavic languages (Croatian, Slovene and Bulgarian). Three different methods were used: a word translation task, a cloze test and a picture task. The results show that in most cases, a division between West and South Slavic languages does exist and that West Slavic languages are more intelligible among speakers of West Slavic languages than among those of South Slavic languages. We found an asymmetry in Croatian-Slovene intelligibility, whereby Slovene speakers can understand written and spoken Croatian better than vice versa. Finally, we compared the three methods and found that the word translation task and the cloze test give very similar results, while the results of the picture task are somewhat unreliable