Ben J. Williamson

Physicochemical characterisation of diesel exhaust particles: factors for assessing biological activity

A range of microscopy and analytical techniques have been used to investigate the physicochemical properties of diluted DEP that may be important in determining its biological activity. Transmission electron microscopy demonstrated four basic categories of particle morphology: (1) “spherulites” [individual particles]; (2) “chains” or “clusters” of spherulites; (3) “spherules”, [large bodies of spherulites]; (4) “flake-like bodies”. Image analysis of TEM photomicrographs determined empirical morphological parameters (30 nm mean spherulite diameter, aspect ratio 1.5, mean particle area 0.078 μm, equivalent spherical diameter 0.23 μm, roundness 2.76) and derived parameters (0.313 μm2 surface area, 3.7 μm2 pg surface area per mass and 0.042 μm3 volume) of DEP. Distributions of the particle sizes by number showed 10.1% were ultrafine ( 2.5 μm), but distributions based on a mass value were different (0.01% ultrafine; 52.6% fine, 47.4% coarse). In contrast, impacted DEP contained 60.87% ultrafine, 39.13% fine and 0% coarse particles by number. Field emission scanning electron microscopy of spherulites revealed smooth surfaces and flocculated spherules with large surface areas. Electron probe X-ray micro-analysis demonstrated the presence of C, O, Na, Mg, K, Al, Si, P, S, Cl, Ca along with a range of metals (Ti, Mn, Fe, Zn, Cr), that were heterogeneous in distribution. Inductively coupled plasma mass and atomic emission spectrometry identified Mg, P, Ca, Cr, Mn, Zn, Sr, Mo, Ba, Na, Fe, S, and Si as the mobile sorbed metals readily removed during sonication in water from DEP suspensions. X-ray Diffraction confirmed previous observations of the presence of nanometer sized crystallites of disordered graphite. Comparison of microscopy and analytical results between sonicated and impacted DEP revealed a physicochemical difference that must be taken into account in any toxicological investigations.

Geochemical constraints on the genesis of Hercynian two-mica leucogranites from the Massif Central, France

Abstract Late Hercynian two-mica leucogranites dated at 340-280 3a old occur across the entire Massif Central, France, and form dykes and stocks up to 130 km in length. They are peraluminous [molecular Al 2 O 3 /(Na 2 O + K 2 O + CaO), ASI = 1.16–1.25] and have low initial ϵNd (−8.2 to −6.1) indicating derivation from the metasedimentary lower crust as sampled in crustal xenoliths (ϵNd 340 = −8.6 to −4.3, ϵNd 280 = −9.0 to −4.8). Their high SiO 2 (70–78 wt%), P 2 O 5 (up to 0.5%), Rb, and Ga, and low Ba, Sr and ΣREE are mainly a result of partial melting processes rather than fractionation. Partial melting was initiated by underplating of the lower crust by mantle-derived basic magmas between 360 and 270 Ma and was intensified by granulite-facies metamorphism between 300 and 280 Ma. From this model, there is little similarity between the genesis of two-mica leucogranite in the Massif Central and that in the Himalaya, with which it has previously been compared.

Sr, Nd al36 (1997) 99–122 Hercynian granodiorites and monzogranites, Massif Central, France

Variations in Sr Nd and Pb initial isotope ratios of three large Hercynian granitoid massifs of the French Massif Central are consistent with formation of the granitoids by partial melting of the lower crust. The nature of the lower crust of the Massif Central is known from the granulite-facies lower-crustal xenoliths brought to the surface by Tertiary alkaline volcanics. Studies of the xenoliths have revealed that, during the Hercynian orogeny (360-290 Ma ago), the pre-existing metasedimentary and acid metaigneous lower crust was intruded by basic magmas, causing anatexis. The mantle-derived basic magmas mixed with melts from the pre-existing lower crust, forming the Hercynian granitoids. The peraluminous Gueret and Margeride granitoids, which are very similar in their major- and trace-element compositions, have 87Sr/86Sri (0.7089 to 0.7121) and ϵNdi (−7.5 to −3.9) values which indicate that they have a high sedimentary component, considered to have been derived from lower-crustal metasedimentary rocks. However, the granitoids differ significantly in their initial Pb isotope compositions, with the Gueret granodiorites being less radiogenic, indicating the presence of a slightly different crustal source component for the Gueret massif. In contrast, monzogranites from the Millevaches massif are less peraluminous and have higher La/YbN and lower 87Sr/86Sri values (0.7064 to 0.7109). These features, together with the relatively radiogenic Pb isotope compositions of the Millevaches granitoids, suggest derivation from the acid metaigneous lower crust.

Role for lichen melanins in uranium remediation

Lichens are successful colonizers in extreme terrestrial habitats world-wide, including metalliferous environments. Their ability to accumulate metals has led to their use in monitoring radionuclide fall-out from Chernobyl and uranium uptake from dust resulting from mining. Here we report for the first time a lichen growing directly on uranium minerals and uranium being concentrated within its tissues. Our study suggests that melanin-like pigments, substances previously unreported within lichens, are involved.

Geochemical constraints on restite composition and unmixing in the Velay anatectic granite, French Massif Central

The main anatectic granite of the Velay complex is unique among major French Massif Central Hercynian granitoids in that rather than having an entirely lower crustal source, it formed by mixing between partial melts of the meta-igneous lower crust and ‘upper crustal’ country rock schists and orthogneisses. The geochemical variations in the Velay main anatectic granites cannot, however, be explained by mixing alone as their compositions range to lower SiO2, with higher Al2O3, Fe2O3 and TiO2 and lower Na2O and CaO, than either end member in mixing. The variations are interpreted as being due to the presence of up to 35% restite in minimum melts of country rock compositions. Primary restites form equilibrium assemblages represented by biotite, ilmenite and surmicaceous enclaves which consist of biotite ± apatite, zircon and almandine. The main anatectic granites more rarely contain schist and gneiss enclaves, quartz resisters and plagioclase restites. Secondary restites are mainly represented by cordierite, and possibly K-feldspar, which formed by recrystallisation of primary biotite-rich restites. The unique characteristics of the Velay main anatectic granites are likely to be due, in part, to its late formation close to the end of the Hercynian orogeny. The metasedimentary lower crust may have become too refractory to yield large volumes of melt following partial melting to form the other major Massif Central granitoids. The heat necessary for partial melting at higher crustal levels was transferred from the lower crust by the intrusion of I-type granites and low volume diorites from the mantle. Upper crustal anatexis was mainly controlled by muscovite breakdown reactions (< 830 to 850 °C) and the liberation of water due to the recrystallisation of biotite to cordierite. The temperatures necessary for biotite breakdown were only achieved locally and resulted in the formation of high-LREE granites.

The relationship between crustal magmatic underplating and granite genesis : an example from the Velay granite complex, Massif Central, France

The Velay granite pluton (Massif Central, France) is the youngest (304 ± 5 Ma) and largest (∼6,900 km 2 ) of the major Massif Central monzogranites/granodiorites and was formed nearly 50 Ma after the cessation of Hercynian continental collision (Pin & Duthou 1990). It is a highly heterogeneous pluton consisting of I-type, high-Sr granites (Sr = 500-900 ppm) with low e sr(304) (+35 to +41) and high e Nd(304) (#753 to #755), at its centre, grading into S-type and mixed I-S-type heterogeneous granites of more normal Sr content (100-420 ppm) and higher e Sr(304) (+40 to +210) and lower e Nd(304) (#753.8 to #757.3) at its margins

Uranium Biosorption by the Lichen Trapelia involuta at a Uranium Mine

Metal localisation was investigated in the lichenised ascomycete Trapelia involuta growing on a range of uraniferous minerals including metazeunerite [Cu(UO2)2(AsO4)2·8H2O], metatorbernite [Cu(UO2)2(PO4)2·8H2O], autunite [Ca(UO2)2(PO4)2·10H2O] and uranium-enriched iron oxide and hydroxide minerals at the abandoned South Terras mine site, Cornwall, UK. Apothecia from samples collected from waste dumps at the mine have an unusually dark colour that decolorized with NaOCl, an observation which together with Fourier Transform Infrared Spectroscopy of apothecial extracts, suggested the presence of melanin-like pigments. X-ray element mapping and probe traverses across the lichen-rock interface identify the highest U, Fe, and Cu concentrations in the outer parts of melanised apothecia. Accumulation of mineral particulates and complexing with lichen acids are not considered responsible for this since element ratios in the traverses do not correspond with those of likely mineral phases and lichen metabolites are localised in different tissues. Metal biosorption by melanin-like pigments are likely to be responsible for the observed metal fixation. No detectable U or Cu was observed in control samples although Fe showed a similar localisation in some specimens. The high concentrations of mucopolysaccharides and P recorded inside apothecia (within asci containing reproductive spores and hypothecium) suggests that the formation of melanised tissues may help protect vital reproductive tissues from the toxic effects of U and other metals, since the uranyl ion complexes strongly with phosphate species.

Lichen biomonitoring near Karabash smelter town, ural mountains, Russia, one of the most polluted areas in the world.

Biogeochemical signatures were investigated in transplanted and native lichens near a major pollution source using sensitive multi–element chemical analysis. Transplants were established across a 60 km transect centred on the smelter town of Karabash, Ural Mountains, Russia. Statistically significant trends in element concentrations were recorded, some below one part per million. Fine metal particles are accumulated from pollution aerosols. Prolonged exposure may lead to cellular damage and enhanced accumulation or element loss. 206Pb : 207Pb isotope ratios are similar to those associated with airborne particles in Europe and Russia; an outlier near Kyshtym with a lower ratio indicates a source with a higher 235U : 238U ratio. The method is discrete, sensitive, able to detect short–term pollution episodes and useful for understanding element cycling, which is of critical importance for human and environmental health.

Characterisation of Airborne Particulate Pollution in The Cu Smelter and Former Mining Town of Karabash, South Ural Mountains of Russia

Airborne total suspended particulates (TSP), dusts from smelter blast furnace and converter stacks, and filtrates of snow melt waters have been characterised in the Cu smelter and former mining town of Karabash, Russia. TSP was collected at sites up- and downwind of the smelter and large waste and tailings dumps (Oct. 2000 and July 2001). Methods for particle size, mineralogical and elemental determinations have been tested and described, and a new PSD-MicroSOURCE™ XRD technique developed for the mineralogical analysis of microsamples on filter substrates. TSP in downwind samples has a mean equivalent spherical diameter of 0.5 μm (s.d. = 0.2) and was found to be 100% respirable. The main element of human health/environmental concern, above Russian maximum permitted levels (1 μg m-3, average over any time period), was Pb which was measured at 16–30 μg m-3 in downwind samples. Individual particulates mainly consisted of complexmixtures of anglesite (PbSO4), Zn2SnO4 and poorly ordered Zn sulphates. From experimental and theoretical considerations,a high proportion of contained Pb, Zn, Cd and As in this material is considered to be in a readily bioavailable form. Chemical and mineralogical differences between the TSP, stack dusts and snow samples are discussed, as well as the implications for human and regional environmental health.

The α–β phase transition in volcanic cristobalite

Volcanic cristobalite commonly contains structural substitutions of Al3+ and Na+ for Si4+. Quantifying the effect of these substitutions on the crystal structure may provide insight into volcanic processes and the variable toxicity of crystalline silica.