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  • 1
    Publication Date: 2019-07-17
    Description: We will present a newly developed algorithm for the retrieval of tropospheric trace gas profiles from MAX-DOAS measurements. A Monte Carlo radiative transfer model, NIMO (NIWA Monte Carlo model) is used to calculate the weighting functions and forward model DSCDs (Differential Slant Column Densities). NIMO uses the local estimation technique to substantially speed up the determination of DSCDs for any given set of measurement ge- ometries, enabling use of the model online rather than using pre-calculated lookup tables. The optimal estimation method is used to retrieve profiles for either single or multiple scan sequences or over prescribed time intervals. This inversion method is used to derive NO2 profiles from MAX-DOAS measurements made during the CINDI campaign at Cabauw, Netherlands, in June/July 2009. BrO profiles retrieved from sea-ice MAX-DOAS measure- ments, made during two Antarctic springtime campaigns in 2006 and 2007, are also presented.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 2
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 3
    Publication Date: 2014-10-22
    Description: Over 10,000 tons of particulate matter (PM) has been emitted over the last 100 years as a result of mining activities in Sudbury, Ontario, Canada. Much of the PM has been deposited in the local soils, causing elevated concentrations of Cu, Ni, Zn, Se, As, and Pb. The goal of this study is to determine the distribution of metals and metalloids in PM in order to draw conclusions about their formation, their weathering, and the mobility of these elements in the local soils. The PM and associated secondary phases have been studied using optical microscopy, SEM, micro-Raman spectroscopy, and laser ablation inductively coupled plasma mass spectrometry. Spherical PM forms during the rapid cooling of hot gasses and is predominantly composed of Cu- and Ni-bearing spinel, silicate, and sulfide mineral inclusions. The collision of precursors of spherical PM with aerosols of residual matte and slag results in the formation of metal- and metalloid-rich outer rims on each sphere. These rims, as well as Fe-silicate and spinel minerals in the silicate-oxide matrix, weather to hematite during a dissolution-precipitation process. Metals and metalloids are released during this process in non-stoichiometric proportions relative to their initial concentration in the spinel, as they have different affinities to sorb on surface sites during their diffusion through the hematite precipitate. Metal-bearing sulfide inclusions alter to sulfate and occasionally into oxide minerals, which are enriched in Ni, Co, and Cu. Particulate matter composed of angular sulfide minerals and NiO particulates is often coated with Fe-Al-hydroxide and aluminosilicate minerals. The coatings contain higher trace-metal and metalloid concentrations than the underlying PM and are thus sinks for metals and metalloids released by other types of PM. The mobility of metals and metalloids in the soils decreases in the sequence Zn 〉 Cu 〉 Ni 〉 Pb and is the result of differences in element adsorption affinities and dissolution rates of phases in the PM.
    Print ISSN: 0008-4476
    Topics: Geosciences
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  • 4
    Publication Date: 2013-12-10
    Description: New data for parnauite from the type locality, Majuba Hill, Nevada, USA (MH; type specimen), and also from Cap Garonne, Var, France (CG), and the Clara Mine, Baden-Württemberg, Germany, are presented. The average chemical composition of MH material is (Cu 8.82 Al 0.16 Fe 0.02 ) 9.00 (As 1.78 Al 0.07 Si 0.08 S 0.07 ) 2.00 O 8 (SO 4 )(OH) 10 ·7H 2 O and that of CG parnauite, (Cu 8.42 Al 0.21 Zn 0.10 ) 8.73 (AsO 4 ) 2 [(S 0.97 As 0.10 ) 1.07 O 4 ](OH 9.23 Cl 0.77 ) 10.00 · 7H 2 O. Both of these formulae confirm the 9:2:1 Cu:As:S ratio obtained from earlier descriptions of parnauite. Raman spectra for parnauite from both localities are very similar. Bands are assigned, but show no evidence of the presence of CO 3 , in contrast to previous studies, and no distinct Cu–Cl stretching mode. It appears that neither the minor CO 3 and PO 4 previously reported nor Cl are essential constituents of parnauite. Single-crystal XRD analysis indicates a primitive orthorhombic unit cell with dimensions 6 x 14 x 15 Å, similar to previous studies, but h = odd reflections were heavily streaked and diffuse, preventing full refinement. A 3 Å substructure was refined, with space group Pmn 2 1 , to R 1 ( F ) = 0.0750 (MH). For a MH crystal, the subcell had a = 3.0113(4), b = 14.259(3), c = 14.932(2) Å, V = 641.13(16) Å 3 and Z = 1. The structure is of a new type, and contains Cu in 6 distinct sites, forming two three-polyhedron wide ribbons of edge-sharing Cu-O polyhedra extended parallel to the a - axis. The two ribbons lie back-to-back and are bridged by two AsO 4 tetrahedra. The collection of 6Cu + 2As cations plus ligands forms a rod-like moiety extended || a . These rods link through polyhedral corners to form complex, corrugated (010) layers. The interlayer space is occupied by H 2 O molecules. Thus, the disorder observed by XRD is of an unusual type, in which the shape of the unit mesh within layers is variable, rather than the stacking of the layers. Disorder arises because each AsO 4 tetrahedron shares a face with a Cu(O,OH,H 2 O) 5–6 polyhedron in the substructure, necessitating partial occupancy of both As and Cu sites. The S atoms were not located in the refinement, but four electron-density maxima in the interlayer region were interpreted as H 2 O molecules. Hence, the simplified structural formula derived from the substructure is (Cu 10 2 )(As 2 2 )O 8 (OH) 14 ·8H 2 O, deviating from that obtained in chemical analyses. The discrepancy presumably arises due to strong delocalisation of the sulphur and the apical oxygen of the SO 4 tetrahedron in the substructure. Short-range order of Cu–As and Cu–S || a can occur independently in the relevant structural rods, which accounts for the observed long-range disorder. Cell parameters and substructures obtained from CG and Clara material are similar to those from the MH crystal. Site splitting of OH positions in the CG refinement indicates that Cl is distributed over several sites in the 3 Å substructure, making the mineral a Cl-rich variety of parnauite rather than a distinct mineral species.
    Print ISSN: 0935-1221
    Electronic ISSN: 1617-4011
    Topics: Geosciences
    Published by Schweizerbart
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  • 5
    Publication Date: 2013-12-13
    Description: The crystal chemistry of a unique Nb-Ti-rich thorite from Mont Saint-Hilaire (Quebec) has been examined by a combination of single crystal and powder X-ray diffraction, electron microprobe analyses, and Fourier-transform infrared spectroscopy. The average of 9 compositions gave (Th 0.21 Nb 0.20 Ti 0.18 Ca 0.13 Y 0.10 REE 0.09 Fe 0.03 Zr 0.01 Sr 0.01 Mn 0.01 K 0.01 Na 0 . 01 ) 1.00 [(Si 0.49 0.41 Al 0.08 P 0.01 S 0.01 ) 1.00 (O 2.33 F 0.02 )](OH) 1.70 . This is the first example in the literature of a zircon-group mineral containing elevated concentrations of Nb (0.20 apfu , 13.33 wt.% Nb 2 O 5 ) and Ti (0.19 apfu Ti, 7.41 wt.% TiO 2 ), and evidence for the (SiO 4 ) 4– (OH) 4 4– "hydrogarnet" substitution. The crystal structure was solved and refined to R = 3.40% and wR 2 = 9.73% for 68 reflections with F o 〉 4( F o ). The studied thorite is slightly metamict, tetragonal, space group I 4 1 / amd , with a 7.058(1) Å, c 6.2260(12) Å, V 310.15(11) Å 3 , and Z = 4. It is isostructural with other zircon-group minerals and has a unit cell which is 4% smaller than that of thorite sensu stricto , a result of the incorporation of high field-strength elements of smaller radii. The structure consists of one eight-coordinated metal site ( A = Th, Zr, U, REE, Y, Nb, Ti, etc. ), one tetrahedral site ( T ), one O site, and one variably-occupied H site. The A site is coordinated by four axial O atoms [ A –O axial = 2.428(5) Å] and four equatorial O atoms [ A –O eq = 2.322(6) Å], which define a bisdisphenoid with 〈 A –O〉 = 2.374 Å. The T site in MSH thorite is only partially occupied by Si (33% vacant) and coordinated by four O with T –O = 1.641(5) Å. A partially occupied H site (31%) is located 0.980 Å away from the O atom, forming (O 4 H 4 ) 4– groups when the T site is vacant. Removal of the center of symmetry in the structure allows for the possibility of the presence of bimodal T –O and A –O bond lengths, leading to both short Si–O bonds and longer –OH bonds, as well as the shorter A –O bonds required for Nb and Ti. Accommodation of Nb and Ti into the thorite structure may be facilitated by increased distortion of the A O 8 bisdisphenoid, relaxation and shortening of A –O bonds as a result of the (SiO 4 ) 4– (OH) 4 4– substitution, and the likely presence of defects (O vacancies) in regions which have undergone slight metamictization, resulting in short-range ordering of Nb, Ti, and Th. Although it is possible that a metastable, limited solid solution exists between thorite and (OH) 4 4– -dominant "thorogummite" with intermediate compositions defined by Th(SiO 4 ) 1 –x (OH) 4 x , reported compositions indicate otherwise and it is suggested that the name "thorogummite" be abandoned.
    Print ISSN: 0008-4476
    Topics: Geosciences
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  • 6
    Publication Date: 2014-05-17
    Description: Steedeite, ideally NaMn 2 Si 3 BO 9 (OH) 2 , is a new mineral discovered in altered sodalite syenite at the Poudrette quarry, La Vallée-du-Richelieu, Montérégie (formerly Rouville County), Québec, Canada. Crystals of steedeite are colorless to pale pink, and acicular with average dimensions of 0.006 x 0.011 x 0.51 mm. They occur as radiating to loose, randomly oriented groupings within vugs associated with aegirine, nepheline, sodalite, eudialyte-group minerals, analcime, natron, pyrrhotite, catapleiite, and two other unidentified minerals temporarily designated UK78 and UK80. Steedeite is transparent to translucent with a vitreous luster and has a weak pale green to pale yellow fluorescence under medium-wave radiation. No partings or cleavages were observed, although crystals exhibit an uneven fracture. The calculated density is 3.106 g/cm 3 . Steedeite is nonpleochroic, biaxial with n min = 1.636(2) and n max = 1.656(2) and a positive elongation. Chemical analyses (n = 14) from seven crystals gave an average (range, standard deviation) of: Na 2 O 7.51 (6.78–8.32, 0.44), CaO 0.17 (0.08–0.22, 0.03), MnO 31.02 (29.91–32.83, 0.93), FeO 0.86 (0.76–1.01, 0.07), SiO 2 46.34 (40.39–49.29, 2.56), S 0.39 (*b.d.– 2.36, 0.71) (*b.d. = below detection), B 2 O 3 (calc.) 8.73, and H 2 O (calc.) 4.52, total 99.53 wt.%. The empirical formula is: Na 0.97 (Mn 1.75 Fe 0.05 Ca 0.01 ) 1.83 (Si 3.07 S 0.02 ) 3.09 BO 9 (OH) 2 , or ideally NaMn 2 Si 3 BO 9 (OH) 2 . The presence of both B and OH in steedeite were inferred from the refinement of the crystal structure. The Raman spectrum for steedeite show bands at 3250–3500 cm –1 attributed to O–H stretching, strong sharp bands at 575–750 cm –1 and 825–1075 cm –1 attributed to Si–O bonds and possibly B–O bonding, as well as weak to strong bands at 50–500 cm –1 attributed to Na–O/Mn–O bonds. Steedeite crystallizes in space group P $$\overline{1}$$ (#2) with a 6.837(1), b 7.575(2), c 8.841(2) Å, α 99.91(3), β 102.19, 102.78(3)°, V 424.81 Å 3 , and Z = 2. The strongest six lines on the X-ray powder-diffraction pattern [ d in Å (I) ( hkl )] are: 8.454 (100) (00 $$\overline{1}$$ ), 7.234 (39) (00 $$\overline{1}$$ ), 3.331 (83) (1 $$\overline{2}$$ 1, 0 $$\overline{1}$$ $$\overline{2}$$ , 20 $$\overline{1}$$ , 1 $$\overline{1}$$ 2), 3.081 (38) (0 $$\overline{2}$$ $$\overline{1}$$ ), 2.859 (52) (0 $$\overline{1}$$ 3), and 2.823 (80) (21 $$\overline{1}$$ ). The crystal structure of steedeite was refined to R = 1.68% and wR 2 = 4.96% for 2409 reflections ( F o 〉 4 F o ). It is based on silicate chains with a periodicity of three (i.e., dreier chain) consisting of four-membered borosilicate rings of composition [BSi 3 O 9 (OH) 2 ] 5– . The borosilicate chains are classed as single loop-branched dreier chains that are linked together through shared corners to bands of edge-sharing MnO 5 (OH) octahedra. Steedeite is a chain silicate mineral closely related to the sérandite-pectolite series of the pyroxenoid group and is the first mineral found to contain single loop-branched dreier silicate chains.
    Print ISSN: 0008-4476
    Topics: Geosciences
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  • 7
    Publication Date: 2014-02-12
    Description: The major and trace element geochemistry of mafic silicate minerals from alkaline pegmatites within the 10 ring sections of the Larvik plutonic complex, Oslo rift, southern Norway, have been studied to shed light on the complex evolutionary history of the pegmatites. Pyroxene compositions plot within the aegirine-diopside-hedenbergite ternary diagram, trending from the 50-50% Di-Hd tie line towards the 100% Ae endmember. Primary magmatic diopside and hedenbergite with minor aegirine occur primarily within miaskitic to low agpaitic pegmatites, with compositions ranging from Ae 3 Di 45 Hd 51 to Ae 89 Di 5 Hd 6 , whereas aegirine and aegirine-augite are the primary magmatic clinopyroxenes in agpaitic pegmatites, with compositions ranging from Ae 31 Di 27 Hd 42 to Ae 90 Di 6 Hd 4 . Secondary clinopyroxene, after amphibole or as a hydrothermal phase within fractures and vugs, is dominantly aegirine, with compositions ranging from Ae 59 Di 16 Hd 25 to Ae 99 Di 1 Hd 0 . Primary amphibole compositions are dominantly calcic (edenite, ferro-edenite, hastingsite, magnesio-hastingsite, pargasite, and ferro-pargasite), with less common late-stage sodic-calcic amphiboles (katophorite, magnesio-katophorite, ferro-richterite, and taramite); sodic amphiboles (ferro-ferri-nybøite, ferri-nybøite) are only observed in agpaitic pegmatites. All early pegmatite mafic minerals in low agpaitic pegmatites have negative Eu anomalies (Eu/Eu* = 0.16–0.26), positive Ce anomalies, and low Nb/Ta N and Y/Ho N ratios. Sodic mafic silicates in highly agpaitic pegmatites are HREE-enriched, with Ce/Yb N = 0.22–0.58 compared to Ce/Yb N 〉 1 for all other primary mafic phases, are strongly depleted in MREE, and have only slightly negative Eu anomalies (Eu/Eu* = 0.66–0.75). On the basis of major and trace element geochemistry, it can be concluded that miaskitic and alkaline pegmatites in Ring Sections 1–8 within the Larvik complex have been derived from the same parental melt, whereas pegmatites in Ring Sections 9 and 10 have a distinct geochemical signature, suggesting a separate source.
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    Topics: Geosciences
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  • 8
    Publication Date: 2012-03-29
    Description: Voyager 1 has entered regions of different propagation conditions for energetic cosmic rays in the outer heliosheath at a distance of about 111 AU from the Sun. The low energy 6–14 MeV galactic electron intensity increased by ~20% over a time period ≤10 days and the electron radial intensity gradient abruptly decreased from ∼19%/AU to ∼8%/AU at 2009.7 at a radial distance of 111.2 AU. At about 2011.2 at a distance of 116.6 AU a second abrupt intensity increase of ∼25% was observed for electrons. After the second sudden electron increase the radial intensity gradient increased to 18%/AU. This large positive gradient and the ∼13 day periodic variations of 〉200 MeV particles observed near the end of 2011 indicate that V1 is still within the overall heliospheric modulating region. The implications of these results regarding the proximity of the heliopause are discussed.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
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  • 9
    Publication Date: 2012-12-06
    Description: Laurentianite, [NbO(H 2 O)] 3 (Si 2 O 7 ) 2 [Na(H 2 O) 2 ] 3 , is a new mineral discovered in siderite-dominant pods in an altered syenite at the Poudrette quarry, Mont Saint-Hilaire, Quebec. Crystals are colorless, acicular, euhedral, and elongate along [001] with average dimensions of 0.012 x 0.012 x 0.25 mm. The mineral generally occurs in loose, randomly oriented groupings (‘nests’) of crystals. Associated minerals include quartz, pyrite, franconite, rutile, lepidochrocite, and an unidentified Fe-bearing mineral. Laurentianite is transparent to translucent with a vitreous luster and is non-fluorescent under long-, medium-, and short-wave radiation. The Mohs hardness could not be measured owing to the small size of the crystals. No partings or cleavages were observed, although crystals do exhibit a splintery fracture. The calculated density is 2.464 g/cm 3 . Laurentianite is nonpleochroic and uniaxial negative, with 1.612(2) and 1.604(2). The average of 12 analyses from several crystals is: Na 2 O 8.88 (4.54–12.80), K 2 O 0.26 (0.14–0.44), CaO 0.22 (0.10–0.43), TiO 2 0.58 (0.31–0.83), Nb 2 O 5 43.64 (36.43–49.90), SiO 2 26.87 (22.81–29.07), and H 2 O (calc.) 17.93, total 98.38 wt.% on the basis of 26 anions, corresponding to [(Nb 0.99 Ti 0.01 ) 1.00 O(H 2 O)] 3 (Si 2.00 O 7 ) 2 [(Na 0.86 0.10 K 0.02 Ca 0.01 ) 0.99 (H 2 O) 2 ] 3 or, ideally, [NbO(H 2 O)] 3 (Si 2 O 7 ) 2 [Na(H 2 O) 2 ] 3 . The presence of H 2 O in laurentianite is inferred from Raman spectroscopy and results from refinement of the crystal structure. The mineral crystallizes in space group P 3 (#143) with a 9.937(1), c 7.004(1) Å, V 599.0(1) Å 3 , and Z = 1. The strongest six lines on the X-ray powder-diffraction pattern [ d in Å (I) ( hkl )] are: 8.608 (100) (010), 7.005 (19) (001), 4.312 (25) (020), 3.675 (25) (201, 021), 3.260 (31) (120, 210), and 2.870 (20) (030). The crystal structure of laurentianite, refined to R = 2.78% for 2347 reflections ( F o 〉 4 F o ) contains one Na , two Nb , and four Si sites. The two Nb sites are coordinated in distorted Nb O 5 (H 2 O) octahedra, with four equatorial bonds of typical Nb–O bond distances (~2 Å) and two highly asymmetric ones (one long, ~2.5 Å and one short, ~1.8 Å). Each site is each only partially occupied (~50%) and because of the short distance between them (~0.7 Å), they are not simultaneously occupied. A novel cation-anion coordination scheme involving the apical oxygens, Nb, and disordered H 2 O groups is developed: when one of the Nb sites is occupied, the other is vacant, resulting in one of the apical O sites being occupied by O 2– and the other by H 2 O. The opposite situation occurs when the occupancy and vacancy of the Nb sites are reversed, leading to both apical O sites having an equal, mixed (O 2– /H 2 O) composition. A minor charge understaturation at both apical O sites is remedied by each of these O sites receiving a single H-bond from one of the H 2 O groups associated with the Na cation. The crystal structure of laurentianite is based on five-membered pinwheels of composition [Nb 3 Si 2 O 17 (H 2 O) 3 ] –11 , consisting of three Nb O 5 (H 2 O) octahedra linked to two SiO 4 tetrahedra. Individual Nb–Si pinwheels are attached to form a layer composed of 18-membered rings of composition [Nb 6 Si 12 O 54 (H 2 O) 6 ] 30– perpendicular to [001]. The crystal structure is also layered along [001], with a silicate layer composed of (Si 2 O 7 ) dimers and a layer of isolated Nb O 5 (H 2 O) octahedra. Sodium atoms are positioned within the silicate layer, occupying sites that almost directly overly the Nb sites but are displaced ~ z + 1/2. Laurentianite is a late-stage mineral intergrown with lepidocrocite, both of which overgrow franconite and quartz. The mineral is believed to have precipitated from a late-stage aqueous fluid enriched in Na, Si, and Nb, possibly arising through the breakdown of franconite, sodalite, and quartz.
    Print ISSN: 0008-4476
    Topics: Geosciences
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  • 10
    Publication Date: 2012-08-09
    Description: Preemptive dosing of plerixafor given to poor stem cell mobilizers on day 5 of G-CSF administration Bone Marrow Transplantation 47, 1051 (August 2012). doi:10.1038/bmt.2011.217 Authors: M E Horwitz, J P Chute, C Gasparetto, G D Long, C McDonald, A Morris, D A Rizzieri, K M Sullivan & N J Chao
    Keywords: stem cellmobilizationplerixaforG-CSFpreemptive
    Print ISSN: 0268-3369
    Electronic ISSN: 1476-5365
    Topics: Medicine
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