The solubility of coal fly ash and marine aerosols in seawater

The elemental solubilities of three coal fly ash samples and two coastal marine-aerosol samples in seawater are different. The coal fly ash samples were collected from the electrostatic precipitators on coal-fired power plants. The air particulates were collected by a high-volume air sampler located near the Washington coast. Samples were neutron-activated then contacted with seawater for several hours. The elements that were partially solubilized from both fly ash and aerosols included As, Sb, Se, Br and Cr. Zinc and Co were more soluble in aerosols then fly ash.     

Photo's from Proceedings of the Third MicroQuasar Workshop; Granada Worshop on Galactic Relativistic Jet Sources – Granada,Spain, 11–13 September 2000

The X-Ray Spectroscopic Explorer (XRASE) has a unique combination of features that will make it possible to address many of NASA's scientific goals. These include how galaxy clusters form, the physics and chemistry of the ISM, the heating of stellar coronae, the amount and content of intergalactic baryonic matter, the mass of black holes and the formation of disks and jets in AGN and galactic binaries. XRASE has a thin foil, multilayered telescope with a large collecting area up to 10 keV, especially in the Fe K region (1100 cm²). Its microcalorimeter array combines high energy resolution (7 eV at 6 keV) and efficiency with a field-of-view of 26 arcmin² . A deep orbit allows for long, continuous observations. Monitoring instruments in the optical (WOM-X), UV (TAUVEX) and hard X-RAY (GRAM) bands will offer exceptional opportunities to make simultaneous multi-wavelength observations.     

Rutile/TiO<Subscript>2</Subscript>II phase equilibria

The transition between rutile and α-PbO₂ structured TiO₂ (TiO₂II) has been investigated at 700–1,200 °C and 4.2–9.6 GPa. Hydrothermal phase equilibrium experiments were performed in the multi-anvil apparatus to bracket the phase boundary at 700, 1,000, and 1,200 °C. The equilibrium phase boundary is described by the equation: P (GPa)=1.29+0.0065 T ( °C). In addition, growth of TiO₂II was observed in experiments at 500 and 600 °C, although growth of rutile was too slow to bracket unambiguously the equilibrium boundary at these temperatures. Water was not detected in either rutile or TiO₂II, and dry synthesis experiments at 1,200 °C were consistent with the phase boundary determined in the fluid-bearing experiments, suggesting that the equilibrium is unaffected by the presence of water. Our bracket of the phase boundary at 700 °C is consistent with the reversed, dry experiments of Akaogi et al. (1992) and the reversals of Olsen et al. (1999). The new data suggest that the phase boundary is linear, in agreement with Akaogi et al. (1992), but in striking contrast to the phase diagram inferred by Olsen et al. (1999). The natural occurrence of TiO₂II requires formation pressures considerably higher than the graphite–diamond phase boundary.     

Rock-magnetic proxies of climate change from loess -paleosol sediments of the Czech Republic

Summary Rock-magnetic characteristics of late Pleistocene loess-paleosol sequences in the Czech Republic show patterns of variation that reflect climate-related depositional and diagenetic processes which acted on the sedimentary profiles. Mass-normalized magnetic susceptibility is high in interglacial and interstadial paleosols, while uniformly low values are measured in unweathered loess horizons. Normalized ferrimagnetic susceptibility and anhysteretic remanent magnetization show an enhancement of ultrafine (superparamagnetic, SP) and fine (single-domain, SD, and pseudo-single-domain, PSD) grains in chernozem paleosols correlated with δ¹⁸O substages 5c and 5a as well as in the Holocene soil. The parabraunerde paleosol associated with peak interglacial conditions, correlated with δ¹⁸O substage 5e, shows evidence of diagenetic loss of fine grained magnetic minerals, although coarse (multidomain, MD) grains appear to be preserved. Low temperature remanence behavior plus high temperature susceptibility measurements of representative samples from each lithologic unit indicate that magnetite and maghemite are the dominant magnetic minerals within the sediments. Variations in concentration-independent rock-magnetic parameters are therefore primarily a function of grain size variations through the profile. It is anticipated that with additional magnetic and non-magnetic sedimentological and geochemical tests, a quantitative rock-magnetic — paleoclimate model can be developed for the central European loess region.     

The land cover and carbon cycle consequences of large-scale utilizations of biomass as an energy source

The use of modern biomass for energy generation has been considered in many studies as a possible measure for reducing or stabilizing global carbon dioxide (CO₂) emissions. In this paper we assess the impacts of large-scale global utilization of biomass on regional and grid scale land cover, greenhouse gas emissions, and carbon cycle. We have implemented in the global environmental change model IMAGE the LESS biomass intensive scenario, which was developed for the Second Assessment Report of IPCC. This scenario illustrates the potential for reducing energy related emission by different sets of fuel mixes and a higher energy efficiency. Our analysis especially covers different consequences involved with such modern biomass scenarios. We emphasize influences of CO₂ concentrations and climate change on biomass crop yield, land use, competition between food and biomass crops, and the different interregional trade patterns for modern biomass based energy. Our simulations show that the original LESS scenario is rather optimistic on the land requirements for large-scale biomass plantations. Our simulations show that 797 Mha is required while the original LESS scenario is based on 550 Mha. Such expansion of agricultural land will influence deforestation patterns and have significant consequenses for environmental issues, such as biodiversity. Altering modern biomass requirements and the locations where they are grown in the scenario shows that the outcome is sensitive for regional emissions and feedbacks in the C cycle and that competition between food and modern biomass can be significant. We conclude that the cultivation of large quantities of modern biomass is feasible, but that its effectiveness to reduce emissions of greenhouse gases has to be evaluated in combination with many other environmental land use and socio-economic factors.     

Impact Of Snow Drift On The Antarctic Ice Sheet Surface Mass Balance: Possible Sensitivity To Snow-Surface Properties

A mesoscale atmospheric numerical model is coupled with a physically based snow-pack model and with a snow-drift model. The snow model is verified for the French Alps by comparing its simulations to observations performed at the Col de Porte in the Chartreuse Massif. The snow erosion threshold depends on snow-pack properties such as density, dendricity, sphericity and particle size. The atmospheric turbulence scheme is modified in order to take into account stabilization effects due to airborne blown snow particles. In particular, vertically integrated stability functions for the stable boundary layer are completed by including the threshold friction velocity for snow erosion. The snow-drift model is calibrated by simulating the conditions observed during the Byrd snow project, held in West Antarctica in 1962. Finally, sensitivity experiments to the snow-surface properties show the importance of their accurate representation when modelling the contribution of deflation to the Antarctic surface mass balance.     

Lacustrine and palustrine carbonate petrography: an overview

Lacustrine limestones were formerly identified by their faunistic (limnea, planorbis) and floristic (Charophytes) content. For 30 years, indications of pedogenesis have been found in many lacustrine deposits, and consequently the concept of palustrine limestone was defined.Lacustrine fabrics are not that numerous: varved, laminated, homogeneous, peloidal, brecciated, gravelly, bioturbated (burrows), bioclastic, algal, and stromatolitic. Detrital beds are sometimes present and are interpreted as bottomset deposits. Palustrine fabrics result from exposure and pedogenesis of lacustrine mud. The main processes involved in this evolution are: cracking, with planar, curved, craze and skew planes, colonization by plants resulting in root traces, marmorization (redistribution of iron due to water table fluctuation), and redistribution of carbonates (needles, subspherical or cylindrical vertical nodules, carbonate coatings, early and late diagenetic crystals, Microcodium). Carbonate palustrine features can be associated with other minerals: palygorskite, gypsum, or silica. Alternation of lacustrine sedimentation and exposure/pedogenesis leads to the pseudo-microkarst facies resulting from enlargement of the complex network of root traces and horizontal cracks. The voids in the pseudo-microkarst facies are infilled with a polyphased internal sediment composed of carbonate and vadose silt and phreatic and vadose cements. Traces of exposure and pedogenesis are less in evidence in lacustrine bioclastic sands and algal-stromatolitic limestones. Finally, under certain conditions, the surficial laminar horizon and its associated perlitic crust (ooids) develops on palustrine muds and form a desert stromatolite.