Energy market failure in road transport: Is there scope for ‘no regrets’ greenhouse gas reduction?

The Australian Government policy on reduction of greenhouse gas emissions announced in 1990 includes exploring the scope for immediate, low cost reductions. Such measures can be taken as including ‘no regrets’ policies: those that, in addition to mitigating potential climate change, confer economic gains (including other environmental benefits) which exceed their costs. Some possible ‘no regrets’ opportunities and policies are identified relevant to energy use by the road transport sector over the period to 2020. The MARKALMENSA multi-period linear programming model of the Australian energy sector is used to investigate the cost-effectiveness of these policies.     

Late Pleistocene woodlands in the Bolson de Mapimi: A refugium for the Chihuahuan Desert Biota?

Packrat middens radiocarbon dated at 12,280 ± 345 and 12,700 ± 165 yr B.P. record expansions of junipers and papershell pinyon (Pinus remota) into the desert lowlands of Durango and Coahuila, Mexico (26° N). Extralocal trees and shrubs presently occur 24–580 km in nearly all directions including more subtropical areas to the northeast and southeast. An equable Late Wisconsin climate marked by mild winters with increased precipitation and by cool summers with reduced summer monsoons is proposed. The extensive playas of the Bolson de Mapimi probably held water at that time. The Bolson de Mapimi was not a geographical refugium unaffected by glacial climates, although many Chihuahuan Desert plants and animals probably remain in situ as members of equable woodlands. Equable climates, low extinction rates, and repeated, rapid glacial/interglacial climatic fluctuations may have been important in the evolution and accumulation of species at lower latitudes.     

Microstructures in carbonates from the Alnø and Fen carbonatites

The nature of carbonates and related second phase minerals in carbonatite samples from the Alnø and Fen regions has been studied by optical and transmission electron microscopy, aided by X-ray diffraction and electron microprobe analysis.Calcite, dolomite and ankerite have been found to exhibit two phase microstructures. Coherent ribbons of calcitic material occur in dolomite and ankerite, while the calcite grains commonly contain a fine dispersion of plate-like and sometimes rod-like precipitates. Calcite and dolomite frequently occur in contact with the same crystallographic lattice orientation, the small lattice mismatch being indicated by moiré patterns at the grain boundaries and occasional misfit dislocations.The two-phase structure of calcite in dolomite reported for the first time in this paper is thought to be a high temperature analogue of the modulated microstructures reported recently in calcian sedimentary dolomites (Wenk et al. 1983).     

The microstructure of minerals in coarse-grained Ca-Al-rich inclusions from the Allende meteorite

The microstructure and microchemistry of minerals in Ca-Al-rich, coarse-grained inclusions (CAI) from the Allende meteorite have been investigated with transmission electron microscopy (TEM). Spinels contain only low to moderate dislocation densities and are characterized by a ubiquitous, fine black spotty texture believed to originate from a slightly non-stoichiometric composition. Ti-Al-pyroxenes are relatively featureless, but contain veins of secondary phases apparently deposited in unhealed cracks. Chromite has been identified in the veins, suggesting transport of oxidized iron during alteration. Melilites exhibit the greatest variety of microstructures and are the most heavily altered phase in CAI. High dislocation densities are common and crystals exhibit considerable internal strain, indicating that they have not been annealed. Alteration occurs both as veins along cracks and in fronts extending across several grains. Plagioclase is commonly twinned, but dislocations are rare. The size and morphology of antiphase domains suggest a high temperature of formation with significant low-temperature annealing. Submicron pyroxene precipitates are a ubiquitous and unusual feature of Allende plagioclase whose properties are most consistent with prolonged slow cooling and equilibration after plagioclase crystallization. The precipitates appear to be sufficiently abundant to contain the majority of Mg present in plagioclase but do not easily account for Na and Ti abundances. Wollastonite needles from a cavity in a “fluffy” Type A inclusion exhibit the growth habits and relatively perfect external surfaces indicative of direct condensation from a vapor. Alteration products are predominantly crystalline and alteration of melilite appears to have proceeded primarily by solid-state diffusion at a temperature of approximately 920°K. Overall, the TEM observations suggest that CAI formed under near equilibrium conditions characterized by slow cooling and that solid-state bulk diffusion was the major process affecting their post-crystallization history.     

Laboratory simulation of the salt weathering of schist: II. Fragmentation of fine schist particles

Recent developments in long term landform evolution modelling have created a new demand for quantitative salt weathering data, and in particular data describing the size distribution of the weathered rock fragments. To enable future development of rock breakdown models for use in landscape evolution and soil production models, laboratory work was undertaken to extend existing schist/salt weathering fragmentation studies to include an examination of the breakdown of sub‐millimetre quartz chlorite schist particles in a seasonally wet tropical climate. Laser particle sizing was used to assess the impact of different experimental procedures on the resulting particle size distribution. The results reveal that salt weathering under a range of realistic simulated tropical wet season conditions produces a significant degree of schist particle breakdown. The fragmentation of the schist is characterized by splitting of the larger fragments into mid‐sized product with finer material produced, possibly from the breakdown of mid‐sized fragments when weathering is more advanced. Salinity, the salt addition method and temperature were all found to affect weathering rates. Subtle differences in mineralogy also produce variations in weathering patterns and rates. It is also shown that an increase in drying temperature leads to accelerated weathering rates, however, the geometry of the fracture process is not significantly affected. Copyright © 2006 John Wiley & Sons, Ltd.     

Morphology of HCN and CN in Comet Hale-Bopp (1995 O1)

We compare images of Comet Hale-Bopp (1995 O1) in HCN and CN taken near perihelion (April 1, 1997) to determine the origin of CN in comets. We imaged the J=1→0 transition of HCN at λ=3 mm with the BIMA Array. Data from two weeks around perihelion were summed within four phase bins based on the rotational period of the comet. This increases both the signal-to-noise ratio and the u-v coverage while decreasing the smearing of the spatial features. The similarly phased narrowband CN images were taken at Lowell Observatory within the same range of dates as the HCN images. We find that there is a better correlation between HCN and CN than between HCN and the optically dominant dust. If the CN in jets does have a dust source it would have to have a very low albedo and/or small particle size. The production rates are consistent with HCN being a primary parent of CN, although there are discrepancies between the HCN destruction scalelength and the CN production scalelength which we discuss.     

天坑释义

天坑是一种特大型塌陷漏斗,它的演化包括大型洞穴厅堂的洞顶崩塌和大型暗河对大量崩塌块石的搬运.天坑这个术语,首先在中国使用,随后成为世界性的喀斯特词汇.     

The effect of organic materials on the mobility and toxicity of metals in contaminated soils

Organic materials such as compost are often proposed as suitable materials for the remediation of contaminated brownfield sites intended for soft end-use. In addition to vitalising the soil, they are also believed to immobilise metals thereby breaking contaminant-receptor pathways and reducing the ecotoxicity of the contaminants. However, some research has demonstrated contradictory effects between composts on metal immobilisation. In the present study, four different composts and a liming product containing organic matter (LimeX70) were tested to examine both their metal retention and toxicity reduction capabilities on three different metal contaminated soils. Leaching tests, a plant growth test with Greek cress (Lepidium sativum), an earthworm (Eisenia fetida) survival and condition test and a bacterial toxicity test using Vibrio fischeri were carried out. The leaching test results showed that spent mushroom compost caused an increase in metal concentration in the leachates, while LimeX70 caused a decrease. The variation in behaviour between different amendments for each soil was high, so a generic conclusion could not be drawn. Toxicity tests showed significant reduction of metal bioavailability and toxicity for Greek cress, earthworms and bacteria. The results also suggest that more research should be undertaken to understand the mechanisms involved in metal complexation using different types of organic matter, in order to optimise the use of organic materials like compost for soil remediation.