The angle of inclination of the sunspot symmetry axis to the solar surface

The Wilson effect, used before only as a method of determining the physical depression of sunspots, is used here to estimate a quite different parameter - the sunspot symmetry axis inclination angle to the solar surface, this explains the observed negative Wilson effect.On the basis of photoheliograms taken with three telescopes of the High-Altitude Solar observatory Peak Alma-Ata, the Wilson effect for the whole solar disk is investigated, the east and west parts of the disk being studied separately. 111 sunspots of regular shape at different heliocentric angles were measured, eight of them being under observations from one limb to the other. To study the dependence of the Wilson effect on the heliocentric angle, all observations within an angular interval of 10° were averaged. The dependence thus derived is described by two sinusoids having the zero point shifted along both axes. The shift of the zero Wilson effect to the west, i.e., a shift along the heliocentric angle axis, can be caused by the deviation of the sunspot axis to the east from the normal to the solar surface. On the line of sight-normal plane the angle corresponding to this deviation is =34°±14°.     

Forestry Projects under the Clean Development Mechanism?

Afforestation is considered an important option for mitigation of greenhousegas emissions. Recently, plantation projects have been suggested for inclusionunder the Clean Development Mechanism. While considered a cheap option,significant uncertainties make it difficult to determine the (net) carbonbenefits and profitability of forestry projects. The current uncertaintiesabout the regulatory framework of the CDM and the environmental and economicperformance of plantation forestry could create uncertainties with respect tothe additionality of such projects and thus their acceptance under themechanism.Six plantation forestry projects that were proposed in Brazil have been usedas cases to study sources of uncertainty for carbon benefits and economics forsuch projects. These cases vary widely in terms of productivity and productsdelivered. A quantitative model for calculating greenhouse gas balances andfinancial benefits and costs, taking a broad range of variables into account,was developed. Data from the developers of the proposed projects was used asmain source material. Subsequently, scenario's were evaluated, containingdifferent and realistic options for baseline vegetation, carbon creditingsystems and CDM modalities, fluctuations in product prices, discount rates andcarbon prices.The real cost of combined carbon sequestration and substitution for the caseprojects was below $3 per ton of carbon avoided, when based exclusivelyon data supplied by project developers. However, potential variations incarbon impact and costs based on scenario options were very large. Differentbaseline vegetation or adopting a different discount rate cause carbon creditsto vary by as much as an order of magnitude. Different carbon crediting systemsor fluctuations in (commodity) product prices cause variations up to200% in carbon credits and NPV. This makes the additionality of suchprojects difficult to determine. Five of the six case projects seem uneligiblefor development under the CDM. A critical attitude towards the use ofplantation projects under the CDM seems justified.     

The Lower Wonderfontein Spruit: an exposé

During the nineteenth century the Wonderfontein Valley and Spruit were described as a 'natural jewel' by adventurers. The valley underlain by dolomitic aquifers contained copious volumes of water and partly overlies gold-mining excavations, which were under a threat of flooding. For safety and economic reasons, large-scale dewatering of some of the dolomitic aquifers was decided upon as a matter of policy. This led to the lowering of the water table, which accelerated the formation of sinkholes and dolines in geologically sensitive areas. The streambed along approximately the first 30 km of the Lower Wonderfontein Spruit is particularly vulnerable. The mining sector attempted to rehabilitate the affected parts of the streambed by filling the sinkholes with various materials. Unfortunately, many of the treated sinkholes were reactivated by storm flow.     

A fluid-pressure feedback model of dehydration reactions: experiments, modelling, and application to subduction zones

Dehydration and melting reactions generate large volumes of fluid in the crust and upper mantle, and play an important role in subduction zone seismicity. The fluid pathway must evolve from isolated pockets in low porosity, low permeability rock, coalescing to interconnected permeable pathways to the surface. When fluid pressures generated from a dehydration or melting reaction are sufficient to induce hydrofracture, then hydrofracture significantly influences the porosity–permeability structure within the dehydrating/melting horizon. If a low fluid-pressure boundary is introduced to the dehydrating rock, then fluid will be driven from the rock along the evolved permeable network toward that boundary. The resulting pressure reduction can then accelerate the dehydration reaction and further drive the flow. The sudden introduction of a low fluid-pressure boundary may occur by the co-seismic (dilatant) rupturing of a pressure seal that connects different fluid pressure states. This mechanism is invoked to explain the observed post-seismic evolution of wave velocities (V_p/V_s) following the 1995 Antofagasta, Chile earthquake. We show experimental results and introduce a conceptual and numerical model that reflects this scenario. The model couples the mechanical and thermodynamic effects of fluid pressure with devolitization kinetics, and is quantitatively consistent with experimental studies of the dehydration of gypsum and serpentine. The experimental results show that dehydration is controlled by access to a free (drained) boundary. The model provides a mechanistic explanation for the experimental observations and has applications in understanding the role of transient transport networks on the large-scale behavior of dehydrating and melting systems.     

Modeling the binding of fulvic acid by goethite: the speciation of adsorbed FA molecules

Under natural conditions, the adsorption of ions at the solid-water interface may be strongly influenced by the adsorption of organic matter. In this paper, we describe the adsorption of fulvic acid (FA) by metal(hydr)oxide surfaces with a heterogeneous surface complexation model, the ligand and charge distribution (LCD) model. The model is a self-consistent combination of the nonideal competitive adsorption (NICA) equation and the CD-MUSIC model. The LCD model can describe simultaneously the concentration, pH, and salt dependency of the adsorption with a minimum of only three adjustable parameters. Furthermore, the model predicts the coadsorption of protons accurately for an extended range of conditions. Surface speciation calculations show that almost all hydroxyl groups of the adsorbed FA molecules are involved in outer sphere complexation reactions. The carboxylic groups of the adsorbed FA molecule form inner and outer sphere complexes. Furthermore, part of the carboxylate groups remain noncoordinated and deprotonated.     

Detection of sinkholes using 2D electrical resistivity imaging

Sinkholes in dolomitic areas are notoriously difficult geophysical targets, and selecting an appropriate geophysical solution is not straightforward. Electrical resistivity imaging, or tomography (RESTOM) is well suited to mapping sinkholes because of the ability of the technique for detecting resistive features and discriminating subtle resistivity variations. RESTOM surveys were conducted at two sinkhole sites near Pretoria, South Africa. The survey areas are located in the dolomites of the Lyttelton Formation, which forms part of the Malamani Subgroup and Chuniespoort Group of the Transvaal Supergroup. The survey results suggest that RESTOM is an ideal geophysical tool to aid in the detection and monitoring of sinkholes and other subsurface cavities.     

Palynological evidence for the astronomical origin of lignite-detritus sequence in the Middle Pleistocene Marathousa Member, Megalopolis, SW Greece

The Marathousa Member, Middle Pleistocene strata in the fluvio-lacustrine Megalopolis basin, southwest Greece, displays distinct but complicated lithological cycles comprising first-order alternation of lignites and detrital muds and second-order alternation expressed by frequent intercalation of organic layers. Palynological evidence indicates that the lithological cycles are driven by the Earth’s orbital forcing. All the lignite seams yield temperate oak forest whereas the detrital beds provide semi-arid steppe mainly of Artemisia. This means that the first-order lithological cycle represents the glacial/interglacial cycle (i.e., the 100-kyr eccentricity cycle), providing a timescale of at least 350 kyr to the Marathousa Member. Pollen also detects smaller-scale climate fluctuations in many of the subordinate organic layers, with the total number of fluctuations being five in a complete lignite-detritus couplet. This means that the second-order lithological cycle reflects the 21-kyr insolation cycle. A tentative phase relation between the lithological cycles and the astronomical cycles is shown based on palynostratigraphy and electron spin resonance dating. Lacustrine environments with increased water tables are implied for the glacial periods sedimentologically, in contrast to local swamp vegetation for the interglacial periods. The subordinate organic layers were formed under intermediate environments (climate, water depth, etc.) between full glacials and interglacials.