Cavernous Weathering in Aeolian Sandstones: An Example from the Yongningshan Hill of the Loess Plateau, Northwest China

Cavernous weathering is commonly found on sandstone slopes in different environments. Either a single dominant process or polygenetic agents require to be invoked in order to interpret the development. The Yongningshan hill of the central Loess Plateau is representative of cliff dwellings in Northwest China, which is characterized by well-developed cavernous weathering features and provides a good opportunity for the better understanding of sandstone weathering in the Loess Plateau. Multiple methods, including field survey, in-situ rock strength measurement, along with experiments on samples for microscopic observation, element composition and salt chemistry, were employed to investigate the controlling factors of cavernous weathering. The results show that cavern development is different on the four slopes with the western slope hosting massive honeycombs, tafoni and hardened surfaces. The porous and permeable aeolian sandstones are fundamental, because they provide space and pathways for the transportation of water and salt, honeycombs dominantly aligning within the lamination of cross-beds. The environmental factors such as the seasonal wetting and drying cycle, aeolian salt, moisture and water vapor are key factors for the development of cavernous weathering forms. The northern and northwestern wind-blown dust storms have brought abundant salts, the lengthier dry periods of the wetting and drying cycle being beneficial for salt accumulation within caverns, favoring salt weathering.     

2-Gyr Simulation of the Oort-Cloud Formation. I. Introduction on a New Model of the Outer Oort-Cloud Formation

The study of the reservoirs of small bodies in the Solar System can help us to refine our theory of the origin and evolution of the whole planetary system we live in. In this contribution, we introduce a simulation of the evolution of an initial proto-planetary disc (PPD) for 2 Gyr period, in which 10,038 studied test particles (TPs), representing the disc, are perturbed by four giant planets in their current orbits and having their current masses. In addition, Galactic-tide and stellar perturbations are considered. The outer Oort cloud (OC) appears to be formed within about 0.5 Gyr. At 2 Gyr, only 0.14% of all TPs reside in the outer OC, according to our simulation. This is the largest discrepancy with the results of previous authors. The TPs in the outer OC originate from almost all regions of the PPD. Specifically, 14, 7, 29, 21, and 29% of all TPs, that are the members of the outer OC at 2 Gyr, originate in the Jupiter, Saturn, Uranus, Neptune, and Edgeworth-Kuiper-belt regions, respectively. The largest number of the TPs, 6,669 (66.4%), was ejected into the interstellar space. Besides other results, we found a dominance of high galactic inclinations of outer-OC orbits. Obviously, this is a consequence of the action of Galactic tide.     

Few Comments on the Relation Between the Initial Proto-planetary Disc Model and the Oort Cloud Formation

A fraction of small bodies from the once existing proto-planetary disc was ejected, by the giant planets, to large heliocentric distances and start to build the comet Oort cloud. Considering four models of initial proto-planetary disc, we attempt to roughly map a dependence between the initial disc’s structure and some properties of the Oort cloud. We find that it is difficult to construct the proto-planetary disc if (i) the amount of heavy chemical elements in Jupiter and Saturn is as high as currently accepted and (ii) the total mass of the minimum-mass solar nebula is assumed to be lower than $\approx0.05\,\hbox{M}_{\odot}.$ The behaviour of the Oort cloud formation does not crucially depend on the initial disc model. Some differences in its structure are obvious: since the cloud is known to be filled mainly by Uranus and Neptune, the efficiency of its formation is higher when the initial amount of particles in the Uranus-Neptune region is relatively higher. A significantly large number of Jupiter Trojans in our simulation appears, however, only in the case of the initially non-gapped disc, with the particles situated also close to the Jupiter’s orbit.     

Exploring earth system governance: A case study of floodplain management along the Tisza river in Hungary

This paper discusses a recently proposed conceptualisation of ‘earth system governance’ by applying it to floodplain management in the Hungarian Tisza river basin. By doing so it aims to improve our understanding of governance systems facilitating adaptation to a changing world. The conceptualisation of earth system governance consists of three elements: problem structure, principles and research challenges. These three elements are assessed using results from actor interviews and policy review. A regional example of natural resources management is found to be a valid case for earth system governance research. The proposed conceptualisation of earth system governance explains well the main problems, barriers and opportunities for adapting floodplain management to climate change in the Tisza region. Problem structure analysis highlights how previous socio-economic and political orders continue to shape expectations and patterns of conduct. Current barriers can be attributed to a lack of the key governance principles credibility, stability, inclusiveness and adaptiveness. Interviewees perceived the lack of credibility and effective cooperation between organisations as the largest barrier. The research challenges proposed for earth system governance agree well with opportunities identified for adapting Tisza floodplain management, calling for inclusion of actors beyond governments and state agencies, and equitable resource allocation in particular. The analysis suggests that an additional challenge for earth system governance is the prioritisation of actions to support an existing governance system and its actors in adapting.     

Comparison of global storm activity rate calculated from Schumann resonance background components to electric field intensity E0Z

This work presents the results of a comparison between the global storm activity rate I_RS and electric field intensity E_0Z. The permanent analysis of the I_RS may become an important tool for testing Global Electric Circuit models. I_RS is determined by a new method that uses the background component of the first 7 Schumann resonances (SR). The rate calculations are based on ELF observations carried out in 2005 and 2006 in the observatory station “Hylaty” of the Jagiellonian University in the Eastern Carpathians (Kułak, A., Zięba, S., Micek, S., Nieckarz, Z., 2003. Solar variations in extremely low frequency propagation parameters: I. A two-dimensional telegraph equation (TDTE) model of ELF propagation and fundamental parameters of Schumann resonances, J. Geophys. Res., 108, 1270, doi:10.1029/2002JA009304). Diurnal runs of the I_RS rate were compared with diurnal runs of E_0Z amplitudes registered at the Earth's surface in the Geophysical Observatory of the Polish Academy of Sciences in Świder (Kubicki, M., 2005. Results of Atmospheric Electricity and Meteorological Observations, S. Kalinowski Geophysical Observatory at Świder 2004, Pub. Inst. Geophysics Polish Academy of Sciences, D-68 (383), Warszawa.). The days with the highest values of the correlation coefficient (R) between amplitudes of both observed parameters characterizing atmosphere electric activity are shown. The seasonal changes of R, I_RS and E_0Z are also presented.     

Milankovic’s theory: multidimensional visualisation of the change of insolation and indicators of climatic change from 100000 before present to 100000 after present (in intervals of 1,000 years)

The deviation of the insolation on the earth’s surface from the past to the present and the present to the future for cloudless days is calculated in intervals of 1,000 years from 100000 years before present (BP) to 100000 years after present (AP), its basis being Milankovic’s theory. But the result are not the well-known Milankovic-curves, which are calculated for different latitudes and in which the x-axis represents years and the y-axis represents the insolation difference to present during the North-summer half-year. The calculations are made for each day of the selected years from the South Pole to the North Pole. Thus, two temporal dimensions are represented, that of a year and that of a day, furthermore the spatial dimension “latitude” and the dimension “energy” (insolation deviation). The performance of modern PCs allows the results of the calculations to be presented by a graphical animation. A determined deviation pattern of the insolation is obtained for each year. δ¹⁸O data, the mean global temperature and the additional ice volume on the continents are added to the graphic representations of those patterns for the period from 100000 years BP to the present. During that period insolation deviation patterns can be recognised which correlate with cool climates or climates getting cooler, and others which correlate with relatively warm climates or climates getting warmer. Correlations between the patterns are calculated and groups of similar patterns can be composed which can be associated in most cases with specific climatic conditions or specific climatic change. Comparison of patterns between 100000 years and present BP with patterns between present and 100000 years AP can help to estimate climatic change during the 100000 years ahead.     

Short-Period Secular Variations (SPSV) of the geomagnetic field recorded in highly scattered palaeomagnetic records of Holocene lake sediments from North Poland

A simple method of calculating running means over different intervals within palaeomagnetic records has been used to identify short-period secular variations of the geomagnetic field. The records from Polish lake sediments reveal variations in declination with a period between 290 and 372 years. The periodicity of variations in the inclination has been estimated to be between 522 and 670 years.     

Electrokinetic remediation of an electroplating site: design and scale-up for an in-situ application in the unsaturated zone

In-situ electrokinetic remediation of contaminated soils requires integrated approaches and adequately engineered setups to control relevant mass fluxes. Based on laboratory findings, this study presents the design of a pilot-scale remediation at an operating electroplating site. The fine-textured soil developed from Jurassic limestone exhibits a chromium, copper, nickel, and zinc contamination down to depths of more than 4 m. The feasibility of an electrokinetic remediation in the unsaturated zone was tested in a lab-scale experiment with subsoil material sampled at the site. The electrodes were placed in water-impermeable, ion-selective membrane wells. This construction allows the necessary watering of the electrodes, maintains unsaturated conditions in the soil compartment, and enables the transfer of contaminant ions into the wells. In addition, the soil is protected from pH changes caused by water electrolysis at the electrodes. The setup includes a watering and drainage system to compensate the electroosmotic water flux and impede desiccation of the anodic region. With a direct current of 70 V and an electric field strength of 2.2 V cm⁻¹, contaminant removal rates amounted up to 27% and 66% (w/w) of the initial zinc/copper and chromium/nickel concentrations. Copper, nickel, and zinc accumulated in the cathode well, while chromate species were enriched in the anode well. Given the successful lab-scale remediation, the pilot plant was designed for the in-situ treatment of a soil volume of 12 m³ below a production hall. A power of 500 V DC at a maximum current of 30 A is supplied by a transformer rectifier. This yields an electric field strength comparable to the lab-scale experiment and thereby similar contaminant transport velocities. A vacuum distillation unit is employed for process water reuse and to control electrolyte conductivity. To cope with chlorine gas generation at the anodes a gas absorber unit is employed. According to the lab-scale results, about 2, 9, 9, and 15 kg zinc, chromium, copper, and nickel, respectively, are expected to be removed from the field plot during an operation time of 10 months.     

Geomorphology of medium‐high mountains under changing human impact,from managed slopes to nature restoration: a study from the Sudetes,SW Poland

In the last few hundred years, medium‐high mountain geomorphic systems of the East Sudetes, central Europe, have evolved under varying human impacts and have shown distinctive behaviours, depending on the nature and intensity of human activities. The general trend within this period has been from initial disturbance brought about by the spread of agriculture, through managed rural landscapes in the 19th and early 20th century, to gradual restoration of natural conditions observed in the last few tens of years, concurrent with considerable population decline in the mountain valleys. Accelerated soil erosion was successfully mitigated by the introduction of agricultural terraces in the 19th century, and most sediment could have been stored within the slopes. The current phase of nature restoration is understood as a return to general slope stability, weak coupling between slopes and channels, and limited sediment transfer across and out of mountainous drainage basins, which typified most of the Holocene prior to human colonization. Copyright © 2006 John Wiley & Sons, Ltd.