Energy resources and utilization in South Africa     

Silberberg R. B. 《GeoJournal》1981,2(2):43-50

South Africa presents the development planner with a challenging problem of energy planning, because the country's large indigenous deposits of fuels (coal, uranium) combined with a demand for imported energy (petroleum products). Coal is South Africa's basic primary energy source and is transformed into a variety of locally used secondary forms, among which thermal electricity and liquid fuels are vitally important. Prospecting for hydrocarbons on the Agulhas Bank off the southern Cape coast has, on the other hand, not been succesful. Both coal and uranium promise to become important export commodities, while the percentage share of imported petroleum products is expected to decrease towards 2000. There is nevertheless an urgent need for an energy policy which will optimise utilization.  相似文献   

Scanning reflectance spectroscopy (380–730 nm): a novel method for quantitative high-resolution climate reconstructions from minerogenic lake sediments     

M. Trachsel  M. Grosjean  D. Schnyder  C. Kamenik  B. Rein 《Journal of Paleolimnology》2010,44(4):979-994

High-resolution (annual to sub-decadal) quantitative reconstructions of climate variables are needed from a variety of paleoclimate archives across the world to place current climate change in the context of long-term natural climate variability. Rapid, high-resolution, non-destructive scanning techniques are required to produce such high-resolution records from lake sediments. In this study we explored the potential of scanning reflectance spectroscopy (VIS-RS; 380–730 nm) to produce quantitative summer temperature reconstructions from minerogenic sediments of proglacial, annually laminated Lake Silvaplana, in the eastern Swiss Alps. The scanning resolution was 2 mm, which corresponded to sediment deposition over 1–2 years. We found correlations up to r = 0.84 (p < 0.05) for the calibration period 1864–1950, between six reflectance-dependent variables and summer (JJAS) temperature. These reflectance-dependent variables (e.g. slope of the reflectance 570/630 nm, indicative of illite, biotite and chlorite; minimum reflectance at 690 nm indicative of chlorite) indicate the mineralogical composition of the clastic sediments, which is, in turn, related to climate in the catchment of this particular proglacial lake. We used multiple linear regression (MLR) to establish a calibration model that explains 84% of the variance of summer (JJAS) temperature during the calibration period 1864–1950. We then applied the calibration model downcore to develop a quantitative summer temperature reconstruction extending back to AD 1177. This temperature reconstruction is in good agreement with two independent temperature reconstructions based on documentary data that extend back to AD 1500 and tree ring data that extend back to AD 1177. This study confirms the great potential of in situ scanning reflectance spectroscopy as a novel non-destructive technique to rapidly acquire high-resolution quantitative paleoclimate information from minerogenic lake sediments.  相似文献   

Characterizing Water Flow in Vegetated Lysimeters with Stable Water Isotopes and Modeling     

Fatemeh Shajari  Florian Einsiedl  Arno Rein 《Ground water》2020,58(5):759-770

We have used stable water isotopes (δ¹⁸O, δ²H) in combination with lumped-parameter modeling for characterizing unsaturated flow in two lysimeters vegetated with maize. The lysimeters contained undisturbed soil cores dominated by sandy gravel (Ly1) and clayey sandy silt (Ly2). Stable water isotopes were analyzed in precipitation and lysimeter outflow water over about 3 years. The mean transit time of water T and dispersion parameter P_D, obtained from modeling, were higher for the silt soil in Ly2 than for the gravel soil in Ly1 (T of 362 vs. 129 d, P_D of 0.7 vs. 0.12). The consideration of preferential flow (PF) paths could substantially improve the model curve fits, with 13 and 11% contribution of PF for Ly1 and Ly2 as best estimates. Different assumptions were compared to estimate the input function, that is, stable water isotope content in the recharging water. Using the isotopic composition of precipitation as input (no modification) resulted in reasonable model estimations. Best model fits for the entire observation were obtained by weighting the recharging isotopes according to average precipitation within periods of 3 and 6 months, in correspondence to changing vegetation phases and seasonal influences. Input functions that consider actual evapotranspiration could significantly improve modeling at some periods, however, this led to deviations between modeled and observed δ¹⁸O at other periods. This may indicate the influence of variable flow, so that dividing the whole observation period into hydraulically characteristic sub-periods for lumped-parameter modeling (which implements steady-state flow) is recommended for possible further improvement.  相似文献   

Optimal stockpile voxel identification based on reclaimer minimum movement for target grade     

Tien-Fu Lu  Maung Thi Rein Myo 《International Journal of Mineral Processing》2011,98(1-2):74-81

The supply of iron ore closest to the target grade with lowest operation cost is the main concern for the ore producer in mining industries. An automatic optimal reclaiming system to reclaim iron ore from stockpiles using the bucket wheel reclaimer (BWR) is proposed. However, this paper only presents a study on identifying optimal stockpile voxels for the target quantity and quality grade. Stockpiles here are represented by combinations of voxels, each possessing certain quality composition. The main focus of this paper is to identify the combination of voxels from available stockpile voxels that will fulfil quality and quantity demand of iron ore while maintaining BWR minimum movement on reclaiming.  相似文献   

Assessment of paleo-recharge under the Fennoscandian Ice Sheet and its impact on regional groundwater flow in the northern Baltic Artesian Basin using a numerical model     

Arnaud Sterckx  Jean-Michel Lemieux  Rein Vaikmäe 《Hydrogeology Journal》2018,26(8):2793-2810

The study investigates the mechanism of glacial meltwater recharge under the Fennosciandian Ice Sheet during the last glacial maximum (LGM) and its impact on regional groundwater flow in the northern Baltic Artesian Basin (BAB) in Estonia and Latvia. The current hypothesis is that a flow reversal occurred in the BAB due to subglacial recharge during the LGM. This hypothesis is supported by an extensive dataset of geochemical and isotopic measurements in the groundwater of northern Estonia, exhibiting significant depletion in δ¹⁸O with respect to modern precipitation. To verify the consistency of this hypothesis and better understand groundwater flow dynamics during the LGM period, a numerical model is developed for this area. Two cross-sectional models have been created across the northern BAB, in which groundwater flow and the transport of δ¹⁸O have been simulated from the beginning of the LGM to present-day. Several simulations were performed with different subglacial boundary conditions, to investigate the uncertainty related to subglacial recharge of meltwater during the LGM and the subsequent flow reversal in the northern BAB. Several simulations provide a satisfying fit between computed and observed values of δ¹⁸O, which means that the hypothesis of subglacial recharge of meltwater is consistent with δ¹⁸O distribution. The numerical model suggests that preservation of meltwater in northern Estonia is controlled by confining layers and the proximity to the outcrop area of aquifers, located in the Gulf of Finland. The results also suggest that glacial meltwater has been preserved under the Baltic Sea in the Gulf of Riga.  相似文献   

In-situ reflectance spectroscopy – analysing techniques for high-resolution pigment logging in sediment cores     

Bert Rein  Frank Sirocko 《International Journal of Earth Sciences》2002,91(5):950-954

The temporal resolution of marine proxy data is limited by analytically required sample size. We present in-situ reflectance spectroscopy techniques (usually applied in remote sensing) to analyse the organic fraction of marine and terrestrial sediment. From absorption band depths, photosynthesis pigment variations are derived for sediments from the upwelling region off Peru, where productivity is related to the annual variability of El Niño strength. Quantitative estimations of diagenetic photosynthesis pigments derived from absorption band analysis in reflectance spectra are highly correlated to organic carbon content. The ratio of pigment fractions is related to chlorine concentration and reflects organic matter preservation and deep-water ventilation changes. The import of terrigenous mineroclastics (TM) by local rivers is semi-quantitatively documented in the spectrum continuum. TM is inversely varying with organic matter preservation and chlorine concentration.  相似文献   

Твердый налет в зимнее время на милешовке     

František Rein 《Studia Geophysica et Geodaetica》1961,5(3):256-263

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Besonderheiten der Windstruktur auf Einem Kegelgipfel     

František Rein 《Studia Geophysica et Geodaetica》1962,6(3):309-311

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Composition and properties of the iron hydroxides-cemented lenses in Estonian sandstone of Middle Devonian age     

Alla Shogenova  Anne Kleesment  Ann Hirt  Enn Pirrus  Toivo Kallaste  Kazbulat Shogenov  Rein Vaher 《Studia Geophysica et Geodaetica》2009,53(1):111-131

The formation of hematite and goethite concretions in different sedimentary rocks including sandstones is an important diagenetic process in the geologic history of the Earth. Its interpretation can also contribute to understanding the diagenetic history of Martian iron hydroxide concretions. A case study of iron-rich concretions from Estonian Middle Devonian sandstones exposed in ancient river valleys in southeastern Estonia was carried out based on the results of mineralogical, petrographical, geochemical, petrophysical and magnetic analyses. It was found that the high Fe₂O₃(total) content (25.0–39.5%), high magnetic susceptibility, bulk and grain density, very low porosity, corrosion and fracturing of the quartz grains of the platy iron concretions are in contrast with properties of the Devonian host sandstones. However the ferrous iron content (measured as FeO) of iron-rich concretions was as low as in the other Devonian rocks, suggesting an oxidizing environment and arid climate during the cementation by iron-hydroxides. The fracturing of quartz grains cemented by iron hydroxides could take place at near-surface conditions including vadose and phreatic zones in arid climate with high evaporation rates. Such climatic conditions have been reported for the Baltic region during Devonian, Upper Permian and Triassic times. We have found that goethite is prevalent in the cement, replacing clay and carbonate minerals. We assume that this iron-rich cement is originated from the mobilization of iron in host sandstones by groundwater, associated with tectonic activity at the end of the Middle Devonian, evidenced by fracturing in Devonian outcrops and caves. Although this mobilization could occur under reducing conditions, precipitation of goethite and hematite for the cementation could take place in oxidizing environment along bedding planes close to the surface during short sedimentation breaks. Another possible time for the formation of iron concretions could be Permian, under the condition of both arid climate and tectonic activity.  相似文献   

Thunderstorm days,thunderstorm duration and the number of lightning flashes in Czechoslovakia and in Finland     

František Popolanský  Leila Laitinen  Reviewer F. Rein 《Studia Geophysica et Geodaetica》1972,16(1):103-106

Zusammenfassung In dem Artikel werden die Gleichungen zwischen der Anzahl von Gewittertagen, der Gewitterdauer und der Anzahl von Blitzentladungen abgeleitet, die durch den CIGRE-Blitzzähler in 13 Stationen in der SSR und 6 Stationen in Finnland während einer 4-jährigen ununterbrochenen Beobachtungspheriode registriert wurden. Es wurde festgestellt, dass die die Beziehungen zwischen der Anzahl von Gewittertagen und der Anzahl von Blitzentladungen und zwischen der Gewitterdauer und der Anzahl von Blitzentladungen nichtlinear sind. Die Nichtlinearität zwischen den Jahressummen ist höher als die Nichtlinearität zwischen den Monatssummen einzelner Parameter.  相似文献