Nickel- und Kupfer-reiche Manganknollen der Tiefsee als Produkte frühdiagenetischer Vorgänge

Zusammenfassung Die Manganknollen in den Tiefseeregionen des Zentralpazifik variieren stark in ihrer chemischen Zusammensetzung, ihrem mineralogischen Aufbau und ihrer äußeren Gestalt. Das von uns untersuchte Probenmaterial stammt aus der abyssalen Hügelregion zwischen der Clarion- und. der Clipperton-Bruchzone. Während Fe-reiche, Ni- und Cu-arme Knollenmeist Polyknollen - in der näheren Umgebung und auf den Hängen von submarinen Bergen vorkommen, sind in den flachen Beckenbereichen Ni-, Cu- und Mn-reiche Knollen in den obersten 5 bis 15 cm (peneliquider Bereich) der pelagischen Sedimente verbreitet. Die Bergknollen (B-Typ-Knollen) wachsen durch Ausfällung von kolloidaler Substanz (Fe-Hydroxyd- und Mn-Oxidhydrat-Sol) aus dem bodennahen Meerwasser (hydrogenetisches Wachstum), die Sedimentknollen (A-Typ-Knollen) enstehen auf Grund einer frühdiagenetischen Mobilisation und Fraktionierung von Mn (Lösung als Mn²⁺ und Wiederausfällung durch Oxydation) und bei einem Zusatzangebot an Cu, Ni und Zn durch partielle oder vollkommene Auflösung von Sedimentbestandteilen. In den Sedimentknollen sind neben Todorokitschichten auch Mikrobereiche mit erhöhten Fe- und Si-Gehalten vorhanden, die röntgenamorphe bis schwach kristallisierte, ebenfalls frühdiagenetisch gebildete Eisensilikate (Nontronit) enthalten. Ein im Zentralpazifik sehr weit verbreiteter Knollentyp (diskoidale AB-Typ-Knollen) ist allerdings durch zwei Quellen gleichzeitig versorgt worden, d. h. diese Knollen wachsen an ihrer Unterseite auf Grund frühdiagenetischer und an ihrer Oberseite auf Grund hydrogenetischer Stoffzufuhr.

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Deep-sea ferromanganese nodules of the Central Pacific Ocean display a great range of variations in their chemical composition, mineralogical property and morphological feature. The nodule and sediment samples investigated by us were taken from the bottom of the abyssal hill region between the Clarion and the Clipperton Fracture Zone. Fe-rich, Ni- and Cu-poor nodules exist, mostly in the shape of polynodules, in the surroundings and on the slopes of seamounts and hills. In contrast to this Ni-, Cu- and Mn-rich nodules are distributed in the flat basin regions and have been accumulated within the uppermost 5 to 15 cm (peneliquid layer) of the pelagic sediment. The hill nodules (B-type nodules) grow by precipitation of colloidal phases (Fe-hydroxide and hydrated Mn-oxide) from the bottom-near sea water (hydrogenetic growth). The sediment nodules (A-type nodules) are formed from an early diagenatic mobilization and fractionating of Mn (dissolution as Mn²⁺ and reprecipitation by oxidation) receiving an additional supply of Cu, Ni, and Zn by partial or complete dissolution of sediment constituents. Within the sediment nodules exist besides the layers of Todorokite also microzones containing higher contents of Si and Fe; in this nodule substance early diagenetically formed iron silicates (nontronite) could be identified being in an X-ray amorphous to weakly crystallized state. A nodule type (discoidal AB-type nodules) being most frequently distributed in the Central Pacific have been supplied by two different sources more or less simultaneously, i. e. these nodules grow at the bottom side by an early diagenetical supply from the pore water and at the top side by a hydrogenetic supply from the bottom-near seawater.

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Résumé Les nodules de manganèse des régions abyssales du Pacifique Central présentent une grande diversité dans leur composition chimique, leur structure minéralogique et leur forme. Les échantillons que nous avons étudiés sont originaires de la région des collines abyssales entre les zones de fractures de Clarion et de Clipperton. Pendant que les nodules riches en Fe et pauvres en Ni et Cu — pour la plupart des polynodules — se trouvent dans le proche entourage et sur les versants des collines abyssales, les nodules riches en Ni, Cu et Mn sont fréquents dans les 5 à 15 cm supérieurs (zone pénéliquide) des sédiments pélagiques des parties plates des bassins. Les nodules des collines (nodules du type B) se forment par précipitation de substances colloidales (sols d'hydroxydes de Fe et d'oxyhydrates de Mn) de F eau de la mer proche du fond (croissance hydrogénée); les nodules sédimentaires (nodules du type A) se forment àpartir d'une mobilisation diagénétique hâtive et du fractionnement du Mn (solution comme Mn²⁺ et précipitation nouvelle par oxydation) et par une addition supplementaire de Cu, Ni et Zn à la suite d'une dissolution partielle ou complète de composants sédimentaires. Dans les nodules sédimentaires on trouve outre des couches de todorokrite des micro-domaines avec des teneurs élevés en Fe et Si qui contiennent des silicates ferreux (nontronite) amorphes à peu cristallisés, également formés au début de la diagénèse. Cependant un type de nodules (nodules discoidaux de type AB) très largement répandu dans le Pacifique Central sédimente à deux sources simultanées, à savoir par addition de substances à leur face inférieure au début de la diagenèse et par addition de substances hydrogénétiques à leur face supérieure.

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Determination of sediment deposition of Hasanlar Dam using bathymetric and remote sensing studies

Natural Hazards - Hasanlar Dam and Hydroelectric Power Plant are located on Küçük Melen Creek in the Western Black Sea Basin of Turkey. The dam was constructed in 1974 to provide...     

Spatial Prediction of Lateral Variability of a Laterite-Type Bauxite Horizon Using Ancillary Ground-Penetrating Radar Data

Tropical laterite-type bauxite deposits often pose a unique challenge for resource modelling and mine planning due to the extreme lateral variability at the base of the bauxite ore unit within the regolith profile. An economically viable drilling grid is often rather sparse for traditional prediction techniques to precisely account for the lateral variability in the lower contact of a bauxite ore unit. However, ground-penetrating radar (GPR) offers an inexpensive and rapid method for delineating laterite profiles by acquiring fine-scale data from the ground. These numerous data (secondary variable) can be merged with sparsely spaced borehole data (primary variable) through various statistical and geostatistical techniques, provided that there is a linear relation between the primary and secondary variables. Four prediction techniques, including standard linear regression, simple kriging with varying local means, co-located cokriging and kriging with an external drift, were used in this study to incorporate exhaustive GPR data in predictive estimation the base of a bauxite ore unit within a lateritic bauxite deposit in Australia. Cross-validation was used to assess the performance of each technique. The most robust estimates are produced using ordinary co-located cokriging in accordance with the cross-validation analysis. Comparison of the estimates against the actual mine floor indicates that the inclusion of ancillary GPR data substantially improves the quality of the estimates representing the bauxite base surface.     

Artificial neural network models for forecasting monthly precipitation in Jordan

Forecasting precipitation in arid and semi-arid regions, in Jordan in the Middle East for example, has particular importance since precipitation is the unique source of water in such regions. In this study, 1-month ahead precipitation forecasts are made using artificial neural network (ANN) models. Feed forward back propagation (FFBP), radial basis function (RBF) and generalized regression type ANNs are used and compared with a simple multiple linear regression (MLR) model. The models are tested on monthly total precipitation recorded at three meteorological stations (Baqura, Amman and Safawi) from different climatological regions in Jordan. For the three stations, it is found that the best calibrated model is FFBP with respect to all performance criteria used in the study, including determination coefficient, mean square error, mean absolute error, the slope and the intercept in the best-fit linear line of the scatter diagram. In the validation stage, FFBP is again the best model in Baqura and Amman. However, in Safawi, the driest station, not only FFBP but also RBF and MLR perform equally well depending on the performance criterion under consideration.     

Adsorption Kinetic and Equilibrium Studies on Removal of Lead(II) onto Glutamic Acid/Sepiolite

In this study, a modified method was used to increase the adsorption of lead ions from aqueous solutions by using modified clay mineral on the laboratory scale. Adsorption experiments have been carried out on the use of both thermal activated sepiolite (TAS) and their glutamate/sepiolite modification (GS) as adsorbents. The experimental data was analyzed using adsorption kinetic models (pseudo first‐ and second‐order equations). The pseudo second‐order kinetic model fitted well to the kinetic data (R² ≥ 0.99). Then, the Freundlich and Langmuir models were applied to describe the uptake of Pb(II) on GS and the Langmuir isotherm model agrees well with the equilibrium experimental data (R² ≥ 0.97). The maximum adsorption capacity was observed to be 128.205 mg/g by GS according to the Langmuir equation. Desorption efficiency of the GS was studied by the batch method using EDTA, HCl, and HNO₃ solutions. Desorption of 69.18, 74.55, and 80% of Pb(II) from GS was achieved with 0.1 M EDTA, 0.1 M HCl, and 0.1 M HNO₃ solutions, respectively. FTIR analysis suggests the importance of functional groups such as amino, hydroxyl, and carboxyl during Pb(II) removal. SEM observations demonstrated that an important interaction at the lead‐modified sepiolite interface occurred during the adsorption process. In addition, the thermodynamic constants was calculated that the values of the Gibbs free energy (ΔG*), enthalpy (ΔH*), and entropy (ΔS*) of modification were 86.79 kJ/mol, ?18.91 kJ/mol, and ?354.70 J/mol/K, respectively. The negative value of ΔH* shows exothermic nature of adsorption.     

Evaluations on the relation of RC building damages with structural parameters after May 19, 2011 Simav (Turkey) earthquake

An earthquake has struck Simav, Kutahya, located in the western part of Turkey on May 19, 2011. This paper focuses on the evaluation of the regional damage data and detailed investigation on a set of selected reinforced concrete buildings in Simav county center. The soil properties in Simav are examined in detail using multi-channel analysis of surface wave measurements, boreholes and laboratory test data. The damages are observed to be independent of soil conditions being hilly or plain, both in regional and Simav county center level. However, a slight relation is observed: as the soil period increases, so does the damage. The most damaged buildings are the four story buildings, resembling the case after some other earthquakes in Turkey. Regarding the detailed numerical evaluations on the building set, the properties highly correlated with seismic damage are investigated. Based on the obtained findings, it is concluded that the global building properties may not be enough to establish a strong relation with damage due to the local damages at the structural member level, especially for smaller seismic events.     

A Fuzzy Rule Based Remedial Priority Ranking System for Contaminated Sites

Contaminated site remediation is generally difficult, time consuming, and expensive. As a result ranking may aid in efficient allocation of resources. In order to rank the priorities of contaminated sites, input parameters relevant to contaminant fate and transport, and exposure assessment should be as accurate as possible. Yet, in most cases these parameters are vague or not precise. Most of the current remediation priority ranking methodologies overlook the vagueness in parameter values or do not go beyond assigning a contaminated site to a risk class. The main objective of this study is to develop an alternative remedial priority ranking system (RPRS) for contaminated sites in which vagueness in parameter values is considered. RPRS aims to evaluate potential human health risks due to contamination using sufficiently comprehensive and readily available parameters in describing the fate and transport of contaminants in air, soil, and groundwater. Vagueness in parameter values is considered by means of fuzzy set theory. A fuzzy expert system is proposed for the evaluation of contaminated sites and a software (ConSiteRPRS) is developed in Microsoft Office Excel 2007 platform. Rankings are employed for hypothetical and real sites. Results show that RPRS is successful in distinguishing between the higher and lower risk cases.     

Comparative analysis of regression and artificial neural network models for wind speed prediction

In this study, wind speed was modeled by linear regression (LR), nonlinear regression (NLR) and artificial neural network (ANN) methods. A three-layer feedforward artificial neural network structure was constructed and a backpropagation algorithm was used for the training of ANNs. To get a successful simulation, firstly, the correlation coefficients between all of the meteorological variables (wind speed, ambient temperature, atmospheric pressure, relative humidity and rainfall) were calculated taking two variables in turn for each calculation. All independent variables were added to the simple regression model. Then, the method of stepwise multiple regression was applied for the selection of the “best” regression equation (model). Thus, the best independent variables were selected for the LR and NLR models and also used in the input layer of the ANN. The results obtained by all methods were compared to each other. Finally, the ANN method was found to provide better performance than the LR and NLR methods.     

Numerical simulations of landslide-stabilizing piles: a remediation project in Söke,Turkey

A catastrophic landslide following a rainy season occurred in the backyard of a school building in Söke, Turkey. The landslide caused property damage and adversely affected the present forest cover. Immediately after the landslide, double-row stabilizing piles were designed and constructed based on the findings of two-dimensional (2D) finite element (FE) analyses to take an urgent precaution. To remedy the problem, pile displacements were monitored using inclinometers, and it was observed that the measured displacements were greater than the values calculated in the design stage. Accordingly, two different three-dimensional (3D) numerical FE models were used in tandem with the inclinometer data to determine the load transfer mechanism. In the first model, numerical analyses were made to predict the pile displacements, and while the model predicted successfully the displacement of the piles constructed in the middle with reasonable accuracy, it failed for the corner piles. In the second model, the soil load transfer between piles was determined considering the sliding mass geometry, the soil arching mechanism and the group interaction between adjacent piles. The results of the second model revealed that the middle piles with large displacements transferred their loads to the corner piles with smaller displacements. The generated soil loads, perpendicular to the sliding direction, restricted pile deformations and piles with less displacement were subjected to greater loads due to the bowl-shaped landslide. A good agreement between the computed pile displacements and inclinometer data indicates that the existing soil pressure theories should be improved considering the position of the pile in the sliding mass, the depth and deformation modulus of stationary soil, the relative movement between the soil and piles and the relative movement of adjacent piles.