Different Behavior of Iron(III) and Aluminum(III) Salts To Coagulate Silica Particle Suspension     

Panyue Zhang  Hermann H. Hahn  Erhard Hoffmann 《洁净——土壤、空气、水》2003,31(2):145-151

The different coagulation‐flocculation behavior of iron(III) and aluminum(III) to coagulate silica particle suspension with four coagulants — FeCl₃, Fe₂(SO₄)₃, AlCl₃, and in our laboratory produced polyaluminum chloride PACl‐2.0 — was investigated through studying particle property changes and coagulation efficiency, for example, variations in zeta potential of particles, particle number, average particle diameter, particle size distribution, and residual turbidity of the supernatant water. Influences of flocculation intensity and pH value on the coagulation‐flocculation process were also studied. The results suggest that, under the test conditions, among these four coagulants FeCl₃ possesses an obviously stronger ability to form larger flocs and to remove turbidity, on the other hand, PACl‐2.0 obviously showed a better charge neutralization ability.  相似文献   

The groundwater resources and sustainable yield of Cheju volcanic island, Korea   总被引：2，自引：0，他引：2  

J. Hahn  Y. Lee  N. Kim  C. Hahn  S. Lee 《Environmental Geology》1997,33(1):43-53

 Hydrogeologic data of 455 water wells comprising geologic logs, water qualities, and aquifer test results are analyzed to determine hydrogeological characteristics, water quality, and sustainable yield of the groundwater resources of Cheju volcanic island. The groundwater of the island occurs in unconsolidated pyroclastic deposits and clinkers interbedded in highly jointed basaltic and andesitic rocks as high-level, basal, and parabasal groundwater under unconfined conditions. The total storage of groundwater is estimated at about 44 billion m³. The average transmissivity and specific yield of the aquifer are at about 0.34 m² s^–1(29300 m² day^–1) and 0.12, respectively. The average annual precipitation is about 3.39 billion m³, of which 1.49 billion m³– equivalent to 44.0% of the total annual precipitation – is recharged into aquifers, with 0.638 billion m³ year^–1 of runoff and 1.26 billion m³ year^–1 of evapotranspiration. Based on a groundwater budget analysis, the sustainable yield is estimated at about 0.62 billion m³ year^–1, equivalent to 41.6% of annual recharge. A low-permeability marine sedimentary formation (Sehwari formation), composed of loosely cemented sandy silt, was recently found to be situated at 120±68 m below mean sea level. If the said marine sediment is distributed as a basal formation of the freshwater zone of the island, most of its groundwater will be of parabasal type. So the marine sediment is one of the most important hydrogeological boundaries and groundwater occurrences in the area. Received: 16 January 1997 / Accepted: 16 June 1997  相似文献   

Urban Waste Waters. Treatment for Use in Steam and Power Generation Von K. M. Abdullaev,I. A. Malakhov,L. N. Polestaev und A. S. Sobol Ellis Horwood Limited,Chichester, 1992, ISBN 0-13-929977-7, 245 Seiten, $ 89.95     

H. H. Hahn 《洁净——土壤、空气、水》1993,21(2):121-122

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High level and low level plagiogranites from the nicoya ophiolite complex,Costa Rica,Central America     

Dr. Heiko G. H. Wildberg 《International Journal of Earth Sciences》1987,76(1):285-301

Two suites of plagiogranitic rocks within the oceanic crust of the Jurassic-Cretaceous ophiolitic Nicoya complex are distinguished. High level plagiogranites (HLP) crop out at the top of the cumulate sequence in the northwestern part of the Nicoya peninsula. They are associated with iron-rich dolerites and noncumulus gabbros. Based on field relationships and geochemical characteristics (e.g. enrichment in REE and HFS elements) the origin of these rocks is explained in terms of a two stage model of fractional crystallization and filter pressing. The first stage comprises the formation of tholeiitic Fe-rich melt and a highly differentiated crystal-melt mush. The second stage is characterized by filter pressing of plagiogranitic interstitial magma. Fe-dolerites form the residual rocks. Crystal fractionation of this plagiogranitic magma is due to the formation of a rather complete series of siliceous rocks.The geochemically different low level plagiogranites (LLP) are restricted to the lowest part of the cumulate ophiolitic sequence of the Lower Nicoya complex. These rocks occur as small dikes or isolated veins within cumulus gabbros. There is some evidence of strong depletion in REE and HFS elements, high silica, and low total iron in these rocks.The samples analysed probably represent a further fractionation series of acid igneous rocks in the Lower Nicoya Complex. The geochemical features and especially the association of LLP with cumulus gabbros and amphibolites may be consistent with a genetic model of partial melting of the surrounding gabbros in the hornblende stability field during a secondary thermal event, which possibly represents the formation of an intraoceanic primitive island arc between the Caribbean and the Pacific in the Upper Cretaceous. Thus the LLP and the possibly residual amphibolites are not necessarily comagmatic with regard to the remaining oceanic igneous rocks of the Lower Nicoya Complex.

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Zusammenfassung Im Unteren Nicoya-Komplex, einer als jurassisch-kretazische Ozeankruste gedeuteten Ophiolith-Sequenz, treten in zwei Stockwerken intermediäre und saure Magmatite auf: Im obersten Bereich der kumulaten Sequenz kommen High Level-Plagiogranite (HLP) vor, die eng mit Fe-reichen Doleriten vergesellschaftet sind. Diese Vorkommen sind immer an Intrusionen von Gabbros gebunden. Low Level-Plagiogranite (LLP) treten an der Basis dieser Sequenz innerhalb kumulater Gabbros zusammen mit Amphiboliten auf, ohne jedoch mit Fe-Doleriten assoziiert sein.Die Genese dieser Gesteine wird an verschiedenen Modellen diskutiert, wobei die High Level-Plagiogranite auf Grund von Geländebefunden und geochemischen Merkmalen (z. B. hohe SE- und HFS-Elementkonzentrationen) durch ein zweistufiges Modell aus fraktionierter Kristallisationsdifferentiation und Filterpressung erklärt werden. Die erste Stufe beinhaltet die Entwicklung von differenzierten Fe-reichen Schmelzen in einem tholeiitischen Fraktionierungstrend. In einem späten Stadium bildet sich ein Gemisch aus Festphasen und intermediärer, plagiogranitischer Restschmelze. Die zweite Stufe beschreibt im Zusammenhang mit dem mechanischen Auspressen dieser Schmelzen in unterschiedlichen Differentiationsstadien die Entstehung separater Plagiogranitschmelzen und die Deutung der Fe-Dolerite als Residualgesteine. Durch weitere Fraktionierungsprozesse in der Plagiogranitschmelze entwickeln sich danach in einer kontinuierlichen Differentiationsreihe zunehmend saure Plagiogranite.Die Low Level-Plagiogranite weisen demgegenüber grundsätzlich verschiedene Haupt- und Spurenelementcharakteristiken auf. Sie tendieren zu höheren SiO₂- und geringeren Fe-Konzentrationen. Soweit aus den wenigen bisher vorliegenden Daten hervorgeht, sind sie verglichen mit den HLP deutlich an HFS-Elementen und Seltenen Erden verarmt. Die chemische Variabilität der LLP kennzeichnet wahrscheinlich eine weitere Fraktionierungsreihe saurer Magmatite im Unteren Nicoya-Komplex mit im Laufe der Differentiation steigenden HFS- und SEE-Konzentrationen. Wenig differenzierte LLP sind im Gegensatz zu der Differentiationsreihe der HLP nicht in den analysierten Proben repräsentiert, so da\ die Interpretation ihrer Genese teilweise spekulativ bleibt. Dennoch passen der Chemismus und insbesondere das geologische Umfeld zum genetischen Modell einer Bildung saurer plagiogranitischer Schmelzen durch einen sekundären, partiellen Aufschmelzungsproze\ der umgebenden Gabbros innerhalb des Hornblende-Stabilitätsfeldes im Zuge eines weiteren Wärmeereignisses, wobei Gabbros und Amphibolite als Edukte bzw. Residualgesteine interpretiert werden könnten.Ein mögliches sekundäres Wärmeereignis kann mit der Intrusion von basischen Schmelzen in den Unteren Nicoya-Komplex bei der Bildung eines primitiven, oberkretazischen Inselbogens zwischen Pazifik und Karibik verbunden sein. Bei einer solchen Genese würden die LLP und die restitischen Amphibolite im Gegensatz zu den HLP nicht notwendigerweise als komagmatisch und damit zeitgleich zu den übrigen Magmatiten des Unteren NicoyaKomplexes gelten.

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Resumen Dos series de plagiogranitos existen en el Complejo de Nicoya Inferior. Este complejo ofiolítico representa una litosfera oceánica de edad Jurásico hasta Cretácico Inferior. Plagiogranitos del nivel alto (high level plagiogranites, HLP) afloran en la parte superior de la secuencia acumulada en la peninsula de Nicoya. Están asociadas con doleritas ricas en hierro dentro de gabros intrusivos. Con respeto a la composición geoquímica y las relaciones con rocas básicas en el campo, el origen de los plagiogranitos está explicado por un modelo, que consiste de cristalización fraccionada y de filtración a presión.Plagiogranitos del nivel bajo (low level plagiogranites, LLP) aloran en la parte inferior de la secuencia acumulada en la peninsula de Santa Elena. La composición geoquímica y la asociación de estas rocas ácidas con gabros de textura acumulada y con anfibolitas coinciden con un modelo, que describe la formación de los LLP por una fusión parcial de las rocas básicas asociadas. Un evento termal, que posiblemente da lugar a una fusión parcial está representado por el origen del Complejo de Nicoya Superior, el cual se formó como arco insular primitivo en el límite intraoceánico de las placas del Caribe y del Pacífico.

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— - — , . (HLP) . . , (LLP), , . , , ( .: REE HFS, ), - , , , . , . , . , , ; , . . LLP : SiO₂ . , , , — HLP — HFS. HLP , LLP , . , , , . , . LLP — HLP — , - .

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Tropical versus high latitude freshwater influence on the Atlantic circulation     

Heiko Goelzer  Juliette Mignot  Anders Levermann  Stefan Rahmstorf 《Climate Dynamics》2006,27(7-8):715-725

We investigate the model sensitivity of the Atlantic meridional overturning circulation (AMOC) to anomalous freshwater flux in the tropical and northern Atlantic. Forcing in both locations leads to the same qualitative response: a positive freshwater anomaly induces a weakening of the AMOC and a negative freshwater anomaly strengthens the AMOC. Strong differences arise in the temporal characteristics and amplitude of the response. The advection of the tropical anomaly up to the deep water formation area leads to a time delayed response compared to a northern forcing. Thus, in its transient response, the AMOC is less sensitive to a constant anomalous freshwater flux in the tropics than in the north. This difference decreases with time and practically vanishes in equilibrium with constant freshwater forcing. The equilibrium response of the AMOC shows a non-linear dependence on freshwater forcing in both locations, with a stronger sensitivity to positive freshwater forcing. As a consequence, competitive forcing in both regions is balanced when the negative forcing is about 1.5 times larger than the positive forcing. The relaxation time of the AMOC after termination of a freshwater perturbation depends significantly on the AMOC strength itself. A strong overturning exhibits a faster relaxation to its unperturbed state. By means of a set of complementary experiments (pulse-perturbations, constant and stochastic forcing) we quantify these effects and discuss the corresponding time scales and physical processes.  相似文献   

A Probabilistic Modelling System for Assessing Flood Risks   总被引：4，自引：2，他引：4  

Heiko Apel  Annegret H. Thieken  Bruno Merz  Günter Blöschl 《Natural Hazards》2006,38(1-2):79-100

In order to be economically viable, flood disaster mitigation should be based on a comprehensive assessment of the flood risk. This requires the estimation of the flood hazard (i.e. runoff and associated probability) and the consequences of flooding (i.e. property damage, damage to persons, etc.). Within the “German Research Network Natural Disasters” project, the working group on “Flood Risk Analysis” investigated the complete flood disaster chain from the triggering event down to its various consequences. The working group developed complex, spatially distributed models representing the relevant meteorological, hydrological, hydraulic, geo-technical, and socio-economic processes. In order to assess flood risk these complex deterministic models were complemented by a simple probabilistic model. The latter model consists of modules each representing one process of the flood disaster chain. Each module is a simple parameterisation of the corresponding more complex model. This ensures that the two approaches (simple probabilistic and complex deterministic) are compatible at all steps of the flood disaster chain. The simple stochastic approach allows a large number of simulation runs in a Monte Carlo framework thus providing the basis for a probabilistic risk assessment. Using the proposed model, the flood risk including an estimation of the flood damage was quantified for an example area at the river Rhine. Additionally, the important influence of upstream levee breaches on the flood risk at the lower reaches was assessed. The proposed model concept is useful for the integrated assessment of flood risks in flood prone areas, for cost-benefit assessment and risk-based design of flood protection measures and as a decision support tool for flood management.  相似文献   

远场地震引起地下水化学异常模拟     

Rongjiang Wang  Heiko Woith  Claus Milkeveit  Jochem zschau  孙小龙 《国际地震动态》2006,(7):61-70

通过对亚美尼亚Kajaran的一口自流井流量数据和电导率数据的多年分析,我们发现这口井对远场大震的响应非常敏感。一般同震流量增加,震后大约滞后一小时传导率减小。传导率在震后大约三周时趋于最小,然后需要数月时间来恢复震前水平。例如,1999年8月17土耳其Izm itMW7.6级地震,相距1 400 km,引起流量增加25%,传导率减小6%。流量也可以显示潮汐的波动,这种波动的幅度(顶点到顶点)约为水井产生的平均波动的5%,但传导率数据的潮汐信号并不明显,且不稳定。监测期11次地震引起最大同震静态应变异常的估算均低于10-9,只有一次正常状态小于潮汐应变。所以,远震相关的井水异常是地震地面振动引起的,而非同震变形。我们提出混有地下水的模型来解释观察到的现象,此模型考虑了这个特殊的地下水系统的特殊状态:封闭的含水层含两类在水化组分上具有很大差异的地下水,地下水和微破裂的混合区域与自流井的液压相互关联。认为与地震相关的异常,是由自流井附近的局部水头增加产生的,而局部水头的增加是由于地震波的通过引起的。本文讨论了可能的机制,对异常的时间变化曲线进行了模拟。  相似文献   

Erosion of bentonite particles at the interface of a compacted bentonite and a fractured granite     

Min-Hoon Baik  Won-Jin Cho  Pil-Soo Hahn 《Engineering Geology》2007,91(2-4):229-239

Compacted bentonite has been considered as a candidate buffer material in the underground repository for the disposal of high-level radioactive waste. An erosion of bentonite particles caused by a groundwater flow at the interface of a compacted bentonite and a fractured granite was studied experimentally under various geochemical conditions. The experimental results showed that bentonite particles could be eroded from a compacted bentonite buffer by a flowing groundwater depending upon the contact time, the flow rate of the groundwater, and the geochemical parameters of the groundwater such as the pH and ionic strength.

A gel formation of the bentonite was observed to be a dominant process in the erosion of bentonite particles although an intrusion of bentonite into a rock fracture also contributed to the erosion. The concentration of the eroded bentonite particles eroded by a flowing groundwater was increased with an increasing flow rate of the groundwater. It was observed from the experiments that the erosion of the bentonite particles was considerably affected by the ionic strength of a groundwater although the effect of the pH was not great within the studied pH range from 7 to 10. An erosion of the bentonite particles in a natural groundwater was also observed to be considerable and the eroded bentonite particles are expected to be stable at the given groundwater condition.

The erosion of the bentonite particles by a flowing groundwater did not significantly reduce the physical stability and thus the performance of a compacted bentonite buffer. However, it is expected that an erosion of the bentonite particles due to a groundwater flow will generate bentonite particles in a given groundwater condition, which can serve as a source of the colloids facilitating radionuclide migration through rock fractures.  相似文献   

Regional modelling of future African climate north of 15°S including greenhouse warming and land degradation     

Heiko Paeth  Hans-Peter Thamm 《Climatic change》2007,83(3):401-427

Previous studies have highlighted the crucial role of land degradation in tropical African climate. This effect urgently has to be taken into account when predicting future African climate under enhanced greenhouse conditions. Here, we present time slice experiments of African climate until 2025, using a high-resolution regional climate model. A supposable scenario of future land use changes, involving vegetation loss and soil degradation, is prescribed simultaneously with increasing greenhouse-gas concentrations in order to detect, where the different forcings counterbalance or reinforce each other. This proceeding allows us to define the regions of highest vulnerability with respect to future freshwater availability and food security in tropical and subtropical Africa and may provide a decision basis for political measures. The model simulates a considerable reduction in precipitation amount until 2025 over most of tropical Africa, amounting to partly more than 500 mm (20–40% of the annual sum), particularly in the Congo Basin and the Sahel Zone. The change is strongest in boreal summer and basically reflects the pattern of maximum vegetation cover during the seasonal cycle. The related change in the surface energy fluxes induces a substantial near-surface warming by up to 7°C. According to the modified temperature gradients over tropical Africa, the summer monsoon circulation intensifies and transports more humid air masses into the southern part of West Africa. This humidifying effect is overcompensated by a remarkable decrease in surface evaporation, leading to the overall drying tendency over most of Africa. Extreme daily rainfall events become stronger in autumn but less intense in spring. Summer and autumn appear to be characterized by more severe heat waves over Subsaharan West Africa. In addition, the Tropical Easterly Jet is weakening, leading to enhanced drought conditions in the Sahel Zone. All these results suggest that the local impact of land degradation and reduction of vegetation cover may be more important in tropical Africa than the global radiative heating, at least until 2025. This implies that vegetation protection measures at a national scale may directly lead to a mitigation of the expected negative implications of future climate change in tropical Africa.  相似文献   

Fluid venting activity on the Costa Rica margin: new results from authigenic carbonates   总被引：8，自引：1，他引：7  

Xiqiu?HanEmail author  Erwin?Suess  Heiko?Sahling  Klaus?Wallmann 《International Journal of Earth Sciences》2004,93(4):596-611

Carbonate precipitates on mounds and along tectonic scarps off the Costa Rica margin are manifestations of subduction-induced dewatering. The long-term dewatering history is recorded in mineralogical, petrological and isotope signals of carbonates recovered from these sites. The carbonates are strongly depleted in ¹³C (–11 to –53 PDB) and enriched in ¹⁸O (+4 to +8 PDB). Thermogenic methane and biogenic methane were identified as sources of the carbon. Chemoherm carbonates and seepage-associated carbonates formed in a focused flow regime have lighter ¹³C values, while others formed in a more diffusive flow regime have slightly enriched C isotope values. Three fluid components were inferred based on the calculation of equilibrium ¹⁸O: clay dehydration water, gas hydrate water and seawater. Calculated equilibrium ¹⁸O values of carbonates from different down-core depths as well as from different precipitation stages show that the ¹⁸O of the precipitating fluid is progressively depleted with time. Dolostones showing a methane-C source and a well constrained O-isotope signature are thought to have formed at depth in the sediment and subsequently became exhumed. Glauconitic sandstones cemented by methane-derived carbonate provide evidence that fluid and solid material have been expelled by the mud volcano.  相似文献