Migration of the Ganga river and its implication on hydro-geological potential of Varanasi area, U.P., India

Borehole data reveals that during Late Quaternary, the Ganga river was non-existent in its present location near Varanasi. Instead, it was flowing further south towards peripheral craton. Himalayan derived grey micaceous sands were being carried by southward flowing rivers beyond the present day water divide of Ganga and mixed with pink arkosic sand brought by northward flowing peninsular rivers. Subsequently, the Ganga shifted to its present position and got incised. Near Varanasi, the Ganga river is flowing along a NW-SE tectonic lineament. The migration of Ganga river is believed to have been in response to basin expansion caused due to Himalayan tectonics during Middle Pleistocene times. Multi-storied sand bodies generated as a result of channel migration provide excellent aquifers confined by a thick zone of muddy sediments near the surface. Good quality potable water is available at various levels below about 70 m depth in sandy aquifers. Craton derived gravelly coarse-to-medium grained sand forms the main aquifer zones of tens of meter thickness with enormous yield. In contrast, the shallow aquifers made up of recycled interfluve silt and sandy silt occur under unconfined conditions and show water-level fluctuation of a few meters during pre-and post-monsoon periods.     

Surface complexation modeling for predicting solid phase arsenic concentrations in the sediments of the Mississippi River Valley alluvial aquifer, Arkansas, USA

The potential health impact of As in drinking water supply systems in the Mississippi River Valley alluvial aquifer in the state of Arkansas, USA is significant. In this context it is important to understand the occurrence, distribution and mobilization of As in the Mississippi River Valley alluvial aquifer. Application of surface complexation models (SCMs) to predict the sorption behavior of As and hydrous Fe oxides (HFO) in the laboratory has increased in the last decade. However, the application of SCMs to predict the sorption of As in natural sediments has not often been reported, and such applications are greatly constrained by the lack of site-specific model parameters. Attempts have been made to use SCMs considering a component additivity (CA) approach which accounts for relative abundances of pure phases in natural sediments, followed by the addition of SCM parameters individually for each phase. Although few reliable and internally consistent sorption databases related to HFO exist, the use of SCMs using laboratory-derived sorption databases to predict the mobility of As in natural sediments has increased. This study is an attempt to evaluate the ability of the SCMs using the geochemical code PHREEQC to predict solid phase As in the sediments of the Mississippi River Valley alluvial aquifer in Arkansas. The SCM option of the double-layer model (DLM) was simulated using ferrihydrite and goethite as sorbents quantified from chemical extractions, calculated surface-site densities, published surface properties, and published laboratory-derived sorption constants for the sorbents. The model results are satisfactory for shallow wells (10.6 m below ground surface), where the redox condition is relatively oxic or mildly suboxic. However, for the deep alluvial aquifer (21-36.6 m below ground surface) where the redox condition is suboxic to anoxic, the model results are unsatisfactory.     

Die Entgiftung von zyanidhaltigen Abwässern durch Oxydation mit Hypochlorit

Ohne Zusammenfassung Mitteilung Nr. 84     

The Late Weichselian and Holocene shoreline displacement on the west-central coast of Svalbard

Three well-developed raised marine shorelines along Nordenskioldkysten have been studied and correlated with the shoreline displacement since the last deglaciation. The marine limit of 64 m in the area is of Late Weichselian age and has been dated to 10, 900- 11, 000 years B.P. An intermediate level at 50 m is estimated to be 10, 600-10, 000 years old and demonstrates a sea level stagnation probably caused by a glacier readvance in eastern Svalbard during the Younger Dryas. A Holocene transgression culminating shortly after 6, 000 years B.P. has been stratigraphically demonstrated, and it probably correlates with the Tapes transgression of Scandinavia. No pre-Late Weichselian marine levels are found, and the large rebound can be attributed only to a Late Weichselian glaciation.     

Discovery of a flare star near Sirius

The discovery of a flare star (R.A. (1950)=6^h43^m6^s.07, Decl.(1950)=?16°45′24″) located about 6 arc min south of Sirius is reported. During photometric observations on the night of 13 January, 1982, using the 102 cm telescope at Kavalur, India, the star was seen to brighten by 2.55 mag. inV band over a duration of about 200 s. Observations on this object for a duration of about 10.5 hr spread over seven more nights indicate the star to be variable. The results of these observations are presented.     

Observation of Filterable Bromine Variabilities During Arctic Tropospheric Ozone Depletion Events in High (1hour) Time Resolution

The halogen ions Br^- and Cl^- together with NO₃ ^-, SO₄ ⁼, MSA^- (methane sulfonate), Na⁺ and NH₄ ⁺ were analysed by ion chromatography in extracts of more than 800 aerosol cellulose filter samples taken at Ny Ålesund, Svalbard (79°N, 12°E) in spring 1996 (March 27 - May 16) within the European Union project ARCTOC (Arctic Tropospheric Ozone Chemistry). Anticorrelated variations between f-Br (filterable bromine, i.e. water soluble bromine species that can be collected by aerosol filters) and ozone within the arctic troposphere were evaluated at a resolution of 1 or 2 hours for periods with depleted ozone and 4 hours at normal ozone. A mean f-Br concentration of 11 ng m^-3 (0.14 nmol m^-3) was observed for the whole campaign, while maximum concentrations of 80 ng m^-3 (1 nmol m^-3) were detected during two total O₃-depletion events (O₃ drop to mixing ratios below the detection limit of < 2 ppb). Anticorrelation between f-Br and O₃ was also seen during minor O₃-depletion episodes (sudden drop in O₃ by at least 10 ppb, but O₃ still exceeding the detection limit) and even for ozone variations near its background level (40-50 ppb). A time lag of about 10 hours between the change of ozone and of f-Br concentrations could only be found during a total ozone depletion event, when f-Br reached its maximum values several hours after ozone was totally destroyed. Bromine oxide (BrO) concentrations, measured by DOAS (Differential Optical Absorption Spectroscopy), and f-Br showed a coincident variability during almost the entire campaign (except in the case of total O₃-loss). Frequently enhanced anthropogenic nitrate and sulphate concentrations were observed during O₃-depletion periods. At O₃ concentrations < 10 ppb sulphate and nitrate exceed their typical mean level by 54% and 77%, respectively. This may indicate a possible connection between acidity and halogen release.     

海南岛鹦歌岭白垩纪红盆中韧性剪切带的地质特征

鹦歌岭白垩纪红盆中的韧性剪切带由糜棱岩系列岩石组成,发育线理、面理和褶皱构造,具有拆离活动的运动学特征。变形差应力变化在27.2~66.2 MPa之间,变形温度高于500℃.近垂直的挤压和近水平的伸展显示剪切带的形成与深部岩浆上侵作用有关,对进一步认识海南岛燕山期构造岩浆作用以及岩浆侵位机制具有重要的地质意义。      

10Be chronology of the last deglaciation of County Donegal, northwestern Ireland

A well-preserved moraine on the northern coast of County Donegal, Ireland, has played a critical role in our understanding of the glacial history of this sector of the Irish Ice Sheet (IIS). Because of a lack of numerical dating of the moraine, however, previous interpretations of its age and significance to the glacial history of this region have varied widely. Here we report eight in situ cosmogenic ¹⁰Be ages on boulders sampled from the moraine. Two of these ages are outliers, with the remaining six ranging from 18.8±1.0 ¹⁰Be kyr to 20.9±1.3 ¹⁰Be kyr, with an uncertainty-weighted mean age of 19.4±0.3 ¹⁰Be kyr (19.4±1.2 kyr accounting for production rate uncertainty). Our results confirm one previous ¹⁰Be age obtained from the moraine, with the combined data ( n =7) constraining the age of initial deglaciation of the IIS from its LGM position on the continental shelf to be 19.3±0.3 ¹⁰Be kyr (19.3±1.2 kyr accounting for production rate uncertainty). These ages are in excellent agreement with calibrated ¹⁴C ages that constrain retreat of the IIS margin from the continental shelf elsewhere in northwestern and western Ireland and the Irish Sea Basin associated with the start of the Cooley Point Interstadial (≥20–≤18.2 cal. kyr BP), suggesting widespread deglaciation of the IIS ∼19.5–20 kyr ago.     

Der Einfluß der Temepratur auf das atmosphärische Ozon

Zusammenfassung A. undE. Vassy haben 1941 versucht, den atmosphärischen Ozongehalt (Gesamtozon) aus den entsprechenden Variationen der Stratosphärentemperatur und der eingestrahlten Sonnenenergie vollständig zu erklären. Sie machten zu diesem Zweck den Ansatze/J=f (T), und zeigten, daß die auf diesem Weg empirisch gefundene Funktionf (T) näherungsweise mit der Temperaturabhängigkeit der für das Ozongleichgewicht wesentlichen Reaktionskonstantenk (T) übereinstimmt. Im Gegensatz dazu kamen andere Autoren (Schröer, Dütsch undCraig), die unabhängig voneinander die photochemische Ozontheorie weiter ausbauten, zum Schluß, daß die gemessenen atmosphärischen Ozonbeträge keine rein photochemischen Gleichgewichtswerte sein können.Zur Aufklärung dieser Differenz wird der von A. undE. Vassy aufgestellte und als erste Näherung bezeichnete Ansatz hier auf Grund der photochemischen Theorie, die noch einmal knapp entwickelt wird, untersucht, wobei vor allem folgende Mängel festgestellt werden: Der Ansatz von A. undE. Vassy bringt eine enorme Überschätzung des Temperatureinflusses auf das Gesamtozon mit sich, was anhand von zwei, nach der photochemischen Theorie durchgerechneten Zahlenbeispielen belegt wird; wegen der Hereinahme der Tageslänge in den Ansatz zur Berechnung vonJ, welches Vorgehen der photochemischen Auffassung widerspricht, wird auch der Einfluß des wechselnden Sonnenstandes falsch eingeschätzt. Auf Grund der hier durchgeführten Untersuchung muß daher die von A. undE. Vassy aufgestellte Hypothese abgelehnt werden.

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Summary In 1941 A. andE. Vassy made an attempt to explain the atmospheric ozone content (total amount of ozone) fully from the corresponding variations of the temperature of the stratosphere and the total incoming solar energy. They started from the equatione/J=f (T) and showed that this empirically established functionf (T) depends on temperature approximately in the same manner as the reaction constantk (T) which is essential for the ozone equilibrium. In opposition to themSchröer, Dütsch andCraig enlarging the photochemical theory of ozone independent of each other infered that the measured total amounts of ozone cannot be explained by purely photochemical equilibrium conditions.An attempt is made here to clear up this difference by examining the formula, put forward by A. andE. Vassy as a first approximation. It is made along the lines of the photochemical theory, which is briefly explained. In this connection some shortcomings of theVassy theory are stated: The formula of A. andE. Vassy comprises a considerable overestimation of the influence of temperature exerted on the total amount of ozone, which criticism is supported by two numerical instances computed according to the photochemical theory. Owing to the fact that the length of the day is also considered in the formula for the calculation ofJ, which proceeding is in plain contradiction to the photochemical conception, the influence of the changing solar position is estimated erroneously as well. On the basis of the examination carried out here the hypothesis set out by A. andE. Vassy must be refused.

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Résumé A. etE. Vassy ont essayé en 1941 d'expliquer la teneur en ozone de l'atmosphère à l'aide des variations correspondantes de la température de la stratosphère et de l'énergie solaire rayonnée. Ils ont à cet effet posé que:e/J=f (T), et ils ont prétendu que la fonctionf (T) trouvée ainsi empiriquement correspond à peu près à celle qui lie la constante de réactionk (T) pour l'équilibre de l'ozone avec la températureT. Par contre trois auteurs (Schröer, Dütsch etCraig) qui indépendamment l'un de l'autre ont élaboré la théorie photochimique de l'ozone ont conclu que les teneurs observées ne peuvent correspondre à un équilibre photochimique pur.Pour expliquer ces divergences, on examine ici l'hypothèse de E. etA. Vassy dans le cadre de la théorie photochimique brièvement rappelée. On constate que cette hypothèse conduit à surestimer fortement le rôle de la température dans la quantité totale de l'ozone, fait confirmé par deux exemples numériques fondés sur la théorie photochimique; en introduisant la longueur du jour dans le calcul deJ — ce qui est contraire au point de vue photochimique — on tient faussement compte de l'effet de la variation de la hauteur solaire. La conclusion de cette étude est que l'hypothèse de E. etA. Vassy doit être rejetée.

     

Environmental geology problems in the Tyrrhenian coastal area of Santa Marinella, province of Rome, central Italy

 The Tyrrhenian resort of S. Marinella (central Italy) is subjected to significant anthropogenic pressures during the summer vacation period, a common situation all along the Italian coast. Located 65 km NW of Rome on the southern slopes of the Tolfa Mountains, S. Marinella is built on a gently sloping, E–W trending belt which is cut by 14 N–S oriented ephemeral streams that discharge into the Tyrrhenian Sea. The low to medium permeability turbiditic sandstones which outcrop along this belt belong to the Late Cretaceous Pietraforte unit. Three environmental problems are addressed in this study. The first problem is related to the high water supply demand during the summer months which has forced local residents to dig a large number of wells. Extensive pumping from these wells has caused salt-water intrusion into the Pietraforte, thus compromising the domestic use of the groundwater. The second problem consists of the illegal dumping of urban solid waste, material that represents a hazard during significant rain events as well as a possible cause of groundwater contamination. The final issue addressed concerns the flooding potential of the 14 ephemeral streams that cross the inhabited area of S. Marinella, a risk which is highlighted by the disastrous flood which occurred on 2 October 1981 and during the period of the Roman Emperor Settimio Severo (205 A.D.). Some suggestions are proposed to mitigate and contain the effects of these problems. Received: 7 November 1995 / Accepted: 5 December 1996