Dynamik der Schilfröhrichte am Bodensee unter dem Einfluss von Wasserstandsvariationen

On the basis of different sets of aerial photos the dynamics of the reed bed areas of Lake Constance were investigated in relation to the dynamics of the water levels. The objectives of the study were to quantify the changes of reed areas due to different flood events in the last decades and their recovery in the time periods between these events. The results should given information of the relevance of water level variations on reed bed dynamics and the regeneration times of reed beds after extreme disturbance events.Following the extreme flood at Lake Constance in 1999 the reed belts of Lake Constance lost approximately 30 ha (24%) of the lakeside reed beds. The loss is comparable to the situation in the late 1960s, when approximately 40 ha died back due to the extreme flood in 1965 and the high spring water levels in the subsequent years. In the time period between the extreme floods of 1965 and 1999, the reed areas expanded to nearly 85% of the area before 1965. The expansion rates increased with increasing distance to the flood event of 1965. Especially in periods with series of years of low spring water level the expansion rates were high.The damage degrees of the reed areas in the years 2000 and 2002 showed a clear relation to the elevation (i.e. average water level) of the stands. The damage degree increased with decreasing elevation. Furthermore the regeneration process of severely damaged stands was related to the elevation level of the stands. Whereas stands at high elevation regenerate fast, those at low elevation died off completely in the years after the extreme flood. This supports the hypothesis that the water level flutuations play a major role in the reed dynamics of Lake Constance.As a consequence of the climate change an increase in the frequency of high spring water levels is expected. Thus, it seems unlikely that reed stands will ever expand again to the same area as before 1965.     

Environmental impacts of dredging and other sediment disturbances on corals: A review

A review of published literature on the sensitivity of corals to turbidity and sedimentation is presented, with an emphasis on the effects of dredging. The risks and severity of impact from dredging (and other sediment disturbances) on corals are primarily related to the intensity, duration and frequency of exposure to increased turbidity and sedimentation. The sensitivity of a coral reef to dredging impacts and its ability to recover depend on the antecedent ecological conditions of the reef, its resilience and the ambient conditions normally experienced. Effects of sediment stress have so far been investigated in 89 coral species (～10% of all known reef-building corals). Results of these investigations have provided a generic understanding of tolerance levels, response mechanisms, adaptations and threshold levels of corals to the effects of natural and anthropogenic sediment disturbances. Coral polyps undergo stress from high suspended-sediment concentrations and the subsequent effects on light attenuation which affect their algal symbionts. Minimum light requirements of corals range from <1% to as much as 60% of surface irradiance. Reported tolerance limits of coral reef systems for chronic suspended-sediment concentrations range from <10mgL(-1) in pristine offshore reef areas to >100mgL(-1) in marginal nearshore reefs. Some individual coral species can tolerate short-term exposure (days) to suspended-sediment concentrations as high as 1000mgL(-1) while others show mortality after exposure (weeks) to concentrations as low as 30mgL(-1). The duration that corals can survive high turbidities ranges from several days (sensitive species) to at least 5-6weeks (tolerant species). Increased sedimentation can cause smothering and burial of coral polyps, shading, tissue necrosis and population explosions of bacteria in coral mucus. Fine sediments tend to have greater effects on corals than coarse sediments. Turbidity and sedimentation also reduce the recruitment, survival and settlement of coral larvae. Maximum sedimentation rates that can be tolerated by different corals range from <10mgcm(-2)d(-1) to >400mgcm(-2)d(-1). The durations that corals can survive high sedimentation rates range from <24h for sensitive species to a few weeks (>4weeks of high sedimentation or >14days complete burial) for very tolerant species. Hypotheses to explain substantial differences in sensitivity between different coral species include the growth form of coral colonies and the size of the coral polyp or calyx. The validity of these hypotheses was tested on the basis of 77 published studies on the effects of turbidity and sedimentation on 89 coral species. The results of this analysis reveal a significant relationship of coral sensitivity to turbidity and sedimentation with growth form, but not with calyx size. Some of the variation in sensitivities reported in the literature may have been caused by differences in the type and particle size of sediments applied in experiments. The ability of many corals (in varying degrees) to actively reject sediment through polyp inflation, mucus production, ciliary and tentacular action (at considerable energetic cost), as well as intraspecific morphological variation and the mobility of free-living mushroom corals, further contribute to the observed differences. Given the wide range of sensitivity levels among coral species and in baseline water quality conditions among reefs, meaningful criteria to limit the extent and turbidity of dredging plumes and their effects on corals will always require site-specific evaluations, taking into account the species assemblage present at the site and the natural variability of local background turbidity and sedimentation.     

Continuous Multi‐probe Measurements in Fastflowing Waters Using a Hydrographic Slot

Taking continuous spatiotemporal in situ measurements with multi‐probes in fast‐flowing waters/rivers can be problematic because the sensors may be damaged by high shear forces and flotsam. To protect the multi‐probe and to enable easy access for the maintenance and calibration of the sensors, a special multi‐probe holder fixed in a hydrographic slot was developed. The validation of the probe system revealed a “memory effect” at short time scales (< 10 s) within sharp gradients caused by the overflow container of the multi‐probe rack keeping the sensors submerged in the sample water. Continuously recorded data (conductivity, temperature, pH, oxygen concentration and saturation, as well as in vivo fluorescence of chlorophyll‐a) from a research cruise on board the RV ALBIS along the river Elbe (river km 309) and entering the river Saale are presented. This river stretch upstream of the city of Magdeburg to the mouth of the Saale tributary was found to have a complex physicochemical character, which is attributable to the long mixing process of water from the river Saale and the river Elbe.     

Quantifying the impact of urban area expansion on groundwater recharge and surface runoff

ABSTRACT

In this surface water modelling study, a new spatial evaluation for assessing the impact of urbanization was applied for the semi-arid watersheds intersecting with the Gaza coastal aquifer. The SWAT model was calibrated and validated in a semi-automated approach for streamflow in the main watersheds. The results show that the model could simulate water budget components adequately within the complex semi-arid watersheds. Linear relationships between the change in urban area and the corresponding change in surface runoff or percolation were concluded for the urbanized sub-basins. The urban-surface runoff index (USI) and the urban-percolation index (UPI) were developed to represent a micro-level evaluation of different urban change scenarios in the sub-basins. The global urban-surface runoff index (GUSI) and the global urban-percolation index (GUPI) were derived as macro-level factors reflecting the influence on the overall Gaza coastal aquifer due to urban area expansion.

Editor D. Koutsoyiannis Associate editor E. Rozos     

Simultaneous Determination of 11 Sulfonamides by HPLC–UV and Application for Fast Screening of Their Aerobic Elimination and Biodegradation in a Simple Test

Sulfonamides (SAs) are one of the most frequently used antibiotics. SAs have been found in various environmental compartments. If SAs are not degraded in the environment, they can affect bacteria by their antibiotic properties and contribute to bacterial antibiotic resistance. Therefore, the biodegradability of 11 SAs (sulfanilamide, sulfaguanidine monohydrate, sulfadiazine, sulfathiazole, sulfapyridine, sulfamerazine, sulfamethoxypyridazine, sulfachloropyridazine, sulfamethazine, sulfamethoxazole, and sulfadimethoxine) was studied. For this purpose, the Closed Bottle Test (CBT, OECD 301D) was performed, which includes a toxicity control. In order to monitor the environmental fate of the parent compound and to check for transformation products, a simple, efficient, and reliable HPLC–UV method for the simultaneous determination of these SAs has been developed. Acetonitrile and water (with 0.1% formic acid) were used as mobile phase solvents for gradient elution. The method was validated in terms of precision, detection and quantitation limits, selectivity, and analytical solution stability. In the CBT, none of these SAs was readily biodegradable. The HPLC–UV analysis confirmed that no degradation of any SA took place. In the toxicity control, these SAs showed no toxic effect in the used concentration of environmental bacteria applied in the test.     

Multi‐method virtual electromagnetic experiments for developing suitable monitoring designs: A fictitious CO2 sequestration scenario in Northern Germany

We present a numerical study for 3D time‐lapse electromagnetic monitoring of a fictitious CO₂ sequestration using the geometry of a real geological site and a suite of suitable electromagnetic methods with different source/receiver configurations and different sensitivity patterns. All available geological information is processed and directly implemented into the computational domain, which is discretized by unstructured tetrahedral grids. We thus demonstrate the performance capability of our numerical simulation techniques. The scenario considers a CO₂ injection in approximately 1100 m depth. The expected changes in conductivity were inferred from preceding laboratory measurements. A resistive anomaly is caused within the conductive brines of the undisturbed reservoir horizon. The resistive nature of the anomaly is enhanced by the CO₂ dissolution regime, which prevails in the high‐salinity environment. Due to the physicochemical properties of CO₂, the affected portion of the subsurface is laterally widespread but very thin. We combine controlled‐source electromagnetics, borehole transient electromagnetics, and the direct‐current resistivity method to perform a virtual experiment with the aim of scrutinizing a set of source/receiver configurations with respect to coverage, resolution, and detectability of the anomalous CO₂ plume prior to the field survey. Our simulation studies are carried out using the 3D codes developed in our working group. They are all based on linear and higher order Lagrange and Nédélec finite‐element formulations on unstructured grids, providing the necessary flexibility with respect to the complex real‐world geometry. We provide different strategies for addressing the accuracy of numerical simulations in the case of arbitrary structures. The presented computations demonstrate the expected great advantage of positioning transmitters or receivers close to the target. For direct‐current geoelectrics, 50% change in electric potential may be detected even at the Earth's surface. Monitoring with inductive methods is also promising. For a well‐positioned surface transmitter, more than 10% difference in the vertical electric field is predicted for a receiver located 200 m above the target. Our borehole transient electromagnetics results demonstrate that traditional transient electromagnetics with a vertical magnetic dipole source is not well suited for monitoring a thin horizontal resistive target. This is due to the mainly horizontal current system, which is induced by a vertical magnetic dipole.     

Composition and origin of lithic fragments and glasses in apollo 11 samples

Approximately 100 glasses and 52 lithic fragments from Apollo 11 lunar fines and microbreccias were analyzed with the electron microprobe. Ranges in bulk composition of lithic fragments are considerably outside the precision (<±1%) and accuracy (±2–5%) of the broad electron beam technique. Results of this study may be summarized as follows: i) A large variety of rock types different from the hand specimens (basalt) were found among the lithic fragments, namely anorthosites, troctolitic and noritic anorthosites, troctolites, and norites (different from Apollo 12 norites). ii) In analogy to the hand specimens, the basaltic lithic fragments may be subdivided into low-K and high-K groups, both of which extend considerably in composition beyond the hand specimens. iii) Glasses were divided into 6 groups: Group 1 are the compositional analogs of the anorthositic-troctolitic lithic fragments and were apparently formed in single-stage impact events directly from parent anorthosites and troctolites. iv) Group 2 glasses are identical in composition to Apollo 12 KREEP glass and noritic lithic fragments, but have no counterparts in our Apollo 11 lithic fragment suite. Occurrence of KREEP in Apollo 11,12, and 14 samples is indicative of its relatively high abundance and suggests that the lunar crust is less depleted in elements that are common in KREEP (e.g. K, rare earths, P) than was originally thought on the basis of Apollo 11 basalt studies. v) Group 3 glasses are the compositional analogs of the basaltic lithic fragments, but low-K and high-K glasses cannot be distinguished because of loss of K (and Na, P) by volatilization in the vitrification process. vi) Group 4 glasses have no compositional analogs among the lithic fragments and were probably derived from as yet unknown Fe-rich, moderately Ti-rich, Mg-poor basalts. vii) Group 5 (low Ti-high Mg peridotite equivalent) and 6 (ilmenite peridotite equivalent) glasses have no counterparts among the Apollo 11 lithic fragments, but rock equivalents to group 5 glasses were found in Apollo 12 samples. Group 6 glasses are abundant, have narrow compositional ranges, and are thought to be the products of impact melting of an as yet unrecognized ultramafic rock type. iix) The great variety of igneous rocks (e.g. anorthosites, troctolites, norites, basalts, peridotites) suggests that large scale melting or partial melting to considerable depth must have occurred on the moon.     

Contributions to mineral chemistry of Hawaiian rocks

Small gabbroic dikes of high TiO₂ content transect massive hawaiite in the Kaena Quarry, Waianae Range, Oahu. One dike studied consists of two rock types: (a) border zone alkali gabbro of high titanomagnetite and titanaugite content and, (b) interior mugearite that contains iron-rich pyroxenes and K-feldspar. The dike probably formed as an in situ latestage segregation enriched in TiO₂, SiO₂, and alkalis.     

Himalayan inverted metamorphism constrained by oxygen isotope thermometry

Inverted metamorphic field gradients are preserved in two amphibolite facies metapelitic sequences forming the crystalline core zone of the Himalayan orogen in the Sutlej valley (NW India). In the High Himalayan Crystalline Sequence (HHCS), metamorphic conditions increase upwards from the staurolite zone at the base, through the kyanite-in and sillimanite-in isograds, finally to reach partial melting conditions at the top. The structurally lower Lesser Himalayan Crystalline Sequence (LHCS) shows a gradual superposition of garnet-in, staurolite-in and kyanite + sillimanite-in isograds. Although phase equilibria constraints imply inverted temperature field gradients in both units, garnet-biotite (GARB) rim thermometry indicates final equilibration at a nearly uniform temperature around T ≈ 600 °C across these sequences. The P-T path and garnet zoning data show that this apparent lack of thermal field gradient is mainly the consequence of a resetting of the GARB equilibria during cooling. In order to constrain peak temperature conditions, 20 samples along the studied section have been analysed for oxygen isotope thermometry. The isotopic fractionations recorded by quartz-garnet and quartz-aluminosilicate mineral pairs indicate temperatures consistent with phase equilibria and P-T path constraints for metamorphic peak conditions. Together with barometry results, based on net transfer continuous reactions, the oxygen isotope thermometry indicates peak conditions characterized by: (1) a temperature increase from T ≈ 570 to 750 °C at a nearly constant pressure around P ≈ 800 MPa, from the base to the top of the HHCS unit; (2) a temperature increase from T ≈ 610 to 700 °C and a pressure decrease from P ≈ 900 to 700 MPa, from the base to the top of the LHCS metapelites. Oxygen isotope thermometry thus provides the first quantitative data demonstrating that the Himalayan inverted metamorphism can be associated with a complete inversion of the thermal field gradient across the crystalline core zone of this orogen. Received: 1 April 1999 / Accepted: 12 July 1999     

Das „Randcenoman“ der Nördlichen Kalkalpen und seine Bedeutung für den Ablauf der ostalpinen Deckenüberschiebungen und ihrer Schubweiten

Zusammenfassung Das Randcenoman erstreckt sich über 220 km als ein der Cenoman-Serie zugehöriger Grenzbereich gegen die Flyschzone am Nordrand der Kalkalpen vom Chiemsee bis in das Große Walsertal.An einer Anzahl durchgehender Profile wurden stratigraphische und sedimentologische Untersuchungen durchgeführt.Nach Mikrofaunen konnten neue stratigraphische Belege für eine örtliche Sedimentationsfortsetzung ohne erkennbare Schichtunterbrechung vom Alb bis in das Cenoman gefunden werden. Hinweise auf unterturones Alter ergaben sich an zwei Stellen. Die alttertiären Tratenbachschichten sind tektonisch von Randcenoman und Flysch abgegrenzt.Trotz eines heterogenen Gesteinsaufbaus in vertikaler und horizontaler Ausdehnung mit einer differenzierten Wechsellagerung von Peliten, Psammiten und Psephiten zeigt die Cenoman-Serie petrographische Konstanz in Gefüge und Mineralzusammensetzung, besonders im Geröllspektrum und der Schwermineralassoziation (Chromit-SpinellPicotit).Die Gesteine des Randcenoman sind in einem einheitlichen Ablagerungsraum sedimentiert worden. Das gilt auch für ihre Anteile in der Arosa-Zone im Allgäu und im Bregenzer Wald.Faziesbeziehungen zur Flyschzone gibt es nicht.Auf das Ablagerungsmilieu deuten Flachwasserbildungen hin, die im flachen Randbereich der Geosynklinale während langdauernder Ruhigwasserfazies mit episodischen Unterbrechungen abgelagert wurden.Die petrographische Zusammensetzung der allothigenen Gerölle, ihr Rundungsgrad, ihre metamorphe Beanspruchung und ihr Erhaltungszustand lassen Analogieschlüsse mit Gesteinen vom Verrucano-Typ zu. Im Zusammenhang mit der Tonmineralführung der Pelite (Kaolinit) und der typischen Chromit-Spinell-Beteiligung kann auf ein breites Festland geschlossen werden. An der Detritusanlieferung sind neben dem mesozoischen kalkalpinen Untergrund und Gesteinen vom Verrucano-Typ Unterostalpin und Südpenninikum beteiligt. Damit sind die nördlichen Kalkalpen im Süden der Tauern beheimatet.Der Zeitraum der Überschiebung über das Penninikum liegt nicht vor Unterturon.Mittelkretazische Bewegungen werden in der Cenoman-Serie nur untergeordnet wirksam, wo sich Konglomerate und Geröllpsammite an der Wende Alb-Cenoman horizontieren lassen.

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The Randcenoman extends over a distance of 220 km as a boundary part of the Cenomanian Series along the alpine Flysch at the northern margin of the Limestone Alps from Chiem-See to the Grosses Walsertal.Series of continuous profiles have been investigated by stratigraphic and sedimentologic methods.By use of microfossils it could be proved that sedimentation lasted from Albian up to Cenomanian without visible interruption. At two different localities it was possible to find references to Turonian age.The Tratenbach layers of Tertiary age are separated tectonically from the Randcenoman and the Flysch.The rocks of Randcenoman show a very constant texture and association of minerals, especially in boulders and heavy minerals (chromite-spinel-picotite).These rocks must have been sedimented into an uniform trough. Same may be said concerning their contents within the Arosa-Zone in the Algovian region and in the Woods of Bregenz. There are no connections possible with facies of the Flysch series.Sediments of low water type show that these series have been deposed along the margin of the Alpine Geosyncline during long times of stagnant waters with episodical interruptions.The petrographic composition of the allothigenic boulders, their roundness, metamorphic stress and their state of conversation allows comparisons with rocks of the series of the Verrucano.The existance of a vast continent may be derived from the clay contents of the pelites (kaolinite) and the typical appearance of chromite-spinel minerals. The detritus has been delivered partly by the Lower Austroalpine unit and southern Penninicum, and by Mesozoic series of the Limestone Alps and rocks of Verrucano type.Concluding the origin of the Northern Limestone Alps has to be located south of the Tauern window.The movement of the Austroalpine nappes over the Penninicum cannot have happened before Lower Turonian age. The movements of Middle Cretaceous time are only of small efficiency on the series of Cenomanian where conglomerates and psammites containing boulders could be dated to be of Albanian-Cenomanian age.

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Résumé Le «Randcenomanien» s'étend sur 220 Km comme un ensemble-limite appartenant au Cénomanien, au contact de la zone du Flysch à la bordure Nord des Alpes calcaires, depuis le Lac de Chiem jusqu'à la «Grosse Walsertal»,L'auteur a effectué, le long d'un certain nombre de profils, des recherches stratigraphiques et sédimentologiques.A partir des microfaunes, on peut trouver de nouvelles preuves stratigraphiques en faveur d'une continuité de la sédimentation de l'Albien jusqu'au Cénomanien, sans aucune interruption reconnaissable. A deux endroits l'auteur a trouvé des indications concernant la présence du Turonien inférieur. Les couches du «Tratenbach» appartenant au Tertiaire inférieur sont séparées par voie tectonique du «Randcenomanien» et du Flysch.Malgré une constitution lithologique hétérogène, tant suivant la verticale que l'horizontale, avec des alternances bien marquées de pélites, psammites et pséphites, la série du Cénomanien montre une constance pétrographique quant à la texture et la composition minéralogique, spécialement dans la gamme des galets et l'association des minéraux lourds (Chromite-Spinelle-Picotite).Les roches du «Randcenomanien» ont été sédimentées dans un bassin uniforme; c'est aussi le cas dans la zone d'Arosa dans l'Allgäu et de la forêt de Bregenz.Il n'y a aucune connection avec les facies de la zone du Flysch.Quant au milieu de sédimentation, is est donné par les formations d'eaux profondes qui ont été déposées dans la région de bordure peu profonde du géosynclinal au cours de périodes de longue durée, en eau calme, avec seulement quelques interruptions épisodiques.La composition pétrographique des galets allothigènes, leur degré d'arrondi, leur degré de métamorphisme et leur état de conservation permettent de faire des analogies avec des roches du type Verrucano. Compte tenu aussi des minéraux argileux intervenant dans la constitution des pélites (kaolinite) et à la participation typique de la Chromite et du spinelle, on en arrive à la conclusion que le continent fournisseur de ces sédiments a été assez vaste. Aux apports détritiques du Mésozoïque inférieur des Alpes calcaires et des roches du type «Verrucano», sont venus s'ajouter ceux en provenance de l'Austroalpin inférieur et du Pennique méridional. C'est pourquoi le lieu d'origine des «Alpes calcaires» du Nord doit se trouver au sud des Tauern.Le chevauchement sur le Penninicum n'a pas eu lieu avant le Turonien inférieur.Les mouvements Crétacé inférieur dans le Cénomanien n'ont été que peu actifs, là où des conglomérats et des psammites à galets se sont épandus entre l'Albien et le Cénomanien.

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Randcenoman 220 , Chiem Große Valsertal. . . , . Tratenbach Randcenoman . , , , , , (- -). Randcenoman . Arosa Allgäu Bregenzer Wald. . . , , . , () - . , . . . Tauern. . , , / .

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Erweiterte Fassung eines am 25. Februar 1972 auf der 62. Jahrestagung der Geologischen Vereinigung in Frankfurt gehaltenen Vortrages.