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Gudrun Massmann Jürgen Sültenfuß Uwe Dünnbier Andrea Knappe Thomas Taute Asaf Pekdeger 《水文研究》2008,22(6):788-801
Berlin relies on induced bank filtration from a broad‐scale, lake‐type surface water system. Because the surface water contains treated sewage, wastewater residues are present in surface water and groundwater. Multiple environmental tracers, including tritium and helium isotopes (3H, 3He, 4He), stable isotopes (δ18O and δ2H) and a number of persistent sewage indicators, such as chloride, boron and a selection of pharmaceutical residues (phenazone‐type analgesics and their metabolites, carbamazepine and anthropogenic gadolinium, Gdexcess), were used to estimate travel times from the surface water to individual production and observation wells at two sites. The study revealed a strong vertical age stratification throughout the upper aquifer, with travel times varying from a few months to several decades in greater depth. Whereas the shallow bank filtrate is characterized by the reflection of the time‐variant tracer input concentrations and young 3H/3He ages, the deeper, older bank filtrate displays no tracer seasonality, 3H/3He ages of a few years to decades and strongly deviating concentrations of several pharmaceutical residues, reflecting concentrations of the source surface water over time. The phenazone‐type pharmaceuticals persist in the aquatic environments for decades. Bank filtration in Berlin is only possible at the sandy lakeshores. In greater water depth, impermeable lacustrine sapropels inhibit infiltration. The young bank filtrate originates from the nearest shore, whereas the older bank filtrate infiltrates at more distant shores. This paper illustrates the importance of using multiple tracer methods, capable of resolving a broad range of residence times, to gain a comprehensive understanding of time‐scales and infiltration characteristics in a bank filtration system. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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This paper tests two assumptions fundamental to the use of fine-grained silicic tephras from Iceland for creating chronological frameworks in northwest Europe. It is shown firstly, that glass shards can retain their overall chemical integrity on at least a four millennial time-scale in contrasting depositional environments in Iceland and Scotland, and secondly, that an acid digestion process, the most practical method for extracting tephra from peat, does not significantly bias the results of major element analysis by electron microprobe. The implication is that there is great potential and an appropriate method for developing both the resolution and the spatial coverage of chronologies based on silicic Icelandic tephras in northwest Europe. 相似文献
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The formation of colloids during the weathering of phyllite was investigated by exposing ground phyllite to Milli-Q water. Secondary mineral colloids of 101–102 nm were detected in significant concentrations. At pH of about 8.5, the solution concentration of these colloids reached up to 10 mg/L (however, acidification to pH 4.0 prevented the formation of the colloids). The mineralogical composition of the secondary mineral colloids is assumed to be a mixture of ferrihydrite, manganese oxyhydroxides, aluminosilicates, amorphous Al(OH)3 and gibbsite with possible additions of iron silicates and␣iron-alumino silicates. The colloids were stable over longer periods of time (at least several weeks), even in the presence of suspended ground rock. Direct formation of iron-containing secondary mineral colloids at the rock–water interface by the weathering of rock material is an alternative to the well-known mechanism of iron colloid formation in the bulk of water bodies by mixing of different waters or by aeration of anoxic waters. This direct mechanism is of relevance for colloid production during the weathering of freshly crushed rock in the unsaturated zone as for instance crushed rock in mine waste rock piles. Colloids produced by this mechanism, too, can influence the transport of contaminants such as actinides because these colloids have a large specific surface area and a high sorption affinity. 相似文献
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Studies evaluating the reproductive pattern of Mytilus edulis L. were conducted in western and eastern Iceland at two sites at about the same latitude but with different temperature regimes. Mussels were sampled once or sometimes twice a month during two years in Breidifjördur, western Iceland and one year at Mjoifjördur, eastern Iceland. Gonad development was monitored by microscopic observation of thin sections of the gonads. The initiation of gonad development was observed in January in Breidifjördur while in Mjoifjördur some of the animals started developing gonads in October, a month before spawning was over in the population. Spawning started in late June or July, peaked in August and continued until November at both sites. Nutrient reserve stores seemed to be limited and used for initiation of gonad development in winter but were not sufficient for maturation of the gonads. The main growth of the gonads occured in spring in conjunction with phytoplankton blooming and renewal of food resources. 相似文献
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Gudrun Richter Joachim Wassermann Martin Zimmer Matthias Ohrnberger 《Journal of Volcanology and Geothermal Research》2004,135(4):331-342
In this paper we present densely sampled fumarole temperature data, recorded continuously at a high-temperature fumarole of Mt. Merapi volcano (Indonesia). These temperature time series are correlated with continuous records of rainfall and seismic waveform data collected at the Indonesian–German multi-parameter monitoring network. The correlation analysis of fumarole temperature and precipitation data shows a clear influence of tropical rain events on fumarole temperature. In addition, there is some evidence that rainfall may influence seismicity rates, indicating interaction of meteoric water with the volcanic system. Knowledge about such interactions is important, as lava dome instabilities caused by heavy-precipitation events may result in pyroclastic flows. Apart from the strong external influences on fumarole temperature and seismicity rate, which may conceal smaller signals caused by volcanic degassing processes, the analysis of fumarole temperature and seismic data indicates a statistically significant correlation between a certain type of seismic activity and an increase in fumarole temperature. This certain type of seismic activity consists of a seismic cluster of several high-frequency transients and an ultra-long-period signal (<0.002 Hz), which are best observed using a broadband seismometer deployed at a distance of 600 m from the active lava dome. The corresponding change in fumarole temperature starts a few minutes after the ultra-long-period signal and simultaneously with the high-frequency seismic cluster. The change in fumarole temperature, an increase of 5 °C on average, resembles a smoothed step. Fifty-four occurrences of simultaneous high-frequency seismic cluster, ultra-long period signal and increase of fumarole temperature have been identified in the data set from August 2000 to January 2001. The observed signals appear to correspond to degassing processes in the summit region of Mt. Merapi. 相似文献
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River incision and vegetation dynamics in cut-off channels 总被引：1，自引：0，他引：1
Gudrun Bornette Claude Amoros Jean-Claude Rostan 《Aquatic Sciences - Research Across Boundaries》1996,58(1):31-51
The consequences of river incision on ecosystems dynamics in cut-off channels were hypothesized to be 1) the reduction of river backflows and overflows of the river in the former channels; 2) the reduction of seepage flows from the river and drainage into the channels; 3) the drainage of the hillslope aquifer by the former channels. The subsequent changes of aquatic plant communities should be 1) the terrestrialization of the higher part of former channels and 2) their change into more oligotraphent ones if the hillslope aquifer is poorer in nutrients than the river. In those reaches where the river bed is aggraded, river backflows in the cut-off channel should increase, as should overflows and seepage, and more eutraphent species should develop. Changes in aquatic vegetation were studied over a ten-year period in four cut-off channels supplied by a nutrient-poor hillslope aquifer and a nutrient-rich river. Two of them were located in an incised reach of the river, one in an aggraded reach and one (reference) in a reach that was neither aggraded nor incised. The vegetation of the reference channel exhibited only minor changes over the ten-year period, indicating that the successional trend is not perceptible at the time scale of the study, and thus that any change observed in the other channels can be ascribed to river incision or aggradation. Terrestrialization expected in the channels located in the incised reach clearly progressed in the downstream parts, but was inhibited by groundwater supplies in the upper parts. As expected, oligotraphent communities progressed or remained dominant in the upper part. The channel located in the aggraded reach of the river exhibited the highest floristic changes. As expected, eutraphent communities progressed in this channel, but unexpectedly, terrestrialization also progressed in the upstream part. Alternative explanations are: 1) aggradation could have instigated more backflows and overflows without modifying significantly the mean water-level and 2) more frequent water overflows could have favoured alluvial deposition and thus terrestrialization. 相似文献
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Gudrun Carl Daniel Doktor Dirk Koslowsky Ingolf Kühn 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(5):1221-1230
Temporal shifts in phenology or vegetation period of plants are seen as indicators of global warming with potentially severe impacts on ecosystem functioning. In spite of increasing knowledge on drivers, it is of utmost importance to disentangle the relationship between air temperatures, phenological events, potential temporal lags (phase shifts) and time scale for certain plant species. Assessing the phase shifts as well as the scale-dependent relationship between temperature and vegetation phenology requires the development of a nonlinear temporal model. Therefore, we use wavelet analysis and present a framework for identifying scale-dependent cross-phase coupling of bivariate time series. It allows the calculation of (a) scale-dependent decompositions of time series, (b) phase shifts of seasonal components in relation to the annual cycle, and (c) inter-annual phase differences between seasonal phases of different time series. The model is applied to air temperature data and remote sensing phenology data of a beech forest in Germany. Our study reveals that certain seasonal changes in amplitude and phase with respect to the normal annual rhythm of temperature and beech phenology are coupled time-delayed components, which are characterized by a time shift of about one year. 相似文献
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Considering river structure and stability in the light of evolution: feedbacks between riparian vegetation and hydrogeomorphology 
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下载免费PDF全文 Dov Corenblit Neil S. Davies Johannes Steiger Martin R. Gibling Gudrun Bornette 《地球表面变化过程与地形》2015,40(2):189-207
River ecological functioning can be conceptualized according to a four‐dimensional framework, based on the responses of aquatic and riparian communities to hydrogeomorphic constraints along the longitudinal, transverse, vertical and temporal dimensions of rivers. Contemporary riparian vegetation responds to river dynamics at ecological timescales, but riparian vegetation, in one form or another, has existed on Earth since at least the Middle Ordovician (c. 450 Ma) and has been a significant controlling factor on river geomorphology since the Late Silurian (c. 420 Ma). On such evolutionary timescales, plant adaptations to the fluvial environment and the subsequent effects of these adaptations on fluvial sediment and landform dynamics resulted in the emergence, from the Silurian to the Carboniferous, of a variety of contrasted fluvial biogeomorphic types where water flow, morphodynamics and vegetation interacted to different degrees. Here we identify several of these types and describe the consequences for biogeomorphic structure and stability (i.e. resistance and resilience), along the four river dimensions, of feedbacks between riparian plants and hydrogeomorphic processes on contrasting ecological and evolutionary timescales. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献