Quantification of karst aquifer discharge components during storm events through end-member mixing analysis using natural chemistry and stable isotopes as tracers   总被引：1，自引：1，他引：1  

Daniel H. Doctor  E. Calvin Alexander Jr  Metka Petrič  Janja Kogovšek  Janko Urbanc  Sonja Lojen  Willibald Stichler 《Hydrogeology Journal》2006,14(7):1171-1191

Karst aquifer components that contribute to the discharge of a water supply well in the Classical Karst (Kras) region (Italy/Slovenia) were quantitatively estimated during storm events. Results show that water released from storage within the epikarst may comprise as much as two-thirds of conduit flow in a karst aquifer following rainfall. Principal components analysis (PCA) and end-member mixing analysis (EMMA) were performed using major ion chemistry and the stable isotopes of water (δ¹⁸O, δ²H) and of dissolved inorganic carbon (δ¹³C_DIC) to estimate mixing proportions among three sources: (1) allogenic river recharge, (2) autogenic recharge, and (3) an anthropogenic component stored within the epikarst. The sinking river most influences the chemical composition of the water-supply well under low-flow conditions; however, this proportion changes rapidly during recharge events. Autogenic recharge water, released from shallow storage in the epikarst, displaces the river water and is observed at the well within hours after the onset of precipitation. The autogenic recharge end member is the second largest component of the well chemistry, and its contribution increases with higher flow. An anthropogenic component derived from epikarstic storage also impacts the well under conditions of elevated hydraulic head, accounting for the majority of the chemical response at the well during the wettest conditions.  相似文献   

Erratum     

Hans-Balder Havenith  Alexander Strom  Fernando Caceres  Eric Pirard 《Landslides》2006,3(1):85-85

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Calculation Of The Height Of The Stable Boundary Layer In Practical Applications     

Sergej Zilitinkevich  Alexander Baklanov 《Boundary-Layer Meteorology》2002,105(3):389-409

Currently used and newly proposed calculation techniques for the heightof the stable boundary layer (SBL), including the bulk-Richardson-numbermethod, diagnostic equations for the equilibrium SBL height, and a relaxation-typeprognostic equation, are discussed from the point of view of their physical basis andrelevance to experimental data. Among diagnostic equations, the best fit to data exhibits an advanced Ekman-layer height model derived recently with due regard to the role of the free-flow stability. Its extension to non-steady regimes provides a prognostic equation recommended for use in practical applications.  相似文献   

Effective and Equitable Dissemination of Seasonal-to-Interannual Climate Forecasts: Policy Implications from the Peruvian Fishery during El Niño 1997–98     

Kenneth Broad  Alexander S. P. Pfaff  Michael H. Glantz 《Climatic change》2002,54(4):415-438

The development of seasonal-to-interannual climate predictions has spurred widespread claims that the dissemination of such forecasts will yield benefits for society. Based on the use as well as non-use of forecasts in the Peruvian fishery during the 1997–98 El Niño event, weidentify: (1) potential constraints on the realization of benefits, such aslimited access to and understanding of information, and unintended reactions; (2) theneed for an appropriately detailed definition of societal benefit, considering whose welfare counts as a benefit among groups such as labor, industry, consumers, citizens of different regions, and future generations.We argue that consideration of who benefits, and an understanding of potential socioeconomic constraints and how they might be addressed, should be brought to bear on forecast dissemination choices. We conclude with examples of relevant dissemination choices made using this process.  相似文献   

Origin of the northern Indus Fan and Murray Ridge, Northern Arabian Sea: interpretation from seismic and magnetic imaging     

Christoph Gaedicke  Hans-Ulrich Schlüter  Hans Albert Roeser  Alexander Prexl  Bernd Schreckenberger  Heinrich Meyer  Christian Reichert  Peter Clift  Shahid Amjad 《Tectonophysics》2002,355(1-4)

The nature and origin of the sediments and crust of the Murray Ridge System and northern Indus Fan are discussed. The uppermost unit consists of Middle Miocene to recent channel–levee complexes typical of submarine fans. This unit is underlain by a second unit composed of hemipelagic to pelagic sediments deposited during the drift phase after the break-up of India–Seychelles–Africa. A predrift sequence of assumed Mesozoic age occurring only as observed above basement ridges is composed of highly consolidated rocks. Different types of the acoustic basement were detected, which reflection seismic pattern, magnetic anomalies and gravity field modeling indicate to be of continental character. The continental crust is extremely thinned in the northern Indus Fan, lacking a typical block-faulted structure. The Indian continent–ocean transition is marked on single MCS profiles by sequences of seaward-dipping reflectors (SDR). In the northwestern Arabian Sea, the Indian plate margin is characterized by several phases of volcanism and deformation revealed from interpretation of multichannel seismic profiles and magnetic anomalies. From this study, thinned continental crust spreads between the northern Murray Ridge System and India underneath the northern Indus Fan.  相似文献   

Do the Austrian blackfly fauna (Diptera: Simuliidae) support the typological approach of the EU water framework directive?     

Thomas Ofenbck  Otto Moog  Manfred Car 《Limnologica》2002,32(3):255

The Austrian blackfly fauna were analysed with regard to spatial (ecoregions, bioregions), vertical (altitude classes) and longitudinal zonation characteristics [stream order, biocoenotic (= fish) regions] on the basis of 2600 investigation sites. Of a total of 45 species recorded, Simulium ornatum, S. variegatum, S. argyreatum and S. reptans are the most common and most frequently distributed species, occurring in 60% of the investigated sites. Although the Austrian blackfly fauna seem to be quite well documented (on average one investigation site per 32 km²) the jackknife analyses indicates that there are still some fauna deficits. Whereas the species diversity of the main ecoregions is quite similar, the number of species differs clearly between the bioregions. Within the typological context of the Water Framework Directive, the Austrian Simuliidae confirm the bioregions as the most useful spatial units for river typology. A further optimisation in predicting a target list of blackfly species of a site can be achieved by subdividing the bioregions into either catchment area and altitude classes or into longitudinal zonation types (biocoenotic regions).  相似文献   

Variability and climate sensitivity of fast ice extent in the north-eastern Kara Sea   总被引：1，自引：0，他引：1  

Dmitry Divine  Reinert Korsnes  Alexander Makshtas 《Polar research》2003,22(1):27-34

This work investigates the temporal and spatial variation of shore-fast ice extent in the north-eastern part of the Kara Sea during 1953-1990 and its sensitivity to interannual variability of the regional climate. The area of fast ice in spring months shows a bimodal distribution. This indicates the existence of two different regimes of fast ice formation driven by the system of prevailing winds. The westward wind transport during the cold season gives larger fast ice extent while the eastward wind transport suppresses the expansion of fast ice. There is a significant correlation (ca. −0.55) between the average winter temperature and the area of fast ice. Linear trends for time records of shore-fast ice area in spring show a decrease during 1953-1990. This decrease is most pronounced in April: the mean fast ice area in April is 12% lower in 1988-1990 compared to 1953-55. A comparison of fast ice regimes for two particular years–1979 and 1985–revealed a significant influence of cyclone activity on fast ice development over the course of the cold season. It is shown that partial break-ups of fast ice in spring 1985 are associated with the passage of cyclones across the area of fast ice.  相似文献   

Single-grain zircon dating of the metamorphic and granitic rocks from the Biscayarhalvøya-Holtedahlfonna zone, north-west Spitsbergen     

Yoshihide Ohta  Alexander N. Larionov  Alexander M. Tebenkov 《Polar research》2003,22(2):247-265

The Biscayarhalvøya-Holtedahlfonna zone (BHZ) in north-western Spitsbergen is a north-south trending, narrow horst, with crystalline basement rocks exposed under a Devonian unconformity. Previous K-Ar, ⁴⁰Ar/³⁹Ar and Rb-Sr analyses have confirmed the occurrence of Caledonian thermal events, and Grenvillian ages have been obtained by conventional zircon U-Pb and single-zircon Pb evaporation methods. A total of 55 zircon grains from three samples (an augen metagranite, a micaceous schist and a granitic neosome of migmatite) have been analysed by the single-zircon Pb evaporation method. The grains with the age range of ca. 950-1100 My (million years) are the major component in all three samples, suggesting tectono-thermal activity in that period. The detrital versus resorption orgin of the rounded shapes of these grains from the granitic neosome is not clear yet. Therefore, the ages of the migmatization and of the sedimentary protoliths are not concluded. The youngest presumed detrital grain from the granitic neosome is 1060 My old. The metagranite, cutting the Richarddalen unit, yielded grains with an age of ca. 950 Mya. A granite dyke with an age range of 955-968 My cuts the Biscayarhuken unit in the northern Liefdefjorden area. These indicate the sedimentary protoliths of the Richarddalen and Biscayarhuken units are pre-Neoproterozoic. The youngest detrital zircon ages of ca. 940 My indicate Neoproterozoic sedimentary protoliths of the Solanderfjellet micaceous schists. A significant population of zircon grains with an age range of 1600-1900 My in all three samples suggests a wide exposure of these rocks in the source areas during Meso- and Neoproterozoic times. Several Archean ages have also been obtained. The results are generally conformable with those obtained from north-western Spitsbergen.  相似文献   

The reproductive features of a mature female of the deep sea planktonic squid Galiteuthis glacialis (Cephalopoda: Cranchiidae) from the Southern Ocean     

Vladimir Laptikhovsky  Alexander Arkhipkin 《Polar research》2003,22(2):395-397

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The northwest european shelf temperature and salinity variability     

Gerd A. Becker  Alexander Frohse  Peter Damm 《Ocean Dynamics》1997,49(2-3):135-151

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