Epikarst communities: biodiversity hotspots and potential water tracers   总被引：1，自引：0，他引：1  

Tanja Pipan  David C. Culver 《Environmental Geology》2007,53(2):265-269

There is an exceptionally rich aquatic fauna in the epikarst, the skin of karst. High species richness in the epikarst, coupled with its special vulnerability as the first point of entry of nearly all toxic spills, makes its protection especially important. The epikarst fauna may also be an useful tool in tracing the potential route of pollutants. Copepods in epikarst have extremely local distributions, and their body size is such that they are largely at the mercy of directional flows. In a series of caves in southwest Slovenia and West Virginia, a significant fraction of the copepod species occur in less than 100 m of linear extent. This suggests a pattern of highly restricted lateral flow under normal conditions and the distribution of copepods could potentially be used to trace water movement. Under high flow conditions as would often be the case with toxic spill, mounding of water may increase the lateral radius of flow. Nevertheless, copepods may be useful tracers.  相似文献   

Small and large scale fluctuations in atmospheric wind speeds     

F. Böttcher  St. Barth  J. Peinke 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(3):299-308

Atmospheric wind speeds and their fluctuations at different locations (onshore and offshore) are examined. One of the most striking features is the marked intermittency of probability density functions (PDF) of velocity differences, no matter what location is considered. The shape of these PDFs is found to be robust over a wide range of scales which seems to contradict the mathematical concept of stability where a Gaussian distribution should be the limiting one. Motivated by the non-stationarity of atmospheric winds it is shown that the intermittent distributions can be understood as a superposition of different subsets of isotropic turbulence. Thus we suggest a simple stochastic model to reproduce the measured statistics of wind speed fluctuations.  相似文献   

Experimental and thermodynamic study of heterogeneous and homogeneous equilibria in the system NaAlSiO4-SiO2     

Tanja Waterwiese  Niranjan D. Chatterjee  Ivana Dierdorf  Jörg Göttlicher  Herbert Kroll 《Contributions to Mineralogy and Petrology》1995,121(1):61-73

Internally consistent thermodynamic datasets available at present call for a further improvement of the data for nepheline (Holland and Powell 1988; Berman 1991). Because nepheline is a common rock-forming mineral, an attempt has been made to improve on the present state of knowledge of its thermodynamic properties. To achieve that goal, two heterogeneous reactions involving nepheline, albite, jadeite and a-quartz in the system NaAlSiO₄-SiO₂ have been reversed bylong duration runs in the range 460 ≤ T(°C) ≤ 960 and 10 ≤ P(kbar) ≤ 22. Given sufficiently long run times, thealbite run products approach internal equilibrium with respect to their Al,Si order-disorder states. Using appropriate thermochemical, thermophysical, and volumetric data, Landau expansion for albite, and the relevant reaction reversals, a refined thermodynamic dataset (Δ_fH_i⁰ and S_i⁰) has been derived for nepheline, jadeite, a-quartz, albite, and monalbite. Our refined data agree very well with theircalorimetric counterparts, but have smaller uncertainties. The refined dataset for Δ_fH_i⁰ and S_i⁰, including their uncertainties and correlation, help generate the NaAlSiO₄-SiO₂ phase diagram including 2a confidence interval for eachP-T curve (Fig. 5). Editorial responsibility: W. Schreyer  相似文献   

Grim4-C1, -C2p: combination solutions of the global earth gravity field     

Ch. Reigber  P. Schwintzer  W. Barth  F. H. Massmann  J. C. Raimondo  A. Bode  H. Li  G. Balmino  R. Biancale  B. Moynot  J. M. Lemoine  J. C. Marty  F. Barlier  Y. Boudon 《Surveys in Geophysics》1993,14(4-5):381-393

On the basis of the GRIM4-S1 satellite-only Earth gravity model, being accomplished in a common effort by DGFI and GRGS, a combination solution, called GRIM4-C1, has been derivcd using 1° × 1° mean gravity anomalies and 1° × 1° Seasat altimeter derived mean geoid undulations. In the meantime improvements could be achieved by incorporating more tracking data (GEOSAT, SPOT2-DORIS) into the solution, resulting in the two new parallel versions, the satellite-only gravity model GRIM4-S2 and the combined solution GRIM4-C2p (preliminary). All GRIM4 Earth gravity models cover the spectral gravitational constituents complete up to degree and order 50.In this report the emphasis is on the discussion of the combined gravity models: combination and estimation techniques, capabilities for application in precise satellite orbit computation and accuracies in long wavelength geoid representation. It is shown that with the new generation of global gravity models general purpose satellite-only models are no longer inferior to combination solutions if applied to satellite orbit restitution.  相似文献   

Fifteen days of continuous activity survey at Stromboli volcano, Italy, in late September 2000: Doppler radar, seismicity, infrared, soil humidity, and mapping of the crater region     

Nico-Alexander Urbanski  Malte Vöge  Ralf Seyfried  Lars Rüpke  Tanja Petersen  Till Hanebuth  Matthias Hort 《International Journal of Earth Sciences》2002,91(4):712-722

The intention of our study was to gain new insight into the complex interplay between different types of eruption of the Stromboli volcano by combining detailed field observation with different geophysical methods. We recorded more than 600 eruptions by use of continuous Doppler radar measurements. We detected the onset of the seismic precursor and the beginning of the visible eruption by use of seismic and infrared data. Two soil samples per day were used to monitor the effect of humidity on the eruptive style. We mapped the crater region as a reference base for the long-term morphological changes of the active region and for the exact positions of our measurement systems. Two distinct types of eruption were distinguished from each other on the basis of seismic and radar data - short, wide-angle Strombolian explosions and pulsating, sharp angle fountain-like eruptions. Data and visual observations imply that weather conditions significantly effect volcanic activity. We also interpret the intensification of eruptive activity during our field study as replenishment of the reservoir with a new batch of magma in late September 2000.  相似文献   

Cool water geyser travertine: Crystal Geyser,Utah, USA          下载免费PDF全文

Jennifer A. Barth  Henry S. Chafetz 《Sedimentology》2015,62(3):607-620

A sloping travertine mound, approximately 85 m across and a few metres thick is actively forming from cool temperature waters issuing out of Crystal Geyser, east‐central Utah, USA. Older travertine deposits exist at the site, the waters having used the Little Grand Wash Fault system as conduits. In contrast, the present Crystal Geyser travertine mound forms from 18°C waters which have been erupting for the last 80 years from an abandoned oil well. The present Crystal Geyser travertine accumulation forms from a ‘man‐made’ cool temperature geyser system; nevertheless, the constituents are an analogue for ancient geyser‐fed carbonate deposits. The travertine primary fabric is composed of couplets of highly porous, thin micritic laminae intercalated with thicker iron oxide rich laminae. Low Mg‐calcite is the dominant mineralogy; however, aragonite is a major constituent in deposits proximal to the vent and decreases in abundance distally. Cements exhibit a variety of fabrics, isopachous being common. Constituents include micro‐stromatolites, clasts, pisoids and the common occurrence of Frutexites‐like iron oxide precipitates. Leptothrix, a common iron‐oxidizing bacterium, is believed to be responsible for the production of the dense iron‐rich laminae. Pisoids litter the ground around the vent and rapidly decrease distally in abundance and size.  相似文献   

Insights into agricultural influences and weathering processes from major ion patterns          下载免费PDF全文

Robert van Geldern  Peter Schulte  Michael Mader  Alfons Baier  Johannes A.C. Barth  Tobias R. Juhlke  Kern Lee 《水文研究》2018,32(7):891-903

Karst areas and their catchments pose a great challenge for protection because fast conduit flow results in low natural attenuation of anthropogenic contaminants. Studies of the hydrochemistry of karst sources and river solutes are an important tool for securing and managing water resources. A study of the geochemical downriver evolution of the Wiesent River and its tributaries, located in a typical karst terrain, revealed unexpected downstream decreases of nitrate with maximum mean values of 30 mg/L at the source to minimum values of 18 mg/L near the river mouth. This trend persisted over the length of the river even though increased agricultural activities are evident in the downstream section of the catchment. This pattern is caused by fertilizer inputs via diffusive and fast conduits flow from karst lithology in the upstream area that may have reached the river's source even from beyond the hydrological catchment boundaries. Further downstream, these influences became diluted by tributary inputs that drain subcatchments dominated by claystone and sandstone lithologies that increased potassium and sulphate concentrations. Our findings indicate that bedrock geology remains the dominant control on the major ion chemistry of the Wiesent River and that agricultural influences are strongest near the headwaters despite increased land use further downstream, due to long‐term storage and accumulation in karst aquifers. This feature may not be unique to the Wiesent River system, as carbonates cover significant portions of the Earth's surface and subsequent work in other river systems could establish whether such patterns are ubiquitous worldwide.  相似文献   

Ozone and the polar hood of Mars     

C.A. Barth  M.L. Dick 《Icarus》1974,22(2):205-211

Ozone co-appears with the clouds of the polar hood in the winter hemisphere of Mars, but each is variable from day to day and location.to location. Both the appearance of ozone and the polar hood clouds correlate with the temperature of the atmosphere which varies from day to day and location to location. A cold, clean, dry atmosphere is conducive to the formation of ozone.  相似文献   

Mariner 9 ultraviolet spectrometer experiment: Observations of ozone on Mars     

A.L. Lane  C.A. Barth  C.W. Hord  A.I. Stewart 《Icarus》1973,18(1):102-108

The Mariner 9 Ultraviolet Spectrometer has observed the 2550 Å ozone spectral absorption feature on Mars. This absorption was previously detected in the south polar region by Mariner 7 in 1969. Mariner 9 did not observe ozone at any time in the equatorial region, nor at the south polar cap during its summer season. However, ozone was found in the north polar region beginning at a latitude of 45°N and extending northward. Ozone later appeared in the southern hemisphere southward of 50°S as the Mars autumnal equinox approached. The presence of ozone on Mars seems to be coupled to the water vapor content of its atmosphere.  相似文献   

Summer Field Meeting in Norway: 7–22 August, 1950     

O. Holtedahl  T.F.W. Barth  N-H. Kolderup  A. Kvale  J.F. Kirkaldy 《Proceedings of the Geologists' Association. Geologists' Association》1951,62(3):203-223

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