Late Pleistocene fans and terraces in the Majes valley, southern Peru, and their relation to climatic variations     

Damian Steffen  Fritz Schlunegger  Frank Preusser 《International Journal of Earth Sciences》2010,99(8):1975-1989

This study investigates the connection between sediment aggradation, erosion and climate in a desert environment of the Majes valley, southern Peru. Luminescence dating of terraces and fans shows that sediment aggradation correlates with wet time intervals on the Altiplano, suggesting a climatic influence on the aggradation–degradation cycles. Major periods of aggradation occurred between ~110–100, ~60–50 and 12–8 ka. More precipitation in the Majes catchment resulted in increased erosion and transportation of sediment from the hillslopes into the trunk river. As a result, the sediment loads exceeded the transport capacity of the Majes River and aggradation started in the lower reaches where the river gradient is less. Depletion of the hillslope sediment reservoirs caused a relative increase in the capacity of the trunk river to entrain and transport sediment, resulting in erosion of the previously deposited sediment. Consequently, although climate change may initiate a phase of sediment accumulation, degradation can be triggered by an autocyclic negative feedback and does not have to be driven by climatic change.  相似文献   

Über die Sexual- und Dauerperioden einiger Zygnemalen aus schweizerischen Kleingewässern     

Fritz Nipkow 《Aquatic Sciences - Research Across Boundaries》1962,24(1):1-43

Ohne Zusammenfassung  相似文献   

Dietrich-Kalle: Allgemeine Meereskunde     

Fritz Model 《Ocean Dynamics》1956,9(6):299-306

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A Survey of Charge-Balance Errors on Published Analyses of Potable Ground and Surface Waters   总被引：2，自引：0，他引：2  

Steven J. Fritz 《Ground water》1994,32(4):539-546

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Theoretical studies of the parameterization of the non-neutral surface boundary layer     

Walter-Georg Panhans  Fritz Herbert 《Boundary-Layer Meteorology》1979,16(2):155-167

The parameterization of the non-neutral atmospheric surface layer has been reexamined using the basic principles of small-scale energetics and thermodynamics. On the basis of this more complete treatment, theK-parameterization has been reformulated. It is found that the linear regression laws between fluxes and driving gradient forces of the turbulent heat and humidity exchanges in the surface layer can be derived in a much more comprehensive manner than by using the commonly used K-theory. With respect to stationary conditions and in the context of similarity concepts, a system of algebraic equations has been formulated which provides reasonable estimates of the distributions of the dimension less rates of viscous energy dissipation as well as turbulent kinetic and thermal-diffusive energy transport as functions of the variablez/L. Quantitative calculations have been performed using the scaling height formulations of Takeuchi and Yokoyama, Prandtl, and von Karman as closure conditions of the equations.  相似文献   

Photobleaching of humic rich dissolved organic matter   总被引：7，自引：0，他引：7  

Thomas?Brinkmann  Daniel?Sartorius  Fritz?H.?FrimmelEmail author 《Aquatic Sciences - Research Across Boundaries》2003,65(4):415-424

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Coupling of a Column System with ICP‐MS for the Characterisation of Colloid‐mediated Metal(loid) Transport in Porous Media     

George Metreveli  Eva‐Maria Kaulisch  Fritz H. Frimmel 《洁净——土壤、空气、水》2005,33(4):337-345

In this work a coupling method for the characterisation of colloid‐mediated transport of the metal(loid) species in porous media was developed. For this transport experiments quartz sand was used as column packing material and the synthetic three‐layer clay mineral laponite as model colloid. The determination of colloids was conducted by means of UV detection. The quantification of the metal(loid) ions was carried out in two different ways: (1) The fractions collected at the column outlet were analysed with an inductively coupled plasma mass spectrometer (ICP‐MS) (offline measurements); (2) the column system was directly coupled with ICP‐MS (online measurements). In the column experiments the influence of laponite colloids on the transport of Cu, Pb, Zn, Pt and As species was investigated. In the offline experiments as a consequence of dilution during sample preparation no metal(loid) species at the column outlet could be found. Unlike this the breakthrough of all metal(loid)s could be detected under the same experimental column conditions in the coupling experiments. This coupling technique offers the online detection of the metal species and colloidal particles with high resolution even at low concentrations and without any time‐consuming preparation. The coupling experiments have shown that the laponite particles accelerate the transport of the cationic metals. For anionic metal(loid) species no influence of laponite on their transport behaviour was found.  相似文献   

Preface     

Theodore A. Fritz  Shing F. Fung 《Surveys in Geophysics》2005,26(1-3):1-3

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Vegetation and climate change on the Bolivian Altiplano between 108,000 and 18,000 yr ago   总被引：1，自引：0，他引：1  

Alex Chepstow-Lusty  Mark B. Bush  Paul A. Baker  Sherilyn C. Fritz  James Aronson 《Quaternary Research》2005,63(1):90-98

A 90,000-yr record of environmental change before 18,000 cal yr B.P. has been constructed using pollen analyses from a sediment core obtained from Salar de Uyuni (3653 m above sea level) on the Bolivian Altiplano. The sequence consists of alternating mud and salt, which reflect shifts between wet and dry periods. Low abundances of aquatic species between 108,000 and 50,000 yr ago (such as Myriophyllum and Isoëtes) and marked fluctuations in Pediastrum suggest generally dry conditions dominated by saltpans. Between 50,000 yr ago and 36,000 cal yr B.P., lacustrine sediments become increasingly dominant. The transition to the formation of paleolake “Minchin” begins with marked rises in Isoëtes and Myriophyllum, suggesting a lake of moderate depth. Similarly, between 36,000 and 26,000 cal yr B.P., the transition to paleolake Tauca is also initiated by rises in Isoëtes and Myriophyllum; the sustained presence of Isoëtes indicates the development of flooded littoral communities associated with a lake maintained at a higher water level. Polylepis tarapacana-dominated communities were probably an important component of the Altiplano terrestrial vegetation during much of the Last Glacial Maximum (LGM) and previous wet phases.  相似文献   

Diatom Paleolimnological Record of Holocene Climatic and Environmental Change in the Altai Mountains, Siberia     

Karlyn S. Westover  Sherilyn C. Fritz  Tatyana A. Blyakharchuk  Herbert E. Wright 《Journal of Paleolimnology》2006,35(3):519-541

The sedimentary diatom records of three shallow lakes in the Altai Mountains, southern Siberia, were examined to assess the nature and timing of Holocene environmental changes. Few paleoenvironmental records, especially reconstructions not based on pollen, have been reported from this region. The lakes differ in elevation, annual precipitation, and catchment vegetation. Diatom assemblages in all lakes were dominated for the entire period of record by small benthic species of Pseudostaurosira Williams & Round, Staurosira Ehrenberg, and Staurosirella Williams & Round. Planktonic taxa only occur in very low abundances (<5%). The most diverse diatom flora was found in Dzhangyskol, which is situated at the lowest elevation within a forested catchment. A lack of detailed information on the ecological preferences of the dominant taxa and the complexity of environmental drivers make direct interpretation of the diatom record difficult. However, other proxies suggest that dramatic shifts in dominance between Staurosira elliptica and Staurosirella pinnata in Grusha Ozero reflect millennial-scale variability in climate. Together, chironomids and diatoms provide evidence of a cooling possibly correlative to the Younger Dryas Stade and subsequent early-Holocene warming consistent with pollen evidence of afforestation, which also is likely linked to increased humidity. By ~6000 cal year BP, the transition to a cooler, more continental climate had begun. The diatom record of Akkol shows significantly less variation in diatom community composition, but biogenic silica accumulation rates, a proxy for diatom productivity, appear to reflect climatic variability driven by insolation trends over the past 8000 years. Long-term variability in Dzhangyskol is not clearly linked to climate.  相似文献