Wind tunnel measurement of boundary-layer response to sediment transport   总被引：3，自引：0，他引：3  

Cheryl McKenna Neuman  Marianne Maljaars 《Boundary-Layer Meteorology》1997,84(1):67-83

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Changes in the importance of lotic and littoral diatoms in a high arctic lake over the last 191 years   总被引：1，自引：0，他引：1  

Stuart D. Ludlam  Susan Feeney  Marianne S. V. Douglas 《Journal of Paleolimnology》1996,16(2):187-204

Both habitat preferences and community associations for some of the most prominent pennate taxa in our profile were established using samples from the modern lake and its watershed. Habitat preferences were used to establish a simple indicator for the relative contribution of lotic communities in this lake (Lotic Index) and indicator taxa for both littoral (Achnanthes spp. and Cymbella spp.) and lotic (Hannaea arcus and Meridion circulare) communities. When profiled, the Lotic Index showed a clear positive relationship to sedimentation rate as recorded in the varves, while profiles of littoral indicator taxa show the opposite trends. It seems likely that the patterns we observed in the Lotic Index are related to changes in runoff. Apparently, there was a period of declining runoff beginning ca. two centuries ago and ending in the late 1800's. This was followed by increasing runoff lasting until the middle of the 20th century. A brief minimum occurred in ca. 1970 followed by a recovery by ca. 1980.A strong positive relationship was also found between the dates of major turbidites, exceptionally thick varves and the concentration of valves in the sediment. It is possible that many of the thicker varves in the profiles contain littoral material transported to the site of deposition by turbid interflows and underflows. For this reason, the concentration of valves in the sediment in our cores appears to be a proxy for sediment deposition from turbidity currents.This is the sixth in a series of papers published in this issue on the Taconite Inlet Lakes project. These papers were collected by Dr R. S. Bradley.  相似文献   

Effects of benthic fauna on organic matter mineralization in fish-farm sediments: importance of size and abundance   总被引：2，自引：0，他引：2  

Heilskov  Anna C.; Holmer  Marianne 《ICES Journal of Marine Science》2001,58(2):427-434

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Groundwater-dependent ecology of the shoreline of the subtropical Lake St Lucia estuary   总被引：1，自引：0，他引：1  

Ricky Taylor  Bruce Kelbe  Sylvi Haldorsen  Greg A. Botha  Bente Wejden  Lars Været  Marianne B. Simonsen 《Environmental Geology》2006,49(4):586-600

The ecology of the St Lucia estuary in South Africa is of unique international importance. During droughts the estuary experiences high salinities, with values above that of seawater. Ion-poor groundwater flowing into the estuary from prominent sand aquifers along its eastern shoreline forms low-salinity habitats for salt-sensitive biota. During droughts, plants and animals can take refuge in the groundwater discharge zone until the condition in the estuary regains tolerable salinity. Simulations of the groundwater discharge indicate that the flow can persist during droughts over at least a decade, and be of great important for the resilience of the estuary. Anthropogenic activities have reduced the river inflow and made the St Lucia estuary more sensitive to droughts. The groundwater has thereby become increasingly important for the estuary’s ecology. Protection of the groundwater discharge along the shoreline itself and actions to increase the groundwater recharge are therefore important management tasks.  相似文献   

Beziehung zwischen Biomasse und Stickstoffgehalt des Phytoplanktons und die daraus ableitbare Anwendung der Bestimmungsmethoden für die Praxis     

Frau Dr. Marianne Pavoni 《Aquatic Sciences - Research Across Boundaries》1969,31(1):110-127

Zusammenfassung Im Zusammenhang mit der Verbesserung der Stickstoffmethode nach Kjeldahl durchSchmid [18] wurde die übereinstimmung des partikul?r gebundenen Stickstoffs (p.N) mit der aus Individuenzahl und Zellvolumen berechneten Biomasse (B) des Phytoplanktons überprüft. Ausser p. N undB wurde zum Teil auch die Trockensubstanz bzw. die aschenfreie Trockensubstanz gleichsam als Kontroll-und Bezugsgr?sse bestimmt. Untersucht wurde das Phytoplankton aus Netzproben und Sch?pfproben des Vierwaldst?ttersees im Ablauf eines Jahres; ferner das Kulturmaterial der PlanktonalgenOscillatoria rubescens undSynedra acus. Sowohl Netzproben als Algen aus Kulturen zeigen eine klare Beziehung 1. zwischen aschenfreier Trockensubstanz und partikul?rem Stickstoff, 2. zwischen aschenfreier Trockensubstanz und Biomasse und 3. zwischen Biomasse und partikul?rem Stickstoff. Die Verh?ltniszahlen der verglichenen Komponenten variieren je nach Algenart und Zusammensetzung des Planktons. Der prozentuale p.N-Gehalt (bezogen auf die aschenfreie Trockensubstanz) derOscillatoria rubescens betr?gt rund 10%, derjenige der Kieselalgen rund 7%. Das Verh?ltnis vonB zu p.N der Sch?pfproben hingegen variierte von Probeserie zu Probeserie. Innerhalb der einzelnen Probeserien jedoch ist das Verh?ltnis vonB zu p.N relativ konstant. Es werden Gründe diskutiert, die diese Unterschiede bedingen. Um das mühsame Ausz?hlen der Planktonorganismen und die Berechnung der Biomasse bei Seeuntersuchungen, speziell bei routinem?ssigen überwachungsprogrammen, teilweise zu umgehen, wird eine Untersuchungsweise vorgeschlagen, die es erm?glicht, die organisch geformte Substanz und zugleich die Zusammensetzung des Planktons mit verh?ltnism?ssig geringem Arbeitsaufwand zu erfassen.

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Summary In connection with the improvement of the nitrogen method bySchmid (18), the agreement of particulate nitrogen with the biomass (determined by the individuals counted and the cell volume calculated) of the phytoplankton was tested. For control and reference the dry weight and the ashfree dry weight or organic dry weight respectively were determined. Three types of material were investigated: Phytoplankton from net samples and samples of unfiltered lakewater which were taken monthly during a year from the Lake of Lucerne and algal material from cultures of the two common plankton algaeOscillatoria rubescens andSynedra acus. Within the net fractions and culture samples a good agreement is observed 1) between ash-free dry weight and particulate nitrogen, 2) between ash-free dry weight and biomass, 3) between biomass and particulate nitrogen. The proportional figures of the compared components vary depending on the alga species and the composition of the plankton. The content of particulate nitrogen (per ash-free dry weight) amounted to about 10% forOscillatoria rubescens and about 7% for diatoms. The ratio of biomass to particulate nitrogen of the samples of unfiltered lakewater may alter from one sample series to another. Within the single sample series however, the relationship of the biomass to the particulate nitrogen is generally constant. Reasons for these differences are discussed. On the basis of the investigations and the results obtained therefrom, a combined method applying the determination of the particulate nitrogenand the biomass is suggested. This method allows to reduce the time consuming calculation of the biomass in lake investigations, more particularly in routine survey programs. On the other hand it enables to determineboth the organic substance formed at the momentand the composition of the plankton in relatively short time.

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Die Bedeutung des Nannoplanktons im Vergleich zum Netzplankton   总被引：1，自引：0，他引：1  

Marianne Pavoni dipl. sc. nat. 《Aquatic Sciences - Research Across Boundaries》1963,25(2):219-341

Ohne Zusammenfassung  相似文献   

Mantle Rheology, Viscomagnetic Coupling At the Core-Mantle Boundary and Differential Rotation of the Core Induced By Pleistocenic Deglaciation   总被引：1，自引：0，他引：1  

Marianne Lefftz  Roberto Sabadini  Hilaire Legros 《Geophysical Journal International》1994,117(1):1-18

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High-frequency magnetotelluric investigation of crustal structure in north-central Abitibi, Quebec, Canada     

Ping Zhang  Michel Chouteau  Marianne Mareschal  Ron Kurtz  Claude Hubert 《Geophysical Journal International》1995,120(2):406-418

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Channelling contribution to tipper vectors: a magnetic equivalent to electrical distortion   总被引：2，自引：0，他引：2  

Ping Zhang  Laust B. Pedersen  Marianne Mareschal  Michel Chouteau 《Geophysical Journal International》1993,113(3):693-700

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Hydrochemistry and environmental isotopes of spring water and their relation to structure and lithology identified with remote sensing methods in Wadi Araba,Egypt     

Wannous  Manal  Theilen-Willige  Barbara  Troeger  Uwe  Falk  Marianne  Siebert  Christian  Bauer  Florian 《Hydrogeology Journal》2021,29(6):2245-2266

Springs located at the historical sites of Wadi Araba (Eastern Desert of Egypt) and emerging from the escarpments of the Northern and Southern Galala Plateaus were investigated. A combination of methods, including hydrochemistry, stable and radioisotope composition, and structural analyses based on satellite data, provided information about the structure of the subsurface and the derived groundwater flow paths. Satellite images reveal karst features within the northern plateau, e.g. conical landforms. Karstic caves were documented along both escarpments. Chemical analysis of floodwater from Wadi Araba indicates higher concentrations of terrestrial salts compared to floodwaters from central and southern parts of the desert. δ¹⁸O and δ²H signatures in spring waters resemble those of floodwater and fall on the global meteoric water line, confirming their fast infiltration with minor influence of evaporation. The aquifer feeding the springs of the Northern Galala Plateau has low retention and the springs dry out quickly, even after heavy rainfall. Contrastingly, ³H activities in springs emerging from the Southern Galala Plateau refer to much slower subsurface passage. With respect to ³H content (3.8 TU) in recent flood waters, the spring water at Southern Galala Plateau contains about 40% recently recharged groundwater. However, its largest spring—the St. Antony spring—discharges water with a radiocarbon age of about 15,000 years. In combination with this spring’s constant and high discharge over a period of several months, that age estimate suggests a large reservoir with moderate to high retention.

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