Abschied von Hermann Tertsch     

H. Meixner 《Mineralogy and Petrology》1965,9(3):191-194

Ohne Zusammenfassung

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Frau Prof.Valerie Auer (Wien), einer alten. Freundin der FamilieTertsch, danke ich herzlich für verschiedene Auskünfte.  相似文献   

Seasonalizing mountain system recharge in semi-arid basins-climate change impacts     

Ajami H  Meixner T  Dominguez F  Hogan J  Maddock T 《Ground water》2012,50(4):585-597

Climate variability and change impact groundwater resources by altering recharge rates. In semi-arid Basin and Range systems, this impact is likely to be most pronounced in mountain system recharge (MSR), a process which constitutes a significant component of recharge in these basins. Despite its importance, the physical processes that control MSR have not been fully investigated because of limited observations and the complexity of recharge processes in mountainous catchments. As a result, empirical equations, that provide a basin-wide estimate of mean annual recharge using mean annual precipitation, are often used to estimate MSR. Here North American Regional Reanalysis data are used to develop seasonal recharge estimates using ratios of seasonal (winter vs. summer) precipitation to seasonal actual or potential evapotranspiration. These seasonal recharge estimates compared favorably to seasonal MSR estimates using the fraction of winter vs. summer recharge determined from isotopic data in the Upper San Pedro River Basin, Arizona. Development of hydrologically based seasonal ratios enhanced seasonal recharge predictions and notably allows evaluation of MSR response to changes in seasonal precipitation and temperature because of climate variability and change using Global Climate Model (GCM) climate projections. Results show that prospective variability in MSR depends on GCM precipitation predictions and on higher temperature. Lower seasonal MSR rates projected for 2050-2099 are associated with decreases in summer precipitation and increases in winter temperature. Uncertainty in seasonal MSR predictions arises from the potential evapotranspiration estimation method, the GCM downscaling technique and the exclusion of snowmelt processes.  相似文献   

The birth of a planetary nebula around the carbon star IRC+10216     

C. J. Skinner  M. Meixner  & M. Bobrowsky 《Monthly notices of the Royal Astronomical Society》1998,300(4):L29-L33

Our current understanding of the evolution of solar-type stars suggests that after a period as a red giant star, during which mass loss occurs continuously in the form of a stellar wind, a period of intense mass loss known as a superwind occurs, during which a significant fraction of the envelope of the star is ejected into space, forming the material from which a planetary nebula (PN) will be constructed. It has been suggested that this superwind ejects material from the star in a toroidal or disc-like fashion, rather than isotropically. Here we present Hubble Space Telescope optical images of a toroidal superwind caught in the act: our images of the carbon star IRC+10216, which is believed to be in the final stages of red giant evolution, show that most of its optical emission is a bipolar reflection nebula. We show that the full spectral energy distribution and these images can be modelled as an equatorially enhanced dusty superwind, providing the first direct observational support for the toroidal superwind model, and supporting the 'interacting winds' model of PN formation.  相似文献   

Eine mineralogische Skizze zur Südtirol-Exkursion der Ö. M. G.     

H. Meixner 《Mineralogy and Petrology》1963,8(4):651-654

Ohne ZusammenfassungLagerstättenuntersuchung der Österr. Alpine Montangesellschaft.  相似文献   

Neue Mineralvorkommen aus den Ostalpen     

Dr. Heinz Meixner 《Contributions to Mineralogy and Petrology》1950,2(3):195-209

Zusammenfassung Bei den hier beschriebenen Mineralfunden handelt es sich teils um Neubearbeitungen alter Stücke aus Museums- oder Privatsammlungen, teils um neue Aufsammlungen.Cölestin von Kreuth bei Bleiberg.Slavikit undFibroferrit bei Rennweg.Pyrargyrit von Ruden bei Völkermarkt. Ein auffallend schönerZinnoberkristall vom steir. Erzberg.- und-Schwefel aus dem Köflach-Voitsberger Braunkohlengebiet. NetteRealgarkristalle vom Mischlinggraben im Lavanttal.Lansfordit undNesquehonit aus dem Serpentingebiet von Kraubat.Valentinit- undArsenolitkristalle, Symplesit undFerrisymplesit vom Hüttenberger Erzberg (Österreichs mineralartenreichster Lagerstätte). Insgesamt eine kleine Auswahl mineralogischer Neuentdeckungen (1947/49) aus dem Ostalpenraum, die zeigen, daß die mineralogische Durchforschung auch hier noch lange nicht abgeschlossen ist. Weitere Mitteilungen sollen folgen.  相似文献   

Evaluation of the importance of clay confining units on groundwater flow in alluvial basins using solute and isotope tracers: the case of Middle San Pedro Basin in southeastern Arizona (USA)     

Candice B. Hopkins  Jennifer C. McIntosh  Chris Eastoe  Jesse E. Dickinson  Thomas Meixner 《Hydrogeology Journal》2014,22(4):829-849

As groundwater becomes an increasingly important water resource worldwide, it is essential to understand how local geology affects groundwater quality, flowpaths and residence times. This study utilized multiple tracers to improve conceptual and numerical models of groundwater flow in the Middle San Pedro Basin in southeastern Arizona (USA) by determining recharge areas, compartmentalization of water sources, flowpaths and residence times. Ninety-five groundwater and surface-water samples were analyzed for major ion chemistry (water type and Ca/Sr ratios) and stable (¹⁸O, ²H, ¹³C) and radiogenic (³H, ¹⁴C) isotopes, and resulting data were used in conjunction with hydrogeologic information (e.g. hydraulic head and hydrostratigraphy). Results show that recent recharge (<60 years) has occurred within mountain systems along the basin margins and in shallow floodplain aquifers adjacent to the San Pedro River. Groundwater in the lower basin fill aquifer (semi confined) was recharged at high elevation in the fractured bedrock and has been extensively modified by water-rock reactions (increasing F and Sr, decreasing ¹⁴C) over long timescales (up to 35,000 years BP). Distinct solute and isotope geochemistries between the lower and upper basin fill aquifers show the importance of a clay confining unit on groundwater flow in the basin, which minimizes vertical groundwater movement.  相似文献   

Hydrologic functioning of the deep critical zone and contributions to streamflow in a high‐elevation catchment: Testing of multiple conceptual models     

Ravindra Dwivedi  Thomas Meixner  Jennifer C. McIntosh  P.A. Ty Ferr  Christopher J. Eastoe  Guo‐Yue Niu  Rebecca L. Minor  Greg A. Barron‐Gafford  Jon Chorover 《水文研究》2019,33(4):476-494

High‐elevation mountain catchments are often subject to large climatic and topographic gradients. Therefore, high‐density hydrogeochemical observations are needed to understand water sources to streamflow and the temporal and spatial behaviour of flow paths. These sources and flow paths vary seasonally, which dictates short‐term storage and the flux of water in the critical zone (CZ) and affect long‐term CZ evolution. This study utilizes multiyear observations of chemical compositions and water residence times from the Santa Catalina Mountains Critical Zone Observatory, Tucson, Arizona to develop and evaluate competing conceptual models of seasonal streamflow generation. These models were tested using endmember mixing analysis, baseflow recession analysis, and tritium model “ages” of various catchment water sources. A conceptual model involving four endmembers (precipitation, soil water, shallow, and deep groundwater) provided the best match to observations. On average, precipitation contributes 39–69% (55 ± 16%), soil water contributes 25–56% (41 ± 16%), shallow groundwater contributes 1–5% (3 ± 2%), and deep groundwater contributes ~0–3% (1 ± 1%) towards annual streamflow. The mixing space comprised two principal planes formed by (a) precipitation‐soil water‐deep groundwater (dry and summer monsoon season samples) and (b) precipitation‐soil water‐shallow groundwater (winter season samples). Groundwater contribution was most important during the wet winter season. During periods of high dynamic groundwater storage and increased hydrologic connectivity (i.e., spring snowmelt), stream water was more geochemically heterogeneous, that is, geochemical heterogeneity of stream water is storage‐dependent. Endmember mixing analysis and ³H model age results indicate that only 1.4 ± 0.3% of the long‐term annual precipitation becomes deep CZ groundwater flux that influences long‐term deep CZ development through both intercatchment and intracatchment deep groundwater flows.  相似文献   

Estimating Net Primary Productivity and Nutrient Stock in Plant in Freshwater Marsh,Northeastern China     

Junbao Yu  Jingshuang Liu  Franz X. Meixner  Jinda Wang  Yongjun Gao  Yang Wang  Xiaoning Qi  Xiaobing Chen 《洁净——土壤、空气、水》2010,38(11):1080-1086

We have investigated the contributions of three dominant macrophyte species, Deyeuxia angustifolia, Carex lasiocarpa, and Carex pseudocuraica (covering about 10 304 km²), to carbon (C), nitrogen (N), and phosphorus (P) stocks in the largest freshwater marsh (17 300 km²) in China for a 3‐year period (from 2002 to 2004). The monthly biomass, seasonal, and annual net primary productivity (NPP), and nutrient concentrations of three species were measured. All three plant species showed rapid growth in the rainy season. The maximum and minimum production rates in the freshwater marsh were ～36.19 and ～9.92 g m^?2 day^?1, respectively. The total NPP accounts 1900–2700 g m^?2 year^?1 in the studied area. Total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) concentrations in roots were higher than those in stem and leaf tissues. The vast beds of the three studied species comprise 80% of the grass covered marsh of Sanjiang plain, contributing annual nutrient stocks of ～10.99 × 10⁶, ～788.36 × 10³, and ～18.10 × 10³ t (tonnes) for TOC, TN, and TP, respectively. Our results suggest that the nutrient bioaccumulation capacity in freshwater marshes depend mainly on plant species, which are decided by hydrological conditions. The nutrient stocks in the Sanjiang plain marsh have been greatly reduced because some of the area occupied by C. lasiocarpa was replaced by D. angustifolia as a result of succession caused by the changes of water table.  相似文献   

RIPGIS-NET: a GIS tool for riparian groundwater evapotranspiration in MODFLOW     

Ajami H  Maddock T  Meixner T  Hogan JF  Guertin DP 《Ground water》2012,50(1):154-158

RIPGIS-NET, an Environmental System Research Institute (ESRI's) ArcGIS 9.2/9.3 custom application, was developed to derive parameters and visualize results of spatially explicit riparian groundwater evapotranspiration (ETg), evapotranspiration from saturated zone, in groundwater flow models for ecohydrology, riparian ecosystem management, and stream restoration. Specifically RIPGIS-NET works with riparian evapotranspiration (RIP-ET), a modeling package that works with the MODFLOW groundwater flow model. RIP-ET improves ETg simulations by using a set of eco-physiologically based ETg curves for plant functional subgroups (PFSGs), and separates ground evaporation and plant transpiration processes from the water table. The RIPGIS-NET program was developed in Visual Basic 2005, .NET framework 2.0, and runs in ArcMap 9.2 and 9.3 applications. RIPGIS-NET, a pre- and post-processor for RIP-ET, incorporates spatial variability of riparian vegetation and land surface elevation into ETg estimation in MODFLOW groundwater models. RIPGIS-NET derives RIP-ET input parameters including PFSG evapotranspiration curve parameters, fractional coverage areas of each PFSG in a MODFLOW cell, and average surface elevation per riparian vegetation polygon using a digital elevation model. RIPGIS-NET also provides visualization tools for modelers to create head maps, depth to water table (DTWT) maps, and plot DTWT for a PFSG in a polygon in the Geographic Information System based on MODFLOW simulation results.  相似文献   

Verdreifachte Achsenbilder an den Magnesitkristallen von Asturreta in Spanien     

Pr. Heinz Meixner 《Mineralogy and Petrology》1954,4(1-4):277-282

Zusammenfassung Die nach einer Scheinbasis tafeligen Magnesitkristalle von Asturreta (und ebenso ähnliche Dolomitkristalle aus den Magnesitlagerstätten Sunk, Oberdorf und Lanersbach) liefern bei Einbettung in den meisten üblichen Immersionsmitteln bei konoskopischer Beobachtung nicht ein, sondern drei einachsige Achsenbilder. Die Erscheinung wird nicht etwa durch Verzwillingung verursacht, sondern, da die Scheinbasis aus zahlreichen winzigen, streng parallelen r aufgebaut ist, durch einen Summeneffekt der symmetriebedingten -Flächenlagen in Abhängigkeit vom Einbettungsmittel. Das konnte durch Rechnung und Messung bewiesen werden.Mit 4 Textabbildungen.  相似文献