太湖西南部河流流域的营养盐排放

以MONERIS河流系统模型为基础,建立了由农业土地营养盐平衡模型、流域营养盐排放模型及河道营养盐滞留模型3个模型组成的模型系统.该系统被用来计算太湖西南部河流流域的营养盐排放量.利用实测的河流系统的负荷数据,对模型系统进行验证.验证结果表明,N、P计算负荷与实测负荷的偏差分别在10%及30%以内.利用该系统,对1992-1996年及1997-2001年间的营养盐排放量进行计算.计算结果表明,1997-2001年间的氮的年平均排放量为5646 t/a,该排放量比前5年的年均排放量减少827 t/a.从磷的排放量来看,1997-2001年间的年排放量为554 t/a,比前5年的均值减少45 t/a.分析结果表明,与1992-1996年相比,1997-2001年间的点源排放量及农业土地营养盐剩余量的减少是流域营养盐排放量减少的主要原因.     

Age constraints on faulting and fault reactivation: a multi-chronological approach

Movement within the Earth’s upper crust is commonly accommodated by faults or shear zones, ranging in scale from micro-displacements to regional tectonic lineaments. Since faults are active on different time scales and can be repeatedly reactivated, their displacement chronology is difficult to reconstruct. This study represents a multi-geochronological approach to unravel the evolution of an intracontinental fault zone locality along the Danube Fault, central Europe. At the investigated fault locality, ancient motion has produced a cataclastic deformation zone in which the cataclastic material was subjected to hydrothermal alteration and K-feldspar was almost completely replaced by illite and other phyllosilicates. Five different geochronological techniques (zircon Pb-evaporation, K–Ar and Rb–Sr illite, apatite fission track and fluorite (U-Th)/He) have been applied to explore the temporal fault activity. The upper time limit for initiation of faulting is constrained by the crystallization age of the primary rock type (known as “Kristallgranit”) at 325 ± 7 Ma, whereas the K–Ar and Rb–Sr ages of two illite fractions <2 μm (266–255 Ma) are interpreted to date fluid infiltration events during the final stage of the cataclastic deformation period. During this time, the “Kristallgranit” was already at or near the Earth’s surface as indicated by the sedimentary record and thermal modelling results of apatite fission track data. (U–Th)/He thermochronology of two single fluorite grains from a fluorite–quartz vein within the fault zone yield Cretaceous ages that clearly postdate their Late-Variscan mineralization age. We propose that later reactivation of the fault caused loss of helium in the fluorites. This assertion is supported by geological evidence, i.e. offsets of Jurassic and Cretaceous sediments along the fault and apatite fission track thermal modelling results are consistent with the prevalence of elevated temperatures (50–80°C) in the fault zone during the Cretaceous.     

Integrated geophysical and geological methods to investigate the inner and outer structures of the Quaternary Mýtina maar (W-Bohemia,Czech Republic)

The Mýtina maar is the first known Quaternary maar in the Bohemian Massif. Based on the results of Mrlina et al. (J Volcanol Geother Res 182:97–112, 2009), a multiparametric geophysical (electrical resistivity tomography, gravimetry, magnetometry, seismics) and geological/petrochemical research study had been carried out. The interpretation of the data has provided new information about the inner structure of the volcanic complex: (1) specification of the depth of post-volcanic sedimentary fill (up to ~100 m) and (2) magnetic and resistivity signs of one (or two) hidden volcanic structures interpreted as intrusions or remains of a scoria cone. The findings at the outer structure of the maar incorporate the (1) evidence of circular fracture zones outside the maar, (2) detection and distribution of volcanic ejecta and tephra-fall deposits at the surface, and (3) indications from electrical resistivity tomography and gravity data in the area between the Mýtina maar and ?elezná h?rka scoria cone, interpreted as a palaeovalley, filled by volcaniclastic rocks, and aligned along the strike line (NW–SE) of the Tachov fault zone. These findings are valuable contributions to extend the knowledge about structure of maar volcanoes in general. Because of ongoing active magmatic processes in the north-east part of the Cheb Basin (ca. 15–30 km north of the investigation area), the Mýtina maar-diatreme volcano and surroundings is a suitable key area for research directed to reconstruction of the palaeovolcanic evolution and assessment of possible future hazard potential in the Bohemian Massif.     

Über einen Keuperton von Zaisersweiher bei Maulbronn

Zusammenfassung Durch röntgenographisehe und differentialthermoanalytische Untersuchungen wurde in einem roten Keuperton (km 3) von Zaisersweiher bei Maulbronn ein quellfähiges chloritisches Mineral (Corrensit) als Hauptbestandteil gefunden, das sick durch doppelten Basisabstand (28 Å) auszeichnet. Daneben treten Illit (Glimmer) und Quarz auf. Nebengemengteile sind Hämatit und Feldspat.Herrn Professor Dr.Carl W. Correns zum 60. Geburtstag gewidmet.     

Penumbral velocity oscillations

Doppler velocity variations of four sunspot penumbrae were observed in November 1988 at the Observatorio del Teide, Tenerife, using the spectral line Fe i 5576 Å. All of the penumbrae show local power maxima in the five-minute range, while no power is found around three minutes. This indicates that the five-minute oscillations are still present in the penumbrae, but the direction of the velocities might be tilted by the magnetic field. On the other hand, the maxima of the power and of the Evershed flow do not always occur at the same locations.The Gregory-Coudé telescope is operated by the Universitäts-Sternwarte Göttingen in cooperation with the Kiepenheuer-Institut für Sonnenphysik in Freiburg and the Institut für Astronomie und Astrophysik der Universität Würzburg.