Assessment of Primary Production by Statistical Analysis of Water‐quality Data     

Wilhelm Petersen  Ulrich Callies 《洁净——土壤、空气、水》2002,30(1):34-40

Time series of weekly water‐quality data at Schnackenburg on the Elbe River (1985—2000) were subjected to principal component analysis (PCA). Considering the amplitudes of composite patterns of variables is a step towards a process‐oriented interpretation of waterquality data. One specific objective was to investigate the impact of improved water quality after the German reunification in 1990 on primary production and the oxygen budget. To discriminate anthropogenic signals from natural fluctuations a separation of the impact of discharge was attempted based on a linear regression approach. A dominant pattern of co‐variation in the residual data could be attributed to biological activity (primary production). The most relevant variables of this 'biomode' are oxygen saturation, pH, and orthophosphate. We conclude that multivariate statistical analysis of water‐quality data can help to estimate primary production when direct observations of algal concentrations are missing. In the years from 1998—2000 the trend of the ‘biomode’ indicates an increased load of oxygen consuming biomass caused by enhanced primary production in the middle stretches of the Elbe River which corresponds with the observation of more severe oxygen deficits in the tidal section of the river.  相似文献   

Geophysical signature of Målingen,the minor crater of the Lockne–Målingen doublet impact structure     

Irene Melero-Asensio  Jens Ormö  Erik Sturkell  Gabrielle Stockmann  Joakim Mansfeld 《Meteoritics & planetary science》2018,53(7):1456-1475

Målingen is the 0.7 km wide minor crater associated to the 10 times larger Lockne crater in the unique Lockne–Målingen doublet. The craters formed at 458 Ma by the impact of a binary asteroid related to the well-known 470 Ma Main Belt breakup event responsible for a large number of Ordovician craters and fossil meteorites. The binary asteroid struck a target sequence including ~500 m of sea water, ~80 m of limestone, ~30 m of dark mud, and a peneplainized Precambrian crystalline basement. Although the Lockne crater has been extensively studied by core drillings and geophysics, little is known about the subsurface morphology of Målingen. We performed magnetic susceptibility and remanence, as well as density, measurements combined with gravity, and magnetic field surveys over the crater and its close vicinity as a base for forward magnetic and gravity modeling. The interior of the crater shows a general magnetic low of 90–100 nT broken by a clustered set of high-amplitude, short wavelength anomalies caused by bodies of mafic rock in the target below the crater and as allogenic blocks in the crater infill. The gravity shows a general −1.4 mgal anomaly over the crater caused by low-density breccia infill and fractured crystalline rocks below the crater floor. The modeling also revealed a slightly asymmetrical shape of the crater that together with the irregular ejecta distribution supports an oblique impact from the east, which is consistent with the direction of impact suggested for the Lockne crater.  相似文献   

Phosphorus input by upwelling in the eastern Gotland Basin (Baltic Sea) in summer and its effects on filamentous cyanobacteria     

Monika Nausch  Günther Nausch  Hans Ulrich Lass  Volker Mohrholz  Klaus Nagel  Herbert Siegel  Norbert Wasmund   《Estuarine, Coastal and Shelf Science》2009,83(4):434-442

In July 2007, phosphorus input by an upwelling event along the east coast of Gotland Island and the response of filamentous cyanobacteria were studied to determine whether introduced phosphorus can intensify cyanobacterial bloom formation in the eastern Gotland Basin. Surface temperature, nutrient concentrations, phytoplankton biomass and its stoichiometry, as well as phosphate uptake rates were determined in two transects between the coasts of Gotland and Latvia and in a short grid offshore of Gotland. In the upwelling area, surface temperatures of 11–12 °C and average dissolved inorganic phosphorus (DIP) concentrations of 0.26 μM were measured. Outside the upwelling, surface temperatures were higher (15.5–16.6 °C) and DIP supplies in the upper 10 m layer were exhausted. Nitrite and nitrate concentrations (0.01–0.22 μM) were very low within and outside the upwelling region. Abundances of filamentous cyanobacteria were highly reduced in the upwelling area, accounting for only 1.4–6.0% of the total phytoplankton biomass, in contrast to 18–20% outside the upwelling. The C:P ratio of filamentous cyanobacteria varied between 32.8 and 310 in the upwelling region, most likely due to the introduction of phosphorus-depleted organisms into the upwelling water. These organisms accumulate DIP in upwelling water and have lower C:P ratios as long as they remain in DIP-rich water. Thus, diazotrophic cyanobacteria benefit from phosphorus input directly in the upwelling region. Outside the upwelling region, the C:P ratios of filamentous cyanobacteria varied widely, between 240 and 463, whereas those of particulate material in the water ranged only between 96 and 224. To reduce their C:P ratio from 300 to 35, cyanobacteria in the upwelling region had to take up 0.05 mmol m⁻³ DIP, which is about 20% of the available DIP. Thus, a larger biomass of filamentous cyanobacteria may be able to benefit from a given DIP input. As determined from the DIP uptake rates measured in upwelling cells, the time needed to reduce the C:P ratio from 300 to 35 was too long to explain the huge bloom formations that typically occur in summer. However, phosphorus uptake rates increased significantly with increasing C:P ratios, allowing phosphorus accumulation within 4–5 days, a span of time suitable for bloom formation in July and August.  相似文献   

A multi-method approach for the identification and quantification of water balance components of two lentic small water bodies     

Lukas P. Loose  Jens Lange  Aaron Budde  Barbara Herbstritt  Nicola Fohrer  Uta Ulrich 《水文研究》2024,38(1):e15058

The protection of the globally widespread lentic small water bodies (LSWB) must be based on detailed knowledge about their hydrological connectivity and water balance. The study aimed to identify and quantify water balance components as well as surface-groundwater interaction of two LSWB in a characteristic lowland region with a combination of different methods. This includes the collection of hydrological data and the use of bromide and water stable isotopes (δ²H and δ¹⁸O) as tracers. With their help, mixing models were established, and daily water balances were assessed. The results show a strong bidirectional interaction of both LSWB systems with shallow groundwater. Bromide and stable isotope tracers allowed for the identification of the most relevant in- and outflow sources and pathways. Thereby, isotope data revealed isotopic enrichment typical for open-water bodies and only minor precipitation inputs mainly relevant at the end of the dry season. Water balance calculations suggested accentuated seasonal dynamics that were strongly influenced by shallow groundwater, which represented large inputs into both LSWB. By that, different phases could be identified, with high inflow rates in winter and spring and decreasing fluxes in summer. In one LSWB, a drainage system was found to have a major impact next to the shallow groundwater interaction. The findings of this research provide detailed insights into the influence and importance of shallow groundwater for LSWB in lowland regions. This impacts the diffuse input of agricultural pollutants into these ecologically important landscape features.  相似文献   

Optical observations of an infrared selected sample of galaxies     

Ulrich Klaas 《Astrophysics and Space Science》1989,157(1-2):245-253

Extragalactic IRAS sources with previously unknown optical counterparts were selected from thePoint Source Catalog within two 300 deg² areas. Deep CCD images have been obtained for 99 objects and long-slit spectroscopy has been performed in 55 fields. The morphological, spectroscopic and photometric properties of these objects are summarized.  相似文献   

S-wave velocity measurements applied to the seismic microzonation of Basel, Upper Rhine Graben     

Hans-Balder Havenith  Donat Fäh  Ulrich Polom  Agathe Roullé 《Geophysical Journal International》2007,170(1):346-358

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Lesson from the past: present insolation minimum holds potential for glacial inception     

Ulrich C. Müller  Jrg Pross 《Quaternary Science Reviews》2007,26(25-28):3025-3029

The community of climatologists predicts a progressive global warming [IPCC Fourth Assessment Report—Climate Change, 2007. The Scientific Basis. Cambridge University Press, Cambridge] that will not be interrupted by a glacial inception for the next 50 ka [Berger and Loutre, 2002. An exceptionally long Interglacial ahead? Science 297, 1287–1288]. These predictions are based on continuously increasing anthropogenic greenhouse gas emissions and on the orbital forcing that will provide only muted insolation variations for the next 50 ka. To assess the potential climate development without human interference, we analyse climate proxy records from Europe and the North Atlantic of Marine Isotope Stage (MIS) 11 (423–362 ka BP), an interval when insolation variations show a strong linear correlation with those of the recent past and the future. This analysis suggests that the insolation minimum at 397 ka BP, which provides the best available analogue to the present insolation minimum, terminated interglacial conditions in Europe. At that time, tundra–steppe vegetation spread in Central Europe and pine forests dominated in the eastern Mediterranean region. Because the intensities of the 397 ka BP and present insolation minima are very similar, we conclude that under natural boundary conditions the present insolation minimum holds the potential to terminate the Holocene interglacial. Our findings support the Ruddiman hypothesis [Ruddiman, W., 2003. The Anthropogenic Greenhouse Era began thousands of years ago. Climate Change 61, 261–293], which proposes that early anthropogenic greenhouse gas emission prevented the inception of a glacial that would otherwise already have started.  相似文献   

Motoji Ikeya (1940–2006)     

Rainer Grün  Ulrich Radtke  Richard G. Roberts 《Quaternary Geochronology》2007,2(1-4):2-3

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Electrical Monitoring of In Situ Chemical Oxidation by Permanganate     

Lisa Cavé  Niels Hartog  Tom Al  Beth Parker  K. Ulrich Mayer  Steven Cogswell 《Ground Water Monitoring & Remediation》2007,27(2):77-84

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Magnetic mapping for the detection and characterization of UXO: Use of multi-sensor fluxgate 3-axis magnetometers and methods of interpretation   总被引：1，自引：0，他引：1  

Marc Munschy  Daniel Boulanger  Patrice Ulrich  Mustapha Bouiflane 《Journal of Applied Geophysics》2007,61(3-4):168-183

Fluxgate vector magnetometers can be powerful instruments in magnetic mapping and in the detection of unexploded ordnance (UXO). Being lightweight and having low power requirements, they allow the development of multi-sensor use. The main problems in using fluxgate magnetometers arise from calibration errors and drift but these can be overcome using a quick and simple method of calibration in the field. This method also has the advantage of compensating permanent and induced magnetic fields generated by magnetized objects carried with the sensors. Measurement accuracy is similar to that obtained with scalar magnetometers. Multi-magnetometer profiling allows direct inversion of raw magnetic data along profiles in order to locate and characterize dipoles typically generated by UXO. The method used is a non-linear inverse procedure that estimates the three coordinates and magnetization vector of the dipole. Application of the technique to both a synthetic case and a field example illustrates the advantages of the method compared with the use of the analytic signal.  相似文献