Strontium isotope identification of water mixing and recharge sources in a river system (Oder River,central Europe): A quantitative approach

This study uses Sr isotope composition (⁸⁷Sr/⁸⁶Sr) and Sr content of waters of the Oder, one of the largest rivers in central Europe, to fingerprint natural and anthropogenic contributions to its Sr budget and to evaluate water mixing processes in its hydrological system. It also demonstrates a simple method of quantifying natural and anthropogenic Sr inputs in the watershed. The method has potential for environmental and archaeological research because past Sr geochemistry of river water can easily be reconstructed. For the first time, a catchment‐scale impact of anthropogenic sources on the Sr budget of a middle‐size river is shown in a quantitative way. The water of the Oder is characterized by a relatively uniform Sr isotope composition, from 0.7100 to 0.7108, contrasting with strong variations in Sr concentration, from 0.25 to 1.27 mg/L. There is a general seasonal trend in variability, with waters becoming more radiogenic and dilute with respect to the Sr in the spring time. This Sr systematics differs significantly from the Sr budgets of the majority of the Oder tributaries that exhibit more radiogenic composition and systematically lower Sr concentrations. A mixing scenario in the Oder involves Sr contribution from four principal water sources: (a) shallow ground waters with Sr derived from near‐surface weathering of silicates, (b) moderately radiogenic mine waters from the Upper Silesian Coal Basin, (c) unradiogenic mine waters from the Permian sequence of the copper district, and (d) unradiogenic ground waters from shallow‐seated Palaeogene, Neogene, and Mesozoic aquifers. The Sr budget of the Oder is primarily controlled by inputs of dissolved Sr from anthropogenic sources, which overprint the natural background, controlled by geology. Thus, about 47.5% of Sr originates from agriculture, industrial, and municipal additions, 31.5% from mine water inputs, and only 21% from natural sources, that is, rock weathering and atmospheric precipitation. Reconstruction of the past Sr chemistry of the Oder reveals that its present‐day Sr isotope composition is temporary and significantly different from that of the preindustrial times.     

Planktonic rotifers in mining lakes in the Silesian Upland: Relationship to environmental parameters

The effects of coal-mine waters on the structure and the density of planktonic rotifer communities were studied in lakes formed as a result of subsidence due to mining (collapse of underground tunnels). Water samples were collected according to the standard methods from four mining lakes in Tychy-Czu?ów (near Katowice, southern Poland), twice a month from June till October in 2004-2006. Two of the studied lakes were fed by mine waters but differed in flow rate, conductivity, water pH, and the amount of aquatic vegetation. The effects of those factors on the planktonic rotifer communities were analysed. In total, 83 species and forms of rotifers were recorded. The highest diversity of rotifers was found in the lakes with the largest patches of aquatic vegetation, while the highest density of rotifers was observed in the smallest and the most eutrophicated lake. High-water conductivity limited both species diversity and densities of rotifers. The rotifer communities of the studied lakes differed significantly in species diversity, although all the lakes were dominated by eurytopic species: Keratella cochlearis, Brachionus angularis, Brachionus calyciflorus, and Polyarthra sp. In the largest lake, characterized by the lowest conductivity and pH, the superdominant was Polyarthra luminosa, which in the other lakes was rare or absent. Higher conductivity was correlated with a lower density of P. luminosa, Brachionus diversicornis, K. cochlearis f. tecta, and a higher density of B. calyciflorus. In the lakes with the largest patches of aquatic vegetation, conductivity affected the number of dominant rotifer species. Apparently no other abiotic factors (pH, phosphates, and nitrates) affected the rotifer communities.     

Religious Belief across ‘Post-secular’ Sydney: the multiple trends in (de)secularisation

Cities were once thought to be crucibles of secularisation, where the retreat from religion and its expression would be most pronounced. This decline in faith was linked to the heightened levels of heterogeneity and cosmopolitanism within cities. However, there is recent evidence of both the continuation and of the recession of the secularisation process in contemporary Western societies, with the mix and pace of these trends being quite unique to different countries. Significantly, this combination of processes has been argued to be part of a ‘post-secularist’ paradigm. Drawing on census data, this paper examines the spatial patterns of religious affiliation and non-belief in the Australian city of Sydney. Sydney has divergent geographies of faith and non-faith indicating the spatial multiplicities of religious belief. The decrease in Christianity in some areas of the city has been matched by an increase in non-Christian faiths, while in other areas there has been little change. Some parts of the city—especially those areas with a strong mix of affluence, diversity and cosmopolitanism—betray the strongest levels of secularisation and the retreat of faith. At least five geographies of faith and non-belief are recognisable within Sydney. While post-secularisation has been recognised as internationally uneven, this research demonstrates that it is also uneven across a world city like Sydney. The Sydney variations in (de)secularisation reflect city-based effects, including the historic and contemporary patterns of immigrant settlement, established and emerging religious communities, the segmented geographies of class and affluence, and the development of zones of cosmopolitanism. The findings point to the need for further research on the micro-geographies of religious belief and non-belief and community relations, and the on links between religious communities and civil society.     

Holocene paleostorms identified by particle size signatures in lake sediments from the northeastern United States

The frequency and timing of Holocene paleofloods in the hilly terrain of New Hampshire and Maine are identified using ¹⁴C and high-resolution (cm-by-cm) particle size analysis of sediment cores taken from six post-glacial lakes (~0.1–1.4 km²). A total of nine sediment cores (4.5–6 m long) were taken near the base of stream delta foreslopes. End-member modeling of the particle-size frequency distributions from each core produces 3–5 representative end member distributions, or end members (EMs). Concurrent increases in mean and median particle size, and in the relative abundance of the coarsest EM(s), indicate increased transport capacity of inflowing tributaries, resulting from rainstorms. In all 9 cores, particle size data show clear signs of episodic, high-energy sediment transport events where proxy measurements such as loss-on-ignition and magnetic susceptibility do not, demonstrating the sensitivity of particle size analysis in paleostorm investigations made using lake sediment cores. Floods caused by storms in this region peaked around 1.4, 2.1, 3.0, 3.9, 6.8, 8.2, and 11.5 ka cal BP, and presently appear to be increasing in frequency. Periods of storminess in New Hampshire and Maine correlate well with other records of precipitation and climate in the northeastern United States during the Holocene, further supporting modern records which show tropical air masses as a primary driver of extreme precipitation events in New England (Ludlum 1996; Konrad 2001; Sisson and Gyakum 2004).     

New Methods for Modeling Laterolog Resistivity Corrections

The paper presents methods for laterolog response modeling. In Coulomb’s charges method, Laplace’s equation is solved for the electric field distribution in rock medium with internal boundaries between different resistivity layers. There, the boundary problem is reduced to Fred-holm integral equation of the second kind. The second method uses a finite element array to model apparent resistivity from laterolog. The task is treated as DC problem and the Laplace equation is solved numerically. The presented methods were applied to borehole data covering a typical stratigraphie section of the Fore-Sudetic Monocline in southwestern Poland. Apparent resistivity was calculated using the Coulomb’s charges method and alternatively modeled using a finite element method which gave similar results. Then, a series of linear corrections for borehole, shoulder bed, and filtration effects for apparent resistivity obtained by the Coulomb’s charges method demonstrated the feasibility of calculating true resistivity of virgin and invaded zones. The proposed methods provide a flexible solution in modeling which can be adapted to other logs.     

Do macrophytes, diatoms and non-diatom benthic algae give redundant information? Results from a case study in Poland

We analyzed species composition and abundance of macrophytes, diatoms and non-diatom benthic algae, water chemistry and habitat structure of 24 river sites in Poland, in order to better understand which parameters structure macrophyte and benthic algae communities. Community patterns for macrophytes and diatoms are most closely related, while macrophytes and non-diatom benthic algae have the weakest relationship. Environmental parameters best explaining community patterns are channel substrate parameters for non-diatom benthic algae, and a combination of channel substrate and river bank characteristics for submerged macrophytes, emergent macrophytes and diatoms. Among the organism groups investigated, the diatom community pattern is best correlated to the environmental data similarity matrix. We hypothesize that the results can be explained by the shorter generation time of diatoms compared to macrophytes, and by a higher dispersal rate of diatoms compared to macrophytes and non-diatom benthic algae. This has several practical consequences for bioindication: (1) Diatoms are usually the organism group most closely following environmental parameters, for both increasing and decreasing impact. (2) Since the biotic indices developed for the Water Framework Directive are meant to primarily indicate ecological changes, not water chemistry, the nature of diatoms to closely reflect water chemistry is not necessarily advantageous. (3) The applicability of macrophyte and probably also non-diatom benthic algae indices is more locally restricted, while diatom indices are applicable to greater areas. (4) In ecosystems which are subject to changing environmental conditions, differences in biotic indices between macrophytes, diatoms and non-diatom benthic algae are to be expected. These differences could provide information relating to ecosystem stability. (5) In stable ecosystems, analyzing one of the three organism groups “diatoms”, “non-diatom benthic algae” and “macrophytes” will be sufficient to characterize the quality element “macrophytes and phytobenthos”, as required by the Water Framework Directive. However, in ecosystems subject to increasing pressure, macrophytes likely will have a tendency to indicate “too good”, while in ecosystems subject to decreasing pressure, diatoms will have a tendency to indicate “too good”.     

双能CT的基本原理、应用和未来展望(英文)

断层影像(CT)的图像对比度与扫描所用的X光源能谱分布有很大关系。传统CT使用具有能谱分布的一个光源进行成像,有时会出现信息模糊致使两种不同材料在CT图像上完全相同。双能CT使用两个不同分布的能谱对物体进行成像,能够消除单能谱情况下的信息模糊。虽然双能CT的基本概念由来已久,但最近商业系统的出现使双能CT迅速成为一个热点。我们首先概述了双能CT的基本物理原理和双能信号处理方法,包括促使双能CT进入现代医学成像的关键技术。其次,双能CT的应用已非常广泛,本文从其在临床应用角度进行了详细介绍使读者有所了解。最后,我们简要探讨了当前的两个技术发展领域:光子技术探测器和技术合成CT。     

Ceilometer observations of the boundary layer over Warsaw,Poland

Jenoptik’s CHM 15k ceilometer was used to monitor the vertical structure of the atmospheric boundary layer (ABL) over Warsaw, from 2008 until 2011, on Mondays and Thursdays, in 24h periods. Hereby, we present an assessment of the signal-to-noise ratio along with a sensitivity study of signal smoothing methods developed in-house. With the proposed averaging, ceilometer attenuated-backscatter signals reached the high troposphere, which makes this sensor competitive to a single-wavelength elastic lidar. The smoothed signals were employed as an input for algorithms developed to automatically detect the ABL height, clouds, fog, and precipitation in the lower troposphere. The classification of weather conditions was validated by the METAR reports from the Warsaw Airport. The obtained ABL heights were compared to those assessed from radio-soundings from a nearby meteorological station WMO12374 in Legionowo. An inter-comparison of the ABL heights, derived by using the Jenoptik’s automated routine against the in-house developed algorithms, is in favor of the latter. The presented four annual cycles of the ABL height, obtained with various derivative-based methods, are the first such long-term results reported using the CHM 15k sensor in Eastern Europe.     

Results of the application of tropospheric corrections from different troposphere models for precise GPS rapid static positioning

In many surveying applications, determination of accurate heights is of significant interest. The delay caused by the neutral atmosphere is one of the main factors limiting the accuracy of GPS positioning and affecting mainly the height coordinate component rather than horizontal ones. Estimation of the zenith total delay is a commonly used technique for accounting for the tropospheric delay in static positioning. However, in the rapid static positioning mode the estimation of the zenith total delay may fail, since for its reliable estimation longer observing sessions are required. In this paper, several troposphere modeling techniques were applied and tested with three processing scenarios: a single baseline solution with various height differences and a multi-baseline solution. In specific, we introduced external zenith total delays obtained from Modified Hopfield troposphere model with standard atmosphere parameters, UNB3m model, COAMPS numerical weather prediction model and zenith total delays interpolated from a reference network solution. The best results were obtained when tropospheric delays derived from the reference network were applied.