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131.
132.
Ayrton F. Martins Tibiriçá G. Vasconcelos Danielle M. Henriques Carla da S. Frank Armin König Klaus Kümmerer 《洁净——土壤、空气、水》2008,36(3):264-269
This study was carried out to evaluate the occurrence of the fluoroquinolone antimicrobial agent ciprofloxacin (CIP) in the effluent of the Hospital of the Federal University of Santa Maria (HUSM). Measured environmental concentrations (MECs) of CIP in the hospital wastewater, both before (P1) and after (P2) cesspit/filter system treatment (CFTS), were determined by means of solid phase extraction and reversed‐phase liquid chromatography with fluorescence detection (LC‐FLD) and reversed‐phase liquid chromatography with mass spectrometric detection (LC‐MS/MS). The MECs (n = 7 daily composed samples) were 19 to 155 μg L–1 (average: 54 ± 21 μg L–1) and 32 to 99 μg L–1 (average: 65 ± 45 μg L–1) in P1 and P2, respectively. No relevant removal was observed from P1 to P2. In a worst case scenario, the final effluent was regarded as MECs of surface water. These MECs were generally 5 to 20,000‐fold higher than what was previously known. If the present data is drawn on to form a model of the situation in developing countries, the picture provides a first rough indication that the environmental risk associated with the use and emission of pharmaceuticals into the environment in developing countries might be higher than in developed countries. 相似文献
133.
Jürgen Oberst Stephan Elgner F. Scott Turner Mark E. Perry Robert W. Gaskell Maria T. Zuber Mark S. Robinson Sean C. Solomon 《Planetary and Space Science》2011,59(15):1918-1924
Analysis of images obtained by the MESSENGER spacecraft during its three flybys of Mercury yields a new estimate for the planet's mean radius of 2439.25±0.69 km, in agreement with results from Mariner 10 and Earth-based observations, as well as with MESSENGER altimeter and occultation data. The mean equatorial radius and polar radius are identical to within error, suggesting that rotational oblateness is negligible when compared with other sources of topography. This result is consistent with the small gravitational oblateness of the planet. Minor differences in radius obtained at different locations reflect regional variations in topography. Residual topography along three limb profiles has a dynamic range of 7.4 km and a root-mean-square roughness of 0.8 km over hemispherical scales. Following MESSENGER's entry into orbit about Mercury in March 2011, we expect considerable additional improvements to our knowledge of Mercury's size and shape. 相似文献
134.
Ryan R. Jensen Sandra S. Brake Stephen F. Wolf Matthew F. Bekker Perry James Hardin Mark W. Jackson 《Environmental Earth Sciences》2010,60(7):1391-1405
The Green Valley Mine in Indiana was abandoned in 1963 after 15 years of coal mining. Reclamation began in 1994 and ended
in 1999 with the dense planting of twelve different tree species. By 2006, only green ash (Fraxinus pennsylvanica Marsh.) and black locust (Robinia pseudoacacia L.) had survived in any significant numbers. Given the acid mine drainage found at the site, we sought to determine whether
element toxicity originating from mine waste was responsible for the extirpation of the trees. Leaf samples taken from 125
mine trees and 29 control trees were acquired and assayed for 41 element concentrations using inductively coupled plasma mass
spectrometry (ICPMS). Except for sodium, there was no compelling evidence to indicate that toxic elemental levels were responsible
for the widespread tree deaths. In addition to sodium toxicity, we suspect that micronutrient deficiency was a primary factor
explaining the extirpation of trees at the mine. 相似文献
135.
The abrasion of coastal rock platforms by individual or clusters of clasts during transport has not been quantitatively assessed. We present a study which identifies the types of abrasion and quantifies erosion due to the transport of clasts during three storms in February and March 2016. We explore relationships between platform roughness, determined by the fractal dimension (D) of the topographic profiles, geomorphic controls and the type and frequency of abrasion feature observed. Clast transport experiments were undertaken in conjunction with the measurement of wave energy to assess transport dynamics under summer and winter (non‐storm) conditions. Platform abrasion occurred extensively during the storms. We identify two types of clast abrasion trails: simple and complex. In addition, we find two forms of erosion occur on these trails: Scratch marks and Percussion marks. An estimated 13.6 m2 of the platform surface was eroded by clast abrasion on simple abrasion trails during the three storms. We attribute approximately two thirds of this to scratch‐type abrasion. The total volume of material removed by abrasion was 67 808 cm3. Despite the larger surface area affected by scratch marks, we find that the volume of material removed through percussion impact was almost seven times greater. We also find that the type and frequency of abrasion features is strongly influenced by the effect of platform morphometry on transport mode, with impact‐type abrasion dominating areas of higher platform roughness. Results of the clast transport experiments indicate that abrasion occurs under non‐storm wave energy conditions with observable geomorphological effects. We suggest that abrasion by clasts is an important component of platform erosion on high energy Atlantic coastlines, particularly over longer timescales, and that the morphogenetic link between the cliff and the platform is important in this context as the sediment supplied by the cliff is used to abrade the platform. © 2018 John Wiley & Sons, Ltd. 相似文献
136.
137.
Using standard instrument software and two independently developed data reduction and analysis procedures, we re-examine the accuracy of plasma velocity information derived from data obtained by the Solar and Heliospheric Observatory (SOHO)–Coronal Diagnostic Spectrometer (CDS). We discuss only the Ov 629 Å line data obtained by the Normal Incidence Spectrometer (NIS) and analyse a quiet Sun (QS) and active region (AR) dataset. Using the QS data, we demonstrate that the well-known North-South tilt in wavelength along the NIS slit varies significantly with time, which is not accounted for in the standard CDS correction procedures. In addition, when residual N – S trends exist in the data after processing, they may not be detected, nor removed, using the standard analysis software. This underscores the need for careful analysis of velocity results for individual datasets when using standard correction procedures. Furthermore, even when the results obtained by the two independent methods are well correlated (coefficients greater than 0.9), discrepancies in the values of the derived Doppler velocities can remain (95% within ±5 km s?1). Therefore, we apply the results to examine the velocities obtained for EUV blinkers by previous authors. It is found that a strong correlation exists in the patterns of variation of the blinker velocities (> 0.98), even though there may be differences in their magnitudes. That is, in a clear majority of cases, the methods agree that a blinker is red-shifted or blue-shifted, although the uncertainty in the absolute velocity may be large. 相似文献
138.
Christopher C. Harvey Michel Gangloff Todd King Christopher H. Perry D. Aaron Roberts James R. Thieman 《Earth Science Informatics》2008,1(1):5-13
As soon as the first data became available online over the Internet, it was obvious that different sites holding related datasets
should appear to the end user as a single data system, even if the data itself is stored at multiple locations. To achieve
this objective in the context of continuing parallel development of multiple data centres, in 2003 several actors in the realm
of space plasmas created the international consortium Space Physics Archive Search and Extract (SPASE). Since 2005 US participation
in SPASE has been supported by NASA, and early in 2006 NASA funded five new Virtual Observatories to cater for different aspects
of solar system plasma science. This paper outlines the current status of the SPASE effort, the opportunities it offers, its
specificities with respect to other parts of the astronomical virtual observatory, and the possibilities it offers for space
weather.
相似文献
Christopher C. HarveyEmail: |
139.
140.
Distinct erosional progressions in the Medusae Fossae Formation, Mars, indicate contrasting environmental conditions 总被引:2,自引:0,他引:2
The form of erosional remnants of the Medusae Fossae Formation (MFF) on Mars provide evidence of their development progression and implicate two spatially distinct environments in the equatorial regions of Mars. Ubiquitous yardangs are clearly the product of strong unidirectional winds acting over time on variably indurated deposits. Yardang orientation is used as a proxy to map regional and local wind direction at meso-scale resolution. In other, more limited areas not subjected to strong unidirectional winds, randomly oriented kilometer-scale mesas and buttes are found to be remnants of progressive cliff recession through mass wasting as support is lost from within the MFF lithology at its margins. The differing processes that dominate the formation of the distinctive landforms have implications for meso-scale variations in climate that remain unresolved by current modeling efforts. Additionally, the variability of erosional forms within the deposit emphasizes the overall complexity of this extensive formation. 相似文献