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481.
With a high-resolution SO2 emission inventory categorized by industries and seasons for Beijing city and gridded meteorological data fields from NCEP, the pollution dispersion model, HYSPLIT4 (Hybrid Single Particulate Lagrangian Integrated Trajectory, version 4), is used to determine the day-to-day variation of surface SO2 in Beijing for 2000 and 2001. Furthermore,the contributions of different emission sources in and around Beijing to the surface SO2 are studied. As shown in comparison with observations, the model does well in simulating the daily variation and seasonal distribution. The model computation of the annual source contributions to Beijing surface SO2 indicates that local emissions from the city give the largest contribution and the sources from the surrounding regions contribute only about 20%. During SO2 polluted or unpolluted days, the contribution from the latter can exceed 30%, and depending upon weather conditions, the contribution may exceed 40%. If the emissions from the surrounding sources during the winter heating season are assumed to be doubled in intensity, their contribution to surface SO2 in Beijing increased from 21% to 35% and 25% to 40% in 2000 and 2001, respectively. Evaluation of 7 types of emission sources identified for Beijing for their relative contribution to the concentration of surface SO2 has shown that area emissions by industrial production and furnaces, though discharging relatively small amounts (less than 1/3 of the total), have the largest contribution to the urban surface SO2, which is the key to the mitigation of the pollutant in the city. 相似文献
482.
In two-dimensional (2D) marine seismic-reflection surveys, out-of-plane rough seafloor bathymetry can cause multiple ocean-bottom reflections that complicate the interpretation of shallow reflections. Although migration corrects for the in-plane position of reflectors, it cannot resolve the inherent ambiguity in their out-of-plane positions. We show how swath bathymetry, routinely collected in many such surveys, can be used to model out-of-plane seafloor reflections and prevent their misinterpretation as subsurface geology. We use both raw and gridded multi-beam bathymetry data to build images that represent seafloor reflections in migrated seismic data. Comparison of these images to the seismic sections reveals whether suspicious features are out-of-plane water bottom reflections or subsurface reflections. Multi-channel seismic surveys across the Marianas intra-oceanic arc system provide examples where rough seafloor topography produced reflections that were initially misinterpreted. We use our seafloor reflection modeling (SRM) approach to help distinguish a possible landslide from a volcanic cone, to help distinguish real from apparent fault-plane reflections bounding a sediment-filled basin, and to verify that a possible magma chamber reflection results from sub-surface structure, not seafloor sideswipe. 相似文献
483.
Kristin Jonsdottir Mattias Lindman Roland Roberts Bjrn Lund Reynir Bdvarsson 《Tectonophysics》2006,424(3-4):195
The distribution of waiting times between time-neighbouring events for a time series obeying the Omori law is examined theoretically and numerically with the aim of understanding the characteristics of these distributions, how these characteristics change (e.g. scale) with the parameters of the Omori series, and thus how empirical waiting time data may be correctly interpreted. It is found that the waiting time distribution, for a single Omori aftershock sequence, consists in general of two power law segments followed by a rapid decay at larger waiting times. The analyses are illustrated using real data from the SIL network on Iceland. This data often shows characteristics predominantly consistent with the Omori law, but there are significant exceptions. We conclude that waiting time distributions and related statistical analysis has meaningful potential for the analysis of earthquake data sets, as a step towards developing physical models of the earthquake process. 相似文献
484.
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486.
A continuous reactor based on the fluidized bed technique was developed in order to study the kinetics and the mechanisms of the initial stages of weathering of albite. Simultaneous determination of Si, Al and Na and the observed low concentrations of the dissolved elements which were always at levels below saturation with respect to possible secondary precipitates, indicate that formation of a residual layer of a few tens of angstroms occurred at the surface of the feldspar. The composition of this layer, enriched in Si and/or Al, is strongly dependent on the pH of the aqueous solution. The formation of the layer is followed by the establishment of a quasi-steady state during which the dissolution of albite tends to become stoichiometric. 相似文献
487.
Roland Rösch 《Aquatic Sciences - Research Across Boundaries》1986,48(1):44-52
Juveniles ofCoregonus lavaretus L. of a body weight (wet weight) between 0.5 and 11g were fed on pond reared livingDaphnia pulicaria. The fish were held in groups of 4 to 8 fish in tanks of a volume of 10 to 20 l at water temperatures of 8, 12, 16 and 20°C.
After a deprivation time of 24 h the fish were fed an amount of livingDaphnia of about 1000 specimen/l. Fish of a body weight (wet weight) less than 1 g showed a continuous food intake until satiation,
whereas the food intake of bigger fish was divided into three phases: During a first feeding period 50 to 73% of the satiation
amount were consumed. This feeding period was followed by a period of no food intake, which was followed by a second feeding
period. At the end of the second feeding period the fish were satiated. The period of no food intake is considered to be a
specific adaptation to planctivory.
The satiation time (min) increased with increasing body weight and increasing water temperature.
The satiation amount, i.e. the amount of food eaten until satiation (mg stomach content, dry weight) increased with increasing
body weight.
The satiation amount expressed in % body weight (dry weight/dry weight) reached a maximum of 10% for fish of a body weight
of 1 g. With increasing body weight it decreased to 5% for fish of 11 g b.wt. At 8°C the satiation amount was significantly
lower than at 12°C.
The experiments were performed at the Limnological Institute, University of Constance, D-7750 Constance, Federal Republic
of Germany. 相似文献
488.
489.
Christoph?MatullaEmail author Brigitta?Hollósi Konrad?Andre Julia?Gringinger Barbara?Chimani Joachim?Namyslo Tobias?Fuchs Markus?Auerbach Carina?Herrmann Brigitte?Sladek Heimo?Berghold Roland?Gschier Eva?Eichinger-Vill 《Theoretical and Applied Climatology》2018,131(1-2):227-243
Air circulation due to the urban heat island (UHI) effect can influence the dispersion of air pollutants in a metropolis. This study focusses on the influence of the UHI effect on particulate matter (PM; including PM2.5 and PM2.5–10) between May and September 2010–2012 in the Taipei basin. Meteorological and PM data were obtained from the sites, owned by the governmental authorities. The analysis was carried out using t test, relative indices (RIs), Pearson product–moment correlation and stepwise regression. The results show that the RI values for PM were the highest at moderate UHI intensity (MUI; 2 °C ≤ UHI < 4 °C) rather than at strong UHI intensity (SUI; 4 °C ≤ UHI) during the peak time for anthropogenic emissions (20:00 LST). Neither the accumulation of PM nor the surface convergence occurred in the hot centre, as shown by the case study. At MUI, more than 89 % of the synoptic weather patterns showed that the weather was clear and hot or that the atmosphere was stable. The variation in PM was associated with horizontal and vertical air dispersion. Poor horizontal air dispersion, with subsidence, caused an increase in PM at MUI. However, the updraft motion diluted the PM at SUI. The stepwise regression models show that the cloud index and surface air pressure determined the variation in PM2.5–10, while cloud index, wind speed and mixing height influenced the variation in PM2.5. In conclusion, a direct relationship between UHI effect and PM was not obvious. 相似文献
490.
Michael Zech Mario Tuthorn Roland Zech Frank Schlütz Wolfgang Zech Bruno Glaser 《Journal of Paleolimnology》2014,51(2):241-251
We investigated a late glacial–Holocene lacustrine sediment archive located at 4,050 m a.s.l. in the small carbonate-free catchment of Lake Panch Pokhari, Helambu Himal, Nepal. A δ18O sugar biomarker record was established by applying novel compound-specific δ18O analysis of plant sugar biomarkers (Zech and Glaser in Rapid Commun Mass Spectrom 23:3522–3532, 2009). This method overcomes analytical challenges such as extraction and purification faced by previous methods aimed at using δ18O of aquatic cellulose as a paleoclimate proxy. The δ18O results for sugar biomarkers arabinose, xylose and fucose agree well and reveal a pronounced trend towards lower δ18O values during the deglaciation and the onset of the Bølling/Allerød interstadial. By contrast, the period of the Younger Dryas is characterized by higher δ18O values. The early Holocene again reveals lower δ18O values. We suggest that our lacustrine δ18O record reflects coupled hydrological and thermal control. It is strongly related to changes in the oxygen isotopic composition of paleo-precipitation and resembles the δ18O records of Asian speleothems. With respect to the ‘amount effect,’ the record is interpreted as reflecting the Indian Summer Monsoon intensity. The precipitation signal is, however, amplified in our record by evaporative 18O enrichment that is controlled by the ratio of precipitation to evaporation. We suggest that our δ18O record reflects the variability of the Indian Summer Monsoon, which was strong during the Bølling/Allerød interstadial and early Holocene, but weak during the Younger Dryas stadial. This interpretation is corroborated by a pollen-based index for Lake Panch Pokhari that estimated the strength of the Indian Summer Monsoon versus the strength of the Westerlies. Millennial-scale synchronicity with the Greenland δ18O temperature records highlights the previously suggested strong teleconnections between the Asian Monsoon system and North Atlantic climate variability. 相似文献