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111.
In order to determine and assess their status sediments from the German coastal waters of the baltic sea were analyzed for structural parameters and for several groups of harmful substances. Regarding all groups of harmful substances, i.e. nutrients, heavy metals and organic toxicants the sediments of the eastern sections investigated (Strelasund, Peenestrom and Stettin Lagoon) are generally more polluted than the sediments of the other ones.The sediments of the examined sections of the Baltic coast compare with North Sea sediments by factors of between 0.05 and 4 with regard to heavy metals.Because of the variability of the concentration of harmful substances in the various coastal sections, it is imperative to make a differentiated assessment of the polluted sediments and to set district-related targets for the various sections of the Baltic coast. 相似文献
112.
To predict the evolution of glaciers in an enhanced greenhouse climate, results from a global climate model, a glacier melt/accumulation model, and a glacier flow model were combined. The method was applied to Storglaciären, a small well-studied glacier in northern Sweden. The difference between the present climate and a 2 × CO2 climate around the year 2050 was extracted from a model experiment with the ECHAM4-T106 high resolution climate model for time slices at present and in 2050, using prescribed boundary conditions of sea surface temperature and sea-ice distribution, which are derived from a lower resolution transient run of the ECHAM4-T42/OPIC-coupled atmosphere ocean model between present and 2050. The local climatic conditions on the glacier for 2050 were obtained by adding the modelled local climate changes to the observed local present-day climate. The combination of the comprehensive models presented offers a tool to test and calibrate simplified models which are applicable to a much larger sample of glaciers. For the region of Storglaciären, the GCM projected temperature is found to increase most strongly during the winter months, but also shows a warming during the transition from spring to summer, and again between summer and fall, thus extending the melt season by three to four weeks. Precipitation, on the other hand, decreases by approximately 5% during May to September while there is a stronger increase of approximately 14% for the rest of the year. The consequent increase in winter accumulation on Storglaciären is more than compensated by the increase in ablation during the melt season. The glacier flow model predicts a 300 m retreat of the glacier terminus by the middle of the next century, and a loss of 30% of the present ice mass. 相似文献
113.
This paper demonstrates a practical simulation approach to analyze domestic water demand and its future uncertainty in water
scarce areas through a case study of Beijing, China. Analytic models and a forecasting model were constructed using statistic
and econometric regression approaches. The analytic models were used to analyze the interrelationships between domestic water
demand and some socio-economic factors of Beijing. The forecasting model was applied to predict domestic water demand from
2009 to 2015, and this model was validated by comparing the prediction values with the observations. Scenario analysis was
applied to simulate uncertainty and risks in domestic water demand in the future. The simulation results proved that domestic
water demand will increase from 13.9×108 m3 to 16.7×108 m3 from 2009 to 2015. Three more sustainable strategies were also found through scenario analysis. The simulation and modeling
approaches and results would be very supportive for water decision makers in allocating water efficiently and making sustainable
water strategies. 相似文献
114.
Sylvestre Gug Philippe Schaeffer Pierre Adam Stéphane Klein Estelle Motsch Pierre Albrecht 《Organic Geochemistry》2009,40(8):876-884
In order to confirm the tentative structure of a dithiane sulfide with a bicyclic squalene hydrocarbon skeleton representing the predominant alkyl sulfide in Shell Beach samples from the Monterey Formation (Miocene, CA) and also occurring in various immature sulphur-rich sediments [Schouten, S., Sinninghe Damsté, J.S., de Leeuw, J.W., 1995. A novel triterpenoid carbon skeleton in immature sulphur-rich sediments. Geochimica et Cosmochimica Acta 59, 953–958], synthesis of a reference compound bearing two thiochromane moieties has been carried out. The product was obtained as a diastereomeric mixture appearing in the form of five peaks (partly) resolved in gas chromatography (GC). This is in sharp contrast with the geochemical compound, which appears as a single broad peak in GC. Co-elution experiments showed that none of the peaks from the synthetic mixture coelute in GC with that of the geochemical sulfide. Furthermore, the different synthetic isomers have identical mass spectra, which are clearly distinct from that of the naturally-occurring compound. The results unambiguously indicate that the natural compound is not the dithiane triterpenoid originally envisaged. Instead, we propose that the compound has a structure of a bicyclic squalene derivative bearing two “S-spiro”-type moieties as is the case for other sulfides related to regular polycyclic polyprenoids and hopanoids in Monterey sediments. 相似文献
115.
Hamdy A. El Desouky Philippe Muchez Adrian J. Boyce Jens Schneider Jacques L. H. Cailteux Stijn Dewaele Albrecht von Quadt 《Mineralium Deposita》2010,45(8):735-763
The sediment-hosted stratiform Cu–Co mineralization of the Luiswishi and Kamoto deposits in the Katangan Copperbelt is hosted
by the Neoproterozoic Mines Subgroup. Two main hypogene Cu–Co sulfide mineralization stages and associated gangue minerals
(dolomite and quartz) are distinguished. The first is an early diagenetic, typical stratiform mineralization with fine-grained
minerals, whereas the second is a multistage syn-orogenic stratiform to stratabound mineralization with coarse-grained minerals.
For both stages, the main hypogene Cu–Co sulfide minerals are chalcopyrite, bornite, carrollite, and chalcocite. These minerals
are in many places replaced by supergene sulfides (e.g., digenite and covellite), especially near the surface, and are completely
oxidized in the weathered superficial zone and in surface outcrops, with malachite, heterogenite, chrysocolla, and azurite
as the main oxidation products. The hypogene sulfides of the first Cu–Co stage display δ34S values (−10.3‰ to +3.1‰ Vienna Canyon Diablo Troilite (V-CDT)), which partly overlap with the δ34S signature of framboidal pyrites (−28.7‰ to 4.2‰ V-CDT) and have ∆34SSO4-Sulfides in the range of 14.4‰ to 27.8‰. This fractionation is consistent with bacterial sulfate reduction (BSR). The hypogene sulfides
of the second Cu–Co stage display δ34S signatures that are either similar (−13.1‰ to +5.2‰ V-CDT) to the δ34S values of the sulfides of the first Cu–Co stage or comparable (+18.6‰ to +21.0‰ V-CDT) to the δ34S of Neoproterozoic seawater. This indicates that the sulfides of the second stage obtained their sulfur by both remobilization
from early diagenetic sulfides and from thermochemical sulfate reduction (TSR). The carbon (−9.9‰ to −1.4‰ Vienna Pee Dee
Belemnite (V-PDB)) and oxygen (−14.3‰ to −7.7‰ V-PDB) isotope signatures of dolomites associated with the first Cu–Co stage
are in agreement with the interpretation that these dolomites are by-products of BSR. The carbon (−8.6‰ to +0.3‰ V-PDB) and
oxygen (−24.0‰ to −10.3‰ V-PDB) isotope signatures of dolomites associated with the second Cu–Co stage are mostly similar
to the δ13C (−7.1‰ to +1.3‰ V-PDB) and δ18O (−14.5‰ to −7.2‰ V-PDB) of the host rock and of the dolomites of the first Cu–Co stage. This indicates that the dolomites
of the second Cu–Co stage precipitated from a high-temperature, host rock-buffered fluid, possibly under the influence of
TSR. The dolomites associated with the first Cu–Co stage are characterized by significantly radiogenic Sr isotope signatures
(0.70987 to 0.73576) that show a good correspondence with the Sr isotope signatures of the granitic basement rocks at an age
of ca. 816 Ma. This indicates that the mineralizing fluid of the first Cu–Co stage has most likely leached radiogenic Sr and
Cu–Co metals by interaction with the underlying basement rocks and/or with arenitic sedimentary rocks derived from such a
basement. In contrast, the Sr isotope signatures (0.70883 to 0.71215) of the dolomites associated with the second stage show
a good correspondence with the 87Sr/86Sr ratios (0.70723 to 0.70927) of poorly mineralized/barren host rocks at ca. 590 Ma. This indicates that the fluid of the
second Cu–Co stage was likely a remobilizing fluid that significantly interacted with the country rocks and possibly did not
mobilize additional metals from the basement rocks. 相似文献
116.
Remy Albrecht Jean Christophe GourryMarie-Odile Simonnot Corinne Leyval 《Journal of Applied Geophysics》2011,75(3):558-564
Several laboratory studies have recently demonstrated the utility of geophysical methods for the investigation of microbial-induced changes over contaminated sites. However, it remains difficult to distinguish the effects due to the new physical properties imparted by microbial processes, to bacterial growth, or to the development of bacterial biofilm. We chose to study the influence of biofilm formation on geophysical response using complex conductivity measurements (0.1-1000 Hz) in phenanthrene-contaminated media. Biotic assays were conducted with two phenanthrene (PHE) degrading bacterial strains: Burkholderia sp (NAH1), which produced biofilm and Stenophomonas maltophilia (MATE10), which did not, and an abiotic control. Results showed that bacterial densities for NAH1 and MATE10 strains continuously increased at the same rate during the experiment. However, the complex conductivity signature showed noticeable differences between the two bacteria, with a phase shift of 50 mrad at 4 Hz for NAH1, which produced biofilm. Biofilm volume was quantified by Scanning Confocal Laser Microscopy (SCLM). Significant correlations were established between phase shift decrease and biofilm volume for NAH1 assays. Results suggest that complex conductivity measurements, specifically phase shift, can be a useful indicator of biofilm formation inside the overall signal of microbial activity on contaminated sites. 相似文献
117.
New evidence for two sharp replacement fronts during albitization of granitoids from northern Aravalli orogen,northwest India 总被引:1,自引:0,他引:1
Parampreet Kaur Naveen Chaudhri Albrecht W. Hofmann 《International Geology Review》2015,57(11-12):1660-1685
We present new evidence of infiltration metasomatism in granitoids that were albitized in a process that produced two sharp replacement fronts, both of which are clearly visible in the field. The two fronts advanced through the original granite simultaneously, but at different rates. Here we focus mainly on the Ajitgarh intrusive in the northern Aravalli orogen of northwest India. This intrusion shows geographically well-defined metasomatic zones on the outcrop scale as well as a large volume of original ferroan granite, both of which were poorly preserved in most of the previously studied Khetri granites. Stage I metasomatism transformed the grey original granite to pink microcline–albite granite, and stage II converted the microcline–albite granite to white albite granite. Both these reaction fronts are sharp and are easily recognized in the field by their different colours. The mineralogical and chemical changes during the first stage are expressed by transformation of original oligoclase to albite, biotite (annite-rich) and hastingsite (amphibole) to hastingsite with low XFe values, dehydration, gain in Na, and losses in Fe and Rb. The second stage of metasomatism caused almost complete conversion of microcline to albite and complete or nearly complete disappearance of amphibole. Chemically, these changes are manifested by substantial gain in Na and extreme losses in K, Rb, Ba, Ca, Sr, Fe, and Mg. Depending on the modal abundances of amphibole, stage II albitized rocks are depleted in light rare earth elements or heavy rare earth elements or both, signifying that rare earth elements are principally hosted by mafic phases. The disparity in whole-rock δ18O values during both stages of albitization is related to the variations in modal amounts of Si-bearing phases. The replacement microstructures are in accord with the fluid-mediated phase transformations by a coupled dissolution–precipitation mechanism. The albitizing event took place at low temperatures of 350–400 °C and the fluid was metamorphic in nature. 相似文献
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