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21.
不同光生物反应器培养坛紫菜
丝状体的比较研究 总被引:1,自引:0,他引:1
Vegetative cells of Porphyra haitanensis sporophytes were grown in a bubble-column and a draft-tube internal-loop airlift bioreactor at 20℃ with an illuminance of 40μmol photons m-2 s-1 for 20days. The draft-tube internal-loop airlift bioreactor yielded maximum cell density of 4850mg DCW (Dried Cell Weight)/L and higher growth rate of 0.094/d, compared to the bubble-column, 3950mg DCW/L and 0.086/d, respectively. The advantages were related to the more homogeneous fluid dynamic characteristics in the draft-tube internal-loop airlift bioreactor than the bubble-column bioreactor. 相似文献
22.
Ana Moreno Blas L. Valero‐Garcés Montserrat Jiménez‐Sánchez María José Domínguez‐Cuesta M. Pilar Mata Ana Navas Penélope González‐Sampériz Heather Stoll Pedro Farias Mario Morellón J. Pablo Corella Mayte Rico 《第四纪科学杂志》2010,25(7):1076-1091
A sedimentological and geochemical study of the Lago Enol sequence (Cantabrian Mountains, northern Spain), together with detailed geomorphological mapping, provides a first record of glacier evolution and climate change over the last 40 ka in the Picos de Europa National Park. The Enol glacier retreated from its maximum extent prior to 40 ka BP as demonstrated by the onset of proglacial lacustrine sedimentation in two glaciated depressions: the Comella hollow to the north (before 40 ka BP) and the Lago Enol (before 38 ka BP). These results support previous evidence that the maximum extent of southern European glaciers occurred earlier than in northern Europe. Alternation of homogeneous and laminated proglacial sediments during the glacier retreat illustrate a dynamic glacial evolution during the Marine Isotope Stage (MIS) 3 (40–26 ka BP). A slight warming is detected at 26 ka ago with the change from proglacial sediments (in a lake located in contact to the glacier) to glaciolacustrine sedimentation (in a non‐contact or distal lake). Finally, the onset of organic‐rich sediments took place at 18 ka ago. This last transition occurred in two phases, similarly to the North Atlantic Last Termination, suggesting a link between North Atlantic Deep Water formation oscillations and palaeohydrological variability in the Cantabrian Mountains. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
23.
Soil water repellency has been conventionally considered as a fire‐induced effect, but an increasing number of studies have suggested that natural background repellency occurs in many soil types, and many of them have suggested that water repellency can be re‐established over time after being destroyed. An experimental fire was conducted to study changes of the soil surface during the first 18 months following intense burning. The main objectives of this paper are as follows: (1) to investigate in situ water repellency changes at three soil depths (0, 2 and 4 cm) immediately after burning; (2) to evaluate the medium‐term evolution of water repellency under field conditions; and (3) to outline the main hydrological consequences of these changes. Also, different water repellency tests (water drop penetration time, ethanol percentage test (EPT) and contact angle (CA) between water drops and the soil surface) were carried out for comparison purposes. Field experiments showed that soil water repellency was partly destroyed after intense burning. Changes were relatively strong at the soil surface, but diminished progressively with depth. Levels of water repellency were practically re‐established 18 months after burning. This suggests that water repellency in the studied area is not necessarily a consequence of fire, but can instead be a natural attribute. Finally, although limited in time, destruction of soil water repellency has important consequences for runoff flow generation and soil loss rates, and, indirectly, for water quality. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
24.
F. Flores-Verdugo F. González-Farías O. Ramírez-Flores F. Amezcua-Linares A. Yáñez-Arancibia M. Alvarez-Rubio J. W. Day 《Estuaries and Coasts》1990,13(2):219-230
Aquatic primary productivity, mangrove ecology, and fish community dynamics were investigated in the Teacapán-Agua Brava lagoon-estuarine system, the most extensive mangrove ecosystem on the Pacific coast of Mexico with three species of mangroves distributed heterogeneously (Laguncularia racemosa, Rhizophora mangle, andAvicennia germinans). Tree density was 3,203 trees ha?1 and basal area was 14.0 m2 ha?1. Litterfall was 1,417 g m?2 yr?1, characteristic of a productive riverine forest. The degradation constant forLaguncularia racemosa leaves varied from 1.71 to 4.7 yr?1 and mean annual net aquatic productivity was 0.41 g C m?3 d?1. There were high concentrations of humic substances (up to 150 mg l?1) early in the wet season. Seasonal variations of the above parameters seemed closely related to the ecology of fish populations. There were 75 fish species distributed in two principal assemblages associated with wet and dry seasons. Diversity and biomass analysis indicated 18 dominant species. Total biomass of the community in this coastal system was estimated at 10 g wet wt m?2. The highest biomass occurred in the wet season. The most common fish species wereMugil curema, Achirus mazatlanus, Galeichthys caerulescens, Arius liropus, Diapterus peruvianus, Lile stolifera, Centropomus robalito, andEucinostomus sp., all of which have fishery importance. Primary productivity and fish community ecology are controlled by habitat characteristics, river discharge, and climatic seasonality. 相似文献
25.
26.
Carlos Pecharromán T. González-Carreño Juan E. Iglesias 《Physics and Chemistry of Minerals》1995,22(1):21-29
The infrared complex permittivity functions of three varieties of maghemite, γ-Fe2O3, having different degrees of vacancy ordering, have been determined from their IR reflectance spectra, measured at near to normal incidence on pressed powder pellets. The optical constants therefrom obtained have been verified by using them in the simulation of the corresponding absorption spectra for KBr-diluted pellets, and these are in excellent agreement with the experimental spectra. All calculations are based on a procedure for the estimation of the effective dielectric function of a mixture, which incorporates percolation features, recently developed by the authors. 相似文献
27.
用二维非静力完全弹性的中-γ尺度数值模式模拟了移动性热岛的大气边界层特征。试验中,热岛移速取为4m·s^-1,热岛强度取△θg=60K和30K两种。△θg=60K时,在热岛后方出现了强烈的垂直运动并形成了水平尺度为3-5km的局地环流,最大上升速度100cm·s^-1,出现在低层300-400m高度;△θg=30K时,移动热岛的边界效应比前大为减弱,且不再出现闭合的局地环流。 相似文献
28.
Modelling the variability of midlatitude storm activity on decadal to century time scales 总被引:1,自引:0,他引:1
Irene Fischer-Bruns H. von Storch J. F. González-Rouco E. Zorita 《Climate Dynamics》2005,25(5):461-476
The output of several multi-century simulations with a coupled ocean–atmosphere general circulation model is examined with
respect to the variability of global storm activity in winter on time scales of decades and longer. The frequency of maximum
wind speed events within a grid box, using the lower limits on the Beaufort wind speed scale of 8 and 10 Bft as thresholds,
is taken as the characteristic parameter. Two historical climate runs with time-dependent forcing of the last five centuries,
one control simulation, and three climate change experiments are considered. The storm frequency shows no trend until recently.
Global maps for the industrially influenced period hardly differ from pre-industrial maps, even though significant temperature
anomalies temporarily emerge in the historical runs. Two indicators describing the frequency and the regional shift of storm
activity are determined. In historical times they are decoupled from temperature. Variations in solar and volcanic forcing
in the historical simulations as well as in greenhouse gas concentrations for the industrially influenced period are not related
to variations in storm activity. Also, anomalous temperature regimes like the Late Maunder Minimum are not associated with
systematic storm conditions. In the climate change experiments, a poleward shift of storm activity is found in all three storm
track regions. Over the North Atlantic and Southern Ocean, storm activity increases, while it decreases over the Pacific Ocean.
In contrast to the historical runs, and with the exception of the North Pacific storm frequency index, the storm indices parallel
the development of temperature, exceeding the 2 σ-range of pre-industrial variations in the early twenty-first century. 相似文献
29.
Partitioning,bioavailability and origin of heavy metals from the Nador Lagoon sediments (Morocco) as a basis for their management 总被引:2,自引:0,他引:2
Nador Lagoon sediments show low trace element concentrations, and, in relation to the lagoon geochemical baseline, only some
anomalies for As, Cd, Cu and Pb in the NW of the lagoon deserve to be outstanding. The distribution of major, minor and trace
elements in the lagoon allows a breakdown in four zones. Between “Beni Ensar” and “Atelouane” (zone A), a quite confined zone
rich in organic matter and S, the most important trace-element anomalies (As, Cd, Co, Cu, Mn, Pb, Zn) were found, mainly around
industry and old mining activities. In the surrounding of the city of Nador (zone B), the anomalies correspond to Mn, Cu and
Zn. The coastal barrier and Kebdana channel (zone C) show moderately concentrations of Cd, Cr and Ni at specific sites. The
less polluted area is the SE of the lagoon (zone D), with no outstanding anomaly. In lagoon sediments, metal bioavailability
is very low. The metal partitioning patterns show that Cu, Pb and Zn present a low availability because they are bounded to
the residual, non-mobile phases of the sediments. Only in some sites, the fraction was associated with organic matter, which
could be liberated easily. Arsenic is concentrated in both the residual phases and the organic matter, the latter being more
available. Cadmium is mainly concentrated in some samples in the interchangeable fraction, which could be considered as a
potentially toxic element because it is easily released. Concerning the origin of these trace elements, those found in zone A
correspond mostly to a natural source by weathering of mount Gourougou volcanic rocks (As, Co, Cu, Pb and Zn), and to an anthropogenic
origin (Cd) owing to the presence of industry and old mines. In zone B, contributions of Cu and Zn enter the lagoon through
soil weathering and river-borne, and as anthropogenic pollution from urban wastes. In zone C the most important pollutant
is Cd deduced to be of anthropogenic origin from the close industry and intensive agriculture area. In spite of the intense
socio-economic activities developed in the Nador Lagoon (agriculture, industry, fishing, tourism) trace element concentrations
in the sediments are low and with scarce bioavailability. Only the NW sector is relativity polluted because of geogenic features. 相似文献
30.
O'Leary González Leonardo Alvarez Mariangela Guidarelli Giuliano F. Panza 《Pure and Applied Geophysics》2007,164(10):1985-2007
An overview of the crust and upper mantle structure of Central America and the Caribbean region is presented as a result of
the processing of more than 200 seismograms recorded by digital broadband stations from SSSN and GSN seismic networks. Group
velocity dispersion curves are obtained in the period range from 10s to 40s by FTAN analysis of the fundamental mode of the
Rayleigh waves; the error of these measurements varies from 0.06 and 0.09 km/s. From the dispersion curve, seven tomographic
maps at different periods and with average spatial resolution of 500 km are obtained. Using the logical combinatorial classification
techniques, eight main groups of dispersion curves are determined from the tomographic maps and eleven main regions, each
one characterized by one kind of dispersion curves, are identified. The average dispersion curves obtained for each region
are extended to 150s by adding data from a larger-scale tomographic study (Vdovin et al., 1999) and inverted using a nonlinear procedure. A set of models of the S-wave velocity vs. depth in the crust and upper
mantle is found as a result of the inversion process. In six regions we identify a typically oceanic crust and upper mantle
structure, while in the other two the models are consistent with the presence of a continental structure. Two regions, located
over the major geological zones of the accretionary crust of the Caribbean region, are characterized by a peculiar crust and
upper mantle structure, indicating the presence of lithospheric roots reaching, at least, about 200 km of depth. 相似文献