排序方式： 共有21条查询结果，搜索用时 15 毫秒
1.
Distinguishing the effect of diapir growth on magnetic fabrics of syn‐diapiric overburden rocks: Basque–Cantabrian basin,Northern Spain 
下载免费PDF全文
下载免费PDF全文 An analysis of Anisotropy of Magnetic Susceptibility was done on Aptian–Albian sediments from the Basque–Cantabrian basin. Samples were collected from 39 sites in the halokinetic sequences of the Bakio, Bermeo, Guernica and Mungia diapirs; 28 sites were sampled close to diapirs, and 11 sites were far from the diapir edges. The magnetic foliation is parallel to bedding, suggesting it reflects depositional and compaction processes, whereas the orientation of magnetic lineation varies. Far from the diapir edges, the magnetic lineation is interpreted as being related to the regional Pyrenean compression. Close to diapir edges, the observed behaviour shows that diapirs, predominantly formed by rigid ophites, have acted as buttresses, with shadow areas at their northern faces being protected from the Pyrenean compression. The high sensitivity of AMS makes it a very useful tool to distinguish deformation in halokinetic sequences related to diapir growth from that related to subsequent compression. 相似文献
2.
Kristie L. Ebi Elisabet Lindgren Jonathan E. Suk Jan C. Semenza 《Climatic change》2013,118(2):355-365
Climate change has the potential to increase the challenge of preventing and controlling outbreaks of infectious diseases. An adaptation assessment is an important aspect of designing and implementing policies and measures to avoid, prepare for, and effectively respond to infectious diseases outbreaks. The main steps in conducting an adaptation assessment include: 1) evaluating the effectiveness of policies and measures that address the burden of climate-sensitive infectious diseases; 2) identifying options to manage the health risks of current and projected climate change; 3) evaluating and prioritizing the options; 4) identifying human and financial resources needs, and possible barriers, constraints, and limits to implementation; and 5) developing monitoring and evaluation programs to ensure continued effectiveness of policies and measures in a changing climate. Optimally, relevant stakeholders are optimally included throughout the adaptation assessment. Although the process of conducting an assessment is similar across nations and regions, the context and content will vary depending on local circumstances, socioeconomic conditions, legal and regulatory frameworks, and other factors. The European Centers for Disease Prevention and Control developed guidelines for conducting assessments, with sufficient consistency to facilitate learning lessons across assessments. 相似文献
3.
Linking sedimentation rates and large‐scale architecture for facies prediction in nonmarine basins (Paleogene,Almazán Basin,Spain) 下载免费PDF全文
下载免费PDF全文 Luis Valero Pedro Huerta Miguel Garcés Ildefonso Armenteros Elisabet Beamud Miriam Gómez‐Paccard 《Basin Research》2017,29(Z1):213-232
This article focuses on the relationships between the large‐scale stratigraphic architecture of the Almazán basin infill and the sedimentation rates (SR) calculated for precise time intervals. Our aim was to improve the understanding of the timing and causes of the architectural changes, their significance in terms of accommodation space and sediment supply and their relationship with climate and tectonics. The study area includes the Gómara fluvial fan, the main sediment transfer system of the Almazán basin during Paleogene times. Its large‐scale architecture shifted through time between a stacking pattern of low density ribbon‐like and high density sheet‐like channel fills. Laterally to the fluvial system, mudstone and evaporitic mudstone units represented evaporitic mudflats which passed laterally into palustrine/lacustrine limestone units interpreted as lakes and ponds. Stacked calcretes occurred in distal alluvial and distal floodplain settings. A magnetostratigraphy encompassing 2600 m guided by available fossil mammal biochronology has provided a temporal framework that spans the complete Paleogene infill of the basin, from Late Lutetian to Late Oligocene, filling a gap in the Cenozoic chronostratigraphy of Spanish basins. This permits to constrain the kinematics of the structures both in the basin and in its margins, and to provide the timing for the depositional sequences. These data, combined with a magnetostratigraphic map, where magnetic reversals were traced through the Gómara monocline, allow a detailed analysis of the SR variability across the fluvial system and its adjacent depositional environments. The results show that high sedimentation rates (around 30–40 cm kyr?1) are related to fluvial environments with low density ribbon‐shaped channels, while low SR (around or below 10 cm kyr?1) are related to high density sheet‐like channels. Laterally, mud dominated environments with high SR (15–20 cm kyr?1) grade into palustrine/lacustrine carbonated environments with low SR (around 9 cm ky?1). The lowest SR (about 3 cm kyr?1) are related to the development of stacked calcrete profiles in distal floodplain and in the connection of distal alluvial and palustrine/lacustrine units. 相似文献
4.
In order to investigate the photobleaching potential of estuarine waters from different depths and redox conditions and with varying degree of biological activity, filtered, unfiltered and chloroform-poisoned water samples from the Baltic Sea were exposed to ambient sunlight. Fluorescence, at excitation 350 nm and emission 450 nm, was used as an indication of humic substance concentration. Fluorescence and organic carbon concentration were measured at regular time intervals during light exposure. We found that the decrease in humic substance fluorescence can be fitted to an exponential decay function. The fluorescence half-lives were within the range 0.4 – 4.6 days in different water masses, with fluorescence decreasing to between 20% and 60% of initial concentration, respectively. Results from the curve fitting procedure indicate a rest concentration of humic substance fluorescence, similar among the sampled sites, that is resistant to further photochemical degradation. The largest relative decreases in fluorescence were found in deep waters, but samples from deep waters also had a higher fluorescence rest concentration than samples from surface waters. Biological activity was reduced by filtering the samples through 0.2μm pore size filters or adding chloroform. No statistically significant differences were found after 3 days of irradiation between samples with and without treatment to reduce biological activity. The highest initial fluorescence values and the largest fluorescence decrease were found in the anoxic waters of the Gotland Deep. The organic carbon concentrations decreased 3–7% at all stations. The shortest half-life of humic substance, and the largest decrease in organic carbon concentrations, were found in samples from the northern basins of the Baltic Sea. 相似文献
5.
Tanja Barth Sylvi Hiland Per Fotland Kjell Magne Askvik Bent Skaare Pedersen Anna Elisabet Borgund 《Organic Geochemistry》2004,35(11-12):1513
Twelve oil samples have been characterised by titration, FT-IR and chromatographic analysis to determine the differences between the organic acid composition of biodegraded and non-biodegraded oils. The biodegraded oils have higher total acid and total base contents, both by titration and extraction. The molecular weight ranges of the extracted acids are lowest in the biodegraded oils, and the equivalent weight calculations indicate a dominance of multi-functional molecules. Gel permeation chromatography gives a molecular weight range with most of the molecules between 300 and 500 g/mol. FT-IR shows that the extracted acids from biodegraded oils are more carboxylic and aliphatic while the non-degraded oils are more phenolic. Molecular analysis of the derivatised extracts give UCM envelopes for biodegraded oils, and no molecular identification. The results indicate that the acidic constituents in biodegraded oils are a product of the biodegradation, as the composition is very different from the non-biodegraded oils. 相似文献
6.
A combined assessment of beach occupancy and public perceptions of beach quality: A case study in the Costa Brava, Spain 总被引：1，自引：0，他引：1
Elisabet Roca Claudia Riera Míriam Villares Rosa Fragell Rosa Junyent 《Ocean & Coastal Management》2008,51(12):839-846
The main objective of this paper is to present an approach that contributes to evaluate beach quality based on a combined analysis of beach occupancy and the perception of beach users. The study area is a major Mediterranean tourist destination in NE Spain. Six beaches that fulfilled different environmental and social criteria were assessed. Sampling took place during 2004 and 2005. An analysis of beach occupancy showed that highly accessible urban beaches suffer the most from overcrowding. A comparison of the two approaches (occupancy and perception) indicates that a higher sand availability increased user satisfaction, although not as much as might have been expected because other parameters are also highly relevant in evaluating beach quality from the perspective of beach user such as physical characteristics, landscape and facilities. 相似文献
7.
K.O. Buesseler C. Lamborg P. Cai R. Escoube R. Johnson S. Pike P. Masque D. McGillicuddy E. Verdeny 《Deep Sea Research Part II: Topical Studies in Oceanography》2008,55(10-13):1426
We examined the impact of a cyclonic eddy and mode-water eddy on particle flux in the Sargasso Sea. The primary method used to quantify flux was based on measurements of the natural radionuclide, 234Th, and these flux estimates were compared to results from sediment traps in both eddies, and a 210Po/210Pb flux method in the mode-water eddy. Particulate organic carbon (POC) fluxes at 150 m ranged 1–4 mmol C m−2 d−1 and were comparable between methods, especially considering differences in integration times scales of each approach. Our main conclusion is that relative to summer mean conditions at the Bermuda Atlantic Time-series Study (BATS) site, eddy-driven changes in biogeochemistry did not enhance local POC fluxes during this later, more mature stage of the eddy life cycle (>6 months old). The absence of an enhancement in POC flux puts a constraint on the timing of higher POC flux events, which are thought to have caused the local O2 minima below each eddy, and must have taken place >2 months prior to our arrival. The mode-water eddy did enhance preferentially diatom biomass in its center, where we estimated a factor of three times higher biogenic Si flux than the BATS summer average. An unexpected finding in the highly depth-resolved 234Th data sets is narrow layers of particle export and remineralization within the eddy. In particular, a strong excess 234Th signal is seen below the deep chlorophyll maxima, which we attribute to remineralization of 234Th-bearing particles. At this depth below the euphotic zone, de novo particle production in the euphotic zone has stopped, yet particle remineralization continues via consumption of labile sinking material by bacteria and/or zooplankton. These data suggest that further study of processes in ocean layers is warranted not only within, but below the euphotic zone. 相似文献
8.
The distribution of barium and other elements related to biological productivity has been studied in two Palaeocene sections from the Middle East. In the bathyal Ben Gurion section, Israel, Ba* (= Ba/Al2O3× 15%) concentrations are low, in the range 0.04% to 0.3% in the lower Palaeocene, and very high, 1% to 2%, throughout most of the upper Palaeocene. In the neritic Gebel Aweina section in Egypt Ba* values are low, < 0.1%, throughout the entire Palaeocene. The Ba* enrichments at Ben Gurion and their correlations with increases in P2O5 and opaline silica, and local and global δ13C maxima, indicate that upwelling and high productivity were important in this region during the late Palaeocene. The absence of Ba* enrichments in the shallower Gebel Aweina section probably reflects the strong depth dependence of biobarium deposition. In the uppermost Palaeocene, at the level where the global benthic extinction event is registered, Ba* concentrations in the Ben Gurion section increase to anomalous 6%. which suggests that upwelling and possibly wind strengths intensified during this event. The results speak against deep-water formation in this region since downwelling and not upwelling is required. 相似文献
9.
J. Kirk Cochran Juan Carlos Miquel Robert Armstrong Scott W. Fowler Pere Masqu Beat Gasser David Hirschberg Jennifer Szlosek Alessia M. Rodriguez y Baena Elisabet Verdeny Gillian M. Stewart 《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(18):1487-1501
Disequilibrium between 234Th and 238U in water column profiles has been used to estimate the settling flux of Th (and, by proxy, of particulate organic carbon); yet potentially major non-steady-state influences on 234Th profiles are often not able to be considered in estimations of flux. We have compared temporal series of 234Th distributions in the upper water column at both coastal and deep-water sites in the northwestern Mediterranean Sea to coeval sediment trap records at the same sites. We have used sediment trap records of 234Th fluxes to predict temporal changes in water column 234Th deficits and have compared the predicted deficits to those measured to determine whether the time-evolution of the two coincide. At the coastal site (327 m water depth), trends in the two estimates of water column 234Th deficits are in fairly close agreement over the 1-month deployment during the spring bloom in 1999. In contrast, the pattern of water column 234Th deficits is poorly predicted by sediment trap records at the deep-water site (DYFAMED, 2300 m water depth) in both 2003 and 2005. In particular, the transition from a mesotrophic to an oligotrophic system, clearly seen in trap fluxes, is not evident in water column 234Th profiles, which show high-frequency variability. Allowing trapping efficiencies to vary from 100% does not reconcile the differences between trap and water column deficit observations; we conclude that substantial lateral and vertical advective influences must be invoked to account for the differences.Advective influences are potentially greater on 234Th fluxes derived from water column deficits relative to those obtained from traps because the calculation of deficits in open-ocean settings is dominated by the magnitude of the “dissolved” 234Th fraction. For observed current velocities of 5–20 cm s−1, in one radioactive mean-life of 234Th, the water column at the DYFAMED site can reflect 234Th scavenging produced tens to hundreds of kilometers away. In contrast, most of the 234Th flux collected in shallow sediment traps at the DFYFAMED site was in the fraction settling >200 m d−1; in effect the sediment trap can integrate the 234Th flux over distances 40-fold less than water column 234Th distributions. In some sense, sediment trap and water column sampling for 234Th provide complementary pictures of 234Th export. However, because the two methods can be dominated by different processes and are subject to different biases, their comparison must be treated with caution. 相似文献
10.
The calibration of the European Paleogene mammal biochronology with the international reference geochronological scale is unconstrained due to the lack of direct marine-continental correlations and insufficient robust magnetostratigraphic data for mammal fossil-bearing sequences. The currently accepted European continental biochronology argues for a correlation of the Paleogene MP14 to MP16 mammal reference levels with the Bartonian stage, and of the MP17 to MP20 levels with the Priabonian. However, new magnetostratigraphic data of the continental sediments of the south-central Pyrenees substantially challenge this chronology. Our new results from the La Pobla de Segur Basin and Sierra de Sis have been integrated into the framework of previous marine-continental stratigraphic correlations and magnetostratigraphic data of the south-central Pyrenees. In this new chronology, MP14 and MP15 reference levels correspond to the Lutetian, whereas MP16 and early MP17 correlate with the early Bartonian. This calibration represents a significant revision of currently accepted marine-continental correlations in Europe, but is not in conflict with the available biostratigraphic data of the south Pyrenean Ebro foreland basin and other western European reference basins. 相似文献