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1.
This study reports the analysis of polycyclic aromatic compound (PAC) metabolites, as biomarkers of exposure to PACs in marine environment. PAC metabolites were measured in bile samples from 14 species of demersal fish caught in the São Sebastião Channel (SSC), SE Brazilian coastline. Naphthalene (NPH) equivalents, phenanthrene (PHN) equivalents, and benzo[a]pyrene (BaP) equivalents were quantified using a reverse-phase high-performance liquid chromatography coupled with fluorescence detection method. For all samples, the means (±standard deviation, n = 37) of concentrations obtained for NPH, PHN, and BaP equivalents were, respectively, 290,000 ± 200,000 ng/g, 18,000 ± 14,000 ng/g, and 970 ± 1900 ng/g. These results indicate recent exposure of these fish to PACs in their environment. In addition, two species (Cyclichthys spinosus and Prionotus nudigula) of fish were analyzed in order to investigate local sources of PAC contamination in the SSC and the influence of the petroleum terminal in fish caught in remote areas. The results showed that these fish species potentially migrate along the channel, especially P. nudigula. Correlations among groups of PAC metabolites indicate the same petrogenic source for NPH and PHN equivalents and a combustion source (e.g., automobile, ships) for BaP equivalents. The ratio BaP/PHN equivalents (0.05 ± 0.07, n = 37) confirms the predominance of petrogenic PACs for contamination by these chemicals in this region.  相似文献   

2.
Ponta de São Lourenço is the deeply eroded eastern end of Madeira’s east–west trending rift zone, located near the geometric intersection of the Madeira rift axis with that of the Desertas Islands to the southeast. It dominantly consists of basaltic pyroclastic deposits from Strombolian and phreatomagmatic eruptions, lava flows, and a dike swarm. Main differences compared to highly productive rift zones such as in Hawai’i are a lower dike intensity (50–60 dikes/km) and the lack of a shallow magma reservoir or summit caldera. 40Ar/39Ar age determinations show that volcanic activity at Ponta de São Lourenço lasted from >5.2 to 4 Ma (early Madeira rift phase) and from 2.4 to 0.9 Ma (late Madeira rift phase), with a hiatus dividing the stratigraphy into lower and upper units. Toward the east, the distribution of eruptive centers becomes diffuse, and the rift axis bends to parallel the Desertas ridge. The bending may have resulted from mutual gravitational influence of the Madeira and Desertas volcanic edifices. We propose that Ponta de São Lourenço represents a type example for the interior of a fading rift arm on oceanic volcanoes, with modern analogues being the terminations of the rift zones at La Palma and El Hierro (Canary Islands). There is no evidence for Ponta de São Lourenço representing a former central volcano that interconnected and fed the Madeira and Desertas rifts. Our results suggest a subdivision of volcanic rift zones into (1) a highly productive endmember characterized by a central volcano with a shallow magma chamber feeding one or more rift arms, and (2) a less productive endmember characterized by rifts fed from deep-seated magma reservoirs rather than from a central volcano, as is the case for Ponta de São Lourenço.  相似文献   

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5.
Limited information is available in the literature on the levels of brominated flame retardants in the southern hemisphere. This study presents concentrations of polybrominated diphenyl ethers (PBDEs) in the blubber of small cetaceans from the coast of São Paulo (Brazil), southwestern Atlantic. PBDE levels were highest in Stenellafrontalis (770 ng g−1 lipid) followed by Stenobredanensis (475 ng g−1 lipid), Sotaliaguianensis (65.6 ng g−1 lipid), Tursiopstruncatus (64.2 ng g−1 lipid) and Pontoporiablainvillei (60.3 ng g−1 lipid). In general, continental shelf individuals exhibited higher contamination than inshore animals. This might be related to larger prey items consumed by continental shelf dolphins. The pattern of contamination indicates that Penta-BDE commercial mixtures are a major source of PBDEs to top predators in the southwestern Atlantic. Congeners found in Octa-BDE formulations were not detected in the investigated animals.  相似文献   

6.
S coda wave of seventy-four local earthquakes recorded in a network of ten seismic stations were used to calculate coda Q attenuation (Qc) in the João Câmara area (northeastern Brazil). The estimates show Qc as a strong function of frequency in the range from 6.0 to 20.0 Hz. We found out that Qc in João Câmara has a functional form given by Qc= Q0 f, where Q0= 151 ± 99 and = 0.98 ± 0.05. If the standard deviations are taken into account,we conclude that there are no relevant changes in both Q0 and values from one station to another. The estimated Q0 values at the different stations suggest that the Samambaia fault is a boundary between two different seismic attenuation zones. In one side of the fault (left), where stations were installed in Pre-Cambrian terrain and thick sedimentary layer, the seismic attenuation is stronger than in the other side (stations installed in thin sedimentary layer and limestone outcrop).The anomalous Q0 values in the left side of the Samambaia fault can be explained due to the presence of a shallow conductive layer in the upper crust( 10 km), such as proposed by Padilha et al. (1992). According to our results, if there is a conductive layer in the area, it probably spreads over João Câmara city and surrounding regions.However, more detailed investigation either with seismic methods (seismic attenuation,3D tomography with P and/or S wave velocities) or with other geophysical methods is needed to interpret the observed differences in Q0 values between the two sides of the Samambaia fault.  相似文献   

7.
This paper describes a study conducted by the National Laboratory for Civil Engineering of Portugal (LNEC), in cooperation with the Defense University Center at the Spanish Naval Academy and “La Sapienza,” University of Rome, to assess the health and safety conditions of the Noble Hall floor in the São Carlos National Theater (Lisbon, Portugal). In a multidisciplinary approach, extensive fieldwork was carried out. The survey included the location and characterization of beams in the various areas of the floor by using two ground penetrating radar (GPR) systems equipped with two different ground- or air-coupled antennas, local inspection openings to visually assess the geometry, timber species and conservation state of structural members, and an assessment of the conservation state of the timber beam ends using drilling equipment. All the tests performed and the results obtained are presented. The potential of using non-destructive tests for the inspection of timber cultural heritage structures, particularly GPR, is discussed, and some practical recommendations are made.  相似文献   

8.
Ocean Dynamics - Marine resources are outstanding among renewable energy for their wide occurrence and diverse possibilities of exploitation. The tidal resource can be harnessed by the use of both...  相似文献   

9.
Ocean Dynamics - The impacts of data assimilation, downscaling, and tidal forcing were investigated with focus on the representation of the Cape São Tomé Eddy (CSTE). Sea level anomaly...  相似文献   

10.
The 2015/2016 El Nio was one of the strongest El Nio events in history, and this strong event was preceded by a weak El Nio in 2014. This study systematically analyzed the dynamical processes responsible for the genesis of these events. It was found that the weak 2014 El Nio had two warming phases, the spring-summer warming was produced by zonal advection and downwelling Kelvin waves driven by westerly wind bursts(WWBs), and the autumn-winter warming was produced by meridional advection, surface heating as well as downwelling Kelvin waves. The 2015/2016 extreme El Nio, on the other hand, was primarily a result of sustained zonal advection and downwelling Kelvin waves driven by a series of WWBs, with enhancement from the Bjerknes positive feedback. The vast difference between these two El Nio events mainly came from the different amount of WWBs in 2014 and 2015. As compared to the 1982/1983 and 1997/1998 extreme El Nio events, the 2015/2016 El Nio exhibited some distinctive characteristics in its genesis and spatial pattern. We need to include the effects of WWBs to the theoretical framework of El Nio to explain these characteristics, and to improve our understanding and prediction of El Nio.  相似文献   

11.
Monthly indices of Southern Atmospheric Oscillation (SOI) and corresponding Wolf numbers, geoeffective solar flares, magnetic AE indices as well as daily average values of the southward component of the interplanetary magnetic field (IMF B z) and data on the wind characteristics at Antarctic stations Vostok, Leningradskaya, and Russkaya are analyzed. It is shown that a sharp decrease in the SOI indices, which corresponds to the beginning of El Nin’o (ENSO), is preceded one or two months before by a 20% increase in the monthly average Wolf numbers. In warm years of Southern Atmospheric Oscillation a linear relationship is observed between the SOI indices and the number of geoeffective solar flares with correlation coefficients p < ?0.5. It is shown that in warm years a change in the general direction of the surface wind to anomalous at the above stations is preceded one or two days before by an increase in the daily average values of IMF B z. An increase in the SOI indices is preceded one or two months before by a considerable increase in the monthly average values of the magnetic AE indices.  相似文献   

12.
The 1997–1998 El Niño was the strongest in known history. However, its effects on rainfall in different parts of the globe were not all as expected (floods were expected in some regions and droughts in others). The characteristics of this El Niño, and the expected and observed precipitation effects are described; the reasons for the expectations not coming true in some regions are discussed. This paper attempts to review the important scientific issues involved in El Niño phenomena for the general reader.  相似文献   

13.
Abstract

The definition of rainfall behaviour at the regional level is of great importance in planning policy for the rational use of water resources for both agricultural and urban uses. It allows the delimitation of areas of homogeneous rainfall features and shows the system dynamics in the area, so providing more comprehensive knowledge about the rainfall. Precipitation zones were identified within the São Francisco River basin, Northeast Brazil, by analysing the rainfall frequencies by means of global wavelet power spectra. Data from 200 raingauges were analysed and the results of the overall power spectra showed a high annual frequency throughout the basin; however, other frequencies are present with minor significance that represent changes in the rainfall regime. Although, the computed global wavelet power spectra presented an annual frequency, they showed peculiar patterns (denoted A and B) that could be used to characterize the region. Thus, three sub-regions with homogeneous rainfall patterns were identified as: Region A (south part of the basin) and Region B (north part of the basin), with frequency patterns A and B, respectively, and a Transition Zone in the central part that shows both frequency patterns.

Citation Santos, C.A.G. and Morais, B.S., 2013. Identification of precipitation zones within São Francisco River basin (Brazil) by global wavelet power spectra. Hydrological Sciences Journal, 58 (4), 789–796.  相似文献   

14.
The statistics of pre-midnight 5-m irregularities in the equatorial F region over São Luís is presented. The data set ranges from October 2001 to December 2008 and covers maximum solar-flux-to-minimum solar flux epoch. The variabilities in irregularity parameters, namely, height and time of their appearance in the radar echoes, with solar-flux variation are presented. The seasonal variations (combined over all years, irrespective of solar-flux) of occurrence of irregularities, occurrence of bottom-type layer (or bottom-side irregularities without plume) and bottom-side/topside plume (or bottom-side irregularities with plume) are presented. The largest occurrences of bottom-side irregularities without plume and with plume are found on April (equinox) and December (summer) months respectively. The ambient ionospheric conditions namely prereversal evening vertical drift, bottom-side density gradient and off-equatorial E region conductivity are inferred using digisonde measurements during April 2002 and December 2002. Based on these conditions and recent studies on gravity wave climatology over Brazil, it is suggested that shear in zonal plasma drift and low gravity wave activity may account for less occurrence of plume during April as compared to December months. This suggestion is quantified using numerical simulation model of collisional-interchange instability (CII) and plasma bubble.  相似文献   

15.
The southwest border of the Parecis Basin (central Brazil) presents several occurrences of gold, copper and zinc. Parallel to this border, there is an alignment of magnetic anomalies with varied size and polarities. In particular, five magnetic anomalies are referred to, in this study, as SJ1 to SJ5. The proximity of these anomalies to each other makes it hard to isolate the magnetic component associated with each source. Furthermore, these anomalies have different magnetization directions, which require the use of a technique which is slightly or not affected by the presence of a remanent magnetization, as the amplitude of the anomalous magnetic field. Considering that, in these intrusions no outcrops are observed, the enhanced horizontal derivative technique was used to estimate the edges location and the depth of these sources. The geological context, allied to the results from the magnetic techniques, allowed to establish binds to restrain the interpretation of the results of the 3D inversion. This procedure permitted to compose three hypothesis to explain the magnetic behavior of the region, from which can be conclusively determined with a borehole analysis.  相似文献   

16.
Ten sediment core samples with lengths ranging from 35 to 100 cm were collected in the Baixada Santista region and analyzed to determine As, Br, Co, Cr, Cs, Fe, Rb, Sb, Ta, Th, U, Zn and rare earths (Sc, Ce, Eu, La, Lu, Nd, Sm, Tb and Yb) level concentrations using instrumental neutron activation analysis (INAA). The studied region is located in the southeastern coast of São Paulo State and is comprised of a densely urbanized area, the largest industrial complex of the country, with a predominance of petrochemical and fertilizer plants. It is also home to Brazil’s most important and busiest port. The conclusions found that the As, La, Sm, Ne, Ce, Eu, Hf, Ta, Th, and U elements have a high background level in the region and that Fe and Zn were the main indicators of anthropogenic contribution in the sediments.  相似文献   

17.
The S?o Sebasti?o Channel, NE S?o Paulo State, Brazil, is an area of environmental interest of that state not only because of the tourism, but also because of the presence of the most important oil terminal of Brazil, the PETROBRAS Maritime Terminal (DTCS). Sediment samples were collected at 15 sites in the channel, extracted and analyzed by GC/FID and GC/MS for composition and levels of the following organic geochemical markers: aliphatic hydrocarbons (normal and isoprenoid alkanes), petroleum biomarkers, linear alkylbenzenes (LABs) and polycyclic aromatic hydrocarbons (PAHs). The total concentrations varied from 0.04 to 8.53 micorg g(-1) for aliphatics, from 51.1 to 422.0 ng g(-1) for petroleum biomarkers, from 12.6 to 27.7 ng g(-1) for LABs and from 20.4 to 200.3 ng g(-1) for PAHs. The PETROBRAS Maritime Terminal (DTCS), Sao Sebasti?o Harbor and sewage outfalls along the area had clear influences on the geochemical marker concentrations, especially at locales in the central and north parts of the channel.  相似文献   

18.
Karst aquifers consist of complex networks of conduits in which groundwater flows and recharge/discharge processes are generally more dynamic than in other types of aquifers. Due to their intrinsic heterogeneity and anisotropy, monitoring, quantifying, and analysing natural responses of karst springs is an efficient tool. Unlike Cenozoic and Mesozoic rocks, in Neoproterozoic karst systems, groundwater circulates and stores generally in dissolution features known as tertiary porosity, as the rock's primary porosity is recrystallized, considered negligible. This article studies the hydrodynamics of a karst portion of the São Miguel River basin, southwest of the state of Minas Gerais, Brazil. The region is predominantly composed of Neoproterozoic carbonate rocks, dating from about 570 to 540 million years ago. During a hydrological year (2019–2020), three karst springs (S1, S2, and S3) were daily monitored through their natural responses (variations of electrical conductivity, EC, temperature, T, and discharge, Q) to rainfall episodes. The data were interpreted based on the analysis of spring hydrographs, time series, recession curves (seasonal and intra-annual), and statistics of EC, T, and Q variations. The results show the three springs generally exhibit quick flow, typically karstic, in the case of hydrosystems with a well-structured and functional underground drainage network. The time series indicate the hydrosystem drained by S1 presents slower circulation and a lower degree of linearity, resulting from the higher sinuosity of the system, while the hydrosystems of S2 and S3 have similar behaviours, of quick water circulations immediately after a rainy episode. The degrees of karstification classify S1 and S2 as complex and extensive karst systems consisting of several subsystems, and S3 as a system in which the conduit network is more developed at the upper epiphreatic zone than near the outlet.  相似文献   

19.
This study carried out a comparative analysis of the changes in tropical cyclone (TC) genesis, TC track, and TC intensity focusing on TCs that affected the Korean peninsula (KP) according to three evolutionary patterns (prolonged, abrupt and symmetric-decay) of the abnormal sea surface temperature in the Central-Pacific (CP) region. As a result of the analysis, the activity pattern of TCs was found to vary depending on the evolution patterns of the CP El Niño, and such changes appeared to result in clear variations in the regional rainfall in Korea. In the prolonged-decaying and symmetric-decaying years, the KP received considerable TC rainfall. On the other hand, in abrupt-decaying years, it was subtly affected by the TC rainfall. Although rather limited conditions and relatively short observation data were used to analyze the effects of the evolution pattern of the CP El Niño on TCs, the results can be used to quantitatively identify the spatial features of TCs affecting the KP. These results are expected to be helpful in managing the disaster risks in vulnerable areas, including plans to secure stable water resources in the basin, and in establishing effective and active measures to cope with natural disasters by extreme events over the KP.  相似文献   

20.
Science China Earth Sciences - The effects of spring soil moisture over the vast region from the lower and middle reaches of the Yangtze River valley to North China (YRNC) and El Niño on the...  相似文献   

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