Mugil curema as a PAH bioavailability monitor for Atlantic west sub-tropical estuaries     

Ana Cecília Rizzatti de Albergaria-Barbosa  Vinicius Faria Patire  Satie Taniguchi  Wellington Silva Fernandez  June Ferraz Dias  Márcia Caruso Bícego 《Marine pollution bulletin》2017,114(1):609-614

This work aimed to evaluate the use of Mugil curema as a biomonitor for polycyclic aromatic hydrocarbon (PAH) bioavailability. Fish biliary metabolites from low-contaminated (Cananéia) and contaminated (Santos) Brazilian estuaries were analysed using a high-performance liquid chromatography apparatus coupled to fluorescence detectors connected in a series. In the Cananéia and Santos estuaries, total metabolite levels ranged from 0.85 to 34.4 μg g^? 1 of bile and from 4.06 to 528 μg g^? 1 of bile, respectively. Metabolite levels were not influenced by feeding status or sexual hormones (p < 0.05), thus suggesting that M. curema is a good biomonitor for PAH bioavailability. In estuarine regions, it is possible to sample both the male and female genders of this species in any reproductive period.  相似文献   

Submarine groundwater discharge studies along the Ubatuba coastal area in south-eastern Brazil     

Pavel P. Povinec 《Estuarine, Coastal and Shelf Science》2008

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The December 26th 2004 Tsunami Recorded along the Southeastern Coast of Brazil     

Carlos A. S. França  Afranio R. De Mesquita 《Natural Hazards》2007,40(1):209-222

Sea level measurements along the southeastern Brazilian coast, between 20° S and 30° S, show the effect of the Sumatra Tsunami of December 26, 2004. Two records from stations, one located inside an estuary and other inside a bay, shows oscillations of about 0.20 m range; one additional record from a station facing the open sea shows up to 1.2 m range oscillations. These oscillations have around 45 min period, starting 20–22 h after the Sumatra earthquake in the Indian Ocean (00:59 UTC) and lasting for 2 days. A computer modelling of the event reproduces the time of arrival of long shallow-water tsunami waves at the southeastern Brazilian coast but with slight longer period and amplitudes smaller than observed at the coast, probably due to its coarse resolution (1/4 of a degree). The high amplitudes observed at the coast suggest a mechanism of amplification of these waves over the southeastern Brazilian shelf.  相似文献   

Transaction links through cities: ‘decision cities’ and ‘service cities’ in outsourcing by leading Brazilian firms   总被引：2，自引：0，他引：2  

Eliana C. Rossi  Peter J. Taylor 《Geoforum》2007,38(4):628-642

Most world city studies focus on where the provision of advanced producer services takes place, but in this study the location of the service clients are also taken into account. Production-service transactions are identified as links between ‘service city’ and ‘decision city’ (client HQ) and classified as intra-city (where a firms uses local (same city) services) and inter-city which may be domestic or foreign depending on whether the client uses services in or out of the country. Sampling the leading firms in Brazil, 218 transaction links are described and analysed in terms of cities, firm sectors, ownership and market. The analyses are used to inform a rereading of gateway city functions that takes into account the concentration/dispersal nexus in economic globalization. Thus, whereas the dominance of Sao Paulo in the Brazilian economy is confirmed, this is not interpreted as a simple gateway function with this one city ‘articulating’ the national economy into the world economy. A much more complex situation is revealed with by-passing of the gateway also much in evidence. The conclusion is that this shows concentration and dispersion of economic activity happening simultaneously in Brazil.  相似文献   

岩石及类岩石材料的劈裂拉伸与直接拉伸强度     

余贤斌  王青蓉  宋战平  谢强 《岩土力学》2006,27(Z1):539-543

采用自行研制的岩石直接拉伸实验装置,对7种（组）岩石和2组混凝土试样进行了直接拉伸和劈裂法（巴西法）间接拉伸试验。试验结果表明,所有岩石和混凝土试样的劈裂拉伸强度SB均大于直接拉伸强度ST,比值SB/ST的范围,在1.06到1.97之间;直接拉伸强度的偏差系数,通常大于劈裂拉伸强度的偏差系数。根据Sundaram等人对圆盘劈裂试验试样内应力分布的有限元分析的结果,当岩石的拉伸弹模ET小于压缩弹模EC时,试样中实际的应力会与经典弹性力学公式所得结果（EC=ET时的情形）不同,需要进行修正。据此对有关岩石的劈裂拉伸强度进行了修正,并发现,在所试验的岩石中,虽然部分岩石的ET与EC的数值相差不大,其SB/ST比却最高。这说明,拉伸与压缩弹模的差别不是造成两种拉伸强度差别的唯一原因。  相似文献   

A relationship between tensile strength and loading stress governing the onset of mode I crack propagation obtained via numerical investigations using a bonded particle model          下载免费PDF全文

Zhenyu Han  Dion Weatherley  Ruslan Puscasu 《国际地质力学数值与分析法杂志》2017,41(18):1979-1991

Numerical models based on the discrete element method are used to study the fracturing process in brittle rock‐like materials under direct and indirect tension. The results demonstrate the capacity of the model to capture the essential characteristics of fracture including the onset of crack propagation, stable and unstable crack growth, arrest and reinitiation of fracturing, and crack branching. Simulations of Brazilian indirect tension tests serve to calibrate the numerical model, relating macroscopic tensile strength of specimens to their micromechanical breakage parameters. A second suite of simulations reveals a linear relationship between the tensile strength of specimens and the loading stress for which mode I tensile crack propagation ensues. Based on these results, a crack initiation criterion for brittle materials is proposed, prescribing the stressing conditions required to induce tensile failure. Such a criterion, if broadly applicable, provides a practical means to rapidly assess the failure potential of brittle materials under tensile loads.  相似文献   

Evaluation of the petroleum composition and quality with increasing thermal maturity as simulated by hydrous pyrolysis: A case study using a Brazilian source rock with Type I kerogen     

《Organic Geochemistry》2015

Hydrous pyrolysis (HP) experiments were used to investigate the petroleum composition and quality of petroleum generated from a Brazilian lacustrine source rock containing Type I kerogen with increasing thermal maturity. The tested sample was of Aptian age from the Araripe Basin (NE-Brazil). The temperatures (280–360 °C) and times (12–132 h) employed in the experiments simulated petroleum generation and expulsion (i.e., oil window) prior to secondary gas generation from the cracking of oil. Results show that similar to other oil prone source rocks, kerogen initially decomposes in part to a polar rich bitumen, which decomposes in part to hydrocarbon rich oil. These two overall reactions overlap with one another and have been recognized in oil shale retorting and natural petroleum generation. During bitumen decomposition to oil, some of the bitumen is converted to pyrobitumen, which results in an increase in the apparent kerogen (i.e., insoluble carbon) content with increasing maturation.The petroleum composition and its quality (i.e., API gravity, gas/oil ratio, C₁₅₊ fractions, alkane distribution, and sulfur content) are affected by thermal maturation within the oil window. API gravity, C₁₅₊ fractions and gas/oil ratios generated by HP are similar to those of natural petroleum considered to be sourced from similar Brazilian lacustrine source rocks with Type I kerogen of Lower Cretaceous age. API gravity of the HP expelled oils shows a complex relationship with increasing thermal maturation that is most influenced by the expulsion of asphaltenes. C₁₅₊ fractions (i.e., saturates, aromatics, resins and asphaltenes) show that expelled oils and bitumen are compositionally separate organic phases with no overlap in composition. Gas/oil ratios (GOR) initially decrease from 508–131 m³/m³ during bitumen generation and remain essentially constant (81–84 m³/m³) to the end of oil generation. This constancy in GOR is different from the continuous increase through the oil window observed in anhydrous pyrolysis experiments. Alkane distributions of the HP expelled oils are similar to those of natural crude oils considered to be sourced from similar Brazilian lacustrine source rocks with Type I kerogen of Lower Cretaceous age. Isoprenoid and n-alkane ratios (i.e., pristane/n-C₁₇ and phytane/n-C₁₈) decrease with increasing thermal maturity as observed in natural crude oils. Pristane/phytane ratios remain constant with increasing thermal maturity through the oil window, with ratios being slightly higher in the expelled oils relative to those in the bitumen. Generated hydrocarbon gases are similar to natural gases associated with crude oils considered to be sourced from similar Brazilian lacustrine source rocks with Type I kerogen of Lower Cretaceous, with the exception of elevated ethane contents. The general overall agreement in composition of natural and hydrous pyrolysis petroleum of lacustrine source rocks observed in this study supports the utility of HP to better characterize petroleum systems and the effects of maturation and expulsion on petroleum composition and quality.  相似文献   

Agreement,significance, and understandings of historical responsibility in climate change negotiations     

Mathias Friman  Mattias Hjerpe 《Climate Policy》2013,13(3):302-320

For over 20 years, Parties to the UN Framework Convention on Climate Change have struggled with the normative significance of history for the differentiation of responsibilities. Negotiations on ‘historical responsibility’ have been marked by considerable conflict between developed and developing countries. However, in 2010, the Parties acknowledged the concept in a consensus decision. This article analyses UN Climate Change Conference delegates' agreement with the decision, whether it reconciled conflict between interpretations of historical responsibility, and the significance that delegates ascribe to the decision for future agreements. The decision has not eliminated conflict between different interpretations. Delegates who understand historical responsibility as linking countries' historical contributions to climate change to their responsibilities to act agree more with the decision and foresee it having a stronger influence on future agreements than do those viewing the concept in more conceptual terms. The decision marks the start of negotiations concerning how rather than whether historical responsibility should guide operative text. This article demonstrates that (1) the divergent interpretations pose clear challenges for a necessary but demanding agreement on operationalization, and (2) focusing on an ambiguous version of proportionality between contribution to change and responsibility can become a first step for convergence between divergent positions.  相似文献   

Differentiating (historic) responsibilities for climate change     

《Climate Policy》2013,13(6):593-611

Following the conclusion of the official work of the Ad Hoc Group for the Modelling and Assessment of Contributions to Climate Change (MATCH), this article considers the politically more sensitive aspect of the Brazilian proposal, namely the issue of differentiating (historic) responsibility for, and not merely (causal) contribution to climate change. Its aim is (1) to highlight the fact that, while related, the two issues (‘contribution to’ and ‘responsibility for’) are fundamentally different and should not be confused, and (2) to propose a methodology for calculating shares of responsibility as opposed to the shares in causal contribution arrived at through the MATCH results. Two conceptions of responsibility (‘strict’ or ‘limited’) are applied in order to operationalize the notion of ‘respective capabilities’ given in Article 3.1 of the UNFCCC. The key message resulting from the calculations is that causal contribution—while an important indicator of (environmental) relevance to the problem—must not be confused with the moral responsibility for it. The rather large difference between the responsibilities at the two extremes of the scale under both conceptions gives pause for thought as to what sorts of burdens can justly be demanded in any application of the UNFCCC principle of common but differentiated responsibilities, whether in the context of the Brazilian proposal or beyond.  相似文献   

考虑层理影响页岩巴西劈裂及声发射试验研究     

侯鹏  高峰  杨玉贵  张志镇  高亚楠  张向向  张骥 《岩土力学》2016,37(6):1603-1612

基于不同层理角度的页岩巴西劈裂试验,利用高速摄像系统和声发射系统,对页岩力学特性、裂纹扩展及声发射特征的层理效应进行了深入研究。结果表明：（1）页岩巴西劈裂破坏过程可以分为压密、弹性和破坏3个阶段;（2）页岩抗拉强度、劈裂模量和应力峰值时变形的各向异性特征明显,层理角度 30°时,层理效应最为明显, 90°时影响最小;（3） 0°和 15°时试样的裂纹破坏面基本是沿着层理面, 30°时裂纹面交切层理面,与加载基线面重合, 45°～90°的各试样的断裂面呈不同程度的偏离加载基线面,为弧面或曲面;（4） 30°和 45°为破坏机制转化角,其中 30°为沿着层理面压致性张拉开裂转化为交切层理面开裂的转化角, 45°为交切层理面开裂转化为交切层理面且沿着层理面不同程度的剪切滑移开裂的转化角;（5）声发射活动性和能量释放随层理角度的增加而加强,主要因为受层理角度的影响,其破坏机制不同,这也进一步验证了页岩随层理角度的变化,其破坏机制的各向异性。能率峰值与抗拉强度具有很好的线性关系,表明声发射能率峰值能很好地反映岩石抗拉伸破坏的程度。  相似文献