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81.
Senal MI Jacinto GS San Diego-McGlone ML Siringan F Zamora P Soria L Cardenas MB Villanoy C Cabrera O 《Marine pollution bulletin》2011,63(5-12):195-200
Submarine groundwater discharge (SGD) on the reef flat of Bolinao, Pangasinan (Philippines) was mapped using electrical resistivity, 222Rn, and nutrient concentration measurements. Nitrate levels as high as 126 μM, or 1-2 orders of magnitude higher than ambient concentrations, were measured in some areas of the reef flat. Nutrient fluxes were higher during the wet season (May-October) than the dry season (November-April). Dissolved inorganic nitrogen (DIN=NO3+NO2+NH4) and soluble reactive phosphorus (SRP) fluxes during the wet season were 4.4 and 0.2 mmoles m(-2) d(-1), respectively. With the increase population size and anthropogenic activities in Bolinao, an enhancement of SGD-derived nitrogen levels is likely. This could lead to eutrophic conditions in the otherwise oligotrophic waters surrounding the Santiago reef flat. 相似文献
82.
Maria Dolores Ruiz Cruz 《Mineralogy and Petrology》2011,101(3-4):225-244
The content and distribution of NH4-bearing micas in micaschists and paragneisses of the Alpujárride complex (Betic Cordillera, Spain) are interpreted on the basis of textures, metamorphic history and crystal-chemical constraints. NH4 is present in important amounts in early micas, recording their older diagenetic-to-metamorphic history. NH4 was inherited by micas formed in successive metamorphic events. At similar metamorphic grade, annite is enriched in NH4 relative to muscovite with a fractionation of 4:1. Maximum NH4 contents were estimated in golden annite from medium-grade schists and in retrogressive annite-chlorite mixed-layers (~1.0?wt.%). A Ti-NH4 avoidance gives rise to associated chemical changes, such as the enrichment in Mg and in VIAl. These data suggest that NH4 can be a decisive factor in chemical equilibrium and element partitioning between coexisting phases, thus affecting to the commonly used thermobarometers. Estimation of the P-T conditions from texturally different muscovite-annite pairs reveals the superposition of several stages of mica growth, under different geothermal gradients. 相似文献
83.
This work analyses the potential consequences of two tsunami scenarios and their impacts on an oil refinery located in Sicily. Two credible tsunamis originating in the Tyrrhenian Sea were selected based on historical data. The potential for damage and hazardous materials releases resulting from the tsunami impacts to a refinery was assessed. The results obtained by the JRC tsunami propagation and inundation code HyFlux2 indicate that in both scenarios there would be eighteen storage tanks (of 43 located within 400 m from the shoreline) at the refinery subject to flooding. Water flow velocities were found to be generally low, <1 m/s, except for a central section of the refinery near the shoreline where the water flow velocities reach 3?C4 m/s. These results indicate that any damage would most likely occur due to buoyancy loads particularly in the western part of the facility where inundation levels are higher and storage tanks are less protected. Potential damage caused by impact of floating debris may be a problem in the central area of the refinery near the shoreline due to high flow velocities (3?C4 m/s) in both tsunami scenarios. Small hazardous materials releases could occur due to breakage of connected pipes and flanges caused by floating off of almost empty storage tanks or other equipment. Salt water intrusion could affect electrical equipment, such as control panels, pumps, and motors that are not raised above the inundation level. We conclude that in the two tsunami scenarios analysed, the risk to nearby residents and neighbouring facilities from potential hazardous materials releases, fires or explosions triggered by the tsunamis is likely to be small. Nonetheless, recommendations are made on prevention measures to reduce the risk of tsunami-triggered accidents and to mitigate their consequences if they do occur. The results of this study are limited by the uncertainty in the input data and most importantly by the accuracy of the elevation data and the model resolution. 相似文献
84.
José Manuel Vaquero María Cruz Gallego Fernando Domínguez-Castro 《Geofísica Internacional》2013,52(1):87-92
In recent years, some authors have shown that some auroras can be observed at relatively low latitude when the geomagnetic activity is quiet or moderate. This very special type of aurora is called “sporadic aurora”. We present and analyze in this work a possible case of “sporadic aurora” observed in Mexico on the 19 April 1843. Moreover, we study the solar and auroral activity around this event. 相似文献
85.
de Souza Luciana Sandra Bastos Silva Maiara Tatiane Lima Alba Elisiane de Moura Magna Soelma Beserra da Cruz Neto José Francisco de Souza Carlos André Alves da Silva Thieres George Freire 《Theoretical and Applied Climatology》2022,149(1-2):593-602
Theoretical and Applied Climatology - Analysing alternative methods for estimating reference evapotranspiration (ET0) is essential for improving the management of water resources, especially where... 相似文献
86.
The geochemistry and mineralogy of samples collected along depth profiles from an As-rich tailing deposit with abundant calcite was studied to determine the processes that influence the mobility of Fe, Zn, Cu, Ni, Cd, As, Sb, Cr and Tl. In spite of their near neutral pH, almost all of them are acid potential generators. Total concentrations decreased as: Fe > As > Zn > Pb > Cu > Sb > Cd > Cr > Ni > Tl. Soluble contents were lower and followed a slightly different order. Mobility decreased as: Tl > Cd, Zn, Cu, Sb, Ni, As > Fe, Pb > Cr. Higher soluble concentrations of Fe, Cu, Zn, As, Pb, and Ni were found in low-pH samples and of Sb and Tl in near-neutral samples. Sulfide oxidation processes are developing in the tailing’s dam. These processes do not have a trend with depth but occur mainly in acid layers. Near neutral layers formed by primary sulfides and calcite probably correspond to wastes produced from the processing of ore coming mainly from pods within the skarn, and acid layers with abundant secondary minerals from material mined from chimneys and mantos. The presence of calcite influences speciation, neutralizes acid mine drainage (AMD), and decreases the mobility of most toxic metals and metalloids (TMMs). However, a hard-pan layer was not observed in the studied profiles. Retention of TMM within tailings probably occurs through the formation of low solubility metal carbonates and from elevation of pH that promotes Fe hydroxides precipitation that may retain As, Sb and metals. Calcite occurrence promotes As, Cd, Cu, Fe, Zn, Pb, Cd and Cr retention, does not play a role on Tl and Ni mobilization, and increases Sb release. 相似文献
87.
88.
Ernesto Heredia‐Zavoni Sandra Santa‐Cruz Francisco L. Silva‐González 《地震工程与结构动力学》2015,44(13):2241-2260
A formulation is developed for modal response analysis of multi‐support structures using a random vibration approach. The spectral moments of the structural response are rigorously decomposed into contributions from spectral moments of uncoupled modal responses. An advantage of the proposed formulation is that the total dynamic response can be obtained on the basis of mode by mode uncoupled analyses. The contributions to the total response from modal responses under individual support ground motions and under cross‐correlated pairs of support ground motions can be recognized explicitly. The application and performance of the formulation is illustrated by means of an example using a well‐established coherency spectrum model and widely known power spectra models, such as white noise and Kanai–Tajimi. The first three spectral moments of displacement, shear, and bending moment responses are computed, showing that the formulation produces the same results as the exact solution. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
89.
传统炮检距域共像集(CIG)在复杂介质中因波传播的多路径而存在反射体位置不确定的问题. 角度域CIG由于克服了这一缺陷而逐步成为速度分析、AVA以及振幅保真偏移成像等研究的主要手段. 以波动理论为基础的地震偏移成像方法的发展为获得高质量的角度域CIG提供了可靠的实现途径. 其中,基于波场局域化分解和传播的小波束域波场延拓和偏移成像方法,因其波场分解基本函数和传播算子在空间和方向上的双重局域特性,而成为角度相关分析研究的有效工具. 本文在采用Gabor Daubechies框架分解的小波束叠前角度域偏移成像基础上,利用不同的叠加方法由局部角度域像矩阵得到了反射角域CIG(CRAIG)和倾角域CIG(CDAIG). 以SEG EAGE二维盐体模型为例,通过对CRAIG和CDAIG的对比,探讨了这两种角度域CIG的特点及其在地震偏移成像中的潜在应用. 相似文献
90.
We re-examine the maximum brightness temperature that a synchrotron source can sustain by adapting standard synchrotron theory
to an electron distribution that exhibits a deficit at low energy. The absence of low energy electrons reduces the absorption
of synchrotron photons, allowing the source to reach a higher brightness temperature without the onset of catastrophic cooling.
We find that a temperature of ∼1014 K is possible at GHz frequencies. In addition, a high degree of intrinsic circular polarisation is produced. We compute the
stationary, synchrotron and self-Compton spectrum arising from the continuous injection of such a distribution (modelled as
a double power-law) balanced by radiative losses and escape, and compare it with the simultaneously observed multi-wavelength
spectrum of the BL Lac object S5 0716+714. This framework may provide an explanation of other high brightness-temperature
sources without the need for mechanisms such as coherent emission or proton synchrotron radiation. 相似文献